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    15 September 2005, Volume 16 Issue 9
    Articles
    Effects of soil temperature and humidity on soil respiration rate under Pinus sylvestriformis forest
    LIU Ying1,2,HAN Shijie1,HU Yanling1,DAI Guanhua3
    2005, 16(09):  1581-1585 . 
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    Employing root-wrenching method and LI-6400-09 soil respiration chamber, this paper measured the diurnal changes of soil respiration rate with and without roots in situ on June 17,August 5,and October 10,2003.The seasonal changes of soil respiration were also measured from May to September,2004. The results showed that both the total and the root-wrenched soil respiration appeared single diurnal pattern,with the peaks presented during 12:00~14:00.The diurnal fluctuation of soil respiration on August 5 was smaller than that on June 17 and October 10.There were also obvious seasonal changes in total and root-wrenched soil respiration,as well as in root respiration,which were higher from June to August but lower in May and September.The average total soil respiration,root-wrenched soil respiration, and root respiration were 3.12,1.94 and 1.18 μmol CO2·m-2·s-1, respectively ,and the contribution of roots to total soil respiration ranged from 26.5% to 52.6% from May to September,2004.There were exponential correlations between respiration rate and soil temperature,and linear correlations between respiration rate and soil humidity.The Q10 values were 2.44,2.55 and 2.27 for total soil respiration,root-wrenched soil respiration, and root respiration,respectively.The effect of soil temperature on root-wrenched soil respiration was lager than that on total soil respiration and root respiration.Soil humidity had a larger effect on total soil respiration than on root respiration and root-wrenched soil respiration.
    Dynamic changes of soil ecological factors in Ziwuling secondary forest area under human disturbance
    ZHOU Zhengchao1,3,SHANGGUAN Zhouping1,2
    2005, 16(09):  1586-1590 . 
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    As a widespread natural phenomenon,disturbance is considered as a discrete event occurred in natural ecosystems at various spatial and temporal scales.The occurrence of disturbance directly affects the structure, function and dynamics of ecosystems.Forest logging and forestland assart, the common human disturbances in forest area,have caused the dynamic changes of forest soil ecological factors in a relatively consistent environment. A study on the dynamics of soil bulk density,soil organic matter,soil microbes and other soil ecological factors under different human disturbance (logging and assart,logging but without assart,control)were conducted in the Ziwuling secondary forest area.The results indicated that human disturbance had a deep impact on the soil ecological factors,with soil physical and chemical properties become bad,soil organic matter decreased from 2.2% to 0.8%,and soil stable aggregates dropped more than 30%.The quantity of soil microbes decreased sharply with enhanced human disturbance. Soil organic matter and soil microbes decreased more than 50% and 90%,respectively,and soil bulk density increased from 0.9 to 1.21 g·cm-3 with increasing soil depth.Ditch edge level also affected the dynamics of soil factors under the same disturbance,with a better soil ecological condition at low-than at high ditch edge level.
    Spatial heterogeneity of soil moisture after raining at forest-grassland landscape boundary in hilly area of Loess Plateau
    YOU Wenzhong 1,2,ZENG Dehui 1,LIU Mingguo 2,SONG Xide 3,YE Yanhui 3, ZHANG Yong 3
    2005, 16(09):  1591-1596 . 
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    Soil moisture is a main factor limiting vegetation restoration in semi-arid region.In this paper,the spatial variability of different layers soil moisture after raining at the forest-grassland boundary in hilly area of Loess Plateau were studied by traditional and geostatistical analysis methods.The results showed that the moisture content in surface (0~10 cm) and subsurface soil layer (10~20 cm) of grassland was higher than that of forestland.The two layers soil moisture content at forest-grassland boundary showed a small variation but an obvious ecological distribution.By using moving split-window techniques,it was obtained that the width of edge influence in surface and subsurface layer was 8 and 6 m,respectively.Geostatistical analyses showed that the spatial distribution of two layers soil moisture had a pure nugget effect in grassland,linear model in forestland,and spherical model in forest-grassland boundary.The spatial heterogeneity of two layers soil moisture was higher at forest-grassland boundary than at forestland and grassland, which had a stronger spatial dependence and autorelation.Kriging maps expressed the spatial structural characters.The distribution of soil moisture in two layers showed a strip shape near forest edge,and a patch shape far from the edge.
    Generation mechanism of woodland runoff and sediment on Loess Plateau under hypo-rainfall
    PAN Chengzhong 1,2,3;SHANGGUAN Zhouping 1
    2005, 16(09):  1597-1602 . 
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    Based on the long-term observation and from the viewpoints of water balance and runoff-and sediment generation,this paper studied the generation processes of runoff and sediment on two typical woodlands, artificial P.tabulaeformis and secondary natural P.dadidiana,and uncultivated slopeland in Loess Plateau under hypo-rainfall.The results showed that within the range of 5.0~50.0 mm rainfall,the total interception of canopy and litter was 15.45%~56.80% for P.tabulaeformis and 20.56%~47.81% for P.dadidiana,and decreased with increasing rainfall.Woodlands had a higher soil water infiltration capacity than uncultivated slope-land,especially in 0~20 cm soil layer.Both the two woodlands did not generate runoff under regular rainfall.Under the assumed rainfall of 2.5 mm·min-1 intensity and 30 min duration,P.dadidiana stand did not produce runoff,but the runoff velocity and sediment-carrying capacity of uncultivated slope-land were 23.5 times,and runoff shearing stress and energy were 8 times as much as P.tabulaeformis stand.The runoff-and sediment generation on P.tabulaeformis stand decreased by 87.6% and 99.4%,respectively,compared with those on uncultivated slope-land,which was well accorded with the average observed value in runoff plots during 1988~2000The theoretical analysis on the generation mechanism of woodland runoff and sediment may be effective to evaluate the benefits of forest in soil and water conservation.
    Temporal variation of soil respiration on sloping pasture of Heihe River basin and effects of temperature and soil moisture on it
    CHANG Zongqiang1,SHI Zuomin2,FENG Qi 1,SU Yonghong 1
    2005, 16(09):  1603-1606 . 
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    Employing LiCor 6400 gas exchange analyzer and soil respiration chamber attachment (LiCor Inc.,Lincoln,NE,USA),this paper continuously measured the soil surface CO2 effluxes on the sloping pasture of Heihe River basin from early April to late October 2003 to investigate the soil CO2 efflux rate and its feedback to the changes of climate and land use.The results showed that from May to October,the diurnal variation of soil respiration was low at night,the lowest at 7:00,6:30,5:30,6:00 and 7:00,raised rapidly at 7:00~8:30,and then descended at 16:00~18:30.The maximum soil CO2 efflux appeared at 15:00,14:30,14:30,13:30,14:00 and 15:00.The mean daily soil respiration rate was 0.31~6.98 μmol·m-2·s-1,with the maximum in July and August,the second in May and September,and nearly consistent in April and October.Soil respiration rate had an exponential and power correlation with temperature and soil moisture,respectively.
    Response of sediment production to land-use change in Luergou watershed of Loess Plateau
    ZHANG Zhiqiang1,WANG Shengping1,SUN Ge2,ZHANG Manliang3,LI Jianlao3
    2005, 16(09):  1607-1612 . 
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    The study on the effects of different land use patterns on the sediment production in Luergou watershed of Loess Plateau indicated that in comparing with 1982,the areas of forest and grass and of terrace in 1989 increased by 5% and 2.09%,respectively,while that of slope plowland decreased by 1.5%,with the area of naked land and shrubbery respectively increased and decreased a little.During 1998~2000,with the increase of vegetation cover and the decrease of steep slope plowland,the sediment production reduced significantly under high precipitation,85 326 and 52 937 t under the precipitation of 803 and 786 mm,respectively,and not distinguishable in dry years.The reduction effect had a strong seasonality, which consisted with rainfall distribution.For example,in a month with 50 mm precipitation,the mean daily sediment concentration was reduced by 6 kg·m-3, while in a month with 100 mm precipitation,the reduction was 12 kg·m-3. Rainfall intensity also played an important role in soil erosion and sediment production,regardless of land use conditions.
    Effects of forest vegetation on runoff and sediment production on sloping lands of Loess area
    ZHANG Xiaoming,YU Xinxiao,WU Sihong,WEI Tianxing,ZHANG Xuepei
    2005, 16(09):  1613-1617 . 
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    Based on the 1985~2003 fixed-position data in 9 runoff plots of Caijiachuan watershed in the Jixian county of Shanxi Province in loess area,this paper discussed the relationships between vegetation and runoff and sediment production on sloping lands of loess area.The results showed that natural-secondary forest had better function in soil and water conservation than artifical Robinia pseudoacacia forest,with runoff and sediment produced 65%~82% and 23%~92%,respectively.Multiple regression analysis indicated that runoff and sediment production had a significant correlation with rainfall and its intensity,but this relationship was decreased gradually with increasing canopy density.Different land-use type had different runoff and sediment production,e.g.,Ostryopsis davidiana and natural-secondary forests had the least runoff and sediment production,artificial Robinia pseudoacacia and Pinus tabulaeformis forests had 5 folds of it as much as Ostryopsis davidiana forest,mixed apple trees and crops had 17.14 and 3.96 folds of it than Ostryopsis davidiana forest,respectively,while high-standard soil preparation could decrease the production obviously.Gray correlation analysis suggested that the stand canopy density and the biomass of herb and litter were the most important factors affecting the runoff and sediment production on sloping land,whose gray correlation degrees all exceeded 0.6.Mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction of loess area,which could help to increase the coverage and litter thickness to dramatically decrease the runoff and sediment production on sloping land.
    Mechanism of watershed soil erosion control by vegetation
    QIN Fucang 1,2,YU Xinxiao1 ,ZHANG Manliang 3,XIE Yuanyuan 1
    2005, 16(09):  1618-1622 . 
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    From the view of hydrodynamics,this paper studied the acting mechanism of tree,grass and forest litter on slope runoff velocity and kinetic energy.The results showed that slope runoff head loss was related to slope gradient, forest density,net rainfall intensity and slope length.The relationship of water head loss with the distance among trees and the diameter at the ground of tree was E∝(D/b)4/3.The grass on slope turned to be curved with s flowing,and thus,increased the bottom resistance of flow,and reduced the shearing stress of soil surface.Therefore,silt-carrying capacity decreased dramatically.The analysis of actually measured materials of each rainfall, runoff and sediment,and the comparison of Qiaozi eastern gully and Qiaozi west gully in Tianshui city of Gansu Province showed that under same precipitation condition,the runoff,sediment yield,flood peak discharge and maximum sediment transport rate in treated watershed was less than those in untreated watershed,suggesting that vegetation was obviously beneficial to water reservation and water and soil conservation.
    Soil properties and water holding capacities of Michelia macclurei,Schima superba and Castanopsis fissa stands
    XUE Li1,2,LI Yan2,QU Ming2,YAN Shu2,WANG Xiang'e 2
    2005, 16(09):  1623-1627 . 
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    The study showed that the soil density,total porosity,natural water capacity and capillary moisture capacity were 1.19 g·cm-3,56.73%,15.7% and 43.2% in Michelia macclurei stand,1.26 g·cm-3,54.18%,13.0% and 37.8% in Schima superb stand,and 1.06 g·cm-3,60.74%,19.4%,and 45.8% in Castanopsis fissa stand,respectively.Soil water holding capacity and aeration were good in Castanopsis fissa stand but bad in Schima superba stand,whereas Michelia macclurei stand had a medium water holding capacity and a bad aeration.The water holding capacity of litter per tree was in order of Michelia macclurei(20 kg)>Castanopsis fissa(15 kg)>Schima superba(8 kg),whereas that of litter in stand was Castanopsis fissa(17 t·hm-2)>Michelia macclurei(16 t·hm-2)>Schima superba(13 t·hm-2).The nutrient storage of litter per tree was 112.71,31.20 and 87.30 g in Michelia macclurei,Schima superba and Castanopsis fissa stands,respectively,and that of litter in stand was 84.35, 51.86 and 98.11 kg·hm-2,respectively.The soil in the three stands was strong acidic,and the content of soil organic matter,total N,total P,total K,alkalized N,available P and available K was 18.43 g·kg-1,0.69 g·kg-1,0.17 g·kg-1,5.83 g·kg-1,45.67 mg·kg-1,0.83 mg·kg-1 and 23.13 mg·kg-1 in Michelia macclurei stand,13.40 g·kg-1,0.68 g·kg-1,0.20 g·kg-1,12.32 g·kg-1,40.78 mg·kg-1,0.85 mg·kg-1 and 90.63 mg·kg-1 in Schima superba stand,and 28.50 g·kg-1,0.97 g·kg-1,0.23 g·kg-1,18.77 g·kg-1,73.40 mg·kg-1,1.45 mg·kg-1 and 66.50 mg·kg-1 in Castanopsis fissa stand, respectively.Soil bacteria accounted for >94% of soil microbes,and their individuals were 41·105,34·104 and 5.3·104 g-1 in Michelia macclurei, Schima superba and Castanopsis fissa stands,respectively.The activities of soil urease,catalase and phosphatase in Castanopsis fissa stand were the greatest among the three stands,while soil cellulase activity in Michelia macclurei stand was greater than that in other two stands.In a word,soil fertility of Castanopsis fissa stand was the highest among three test stands.
    Evapotranspiration of natural Quercus liaotungensis and Tilia paucicostata secondary stands in Liupan Mountains of Ningxia
    XIONG Wei,WANG Yanhui,YU Pengtao,Shi Zhongjie,Shen Zhenxi,Guo Mingchun
    2005, 16(09):  1628-1632 . 
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    With heat dissipation probe technique and combined with microlysimeter and hydrological methods,this paper studied the evapotranspiration of secondary Quercus liaotungensis and Tilia paucicostata stands,and its relationship to forest structure from August to September 2004.The results indicated that the stem sap flux density (SFD) of Quercus liaotungensis and Tilia paucicostata changed regularly from day to night in later growth season.In relatively still period (nighttime),the SFD kept low values continuously,usually below 0.05 μl·cm-2·min-1,while in active period (daytime),it increased quickly,usually below 0.25 μl·cm-2·min-1.The daily transpiration of whole-tree was estimated based on the calculation of daily cumulative SFD,which showed that there existed a significant difference between two tree species.The daily transpiration of Quercus liaotungensis reached 5.31 and 2.48 L·d-1 in sunny-and cloudy-days,2.35 and 3.75 folds as that of Tilia paucicostata,respectively.There was no significant difference in daily leaf transpiration rate between these two shrub species.During measurement periods,the average daily stand evapotranspiration was 1.45 mm·d-1, including transpiration (0.72 mm·d-1),soil evaporation (0.19 mm·d-1),and canopy interception (0.54 mm·d-1),which accounted for 49.6%,13.3% and 37.1% of the total evapotranspiration,respectively.The results showed that the difference of whole-tree transpiration between tree species contributed significantly to the difference of tree canopy transpiration,while the difference of shrub canopy transpiration was on account of the leaf amount in the canopy.The effects of vertical layers in the stand on total stand evapotran-spiration also differed,with a percentage of 65.8%,20.9% and 13.3% for tree canopy,shrub canopy and floor,respectively,which meant that the transpiration and interception of tree canopy contributed most to the total evpotranspiration,followed by shrub transpiration,soil evaporation, and grass transpiration.
    Rainfall interception model of forest canopy:A preliminary study
    GUO Mingchun1,YU Pengtao1,WANG Yanhui1,SHEN Zhenxi1,SHI Zhongjie1,DU Apeng2, HE Changqing2
    2005, 16(09):  1633-1637 . 
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    Canopy interception is an important hydrological process in forest ecosystem, and its modelling is of significance to understand and estimate the rainfall interception by the canopy.In this paper,a canopy rainfall interception model was established by dividing a rain incident into a set of short period, calculating the rainfall distribution intercepted by the canopy,and educing the process of the rain incident.This model considered the effects of the dryness of canopy and trunk on the evaporation from wet canopy and trunk during one rain incident,and introduced two factors,leaf area index (LAI) and surface area of trunk per unit area of ground (SAI),when computing the evaporation. The application of the model to simulate the rainfall interception process in a Larix principis-rupprechtii plantation in Guyuan,south Ningxia Hui autonomous region of China showed that the simulated and measured throughfall were identical,and the absolute deviation between simulated and measured results was within ±1 mm.But,when the precipitation was smaller than 6 mm,the simulated throughfall was lower than the measured one.The values of simulated stemflow were lower than the measured values,and the relative deviation between simulated and measured values was smaller when the precipitation was larger.The process of throughfall in the forest was also simulated,with the results fitted well to the measured one.
    Construction and verification of distributed rainfall-runoff model for forested watershed in alpine and gorge region
    LIU Jianmei 1,2,PEI Tiefan 1,WANG Anzhi 1,YANG Hong 1,2
    2005, 16(09):  1638-1644 . 
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    Considering of the main hydrological characteristics in the upper Zagunao River watershed of the upper reach of Minjiang River,general hydrological models were selected to construct the distributed rainfall-runoff process model for the forested watershed in typical alpine and gorge terrains. Calibration of too many regional parameters was avoided to assure the transportability of the models in similar watersheds.Two flow series of 1 000 hours in 1999 and 2000 were simulated by using the distributed model.The runoff hydrograph,accumulative runoff volume,peak discharge,and peak time showed good fittings with observed series.The simple structure and less empirical parameters gave the distributed model the ability to simulate the rainfall-runoff processes in similar watershed across scales,which provided the basic approach to the hydrological scaling research.
    Application of wavelet transform to monthly runoff time serial analysis in Zagunao watershed,the upper Minjiang River
    LIN Yong1,LIU Shirong2,LI Chongwei1,GE Jianping1,SUO Anning1,CHEN Baoyu 1
    2005, 16(09):  1645-1649 . 
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    Runoff is an important component of regional water resources,and its dynamics is to some extent an indicator of water resources dynamics in a region.To know the runoff dynamics and water resources in a region is essential for the sustainable utilization and planning of water resources,and for the research on hydrological response of vegetation change at watershed scale.To disclose the water resources dynamics in Upper Minjiang River,one of the large reaches of Yangze River in southwest China,this paper analyzed the runoff dynamic features of Zagunao watershed,an important watershed in Minjiang River basin.Multi-Resolution Analysis (MRA) and periodicity analysis were conducted with Dmey wavelet function on the monthly runoff data from 1962 to 2002 observed by Zagunao hydrological station,which provided a data-based approximation on the evolution of monthly runoff in Zagunao watershed.It was found that the runoff dynamics in Zagunao watershed was relatively stable during 1962~1978,despite that this period was just in correspondence with the term of intensive deforestation activities in Upper Minjiang River basin.It was also clear that the runofff in Zagunao watershed was increased from 1986 to 1997,which was inconsistent with the commonly accepted viewpoint that the runoff decreased with increasing vegetation cover in forest watershed.However,the increasing trend from 1986~1997 was consistent with the research results in Yichang by Wang Wensheng and with the global warming at global and continent scale,which meant that global climate change plays a big role in runoff dynamics in Upper Minjiang River.Periodicity analysis showed that the rich-short water periodicity at the scale of 10 years (120 months) and 5 years (60 months) was 3 and 7 times,respectively,which could provide invaluable information for the eco-hydrological function research of forest landscape in Minjiang river basin and the sustainable utilization of water resources.The results from the case study highlighted that sometimes,it was very necessary to consider the role of global climatic warming in disclosing the hydrological response of land use/cover change at watershed scale,otherwise,it would be difficult to explain some hydrological phenomena.
    Microclimate characters of urban forest in Shenyang City
    XU Wenduo 1,HE Xingyuan 1,CHEN Wei 1,2,LIU Changfu 1,3,SUN Yu 1
    2005, 16(09):  1650-1654 . 
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    This paper analyzed the diurnal changes of the temperature and humidity in Shenyang urban forest during its different growth stages.The results showed that air temperature was the lowest in the morning and the highest at noon.The highest peak point of air temperature lagged behind that of solar radiation about 2 hours,due to the influence of forest environment.The annual air temperature amplitude was in order of stop-growth period (dormancy stage) (DS)>prophase of growth season (PGS)>anaphase of growth season (AGS)>medium-term of growth season (MGS).Soil temperature of PGS,MGS and AGS at daytime was higher than that at night, while that of DS was in reverse.The daily soil temperature amplitude at different growth stages was in order of upper soil layer (20 cm)>medium soil layer (40 cm)>lower soil layer(80 cm),while the diurnal soil temperature amplitude in the same soil layer was in order of PGS>AGS>DS>MGS (20 cm) and PGS>DS>AGS>MGS (80 cm).The diurnal change of relative humidity was reverse to that of air-and soil temperature,which was higher at night than at daytime,and was in order of MGS>AGS>DS>PGS.
    Dynamics of total organic carbon (TOC) in hydrological processes in coniferous and broad-leaved mixed forest of Dinghushan
    YIN Guangcai 1,2,ZHOU Guoyi 2,ZHANG Deqiang 2,Wang Xu 2,CHU Guowei 2, LIU Yan 2
    2005, 16(09):  1655-1660 . 
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    The total flux and concentration of total organic carbon (TOC) in hydrological processes in coniferous and broad-leaved mixed forest of Dinghushan were measured from July 2002 to July 2003. The results showed that the TOC input by precipitation was 41.80 kg·hm-2·yr-1,while its output by surface runoff and groundwater (soil solution at 50 cm depth) was 17.54 and 1.80 kg·hm-2·yr-1,respectively.The difference between input and output was 22.46 kg·hm-2·yr-1,indicating that the ecosystem TOC was in positive balance.The monthly variation of TOC flux in hydrological processes was very similar to that in precipitation.The mean TOC concentration in precipitation was 3.64 mg·L-1,while that in throughfall and stemflow increased 6.10 and 7.39 times after rain passed through the tree canopies and barks.The mean TOC concentration in surface runoff and in soil solution at 25 and 50 cm depths was 12.72,7.905 and 3.06 mg·L-1,respectively.The monthly TOC concentration in throughfall and stemflow had a similar changing tendency, showing an increase at the beginning of growth season (March),a decrease after September,and a little increase in December.The TOC concentration in runoff was much higher during high precipitation months.No obvious monthly variation was observed in soil solution TOC concentration (25 and 50 cm below the surface).Stemflow TOC concentration differed greatly between different tree species.The TOC concentration in precipitation,throughfall,and soil solution (25 and 50 cm depths) decreased with increasing precipitation, and no significant relationship existed between the TOC concentrations in stemflow,surface runoff and precipitation.The TOC concentrations in the hydrological processes fluctuated with precipitation intensity,except for that in stemflow and soil solutions.
    Application of phenological pattern recognition in ecological dynamic forecasting
    PEI Tiefan,JIN Changjie
    2005, 16(09):  1661-1666 . 
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    This paper described the principles,methods,and procedures of ecological dynamic forecasting by the automation techniques of pattern recognition and mathematical logic judgment on the basis of phenological data and model output maps from T42L9 numerical weather prediction model.This new forecasting method proposed on the basis of modern meteorology and automation techniques enables the classic phenology to apply to a new field ecological forecasting.It enables phenological forecasting to develop from single-station forecasting stage to regional forecasting stage,which is greatly corresponded to the development stage from single station forecasting stage to synoptic stage in weather forecasting,and enables agro-meteorological forecasting to develop from qualitative and statistical forecasting stage to ecological dynamic forecasting stage.With this new qualitative forecasting method,both the predicted objective and predictors are of considerable bio-physical interests.The ecological dynamic forecasting method could be applied to crop sowing,crop growth,irrigation and fertilization,and diseases and pests control.
    Effects of continuous cropping on understorey species diversity in Eucalypt plantations
    WEN Yuanguang 1,2,LIU Shirong 3,CHEN Fang 1
    2005, 16(09):  1667-1671 . 
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    By the methods of time-space series analysis and field monitoring,this paper studied the species diversity and its maintaining mechanism in Dongmen Eucalypt plantations of Guangxi.The results indicated that during the period of 1998~2003,continuous cropping of Eucalyptus plantation resulted in a reduction of species diversity.The plant species number of second generation was reduced by 54.43% in a 667 m2 plot,and by 50% in 18 sampling plots (each of 4 m2),and the species richness and Shannon-Wiener index of 6-year second generation forest decreased by 39.39% and 17.76%,respectively, compared with the first generation.The continuous cropping not only decreased the species diversity,but also changed the species composition and characteristics of the community.Life-form spectra of Eucalypt plantations varied with generation.The plant life-form consisted of micro-phanerophytes, liana phanerophytes,and nana-phanerophytes in the first generation,while the herbaceous-phanerophytes and chamaephytes occurred in the second generation.The k-strategy and r-strategy species accounted for 69.32% and 30.68% in the first generation,while 47.83% and 52.17% in the second generation,respectively.Therefore,continuous cropping of Eucalypt plantations was advantage for herb,therophytes and r-strategy species,but disadvantage for woody plants and k-strategy species.Seed band and vegetative body in soil were considered to play an important role in maintaining diversity.A new hypothesis,initial plant Diaspora,on the maintaining mechanism of species diversity in Eucalypt plantation was put forward.
    Effects of islanding on plant species diversity in Thousand-island Lake region
    LU Jianbo 1,DING Lizhong1,XU Gaofu 2
    2005, 16(09):  1672-1676 . 
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    In this paper,the typical area of fragmentation in Thousand-island Lake region was selected to study the effects of islanding on plant species diversity after reservoir built.26 quadrates were installed on 18 small,medium and large islands to investigate the species and number of trees and shrubs,with inland as the control One-way variance analysis (ANOVA) showed that the species richness of trees was significantly different (F=13.055,P=0.000) among all kinds of islands,which was significantly higher on large islands than on small and medium ones,but not significantly different from that on inland.The species richness of shrubs was not significantly different among all kinds of islands and inland.Spearman correlation analysis showed that the species richness of trees was significantly positively correlated with island area,while the correlation between specie richness of shrubs and island area was not significant.Shannon-Wiener Index (H) analysis suggested that the diversity of both trees and shrubs on large islands was the highest,followed by on inland,but the diversity of shrubs was larger on small than on medium islands.The analysis of Simpson index and Pielou index showed that the species evenness of trees was the highest,but the dominance was the lowest on medium and large islands,while the species evenness of shrubs was the highest on medium and small islands, but the dominance was the lowest on small islands.
    Secondary succession characteristics of vegetations on reclaimed land inside Chongming wetland seawall
    GE Zhenming,WANG Tianhou,SHI Wenyu,ZHAO Ping
    2005, 16(09):  1677-1681 . 
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    National reserve Chongming Dongtan wetland was designated as an important international wetland (ramsar site) in 2002.The area outside 98 seawalls is the core area of the reserve,while their inside is the experimental area.A wetland restoration project was started in June 2003,and a large pond behind the seawall was unwatered,which changed the soil condition and appeared drought and salinization.The vegetations presented typical secondary succession,and Aeluropus littoralis and Suaeda glauca invaded the area originally dominated by reed.From July 2003 to April 2004,the soil moisture content and salinity of 15 samples were determined,with the biomass,height,density,and coverage of each kind of vegetations measured.The results showed that the vegetation layout had become an obviously zonary distribution of Aeluropus littoralis-Aeluropus littoralis/Suaed a glauca-Suaeda glauca/Phragmites communis-Phragmites communis community.Suaeda glauca gradually extended to the reed area,and became the dominant species of the area,with an average biomass of 2003 415.4 g·m-2 in autumn,and of 2004 391.53 g·m-2 in spring.The biomass and height of Suaeda glauca increased,and its density was getting stable,suggesting that the plant had strong growth ability in drought area.
    Physiological responses of 2-year-old Acer davidii seedlings to short-term enhanced UV-B radiation
    ZUO Yuanyuan 1,2,LIU Qing 1,LIN Bo 1,HE Hai 1,3
    2005, 16(09):  1682-1686 . 
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    At the Maoxian Ecological Experimental Station of Chinese Academy of Sciences in northwest Sichuan Province,2-year-old native maple(Acer davidii) seedlings were potted outdoors with enhanced UV-B radiation(280~320 nm) of 0.27 W·m-2(7.7 kJ·m-2·d-1),which was approximated to the predicted enhanced UV-B reaching the earth surface when stratosphere ozone was depleted by 15% in the local area,with the control plant received ambient UV-B.The gas exchange index and chlorophyll fluorescence,and the contents of chlorophyll and UV-absorbing compounds were examined after 50 days of the radiation.The results showed that enhanced UV-B radiation significantly lowered the maximal net photosynthetic rate(CK=6.214,TR=4.452),raised the dark respiration rate(CK=0.413,TR=1.295) and light compensation point(CK=21.629,TR=59.861),but had little effect on quantum yield(CK=0.021,TR=0.032).Under enhanced UV-B radiation,the diurnal changes in net photosynthetic rate,water use efficiency,quantum efficiency of photosystem Ⅱ centers(Fv/Fm),and quantum yield of photosystem Ⅱ photochemistry (ΦPSП) were reduced,chlorophyll a,total chlorophylls, and chlorophyll a/b(CK=16.23,5.39,TR=13.17,4.93) were also markedly reduced,but chlorophyll b remained nearly unchanged.Contrary to the previous studies,enhanced UV-B radiation decreased the content of UV-absorbing compounds(CK=0.87,TR=0.79) in 2-year-old Acer davidii seedling leaves,indicating that the measurement of leaf UV-B absorbing compounds didn't necessarily provide a good indicator of plant tolerance to UV-B.It could be concluded that enhanced UV-B radiation had some inhibitory effects on the photosynthesis of Acer davidii seedlings.Long-term researches are necessary to confirm this conclusion.
    Fitness analysis of seed-and vegetative reproduction of clonal tree Symplocos laurina
    ZHANG Yunchun 1,2,DU Xiaojun 1,ZHANG Qiaoying 3,GAO Xianming 1,SU Zhixian 4
    2005, 16(09):  1687-1692 . 
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    There are two ways in Symplocos laurina propagation,clonal and sexual reproduction.The study showed that under different habitat conditions, Symplocos laurina could adopt different ways to propagate and occupy space.In conditions with abundant water and nutrient resources,such as in evergreen broad-leaved forests or bamboo forests,the survival rate and space-occupying ability of both ramets and sexual seedlings were relatively high,with clonal ramets took advantage in terms of number and space, suggesting that clonal propagation was the dominant way in such environments.Oppositely,in habitats lack of sufficient nutrition,the survival rate and space-occupying ability of seedlings were low,and grown-up plantlets would preempt in number and space occupation.Bottleneck in sexual propagation appeared in the stage from seed to seedling,while clonal propagation appeared during the period from seedling to ramet.The way of Symplocos laurina invasion was to settle a plantlet,and then occupied the space rapidly by clonal growth,with clonal seedlings dominated in initial stage and lost the advantage after 15 ages.
    Landscape stability and its pattern transition in Jinghe watershed
    XIE Gaodi,ZHEN Lin,YANG Li,GUO Guangmeng
    2005, 16(09):  1693-1698 . 
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    Based on remote sensing and GIS,this paper analyzed the landscape change patterns in the Jinghe watershed of northwest Loess Plateau,one of the areas most suffered from soil and water erosion.The results indicated that the landscape structure in the watershed did not change very much over the past 15 years,and was dominated by grassland and arable land,which occupied 85% of total watershed area.Forest and other land use accounted for 10% and 5% of total area,respectively.A transition of landscape patterns occurred at large-scale watershed level.During 1986~2000,the inter-transitions between different landscape types were very complicated,mainly occurred among woodland,grassland and arable land.The self-stableness of dominant landscape patterns was >89%,and only 11% of them transferred into other types.Among landscape types,the one sharing small percentage of the total had a high speed of vanishing or transferring into other types.A significant transition was found between sub-patterns of a large landscape pattern,e.g.,the transition of medium-into low-coverage grassland during 1986~1995 and the reverse during 1995~2000 was occurred,implying a situation of grassland degradation and improvement over the decades.The spatial-temporal changes of landscape features were observed in the watershed.In terms of spatial change,the dominance index and contagion index of the landscape showed an increasing trend,fractal dimension index showed a decreasing trend,while patch density showed an increasing trend,followed by a decreasing trend from upper to down streams.For temporal change,both landscape dominance and contagion decreased to a certain extent,fractal index remained stable,while patch density increased, showing a fragmentation direction of the landscape in the watershed.The NDVI value changed since the implementation of the policy of conversing farmland into grassland and forest in 2000,which was from 7.4% to 0.8% in low value class,from 29.8% to 25.1% in high value class,from 18.3% to 25.7% in higher value class,and from 2.3% to 5.5% in the highest class, showing an improving trend in landscape quality.
    Landscape pattern and its functioning after ecological reconstruction in black soil region of northeast China
    WEI Jianbing1,2,XIAO Duning1,3
    2005, 16(09):  1699-1705 . 
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    Taken Baiquan County in Heilongjiang Province as a case,this paper studied the effects of regional ecological reconstruction on agricultural landscape pattern and its functioning in soil and water conservation,with the spatial expression and quantity identification investigated based on Geographic Information System (GIS) and field data.The landscape pattern index in class scale,transition matrix of landscape elements,macrostructure of shelterbelt networks,and spatial distribution and hydrological characteristic of reservoirs and ponds in 1989 and 2002,as well as the effects of landscape pattern and its spatial configuration change on soil and water loss were compared.The results showed that artificial ecological reconstruction changed the quantity and spatial configuration of landscape patterns in regional scale,and exerted a significant effect on soil and water conservation.From 1989 to 2002, farmland area reduced 24 731.01 hm2,while forest land,grassland and water area increased 11 728.56,1 838.97 and 1 190.97 hm2,respectively.The controlled eroded land increased by 55%,and the shelterbelt-protected farmland increased by 82.2%.The number and storage capacity of reservoirs and ponds added up to 1 490 and 2.4×108 m3,respectively,and 43.7% of intercepted surface runoff of whole landscape was collected.
    Spatial pattern of sub-alpine forest restoration in west Sichuan
    ZHANG Yuandong,LIU Shirong,ZHAO Changming
    2005, 16(09):  1706-1710 . 
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    West Sichuan sub-alpine is an extension of Qinghai-Tibet Plateau to southeast China,which is covered mainly with dark coniferous forest.As a result of long-term large scale over-logging,the forests have been greatly reduced and degraded.Nowadays,the forest restoration and regeneration in the region are being highlighted.Selecting Miyaluo as a case study area and employing the methods of plot investigation,ETM image interpretation,and overlaying vegetation map with digital topography,this paper analyzed the relations between the appearance and origin of four forest vegetation types,along with their topography differentiation and spatial patterns after a large scale logging and regeneration.The results showed that the appearance of forest vegetations was significantly correlated with their origin.Old coniferous forests (OC) were primitive ones,middle-aged and young coniferous forests (MYC) were from artificial regeneration,deciduous broadleaf forests (DB) were natural secondary ones,while mixed coniferous and deciduous forests (MCD) were partly from natural secondary ones and others from the conjunct action of artificial and natural regeneration.The main cut area in Miyaluo located in the sites with elevation from 2 800 to 3 600 m,where forest restoration appeared difference among different aspects.MYC was mainly distributed on sunny and half-sunny slope,DB and MCD were distributed on shady and half-shady slope,and OC were reserved on the sites with elevation more than 3 600 m.In the process of forest restoration, the four forest vegetation types were in mosaic pattern,and the landscape was seriously fragmentized.
    Forest landscape restoration and its affecting factors in burned area of northern Great Xing′an Mountains—Taking forest coverage as an example
    XIE Fuju 1,2,XIAO Duning 1,LI Xiuzhen 1,WEI Jianbing 1,2,WANG Xugao 1,2
    2005, 16(09):  1711-1718 . 
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    Forest landscape restoration has been an attractive issue since the catastrophic fire took place on the northern slope of Great Xing′an Mountains in 1987 Based on the China forest inventory data and employing Kendall Bivariate and Distances Correlation Analyses,an investigation was made to search for what changes of the forest coverage pattern being happened in this area during the past 13 years after fire,and how the fire severity,foster type and terrain factors influenced the restoration of forest coverage.The results showed that the forest coverage in 2000 changed a lot,in comparing with that in 1987 before fire.The percentage of non-stocked land area and coverage grade declined markedly,with lower coverage grade increased.Among all test factors,fire severity which was inversely correlated with forest coverage grade was the key one.Though the regeneration measures didn't markedly affect forest coverage restoration within a short period,they might shorten the cycle of forest succession and promote the productivity of coniferous forest in the future.Among three terrain factors, slope was the strongest one affecting forest coverage,followed by position and aspect.
    Relationships between soil and water loss and landscape pattern on Loess Plateau
    SUO An′ning,HONG Jun,LIN Yong,GE Jianping
    2005, 16(09):  1719-1723 . 
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    Based on the theories of detrended canonical correspondence analysis (DCCA),12 soil and water loss indices (“species”) and 7 landscape indices (“environmental factors") were adopted to quantitatively analyze the effects of landscape pattern on the soil and water loss in Jinghe River basin on Loess Plateau.The results showed that the first four DCCA axes were significantly correlated to agricultural land ratio,landscape diversity index, forest land ratio,and landscape contagion index.The characteristics of soil and water loss changed obviously with landscape pattern gradient, e.g.,Sanshuihe watershed with a forest cover larger than 65% and low landscape diversity had a big and stable runoff,but small sediment and low river sand content.The runoff generation coefficient and runoff depth as well as the sediment transport and river sand content increased with the increasing agricultural land ratio and landscape diversity and the decreasing forest land ratio.As for Honghe watershed with a very low forest cover but high agricultural land ratio (53.41%),and with a relatively high landscape diversity and complex landscape pattern,it had the highest river sand content and the biggest sediment transport,and its monthly runoff and sediment transport varied markedly.The soil and water loss in the Upper-Huan,Down-Huan and Dongchuan watersheds with smaller forest and agricultural land ratio and relatively simple landscape pattern was smaller than that of the watersheds with dominated agricultural land.
    Landscape ecological planning of Jiaozuo city
    WANG Wei 1,2,FANG Chuanglin 1,LI Hongwei 2
    2005, 16(09):  1724-1728 . 
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    With the application of the principles of landscape ecology and the techniques of geographic information systems,the landscape of Jiaozuo city was divided into six types,i.e.,farmland,garden plot,woodland,residential and industrial area,waters,and others.The landscape diversity,dominance, fragmentation,and isolation indexes were calculated by models and GIS to analyze the spatial patterns of these landscape types.Based on the optimization of landscape spatial patterns,a pattern for developing a rational and natural ecosystem in Jiaozuo city was proposed,i.e.,keeping four or five large natural patches,planning small artificial green patches,linking the large and small patches by various corridors to ensure the ecosystem inside the city to circulate well,combining residential areas properly to form a urban troop with Jiaozuo town as the center and with seven surrounding towns joined through highways to form a network city pattern.After doing these, urban built-up areas could be linked each other,and inlayed in a natural ecological matrix.This pattern could strengthen the ecological connection, raise the stability of the ecosystem,and maintain the balance of urban ecological system.
    Landscape change in Kangbao County of Hebei Province
    LIU Miao1,2,HU Yuanman1,BU Renchang1,2,CHANG Yu1,HAN Wenquan 1,2,HU Zhibin 1,2
    2005, 16(09):  1729-1734 . 
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    Based on RS image TM5 of 1999 and SPOT5 of 2003,this paper studied the landscape change from 1999 to 2003 of Kangbao County,Hebei Province. Logistic regression was adopted to analyze the driving factors,and Kappa index was used to evaluate the accuracy of the landscape classification result,which was 86.72% for 1999,and 89.76% for 2003.The area of cropland in Kangbao County reduced largely,while that of vegetable field,forestland and artificial grassland increased sharply,among which,vegetable field and artificial grassland had the greatest increasing rate.The landscape fragmentation aggravated in the region.The landscape change was mainly caused by the policy of reducing cultivated land,with the main driving factor slope,and the direct driving factor water-heat condition and soil fertility determined by slope aspect.
    Fine-root character and its action mechanism of forest at its initial reestablished stage on degraded red soil
    LIU Yuanqiu,LUO Liangxing,LIU Liangying,YANG Jialin,XIA Xiaolan
    2005, 16(09):  1735-1739 . 
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    This paper studied the fine-root character and its action mechanism of forest reestablished by different models for 10 years on a seriously degraded red soil,and analyzed their correlation with soil property.The results showed that fine-roots mostly distributed in 0~20 cm soil layer,accounted for 73.39%~87.41% of those in 0~40 cm soil layer.There were notable differences in nutrient storage of fine-roots under different reestablishment models.The fine-roots of medium density pure Pinus serotina forest had a much higher storage of total nitrogen,phosphorus and potassium,with the content of total nitrogen,phosphorus,potassium,calcium and magnesium being 84.47,5.55, 38.42,17.00 and 10.76 kg·hm-2,respectively.Soil organic matter,total nitrogen,available nitrogen,available potassium and pH had significant correlations with fine-root biomass (P<0.05).The effects of fine-roots on soil physical properties mainly reflected on soil capillary porosity and total porosity.Fine-roots obviously increased the contents of >0.25 mm and >5 mm soil waterstable aggregates,and improved soil structure-stability.The correlations between fine-roots and soil bacteria and microbial quantities were significant.
    Effects of different cutting intensities on above-and underground growth of Stylosanthes guianensis
    ZHANG Jia'en,LIU Wengao,CHEN Jingqing,SHI Yaocai,CAI Yanfei
    2005, 16(09):  1740-1744 . 
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    The study on the effects of different cutting intensities on the eco-physiological characteristics and growth status of Stylosanthes guianensis showed that moderate cutting could promote the regrowth capacity of the grass.The total content of leaf chlorophyll had no significant difference between zero,light-and heavy cutting,but the ratio of leaf chlorophyll a/b increased to 1.59∶1 and 1.52∶1 under light-and heavy cutting,respectively, compared with 1.22∶1 under zero-cutting,which could be very helpful for the plant to over-compensate itself.Cutting also affected the growth status and activities of plant roots.At the earlier stage of heavy cutting,the total length, total surface area and mean diameter of plant roots decreased by 54.9%, 66.5% and 27.2%,respectively,and root activities also decreased greatly,in comparing with zero-cutting.But,the above-mentioned indices could be recovered to a higher level under different cutting treatments than under zero-cutting at the later growth period of the grass.As for the total annual yield of the grass,it was 3 179.8 g·m-2 under light-cutting,3 006.1 g·m-2 under heavy-cutting,and 2 936.98 g·m-2 under zero-cutting,indicating that rational cutting could improve grass productivity.
    Economic values of nitrogen transformation in rice field ecosystems
    XIAO Yu 1,2,XIE Gaodi 1,LU Chunxia 1
    2005, 16(09):  1745-1750 . 
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    Based on the 2002 field experimental results in the Wusi Farm of Fengxian County in Shanghai and related studies,and by the methods of ecological economy and environmental economy,this article examined and estimated the nitrogen input and output,and the economic values of nitrogen transformation in rice field ecosystems.The results indicated that the plot without N fertilization showed a deficit of nitrogen budget,while those with urea application showed a surplus.The economic value of the plot without urea amendment was evaluated to be positive,while that of the plots with urea application was calculated to be negative.The negative value of the plots with urea amendment resulted from the nitrogen losses through ammonia volatilization,nitrogen leaching and runoff,which had serious harmful impacts on environment and human society.Therefore,only when some measures were taken to encourage and facilitate farmers to improve the efficiency of urea application and to mitigate the environment problems from N losses in the process of food production,the advantages of nitrogen transformation in rice fields could be promoted,and the sustainability of agriculture would become reality.
    Sex pheromone secondary components of Indian meal moth Plodia interpunctella in China
    HU Wenli 1,2,DU Jiawei 1
    2005, 16(09):  1751-1755 . 
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    Indian meal moth Plodia interpunctella Hübner (Lepidoptera:Pyralidae) is considered as an important insect pest infesting stored grains and other products in China.The major sex pheromone component of P.interpunctella, Z9,E12-14:OAc (TDA),has already been identified.Though the efficiency of male capture by using the bait with this component alone is quite good,the pheromone system is far from fully understood.The identification with capillary chromatographic analysis and GC-MS methods showed that there were four main components,i.e.,Z9,E12-14:OAc(A),Z9,E12-14:OH(B),Z9,E12-14:Ald(C),and Z9-14:OAc(D),in the sex pheromone gland of female P.interpunctella,and the ratio of these four components was A∶B∶C∶D=100∶22∶12∶9.Wind tunnel experimental results suggested that the response of male P.interpunctella to a blend (A∶B∶C∶D=8∶2∶1∶0.8) was not significantly different from that to female sex pheromone gland extracts.
    Phosphate adsorption and desorption characteristics of several fly ashes
    FENG Yuehua 1,2,HU Ruizhi 1,ZHANG Yangzhu 1,ZOU Yingbin 2,HUANG Yunxiang 1,WANG Cuihong 1,LIFayun 3
    2005, 16(09):  1756-1760 . 
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    Through adsorption-desorption experiment and incubation test,this paper studied the phosphate adsorption and desorption characteristics of several fly ashes.The test fly ashes contained 0.545~4.540 g·kg-1 of total P and 19.55~163.0 mg·kg-1 of available P,which were significantly higher than those in soils.The P adsorption capacity of fly ashes increased with increasing added P,while their P adsorption rate was in adverse.Fly ashes had a higher P adsorption rate but a lower P desorption rate than soils,mainly because fly ashes had more P adsorption sites and stronger bound energy.In this study, Langmuir,Freundlich,and Temkin equations were fit to the measured data, and the MBC value in Langmuir equation,a value in Freundlich equation, and k2 value in Temkin equation could be used as a comprehensive index to characterize the potential phosphate adsorptivity of fly ashes.The larger these values were,the stronger the P adsorptivity was.The MBC,a and k2 value of 5 fly ashes collected from different locations was in order of Xiangtan power factory (5 167.7,4 056.2 and 831.5) >Yueyang paper factory (1 650.7,2 803.4 and 711.9)>Huaneng power factory (303.0,1 677.6 and 368.7)>Zhuzhou power factory (34.7,413.48 and 213.8)>Dongting nitrogen fertilizer factory (34.7,413.48 and 213.8).The P fixation by fly ashes generally increased with their increasing water content,and their phosphate adsorption was mainly specific adsorption and chemical precipitation, suggesting that the P fixation and the water content of fly ashes should be considered when fly ash was used as soil amendment or as compound fertilizer filling substance.
    Degradation-detoxification behavior of methamidophos in phaiozem and burozem rhizosphere
    YU Ying 1,2,ZHOU Qixing 1
    2005, 16(09):  1761-1764 . 
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    With plastic rhizobox system,this paper studied the degradation behavior of methamidophos in the rhizosphere and non-rhizosphere of phaiozem and burozem planted with soybean.The results suggested that methamidophos could be rapidly decomposed in soil environment despite its higher acute toxicity,and its residual amount in phaiozem was generally below the level in burozem under same condition.In the absence of soybean (control),the residual amount of methamidophos at the 2nd day of incubation was about 33% in burozem,whereas only about 26% in phaiozem.An accelerated degradation of methamidophos in soybean rhizospheric soil was observed, especially in phaiozem.At the 9th day of incubation,the insecticide residue in the middle rhizobox phaiozem and burozem with soybean was decreased by 87.5% and 76.0%,respectively,compared with that of the control.The degradation process of methamidophos in soil environment followed the first-order equation,and its half-life was about 2 days.
    Bt toxin distribution in transgenic Bt cotton and soil system
    SUN Caixia 1,2,CHEN Lijun 1,WU Zhijie 1
    2005, 16(09):  1765-1768 . 
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    This study showed that the amounts of Bt toxin expressed in transgenic Bt cotton leaves and stems (103.5~134.1 ng·g-1) were rather higher than those expressed in transgenic Bt cotton roots (44.7~21.2 ng·g-1), indicating that total amount of soil Bt toxin introduced by transgenic Bt cotton could be decreased through treating its above-ground biomass.In comparing with the amount of Bt toxin expressed in transgenic Bt cotton plant,that expressed in its root exudates was rather lower,showing that the effects of plant Bt toxin on soil ecosystem would be limited if other sources of Bt toxin introduced into soil were controlled.
    Research advances in inverse methods used for modeling plant-atmosphere exchange
    DIAO Yiwei 1,2,PEI Tiefan 1
    2005, 16(09):  1769-1772 . 
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    To estimate the source/sink and the vertical fluxes of mass and energy within and above plant canopies continues to be a critical research problem in biosphere-atmosphere exchange processes.The underlying approaches in such problem are to exploit the natural properties of turbulence within and above vegetation,such as Lagrangian inverse analysis,high order Eulerian closure model,and hybrid Eulerian-Lagrangian method.This paper introduced the recent development in multilayer turbulent transport methods to compute the distributions of the strengths of scalar sources and sinks within plant-atmosphere continuum,and in particular,focused on the so-called “inverse methods",and described above three methods and their characteristics in detail.The limitation and prospect of these methods were also mentioned.
    Research progress on unsaturated and saturated soil water movement in forest catchments
    YANG Hong 1,2,PEI Tiefan 1
    2005, 16(09):  1773-1779 . 
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    This paper reviewed the studies on the movement ways,i.e.,infiltration, phreatic evaporation,ground water recharge and interflow,of unsaturated and saturated soil water in forest catchments,and introduced the present advances in soil hydraulic parameters,including soil water characteristic curve,and unsaturated and saturated soil hydraulic conductivity.Research directions in the future were also proposed.
    Advances in research effects of temperature fluctuation on aquatic fauna
    TIAN Xiangli,DONG Shuanglin
    2005, 16(09):  1780-1785 . 
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    This paper reviewed the researches on the effects of diurnal temperature fluctuation on aquatic fauna,including the test species involved,design of thermal regimes,growth responses of aquatic fauna to various fluctuated temperature,and growth-promotion mechanisms of temperature fluctuation. The problems existed in related researches and the application perspectives in the future were also highlighted.
    Understory vegetation composition and main woody population niche of artificial masson pine forest in south subtropical area
    KANG Bing1,2,LIU Shirong2,SHI Zuomin2,WEN Yuanguang3,CAI Daoxiong4,LU Lihua4,LIANG Hongwen3,FENG Changlin4
    2005, 16(09):  1786-1790 . 
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    This paper studied the characteristics of the natural understory vegetation in the artificial masson pine forest replanted after Chinese fir cut for 13 years. The results indicated that there were 100 species of understory vegetation, including 74 species of shrub or small arbor,accounting for 74.0% of the total species,belonging to 41 faculties and 63 categories,and 26 herbs belonging to 14 faculties and 23 categories.The tropical and subtropical elements were dominant in the vegetation,while the temperate ones were scare.The species diversity and richness were decreased after masson pine regenerated from Chinese fir.The analysis of important value showed that the main species of shrub or small arbor were Tinomiscium tonkinensis,Mycetia longiflora,Evodia lepta,Paederia scandens,Mussaenda pubuscens,Actinodaphne pilosa and Quercus glauca,and those of herb were Cyrtococcum patens,Blechnum orientale,Dicranopteris dichotoma,Adiantum flabellulatum,Adiantum edgeworthii and Pteris semipinnata.The biomass of the vegetation in different slope positions was decreased in order of upside>downside>middle part.There was a significantly positive correlation between the niche breath and the important value of main woody population.The important values of woody populations were higher than those of the others,and their niche breadths were also larger,which meant that they were more adaptable to the habitat.The niche overlaps of six population counterparts Tinomiscium tonkinensis-Mycetia longiflora,Tinomiscium tonkinensis-Evodia lepta, Mussaenda pubuscens-Maesa japonica,Quercus glauca-Aphananthe aspera,Actinodaphne pilosa-Saraca chinensis and Evodia lepta-Quercus glaucathese were very large,which could offer information for the restoration and reconstruction in selecting natural vegetation.The large niche overlaps of major woody population counterparts suggested their similar utilization of natural resources.
    Biodiversity of main coniferous forests at low elevation of Three Gorges Reservoir area
    CHENG Ruimei,XIAO Wenfa
    2005, 16(09):  1791-1794 . 
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    The study showed that at low elevation of Three Gorges Reservoir area,Pinus massoniana,Cupressus funebris and Cunninghamia lanceolata were the main coniferous forests,which were respectively divided into 14,9 and 5 community types based on field investigation.The whole trend of their species richness index,species diversity index and species evenness index was that shrub layer and herb layer were larger than tree layer.The diversity indices had no obvious trend along the low elevation gradients,which was probably relevant to the high intensity of human activities in the area.
    Application of fractal theory in studying soil aggregates under different skidding modes
    LI Junfeng,ZHAO Xiuhai
    2005, 16(09):  1795-1797 . 
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    In this paper,the characters of soil aggregates under different skidding modes were investigated by fractal theory.The results showed that the particle fraction of soil aggregates was smaller under tractor-than under animal traction skidding.As for different parts of skidding road,the particle fraction of air-dried soil aggregates was in the order of bottom (2.309) > middle (2.291) > upper (2.014),while that of water-stable aggregates followed the sequence of bottom (2.04) < middle (2.143) < upper (2.262).The particle fraction of aggregates was 2.215 in forest soil and 2.175 in skidding roads.Skidding movement could improve soil aggregates when the cutting intensity was 15%.Tractor skidding was more favorable for soil aggregates formation.
    Effects of soil temperature and humidity on soil respiration rate under Pinus sylvestriformis forest
    LIU Ying, HAN Shijie, HU Yanling, DAI Guanhua
    2005, 16(9):  1581-1585. 
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    Employing root-wrenching method and LI-6400-09 soil respiration chamber,this paper measured the diurnal changes of soil respiration rate with and without roots in situ on June 17,August 5,and October 10,2003.The seasonal changes of soil respiration were also measured from May to September,2004.The results showed that both the total and the root-wrenched soil respiration appeared single diurnal pattern,with the peaks presented during 12:00~14:00.The diurnal fluctuation of soil respiration on August 5 was smaller than that on June 17 and October 10.There were also obvious seasonal changes in total and root-wrenched soil respiration,as well as in root respiration,which were higher from June to August but lower in May and September.The average total soil respiration,root-wrenched soil respiration,and root respiration were 3.12,1.94 and 1.18 μmol CO2·m-2·s-1,respectively,and the contribution of roots to total soil respiration ranged from 26.5% to 52.6% from May to September,2004.There were exponential correlations between respiration rate and soil temperature,and linear correlations between respiration rate and soil humidity.The Q10 values were 2.44,2.55 and 2.27 for total soil respiration,root-wrenched soil respiration,and root respiration,respectively.The effect of soil temperature on root-wrenched soil respiration was lager than that on total soil respiration and root respiration.Soil humidity had a larger effect on total soil respiration than on root respiration and root-wrenched soil respiration.
    Dynamic changes of soil ecological factors in Ziwuling secondary forest area under human disturbance
    ZHOU Zhengchao, SHANGGUAN Zhouping
    2005, 16(9):  1586-1590. 
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    As a widespread natural phenomenon,disturbance is considered as a discrete event occurred in natural ecosystems at various spatial and temporal scales.The occurrence of disturbance directly affects the structure,function and dynamics of ecosystems.Forest logging and forestland assart,the common human disturbances in forest area,have caused the dynamic changes of forest soil ecological factors in a relatively consistent environment.A study on the dynamics of soil bulk density,soil organic matter,soil microbes and other soil ecological factors under different human disturbance (logging and assart,logging but without assart,control)were conducted in the Ziwuling secondary forest area.The results indicated that human disturbance had a deep impact on the soil ecological factors,with soil physical and chemical properties become bad,soil organic matter decreased from 2.2% to 0.8%,and soil stable aggregates dropped more than 30%.The quantity of soil microbes decreased sharply with enhanced human disturbance.Soil organic matter and soil microbes decreased more than 50% and 90%,respectively,and soil bulk density increased from 0.9 to 1.21 g穋m-3 with increasing soil depth.Ditch edge level also affected the dynamics of soil factors under the same disturbance,with a better soil ecological condition at low-than at high ditch edge level.
    Spatial heterogeneity of soil moisture after raining at forest-grassland landscape boundary in hilly area of Loess Plateau
    YOU Wenzhong, ZENG Dehui, LIU Mingguo, SONG Xide, YE Yanhui, ZHANG Yong
    2005, 16(9):  1591-1596. 
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    Soil moisture is a main factor limiting vegetation restoration in semi-arid region.In this paper,the spatial variability of different layers soil moisture after raining at the forest-grassland boundary in hilly area of Loess Plateau were studied by traditional and geostatistical analysis methods.The results showed that the moisture content in surface (0~10 cm) and subsurface soil layer (10~20 cm) of grassland was higher than that of forestland.The two layers soil moisture content at forest-grassland boundary showed a small variation but an obvious ecological distribution.By using moving split-window techniques,it was obtained that the width of edge influence in surface and subsurface layer was 8 and 6 m,respectively.Geostatistical analyses showed that the spatial distribution of two layers soil moisture had a pure nugget effect in grassland,linear model in forestland,and spherical model in forest-grassland boundary.The spatial heterogeneity of two layers soil moisture was higher at forest-grassland boundary than at forestland and grassland,which had a stronger spatial dependence and autorelation.Kriging maps expressed the spatial structural characters.The distribution of soil moisture in two layers showed a strip shape near forest edge,and a patch shape far from the edge.
    Generation mechanism of woodland runoff and sediment on Loess Plateau under hypo-rainfall—A case study of artificial P.tabulaeformis and secondary natural P.dadidiana stands
    PAN Chengzhong, SHANGGUAN Zhouping
    2005, 16(9):  1597-1602. 
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    Based on the long-term observation and from the viewpoints of water balance and runoff-and sediment generation,this paper studied the generation processes of runoff and sediment on two typical woodlands,artificial P.tabulaeformis and secondary natural P.dadidiana,and uncultivated slope-land in Loess Plateau under hypo-rainfall.The results showed that within the range of 5.0~50.0 mm rainfall,the total interception of canopy and litter was 15.45%~56.80% for P.tabulaeformis and 20.56%~47.81% for P.dadidiana,and decreased with increasing rainfall.Woodlands had a higher soil water infiltration capacity than uncultivated slope-land,especially in 0~20 cm soil layer.Both the two woodlands did not generate runoff under regular rainfall.Under the assumed rainfall of 2.5 mm·min-1 intensity and 30 min duration,P.dadidiana stand did not produce runoff,but the runoff velocity and sediment-carrying capacity of uncultivated slope-land were 23.5 times,and runoff shearing stress and energy were 8 times as much as P.tabulaeformis stand.The runoff-and sediment generation on P.tabulaeformis stand decreased by 87.6% and 99.4%,respectively,compared with those on uncultivated slope-land,which was well accorded with the average observed value in runoff plots during 1988~2000.The theoretical analysis on the generation mechanism of woodland runoff and sediment may be effective to evaluate the benefits of forest in soil and water conservation.
    Temporal variation of soil respiration on sloping pasture of Heihe River basin and effects of temperature and soil moisture on it
    CHANG Zongqiang, SHI Zuomin, FENG Qi, SU Yonghong
    2005, 16(9):  1603-1606. 
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    Employing LiCor 6400 gas exchange analyzer and soil respiration chamber attachment (LiCor Inc.,Lincoln,NE,USA),this paper continuously measured the soil surface CO2 effluxes on the sloping pasture of Heihe River basin from early April to late October 2003 to investigate the soil CO2 efflux rate and its feedback to the changes of climate and land use.The results showed that from May to October,the diurnal variation of soil respiration was low at night,the lowest at 7:00,6:30,5:30,6:00 and 7:00,raised rapidly at 7:00~8:30,and then descended at 16:00~18:30.The maximum soil CO2 efflux appeared at 15:00,14:30,14:30,13:30,14:00 and 15:00.The mean daily soil respiration rate was 0.31~6.98 μmol·m-2·s-1,with the maximum in July and August,the second in May and September,and nearly consistent in April and October.Soil respiration rate had an exponential and power correlation with temperature and soil moisture,respectively.
    Response of sediment production to land-use change in Luergou watershed of Loess Plateau
    ZHANG Zhiqiang, WANG Shengping, SUN Ge, ZHANG Manliang, LI Jianlao
    2005, 16(9):  1607-1612. 
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    The study on the effects of different land use patterns on the sediment production in Luergou watershed of Loess Plateau indicated that in comparing with 1982,the areas of forest and grass and of terrace in 1989 increased by 5% and 2.09%,respectively,while that of slope plowland decreased by 1.5%,with the area of naked land and shrubbery respectively increased and decreased a little.During 1998~2000,with the increase of vegetation cover and the decrease of steep slope plowland,the sediment production reduced significantly under high precipitation,85 326 and 52 937 t under the precipitation of 803 and 786 mm,respectively,and not distinguishable in dry years.The reduction effect had a strong seasonality,which consisted with rainfall distribution.For example,in a month with 50 mm precipitation,the mean daily sediment concentration was reduced by 6 kg·m-3,while in a month with 100 mm precipitation,the reduction was 12 kg·m-3.Rainfall intensity also played an important role in soil erosion and sediment production,regardless of land use conditions.
    Effects of forest vegetation on runoff and sediment production on sloping lands of Loess area
    ZHANG Xiaoming, YU Xinxiao, WU Sihong, WEI Tianxing, ZHANG Xuepei
    2005, 16(9):  1613-1617. 
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    Based on the 1985~2003 fixed-position data in 9 runoff plots of Caijiachuan watershed in the Jixian county of Shanxi Province in loess area,this paper discussed the relationships between vegetation and runoff and sediment production on sloping lands of loess area.The results showed that natural-secondary forest had better function in soil and water conservation than artifical Robinia pseudoacacia forest,with runoff and sediment produced 65%~82% and 23%~92%,respectively.Multiple regression analysis indicated that runoff and sediment production had a significant correlation with rainfall and its intensity,but this relationship was decreased gradually with increasing canopy density.Different land-use type had different runoff and sediment production,e.g.,Ostryopsis davidiana and natural-secondary forests had the least runoff and sediment production,artificial Robinia pseudoacacia and Pinus tabulaeformis forests had 5 folds of it as much as Ostryopsis davidiana forest,mixed apple trees and crops had 17.14 and 3.96 folds of it than Ostryopsis davidiana forest,respectively,while high-standard soil preparation could decrease the production obviously.Gray correlation analysis suggested that the stand canopy density and the biomass of herb and litter were the most important factors affecting the runoff and sediment production on sloping land,whose gray correlation degrees all exceeded 0.6.Mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction of loess area,which could help to increase the coverage and litter thickness to dramatically decrease the runoff and sediment production on sloping land.
    Mechanism of watershed soil erosion control by vegetation
    QIN Fucang, YU Xinxiao, ZHANG Manliang, XIE Yuanyuan
    2005, 16(9):  1618-1622. 
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    From the view of hydrodynamics,this paper studied the acting mechanism of tree,grass and forest litter on slope runoff velocity and kinetic energy.The results showed that slope runoff head loss was related to slope gradient,forest density,net rainfall intensity and slope length.The relationship of water head loss with the distance among trees and the diameter at the ground of tree was E(D/b)4/3.The grass on slope turned to be curved with s flowing,and thus,increased the bottom resistance of flow,and reduced the shearing stress of soil surface.Therefore,silt-carrying capacity decreased dramatically.The analysis of actually measured materials of each rainfall,runoff and sediment,and the comparison of Qiaozi eastern gully and Qiaozi west gully in Tianshui city of Gansu Province showed that under same precipitation condition,the runoff,sediment yield,flood peak discharge and maximum sediment transport rate in treated watershed was less than those in untreated watershed,suggesting that vegetation was obviously beneficial to water reservation and water and soil conservation.
    Soil properties and water holding capacities of Michelia macclurei,Schima superba and Castanopsis fissa stands
    XUE Li, LI Yan, QU Ming, YAN Shu, WANG Xiang'e
    2005, 16(9):  1623-1627. 
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    The study showed that the soil density,total porosity,natural water capacity and capillary moisture capacity were 1.19 g穋m-3,56.73%,15.7% and 43.2% in Michelia macclurei stand,1.26 g穋m-3,54.18%,13.0% and 37.8% in Schima superb stand,and 1.06 g穋m-3,60.74%,19.4%,and 45.8% in Castanopsis fissa stand,respectively.Soil water holding capacity and aeration were good in Castanopsis fissa stand but bad in Schima superba stand,whereas Michelia macclurei stand had a medium water holding capacity and a bad aeration.The water holding capacity of litter per tree was in order of Michelia macclurei (20 kg)>Castanopsis fissa(15 kg)>Schima superba(8 kg),whereas that of litter in stand was Castanopsis fissa(17 t穐m-2)>Michelia macclurei(16 t穐m-2)>Schima superba(13 t穐m-2).The nutrient storage of litter per tree was 112.71,31.20 and 87.30 g in Michelia macclurei,Schima superba and Castanopsis fissa stands,respectively,and that of litter in stand was 84.35,51.86 and 98.11 kg穐m-2,respectively.The soil in the three stands was strong acidic,and the content of soil organic matter,total N,total P,total K,alkalized N,available P and available K was 18.43 g穔g-1,0.69 g穔g-1,0.17 g穔g-1,5.83 g穔g-1,45.67 mg穔g-1,0.83 mg穔g-1 and 23.13 mg穔g-1 in Michelia macclurei stand,13.40 g穔g-1,0.68 g穔g-1,0.20 g穔g-1,12.32 g穔g-1,40.78 mg穔g-1,0.85 mg穔g-1 and 90.63 mg穔g-1 in Schima superba stand,and 28.50 g穔g-1,0.97 g穔g-1,0.23 g穔g-1,18.77 g穔g-1,73.40 mg穔g-1,1.45 mg穔g-1 and 66.50 mg穔g-1 in Castanopsis fissa stand,respectively.Soil bacteria accounted for >94% of soil microbes,and their individuals were 41?105,34?104 and 5.3?104 g-1 in Michelia macclurei,Schima superba and Castanopsis fissa stands,respectively.The activities of soil urease,catalase and phosphatase in Castanopsis fissa stand were the greatest among the three stands,while soil cellulase activity in Michelia macclurei stand was greater than that in other two stands.In a word,soil fertility of Castanopsis fissa stand was the highest among three test stands.
    Evapotranspiration of natural Quercus liaotungensis and Tilia paucicostata secondary stands in Liupan Mountains of Ningxia
    XIONG Wei, WANG Yanhui, YU Pengtao, Shi Zhongjie, Shen Zhenxi, Guo Mingchun
    2005, 16(9):  1628-1632. 
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    With heat dissipation probe technique and combined with microlysimeter and hydrological methods,this paper studied the evapotranspiration of secondary Quercus liaotungensis and Tilia paucicostata stands,and its relationship to forest structure from August to September 2004.The results indicated that the stem sap flux density (SFD) of Quercus liaotungensis and Tilia paucicostata changed regularly from day to night in later growth season.In relatively still period (nighttime),the SFD kept low values continuously,usually below 0.05 μl·cm-2·min-1,while in active period (daytime),it increased quickly,usually below 0.25 μl·cm-2·min-1.The daily transpiration of whole-tree was estimated based on the calculation of daily cumulative SFD,which showed that there existed a significant difference between two tree species.The daily transpiration of Quercus liaotungensis reached 5.31 and 2.48 L·d-1 in sunny- and cloudy-days,2.35 and 3.75 folds as that of Tilia paucicostata,respectively.There was no significant difference in daily leaf transpiration rate between these two shrub species.During measurement periods,the average daily stand evapotranspiration was 1.45 mm·d-1,including transpiration (0.72 mm·d-1),soil evaporation (0.19 mm·d-1),and canopy interception (0.54 mm·d-1),which accounted for 49.6%,13.3% and 37.1% of the total evapotranspiration,respectively.The results showed that the difference of whole-tree transpiration between tree species contributed significantly to the difference of tree canopy transpiration,while the difference of shrub canopy transpiration was on account of the leaf amount in the canopy.The effects of vertical layers in the stand on total stand evapotranspiration also differed,with a percentage of 65.8%,20.9% and 13.3% for tree canopy,shrub canopy and floor,respectively,which meant that the transpiration and interception of tree canopy contributed most to the total evpotranspiration,followed by shrub transpiration,soil evaporation,and grass transpiration.
    Rainfall interception model of forest canopy:A preliminary study
    GUO Mingchun, YU Pengtao, WANG Yanhui, SHEN Zhenxi, SHI Zhongjie, DU Apeng, HE Changqing
    2005, 16(9):  1633-1637. 
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    Canopy interception is an important hydrological process in forest ecosystem,and its modelling is of significance to understand and estimate the rainfall interception by the canopy.In this paper,a canopy rainfall interception model was established by dividing a rain incident into a set of short period,calculating the rainfall distribution intercepted by the canopy,and educing the process of the rain incident.This model considered the effects of the dryness of canopy and trunk on the evaporation from wet canopy and trunk during one rain incident,and introduced two factors,leaf area index (LAI) and surface area of trunk per unit area of ground (SAI),when computing the evaporation.The application of the model to simulate the rainfall interception process in a Larix principis-rupprechtii plantation in Guyuan,south Ningxia Hui autonomous region of China showed that the simulated and measured throughfall were identical,and the absolute deviation between simulated and measured results was within ?1 mm.But,when the precipitation was smaller than 6 mm,the simulated throughfall was lower than the measured one.The values of simulated stemflow were lower than the measured values,and the relative deviation between simulated and measured values was smaller when the precipitation was larger.The process of throughfall in the forest was also simulated,with the results fitted well to the measured one.
    Construction and verification of distributed rainfall-runoff model for forested watershed in alpine and gorge region
    LIU Jianmei, PEI Tiefan, WANG Anzhi, YANG Hong
    2005, 16(9):  1638-1644. 
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    Considering of the main hydrological characteristics in the upper Zagunao River watershed of the upper reach of Minjiang River,general hydrological models were selected to construct the distributed rainfall-runoff process model for the forested watershed in typical alpine and gorge terrains.Calibration of too many regional parameters was avoided to assure the transportability of the models in similar watersheds.Two flow series of 1 000 hours in 1999 and 2000 were simulated by using the distributed model.The runoff hydrograph,accumulative runoff volume,peak discharge,and peak time showed good fittings with observed series.The simple structure and less empirical parameters gave the distributed model the ability to simulate the rainfall-runoff processes in similar watershed across scales,which provided the basic approach to the hydrological scaling research.
    Application of wavelet transform to monthly runoff time serial analysis in Zagunao watershed,the upper Minjiang River
    LIN Yong, LIU Shirong, LI Chongwei, GE Jianping, SUO Anning, CHEN Baoyu
    2005, 16(9):  1645-1649. 
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    Runoff is an important component of regional water resources,and its dynamics is to some extent an indicator of water resources dynamics in a region.To know the runoff dynamics and water resources in a region is essential for the sustainable utilization and planning of water resources,and for the research on hydrological response of vegetation change at watershed scale.To disclose the water resources dynamics in Upper Minjiang River,one of the large reaches of Yangze River in southwest China,this paper analyzed the runoff dynamic features of Zagunao watershed,an important watershed in Minjiang River basin.Multi-Resolution Analysis (MRA) and periodicity analysis were conducted with Dmey wavelet function on the monthly runoff data from 1962 to 2002 observed by Zagunao hydrological station,which provided a data-based approximation on the evolution of monthly runoff in Zagunao watershed.It was found that the runoff dynamics in Zagunao watershed was relatively stable during 1962~1978,despite that this period was just in correspondence with the term of intensive deforestation activities in Upper Minjiang River basin.It was also clear that the runofff in Zagunao watershed was increased from 1986 to 1997,which was inconsistent with the commonly accepted viewpoint that the runoff decreased with increasing vegetation cover in forest watershed.However,the increasing trend from 1986~1997 was consistent with the research results in Yichang by Wang Wensheng and with the global warming at global and continent scale,which meant that global climate change plays a big role in runoff dynamics in Upper Minjiang River.Periodicity analysis showed that the rich-short water periodicity at the scale of 10 years (120 months) and 5 years (60 months) was 3 and 7 times,respectively,which could provide invaluable information for the eco-hydrological function research of forest landscape in Minjiang river basin and the sustainable utilization of water resources.The results from the case study highlighted that sometimes,it was very necessary to consider the role of global climatic warming in disclosing the hydrological response of land use/cover change at watershed scale,otherwise,it would be difficult to explain some hydrological phenomena.
    Microclimate characters of urban forest in Shenyang City
    XU Wenduo, HE Xingyuan, CHEN Wei, LIU Changfu, SUN Yu
    2005, 16(9):  1650-1654. 
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    This paper analyzed the diurnal changes of the temperature and humidity in Shenyang urban forest during its different growth stages.The results showed that air temperature was the lowest in the morning and the highest at noon.The highest peak point of air temperature lagged behind that of solar radiation about 2 hours,due to the influence of forest environment.The annual air temperature amplitude was in order of stop-growth period (dormancy stage) (DS)>prophase of growth season (PGS)>anaphase of growth season (AGS)>medium-term of growth season (MGS).Soil temperature of PGS,MGS and AGS at daytime was higher than that at night,while that of DS was in reverse.The daily soil temperature amplitude at different growth stages was in order of upper soil layer (20 cm)>medium soil layer (40 cm)>lower soil layer(80 cm),while the diurnal soil temperature amplitude in the same soil layer was in order of PGS>AGS>DS>MGS (20 cm) and PGS>DS>AGS>MGS (80 cm).The diurnal change of relative humidity was reverse to that of air- and soil temperature,which was higher at night than at daytime,and was in order of MGS>AGS>DS>PGS.
    Dynamics of total organic carbon (TOC) in hydrological processes in coniferous and broad-leaved mixed forest of Dinghushan
    YIN Guangcai, ZHOU Guoyi, ZHANG Deqiang, Wang Xu, CHU Guowei, LIU Yan
    2005, 16(9):  1655-1660. 
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    The total flux and concentration of total organic carbon (TOC) in hydrological processes in coniferous and broad-leaved mixed forest of Dinghushan were measured from July 2002 to July 2003.The results showed that the TOC input by precipitation was 41.80 kg穐m-2穣r-1,while its output by surface runoff and groundwater (soil solution at 50 cm depth) was 17.54 and 1.80 kg穐m-2穣r-1,respectively.The difference between input and output was 22.46 kg穐m-2穣r-1,indicating that the ecosystem TOC was in positive balance.The monthly variation of TOC flux in hydrological processes was very similar to that in precipitation.The mean TOC concentration in precipitation was 3.64 mg稬-1,while that in throughfall and stemflow increased 6.10 and 7.39 times after rain passed through the tree canopies and barks.The mean TOC concentration in surface runoff and in soil solution at 25 and 50 cm depths was 12.72,7.905 and 3.06 mg稬-1,respectively.The monthly TOC concentration in throughfall and stemflow had a similar changing tendency,showing an increase at the beginning of growth season (March),a decrease after September,and a little increase in December.The TOC concentration in runoff was much higher during high precipitation months.No obvious monthly variation was observed in soil solution TOC concentration (25 and 50 cm below the surface).Stemflow TOC concentration differed greatly between different tree species.The TOC concentration in precipitation,throughfall,and soil solution (25 and 50 cm depths) decreased with increasing precipitation,and no significant relationship existed between the TOC concentrations in stemflow,surface runoff and precipitation.The TOC concentrations in the hydrological processes fluctuated with precipitation intensity,except for that in stemflow and soil solutions.
    Application of phenological pattern recognition in ecological dynamic forecasting
    PEI Tiefan, JIN Changjie
    2005, 16(9):  1661-1666. 
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    This paper described the principles,methods,and procedures of ecological dynamic forecasting by the automation techniques of pattern recognition and mathematical logic judgment on the basis of phenological data and model output maps from T42L9 numerical weather prediction model.This new forecasting method proposed on the basis of modern meteorology and automation techniques enables the classic phenology to apply to a new field ecological forecasting.It enables phenological forecasting to develop from single-station forecasting stage to regional forecasting stage,which is greatly corresponded to the development stage from single station forecasting stage to synoptic stage in weather forecasting,and enables agro-meteorological forecasting to develop from qualitative and statistical forecasting stage to ecological dynamic forecasting stage.With this new qualitative forecasting method,both the predicted objective and predictors are of considerable bio-physical interests.The ecological dynamic forecasting method could be applied to crop sowing,crop growth,irrigation and fertilization,and diseases and pests control.
    Effects of continuous cropping on understorey species diversity in Eucalypt plantations
    WEN Yuanguang, LIU Shirong, CHEN Fang
    2005, 16(9):  1667-1671. 
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    By the methods of time-space series analysis and field monitoring,this paper studied the species diversity and its maintaining mechanism in Dongmen Eucalypt plantations of Guangxi.The results indicated that during the period of 1998~2003,continuous cropping of Eucalyptus plantation resulted in a reduction of species diversity.The plant species number of second generation was reduced by 54.43% in a 667 m2 plot,and by 50% in 18 sampling plots (each of 4 m2),and the species richness and Shannon-Wiener index of 6-year second generation forest decreased by 39.39% and 17.76%,respectively,compared with the first generation.The continuous cropping not only decreased the species diversity,but also changed the species composition and characteristics of the community.Life-form spectra of Eucalypt plantations varied with generation.The plant life-form consisted of micro-phanerophytes,liana phanerophytes,and nana-phanerophytes in the first generation,while the herbaceous-phanerophytes and chamaephytes occurred in the second generation.The k-strategy and r-strategy species accounted for 69.32% and 30.68% in the first generation,while 47.83% and 52.17% in the second generation,respectively.Therefore,continuous cropping of Eucalypt plantations was advantage for herb,therophytes and r-strategy species,but disadvantage for woody plants and k-strategy species.Seed band and vegetative body in soil were considered to play an important role in maintaining diversity.A new hypothesis,initial plant Diaspora,on the maintaining mechanism of species diversity in Eucalypt plantation was put forward.
    Effects of islanding on plant species diversity in Thousand-island Lake region
    LU Jianbo, DING Lizhong, XU Gaofu
    2005, 16(9):  1672-1676. 
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    In this paper,the typical area of fragmentation in Thousand-island Lake region was selected to study the effects of islanding on plant species diversity after reservoir built.26 quadrates were installed on 18 small,medium and large islands to investigate the species and number of trees and shrubs,with inland as the control One-way variance analysis (ANOVA) showed that the species richness of trees was significantly different (F=13.055,P=0.000) among all kinds of islands,which was significantly higher on large islands than on small and medium ones,but not significantly different from that on inland.The species richness of shrubs was not significantly different among all kinds of islands and inland.Spearman correlation analysis showed that the species richness of trees was significantly positively correlated with island area,while the correlation between specie richness of shrubs and island area was not significant.Shannon-Wiener Index (H) analysis suggested that the diversity of both trees and shrubs on large islands was the highest,followed by on inland,but the diversity of shrubs was larger on small than on medium islands.The analysis of Simpson index and Pielou index showed that the species evenness of trees was the highest,but the dominance was the lowest on medium and large islands,while the species evenness of shrubs was the highest on medium and small islands,but the dominance was the lowest on small islands.
    Secondary succession characteristics of vegetations on reclaimed land inside Chongming wetland seawall
    GE Zhenming, WANG Tianhou, SHI Wenyu, ZHAO Ping
    2005, 16(9):  1677-1681. 
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    National reserve Chongming Dongtan wetland was designated as an important international wetland (ramsar site) in 2002.The area outside 98 seawalls is the core area of the reserve,while their inside is the experimental area.A wetland restoration project was started in June 2003,and a large pond behind the seawall was unwatered,which changed the soil condition and appeared drought and salinization.The vegetations presented typical secondary succession,and Aeluropus littoralis and Suaeda glauca invaded the area originally dominated by reed.From July 2003 to April 2004,the soil moisture content and salinity of 15 samples were determined,with the biomass,height,density,and coverage of each kind of vegetations measured.The results showed that the vegetation layout had become an obviously zonary distribution of Aeluropus littoralis-Aeluropus littoralis/Suaeda glauca-Suaeda glauca/Phragmites communis-Phragmites communis community.Suaeda glauca gradually extended to the reed area,and became the dominant species of the area,with an average biomass of 2003 415.4 g穖-2 in autumn,and of 2004 391.53 g穖-2 in spring.The biomass and height of Suaeda glauca increased,and its density was getting stable,suggesting that the plant had strong growth ability in drought area.
    Physiological responses of 2-year-old Acer davidii seedlings to short-term enhanced UV-B radiation
    ZUO Yuanyuan, LIU Qing, LIN Bo, HE Hai
    2005, 16(9):  1682-1686. 
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    At the Maoxian Ecological Experimental Station of Chinese Academy of Sciences in northwest Sichuan Province,2-year-old native maple(Acer davidii) seedlings were potted outdoors with enhanced UV-B radiation(280~320 nm) of 0.27 W·m-2(7.7 kJ·m-2·d-1),which was approximated to the predicted enhanced UV-B reaching the earth surface when stratosphere ozone was depleted by 15% in the local area,with the control plant received ambient UV-B.The gas exchange index and chlorophyll fluorescence,and the contents of chlorophyll and UV-absorbing compounds were examined after 50 days of the radiation.The results showed that enhanced UV-B radiation significantly lowered the maximal net photosynthetic rate(CK=6.214,TR=4.452),raised the dark respiration rate(CK=0.413,TR=1.295) and light compensation point(CK=21.629,TR=59.861),but had little effect on quantum yield(CK=0.021,TR=0.032).Under enhanced UV-B radiation,the diurnal changes in net photosynthetic rate,water use efficiency,quantum efficiency of photosystem Ⅱ centers(Fv/Fm),and quantum yield of photosystem Ⅱ photochemistry(ΦPSП) were reduced,chlorophyll a,total chlorophylls,and chlorophyll a/b(CK=16.23,5.39,TR=13.17,4.93) were also markedly reduced,but chlorophyll b remained nearly unchanged.Contrary to the previous studies,enhanced UV-B radiation decreased the content of UV-absorbing compounds(CK=0.87,TR=0.79) in 2-year-old Acer davidii seedling leaves,indicating that the measurement of leaf UV-B absorbing compounds didn't necessarily provide a good indicator of plant tolerance to UV-B.It could be concluded that enhanced UV-B radiation had some inhibitory effects on the photosynthesis of Acer davidii seedlings.Long-term researches are necessary to confirm this conclusion.
    Fitness analysis of seed- and vegetative reproduction of clonal tree Symplocos laurina
    ZHANG Yunchun, DU Xiaojun, ZHANG Qiaoying, GAO Xianming, SU Zhixian
    2005, 16(9):  1687-1692. 
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    There are two ways in Symplocos laurina propagation,clonal and sexual reproduction.The study showed that under different habitat conditions,Symplocos laurina could adopt different ways to propagate and occupy space.In conditions with abundant water and nutrient resources,such as in evergreen broad-leaved forests or bamboo forests,the survival rate and space-occupying ability of both ramets and sexual seedlings were relatively high,with clonal ramets took advantage in terms of number and space,suggesting that clonal propagation was the dominant way in such environments.Oppositely,in habitats lack of sufficient nutrition,the survival rate and space-occupying ability of seedlings were low,and grown-up plantlets would preempt in number and space occupation.Bottleneck in sexual propagation appeared in the stage from seed to seedling,while clonal propagation appeared during the period from seedling to ramet.The way of Symplocos laurina invasion was to settle a plantlet,and then occupied the space rapidly by clonal growth,with clonal seedlings dominated in initial stage and lost the advantage after 15 ages.
    Landscape stability and its pattern transition in Jinghe watershed
    XIE Gaodi, ZHEN Lin, YANG Li, GUO Guangmeng
    2005, 16(9):  1693-1698. 
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    Based on remote sensing and GIS,this paper analyzed the landscape change patterns in the Jinghe watershed of northwest Loess Plateau,one of the areas most suffered from soil and water erosion.The results indicated that the landscape structure in the watershed did not change very much over the past 15 years,and was dominated by grassland and arable land,which occupied 85% of total watershed area.Forest and other land use accounted for 10% and 5% of total area,respectively.A transition of landscape patterns occurred at large-scale watershed level.During 1986~2000,the inter-transitions between different landscape types were very complicated,mainly occurred among woodland,grassland and arable land.The self-stableness of dominant landscape patterns was >89%,and only 11% of them transferred into other types.Among landscape types,the one sharing small percentage of the total had a high speed of vanishing or transferring into other types.A significant transition was found between sub-patterns of a large landscape pattern,e.g.,the transition of medium- into low-coverage grassland during 1986~1995 and the reverse during 1995~2000 was occurred,implying a situation of grassland degradation and improvement over the decades.The spatial-temporal changes of landscape features were observed in the watershed.In terms of spatial change,the dominance index and contagion index of the landscape showed an increasing trend,fractal dimension index showed a decreasing trend,while patch density showed an increasing trend,followed by a decreasing trend from upper to down streams.For temporal change,both landscape dominance and contagion decreased to a certain extent,fractal index remained stable,while patch density increased,showing a fragmentation direction of the landscape in the watershed.The NDVI value changed since the implementation of the policy of conversing farmland into grassland and forest in 2000,which was from 7.4% to 0.8% in low value class,from 29.8% to 25.1% in high value class,from 18.3% to 25.7% in higher value class,and from 2.3% to 5.5% in the highest class,showing an improving trend in landscape quality.
    Landscape pattern and its functioning after ecological reconstruction in black soil region of northeast China
    WEI Jianbing, XIAO Duning
    2005, 16(9):  1699-1705. 
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    Taken Baiquan County in Heilongjiang Province as a case,this paper studied the effects of regional ecological reconstruction on agricultural landscape pattern and its functioning in soil and water conservation,with the spatial expression and quantity identification investigated based on Geographic Information System (GIS) and field data.The landscape pattern index in class scale,transition matrix of landscape elements,macrostructure of shelterbelt networks,and spatial distribution and hydrological characteristic of reservoirs and ponds in 1989 and 2002,as well as the effects of landscape pattern and its spatial configuration change on soil and water loss were compared.The results showed that artificial ecological reconstruction changed the quantity and spatial configuration of landscape patterns in regional scale,and exerted a significant effect on soil and water conservation.From 1989 to 2002,farmland area reduced 24 731.01 hm2,while forest land,grassland and water area increased 11 728.56,(1 838.97) and 1 190.97 hm2,respectively.The controlled eroded land increased by 55%,and the shelterbelt-protected farmland increased by 82.2%.The number and storage capacity of reservoirs and ponds added up to 1 490 and 2.4×108 m3,respectively,and 43.7% of intercepted surface runoff of whole landscape was collected.
    Spatial pattern of sub-alpine forest restoration in west Sichuan
    ZHANG Yuandong, LIU Shirong, ZHAO Changming
    2005, 16(9):  1706-1710. 
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    West Sichuan sub-alpine is an extension of Qinghai-Tibet Plateau to southeast China,which is covered mainly with dark coniferous forest.As a result of long-term large scale over-logging,the forests have been greatly reduced and degraded.Nowadays,the forest restoration and regeneration in the region are being highlighted.Selecting Miyaluo as a case study area and employing the methods of plot investigation,ETM image interpretation,and overlaying vegetation map with digital topography,this paper analyzed the relations between the appearance and origin of four forest vegetation types,along with their topography differentiation and spatial patterns after a large scale logging and regeneration.The results showed that the appearance of forest vegetations was significantly correlated with their origin.Old coniferous forests (OC) were primitive ones,middle-aged and young coniferous forests (MYC) were from artificial regeneration,deciduous broadleaf forests (DB) were natural secondary ones,while mixed coniferous and deciduous forests (MCD) were partly from natural secondary ones and others from the conjunct action of artificial and natural regeneration.The main cut area in Miyaluo located in the sites with elevation from 2 800 to 3 600 m,where forest restoration appeared difference among different aspects.MYC was mainly distributed on sunny and half-sunny slope,DB and MCD were distributed on shady and half-shady slope,and OC were reserved on the sites with elevation more than 3 600 m.In the process of forest restoration,the four forest vegetation types were in mosaic pattern,and the landscape was seriously fragmentized.
    Forest landscape restoration and its affecting factors in burned area of northern Great Xing′an Mountains—Taking forest coverage as an example
    XIE Fuju, XIAO Duning, LI Xiuzhen, WEI Jianbing, WANG Xugao
    2005, 16(9):  1711-1718. 
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    Forest landscape restoration has been an attractive issue since the catastrophic fire took place on the northern slope of Great Xing′an Mountains in 1987.Based on the China forest inventory data and employing Kendall Bivariate and Distances Correlation Analyses,an investigation was made to search for what changes of the forest coverage pattern being happened in this area during the past 13 years after fire,and how the fire severity,foster type and terrain factors influenced the restoration of forest coverage.The results showed that the forest coverage in 2000 changed a lot,in comparing with that in 1987 before fire.The percentage of non-stocked land area and coverage grade declined markedly,with lower coverage grade increased.Among all test factors,fire severity which was inversely correlated with forest coverage grade was the key one.Though the regeneration measures didn't markedly affect forest coverage restoration within a short period,they might shorten the cycle of forest succession and promote the productivity of coniferous forest in the future.Among three terrain factors,slope was the strongest one affecting forest coverage,followed by position and aspect.
    Relationships between soil and water loss and landscape pattern on Loess Plateau
    SUO An′ning, HONG Jun, LIN Yong, GE Jianping
    2005, 16(9):  1719-1723. 
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    Based on the theories of detrended canonical correspondence analysis (DCCA),12 soil and water loss indices ("species") and 7 landscape indices ("environmental factors") were adopted to quantitatively analyze the effects of landscape pattern on the soil and water loss in Jinghe River basin on Loess Plateau.The results showed that the first four DCCA axes were significantly correlated to agricultural land ratio,landscape diversity index,forest land ratio,and landscape contagion index.The characteristics of soil and water loss changed obviously with landscape pattern gradient,e.g.,Sanshuihe watershed with a forest cover larger than 65% and low landscape diversity had a big and stable runoff,but small sediment and low river sand content.The runoff generation coefficient and runoff depth as well as the sediment transport and river sand content increased with the increasing agricultural land ratio and landscape diversity and the decreasing forest land ratio.As for Honghe watershed with a very low forest cover but high agricultural land ratio (53.41%),and with a relatively high landscape diversity and complex landscape pattern,it had the highest river sand content and the biggest sediment transport,and its monthly runoff and sediment transport varied markedly.The soil and water loss in the Upper-Huan,Down-Huan and Dongchuan watersheds with smaller forest and agricultural land ratio and relatively simple landscape pattern was smaller than that of the watersheds with dominated agricultural land.
    Landscape change in Kangbao County of Hebei Province
    LIU Miao, HU Yuanman, BU Renchang, CHANG Yu, HAN Wenquan, HU Zhibin
    2005, 16(9):  1724-1728. 
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    Based on RS image TM5 of 1999 and SPOT5 of 2003,this paper studied the landscape change from 1999 to 2003 of Kangbao County,Hebei Province.Logistic regression was adopted to analyze the driving factors,and Kappa index was used to evaluate the accuracy of the landscape classification result,which was 86.72% for 1999,and 89.76% for 2003.The area of cropland in Kangbao County reduced largely,while that of vegetable field,forestland and artificial grassland increased sharply,among which,vegetable field and artificial grassland had the greatest increasing rate.The landscape fragmentation aggravated in the region.The landscape change was mainly caused by the policy of reducing cultivated land,with the main driving factor slope,and the direct driving factor water-heat condition and soil fertility determined by slope aspect.
    Fine-root character and its action mechanism of forest at its initial reestablished stage on degraded red soil
    LIU Yuanqiu, LUO Liangxing, LIU Liangying, YANG Jialin, XIA Xiaolan
    2005, 16(9):  1729-1734. 
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    This paper studied the fine-root character and its action mechanism of forest reestablished by different models for 10 years on a seriously degraded red soil,and analyzed their correlation with soil property.The results showed that fine-roots mostly distributed in 0~20 cm soil layer,accounted for 73.39%~87.41% of those in 0~40 cm soil layer.There were notable differences in nutrient storage of fine-roots under different reestablishment models.The fine- roots of medium density pure Pinus serotina forest had a much higher storage of total nitrogen,phosphorus and potassium,with the content of total nitrogen,phosphorus,potassium,calcium and magnesium being 84.47,5.55,38.42,17.00 and 10.76 kg·hm-2,respectively.Soil organic matter,total nitrogen,available nitrogen,available potassium and pH had significant correlations with fine-root biomass (P<0.05).The effects of fine-roots on soil physical properties mainly reflected on soil capillary porosity and total porosity.Fine-roots obviously increased the contents of >0.25 mm and >5 mm soil waterstable aggregates,and improved soil structure-stability.The correlations between fine-roots and soil bacteria and microbial quantities were significant.
    Effects of different cutting intensities on above- and underground growth of Stylosanthes guianensis
    ZHANG Jia'en, LIU Wengao, CHEN Jingqing, SHI Yaocai, CAI Yanfei
    2005, 16(9):  1735-1739. 
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    The study on the effects of different cutting intensities on the eco-physiological characteristics and growth status of Stylosanthes guianensis showed that moderate cutting could promote the regrowth capacity of the grass.The total content of leaf chlorophyll had no significant difference between zero-,light-and heavy cutting,but the ratio of leaf chlorophyll a/b increased to 1.59:1 and 1.52:1 under light-and heavy cutting,respectively,compared with 1.22:1 under zero-cutting,which could be very helpful for the plant to over-compensate itself.Cutting also affected the growth status and activities of plant roots.At the earlier stage of heavy cutting,the total length,total surface area and mean diameter of plant roots decreased by 54.9%,66.5% and 27.2%,respectively,and root activities also decreased greatly,in comparing with zero-cutting.But,the above-mentioned indices could be recovered to a higher level under different cutting treatments than under zero-cutting at the later growth period of the grass.As for the total annual yield of the grass,it was 3 179.8 g穖-2 under light-cutting,3 006.1 g穖-2 under heavy- cutting,and 2 936.98 g穖-2 under zero-cutting,indicating that rational cutting could improve grass productivity.
    Economic values of nitrogen transformation in rice field ecosystems
    XIAO Yu, XIE Gaodi, LU Chunxia
    2005, 16(9):  1740-1744. 
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    Based on the 2002 field experimental results in the Wusi Farm of Fengxian County in Shanghai and related studies,and by the methods of ecological economy and environmental economy,this article examined and estimated the nitrogen input and output,and the economic values of nitrogen transformation in rice field ecosystems.The results indicated that the plot without N fertilization showed a deficit of nitrogen budget,while those with urea application showed a surplus.The economic value of the plot without urea amendment was evaluated to be positive,while that of the plots with urea application was calculated to be negative.The negative value of the plots with urea amendment resulted from the nitrogen losses through ammonia volatilization,nitrogen leaching and runoff,which had serious harmful impacts on environment and human society.Therefore,only when some measures were taken to encourage and facilitate farmers to improve the efficiency of urea application and to mitigate the environment problems from N losses in the process of food production,the advantages of nitrogen transformation in rice fields could be promoted,and the sustainability of agriculture would become reality.
    Sex pheromone secondary components of Indian meal moth Plodia interpunctella in China
    HU Wenli, DU Jiawei
    2005, 16(9):  1745-1750. 
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    Indian meal moth Plodia interpunctella H黚ner (Lepidoptera:Pyralidae) is considered as an important insect pest infesting stored grains and other products in China.The major sex pheromone component of P.interpunctella,Z9,E12-14:OAc (TDA),has already been identified.Though the efficiency of male capture by using the bait with this component alone is quite good,the pheromone system is far from fully understood.The identification with capillary chromatographic analysis and GC-MS methods showed that there were four main components,i.e.,Z9,E12-14:OAc(A),Z9,E12-14:OH(B),Z9,E12-14:Ald(C),and Z9-14:OAc(D),in the sex pheromone gland of female P.interpunctella,and the ratio of these four components was A:B:C:D=100:22:12:9.Wind tunnel experimental results suggested that the response of male P.interpunctella to a blend (A:B:C:D=8:2:1:0.8) was not significantly different from that to female sex pheromone gland extracts.
    Phosphate adsorption and desorption characteristics of several fly ashes
    FENG Yuehua, HU Ruizhi, ZHANG Yangzhu, ZOU Yingbin, HUANG Yunxiang, WANG Cuihong, LI Fayun
    2005, 16(9):  1751-1755. 
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    Through adsorption-desorption experiment and incubation test,this paper studied the phosphate adsorption and desorption characteristics of several fly ashes.The test fly ashes contained 0.545~4.540 g·kg-1 of total P and 19.55~163.0 mg·kg-1 of available P,which were significantly higher than those in soils.The P adsorption capacity of fly ashes increased with increasing added P,while their P adsorption rate was in adverse.Fly ashes had a higher P adsorption rate but a lower P desorption rate than soils,mainly because fly ashes had more P adsorption sites and stronger bound energy.In this study,Langmuir,Freundlich,and Temkin equations were fit to the measured data,and the MBC value in Langmuir equation,a value in Freundlich equation,and k2> value in Temkin equation could be used as a comprehensive index to characterize the potential phosphate adsorptivity of fly ashes.The larger these values were,the stronger the P adsorptivity was.The MBC,a and k2> value of 5 fly ashes collected from different locations was in order of Xiangtan power factory (5 167.7,4 056.2 and 831.5) >Yueyang paper factory (1 650.7,2 803.4 and 711.9)>Huaneng power factory (303.0,1 677.6 and 368.7)>Zhuzhou power factory (34.7,413.48 and 213.8)>Dongting nitrogen fertilizer factory (34.7,413.48 and 213.8).The P fixation by fly ashes generally increased with their increasing water content,and their phosphate adsorption was mainly specific adsorption and chemical precipitation,suggesting that the P fixation and the water content of fly ashes should be considered when fly ash was used as soil amendment or as compound fertilizer filling substance.
    Degradation-detoxification behavior of methamidophos in phaiozem and burozem rhizosphere
    YU Ying, ZHOU Qixing
    2005, 16(9):  1756-1760. 
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    With plastic rhizobox system,this paper studied the degradation behavior of methamidophos in the rhizosphere and non-rhizosphere of phaiozem and burozem planted with soybean.The results suggested that methamidophos could be rapidly decomposed in soil environment despite its higher acute toxicity,and its residual amount in phaiozem was generally below the level in burozem under same condition.In the absence of soybean (control),the residual amount of methamidophos at the 2nd day of incubation was about 33% in burozem,whereas only about 26% in phaiozem.An accelerated degradation of methamidophos in soybean rhizospheric soil was observed,especially in phaiozem.At the 9th day of incubation,the insecticide residue in the middle rhizobox phaiozem and burozem with soybean was decreased by 87.5% and 76.0%,respectively,compared with that of the control.The degradation process of methamidophos in soil environment followed the first-order equation,and its half-life was about 2 days.
    Bt toxin distribution in transgenic Bt cotton and soil system
    SUN Caixia, CHEN Lijun, WU Zhijie
    2005, 16(9):  1761-1764. 
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    This study showed that the amounts of Bt toxin expressed in transgenic Bt cotton leaves and stems (103.5~134.1 ng·g-1) were rather higher than those expressed in transgenic Bt cotton roots (44.7~21.2 ng·g-1),indicating that total amount of soil Bt toxin introduced by transgenic Bt cotton could be decreased through treating its above-ground biomass.In comparing with the amount of Bt toxin expressed in transgenic Bt cotton plant,that expressed in its root exudates was rather lower,showing that the effects of plant Bt toxin on soil ecosystem would be limited if other sources of Bt toxin introduced into soil were controlled.
    Research advances in inverse methods used for modeling plant-atmosphere exchange
    DIAO Yiwei, PEI Tiefan
    2005, 16(9):  1765-1768. 
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    To estimate the source/sink and the vertical fluxes of mass and energy within and above plant canopies continues to be a critical research problem in biosphere-atmosphere exchange processes.The underlying approaches in such problem are to exploit the natural properties of turbulence within and above vegetation,such as Lagrangian inverse analysis,high order Eulerian closure model,and hybrid Eulerian-Lagrangian method.This paper introduced the recent development in multilayer turbulent transport methods to compute the distributions of the strengths of scalar sources and sinks within plant-atmosphere continuum,and in particular,focused on the so-called "inverse methods",and described above three methods and their characteristics in detail.The limitation and prospect of these methods were also mentioned.
    Research progress on unsaturated and saturated soil water movement in forest catchments
    YANG Hong, PEI Tiefan
    2005, 16(9):  1769-1772. 
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    This paper reviewed the studies on the movement ways,i.e.,infiltration,phreatic evaporation,ground water recharge and interflow,of unsaturated and saturated soil water in forest catchments,and introduced the present advances in soil hydraulic parameters,including soil water characteristic curve,and unsaturated and saturated soil hydraulic conductivity.Research directions in the future were also proposed.
    Advances in research effects of temperature fluctuation on aquatic fauna
    TIAN Xiangli, DONG Shuanglin
    2005, 16(9):  1773-1779. 
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    This paper reviewed the researches on the effects of diurnal temperature fluctuation on aquatic fauna,including the test species involved,design of thermal regimes,growth responses of aquatic fauna to various fluctuated temperature,and growth-promotion mechanisms of temperature fluctuation.The problems existed in related researches and the application perspectives in the future were also highlighted.
    Understory vegetation composition and main woody population niche of artificial masson pine forest in south subtropical area
    KANG Bing, LIU Shirong, SHI Zuomin, WEN Yuanguang, CAI Daoxiong, LU Lihua, LIANG Hongwen, FENG Changlin
    2005, 16(9):  1780-1785. 
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    This paper studied the characteristics of the natural understory vegetation in the artificial masson pine forest replanted after Chinese fir cut for 13 years.The results indicated that there were 100 species of understory vegetation,including 74 species of shrub or small arbor,accounting for 74.0% of the total species,belonging to 41 faculties and 63 categories,and 26 herbs belonging to 14 faculties and 23 categories.The tropical and subtropical elements were dominant in the vegetation,while the temperate ones were scare.The species diversity and richness were decreased after masson pine regenerated from Chinese fir.The analysis of important value showed that the main species of shrub or small arbor were Tinomiscium tonkinensis,Mycetia longiflora,Evodia lepta,Paederia scandens,Mussaenda pubuscens,Actinodaphne pilosa and Quercus glauca,and those of herb were Cyrtococcum patens,Blechnum orientale,Dicranopteris dichotoma,Adiantum flabellulatum,Adiantum edgeworthii and Pteris semipinnata.The biomass of the vegetation in different slope positions was decreased in order of upside>downside>middle part.There was a significantly positive correlation between the niche breath and the important value of main woody population.The important values of woody populations were higher than those of the others,and their niche breadths were also larger,which meant that they were more adaptable to the habitat.The niche overlaps of six population counterparts Tinomiscium tonkinensis-Mycetia longiflora,Tinomiscium tonkinensis-Evodia lepta,Mussaenda pubuscens-Maesa japonica,Quercus glauca-Aphananthe aspera,Actinodaphne pilosa-Saraca chinensis and Evodia lepta-Quercus glaucathese were very large,which could offer information for the restoration and reconstruction in selecting natural vegetation.The large niche overlaps of major woody population counterparts suggested their similar utilization of natural resources.
    Biodiversity of main coniferous forests at low elevation of Three Gorges Reservoir area
    CHENG Ruimei, XIAO Wenfa
    2005, 16(9):  1786-1790. 
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    The study showed that at low elevation of Three Gorges Reservoir area,Pinus massoniana,Cupressus funebris and Cunninghamia lanceolata were the main coniferous forests,which were respectively divided into 14,9 and 5 community types based on field investigation.The whole trend of their species richness index,species diversity index and species evenness index was that shrub layer and herb layer were larger than tree layer.The diversity indices had no obvious trend along the low elevation gradients,which was probably relevant to the high intensity of human activities in the area.
    Application of fractal theory in studying soil aggregates under different skidding modes
    LI Junfeng, ZHAO Xiuhai
    2005, 16(9):  1791-1794. 
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    In this paper,the characters of soil aggregates under different skidding modes were investigated by fractal theory.The results showed that the particle fraction of soil aggregates was smaller under tractor- than under animal traction skidding.As for different parts of skidding road,the particle fraction of air-dried soil aggregates was in the order of bottom (2.309) > middle (2.291) > upper (2.014),while that of water-stable aggregates followed the sequence of bottom (2.04) < middle (2.143) < upper (2.262).The particle fraction of aggregates was 2.215 in forest soil and 2.175 in skidding roads.Skidding movement could improve soil aggregates when the cutting intensity was 15%.Tractor skidding was more favorable for soil aggregates formation.