Table of Content

21 February 2008, Volume 19 Issue 02

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Articles

Time lag effect between stem sap flow and photosynthetically active radiation, vapor pressure deficit of Acacia mangium.

WANG Hua^1,2,3; ZHAO Ping¹; CAI Xi-an¹; MA Ling¹; RAO Xing-quan¹; ZENG Xiao-ping¹

2008, 19(02):  225-230 . 

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Based on the measurement of the stem sap flow of Acacia mangium with Granier’s thermal dissipation probe, and the cross-correlation and time serial analysis of the sap flow and corresponding photosynthetically active radiation and vapor pressure deficit, this paper studied the time lag effect between the stem sap flow of A. mangium and the driving factors of the tree canopy transpiration. The results indicated that the main driving factors of the transpiration were photosynthetically active radiation (PAR) and vapor pressure deficit (VPD). Sap flux density (J_s) was more dependent onPAR than on VPD, and the dependence was more significant in dry season than in wet season. Sap flow lagged behind PAR but advanced than VPD in both dry and wet seasons. The time lag did not show any significant variation across different size tree individuals, but showed significant variation in different seasons. Time lag effect was not correlated with tree height, diameter at the breast, and canopy size. The time lag between J_s and VPD was significantly related to nighttime water recharge in dry season, but reversed in wet season.

Spatiotemporal characteristics of photosynthetically active radiation in understory of Korean pine and broadleaved mixed forest in Changbai Mountains.

YUAN Feng-hui^1,2; GUAN De-xin¹; WU Jia-bing¹; WANG An-zhi¹; SHI Ting-ting^1,2; ZHANG Xiao-jing^1,2

2008, 19(02):  231-237 . 

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Based on the data of three years successive automatic measurement with five horizontal quantum PAR sensors, this paper studied the spatiotemporal characteristics of photosynthetically active radiation (PAR) in the understory of Korean pine and broadleaved mixed forest in Changbai Mountains, in contrast with abovecanopyPAR. It was found that the annual dynamics of abovecanopyPAR showed two or more peaks, which was mainly affected by the weather conditions such as cloudy, foggy and rainy events. The annual dynamics of understory PAR followed the same trend of abovecanopy PAR in non-growth season, but was steady and lower in numerical value in growth season. On clear days, larger differences were observed in the diurnal variation and frequency distribution of the understory PAR. As for the spatial variation of the understory PAR, the coefficient of variation (CV) was smaller in non-growth season (about 0.15) than in growth season (>0.22), with the greatest in August. On the clear days in growth season, the understory PAR had a greater spatial variation when the solar elevation angle was between 38°and 48° (at 9:00-10：00 or 13:00-14:00).

Effects of forest gap on the seedling growth of a canopy tree species Pometia tomentosa in tropical rainforest of Xishuangbanna.

YAN Xing-fu^1,2; CAO Min¹

2008, 19(02):  238-244 . 

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In this paper, the seedling’s early growth and establishment of Pometia tomentosa, a canopy tree species in Xishuangbanna tropical seasonal rainforest, were investigated under different illumination gradients (gap center, gap edge, and under canopy). The seedling height, basal stem diameter, total dry mass, leaf area per seedling, and relative growth rate at early stage peaked in gap center, with the values of 24.45 cm, 3.17 mm, 0.79 g, 122.45 cm², and 14.78×10^-3 g·d^-1, respectively. The seedlings had a higher root-shoot ratio under canopy (0.87) than in gap center (0.20) due to the influence of both illumination and water. The brighter illumination in gap center facilitated the growth of established seedlings, with the peaks of seedling height (31.48 cm), basal stem diameter (3.80 mm), total dry mass (2.22 g), leaf area per seedling (174.52 cm²), relative growth rate (2.29×10^-3 g·d^-1), and net assimilation rate (2.54×10^-5 g·cm^-2·d^-1) attained by the end of the investigation. The death of established seedlings might be closely related to water stress. Under canopy, the death rate caused by water stress was the highest (26.88%) but that caused by the predation of vertebrates was the lowest (2.93%), which in final, induced the highest survival rate (70.19%) of the seedlings. Illumination was the important factor affecting the morphological regulation of P. tomentosa eedlings. In gap center, the specific leaf area of the seedlings at their different growth stages was the smallest, but their relative growth rate and net assimilation rate were the greatest. The root-shoot ratio of established seedlings peaked at gap edge (0.33), suggesting that water stress and illumination were the important factors affecting the biomass allocation of established seedlings.

Decomposition of litter organic matter and its relations to C, N and P release in secondary conifer and broadleaf mixed forest in Changbai Mountains.

LI Xue-eng¹;HAN Shi-ie¹;HU Yan-ing^1,2;ZHAO Yu-ao^1,2

2008, 19(02):  245-251 . 

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By using litterbag method, the decomposition processes of 9 types of foliar litter in secondary conifer and broadleaf mixed forest in Changbai Mountains were assessed during a period of 34 months. The initial N and P concentrations varied greatly among the litters, and there were significant relationships between litter decomposition constant (k) and initial N concentration and C/N. The percent organic matter remaining had a significant linear correlation with percent C remaining, and a significant polynomial correlation with percent N and P remaining. The percent N and P remaining increased with the decomposition of organic matter in its initial decomposition phase, but decreased gradually in the latter decomposition phase. C/N and C/P declined with the decrease of percent organic matter remaining, and the differences in C/N or C/P among litter types decreased, being approached to 23 and 350, respectively by the end of the study. During organic matter decomposition, N/P did not change greatly, and the differences in N/P between litter types declined when the percent organic matter remaining was below 25%. Our study showed that percent of C、N and P mass remaining can be predicted by percent of organic matter mass remaining.

Viability and germination characteristics of canopy-stored seeds of plants in sand dune area.

MA Jun-ling^1,2; LIU Zhi-min¹

2008, 19(02):  252-256 . 

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The study on the viability and germination characteristics of canopy-stored seeds remained in canopy until next May after maturation of 10 plants species in Horqin sandy land showed that more than 80% of the canopystored seeds of psammophytes such as Agriophyllum squarrosum, Artemisia wudanica and A. halodendron had viability, while less than 80% or even less than 30% of nonpsammophytes seeds had viability. The canopystored seeds of psammophytes presented a rapid germination pattern. The canopy seed bank made the seed release of psammophytes postponed until the windy season ended and the rainy season started, when the seeds had high viability and could germinate rapidly. The canopy seed bank is one of ways for psammophytes to adapt drift sand and seasonal drought.

Structural characteristics of Hemiptelea davidii community on Kerqin sandy land.

BAI Yun-peng;HAN Da-yong; DONG Yan-hong; ZHAO Yu-jing; LI Jian-dong

2008, 19(02):  257-260 . 

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An investigation was made on the species composition and eco-type of Hemiptelea davidiicommunity on Kerqin sandy land. The results showed that in study area, no shrub layer existed in H. davidiiforest, while arbor layer could be divided into two sub-layers, with a height of 4.05-7.86 m for the upper layer, and of 2.05-3.20 m for the lower layer. In the community, there were 32 herbal species belonging to 27 genera of 13 families and dominant by Poaceae, Fabaceae and Compositae, and 11 areal types, among which, the species number in MongolianNortheastern China-Dahuricia-North China areal type was the highest (34.38%), followed by that in Northeastern China-North China areal type (12.5%). Among three water ecological types, mesophytes occupied 59.37% of the total, and mesoxerophytes and xerophytes occupied 25% and 15.63%, respectively. Hemicryptophytes had a larger amount in six life forms, accounting for 31.25% of the total. H. davidii community had the typical life form characteristics of temperate steppe.

Remote sensing estimation of natural forest biomass based on an artificial neural network.

WANG Li-hai; XING Yan-qiu

2008, 19(02):  261-266 . 

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Based on Landsat TM images and with the natural forest area of Wangqing in Jilin Province as a case, a nonlinear RS (remote sensing) modeling system of forest biomass was built by using a back-propogation artificial neural network (B-P ANN). In addition to RS data, the factors representing terrain conditions, such as elevation, slope, aspect and site type, were also included as independent variables in the modeling system. The standard B-P ANN was made more robust by reducing the size of input data and by improving the training algorithms, thereby leading to faster convergence speed and stronger capabilities of self-study and self-adaptation. The simulation results showed that the robust B-P ANN was able to utilize previous knowledge of data sets, and to automatically determine reasonable models. Model predictions of forest biomass were successful, with the mean relative errors and the mean absolute of relative errors for needle-leaved, broad-leaved, and mixed forests being -1.47%, 2.38% and 3.56%, and 6.33%, 8.46% and 8.91%, respectively. A forest biomass distribution map was derived, and the overall accuracy of the map was 88.04%.〖KH*2D〗

Application of ecological classification system in China’s digital forestry.

TANG Li-na^1,2; DAI Li-min²

2008, 19(02):  267-272 . 

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In China’s conventional forest management system, there are two types of sub-compartment,i.e., the 2nd- and 3rd-level sub-compartments, which are ncurrent but inconsistent in size and boundary locations. Even in the same type of sub-compartments, the inconsistency still existed at different time, which is unbeneficial to the long-term forest management planning by using digital technologies. With the mountainous region in eastern Liaoning Province as a case, this paper established an ecological classification system (ECS), which contained 5 ecological land types (ELTs) and 34 ecological land type phases (ELTPs). Based on the basic technical needs of China’s digital forestry, the ELTPs could be used as a fixed subcompartment system. A compatible forest inventory system was designed then. It was concluded that ecosystem management based on ECS and geospatial information technologies combined with computer models and decision-support systems would be the important component of digital forestry.

Estimation of forest canopy closure by using partial least square regression.

DU Xiao-ming^1,2; CAI Ti-jiu¹; JU Cun-yong¹

2008, 19(02):  273-277 . 

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Based on remote sensing and forest resources inventory data, this paper approached the feasibility of using Bootstrap approach to select optimal variables and using partial least square (PLS) regression to build a model for estimating forest canopy closure. The results showed that whether using a model built with all variables or a model with the optimal variables selected by Bootstrap approach, the relative deviation in estimating forest canopy closure was about 5%. The optimal variables selected in this paper differed greatly with those in the studies for other areas, suggesting that besides selection method, zonal vegetation and terrain could also induce the differences of selected optimal variables for the estimation of forest canopy closure.

Dynamic assessment of grassland degradation in Naqu of northern Tibet.

MAO Fei^1,2; ZHANG Yang-hong³; HOU Ying-yu³; TANG Shi-hao⁴; LU Zhi-guang²; ZHANG Jia-hua¹

2008, 19(02):  278-284 . 

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Based on the past years vegetation cover, annual maximal grass yield and June-September mean modified soil-adjusted vegetation index (MSAVI) that were inversely deduced from the 10-day composite data of NOAA/AVHRR channels 1 and 2 and NDVI in 1982-2000, this paper analyzed the recent 20 years dynamics of grassland desertification in Naqu of northern Tibet. The results showed that in recent 20 years, the area of degraded grassland in Naqu was averagely 43.1% of the total land area. It was decreased in the former ten years while increased in the latter ten years, but overall, had a decreasing trend. The degraded area was larger in west part of Naqu than in its other regions. Among the eight climatic factors including temperature, precipitation, potential evapotranspiration, vapor pressure, wind velocity, sunshine hour, ratio of precipitation to evapotranspiration, and ratio of temperature to precipitation, the most remarkable factor affecting the dynamic of grassland degradation was the potential evapotranspiration.

CO₂ fluxes in mire and grassland on Ruoergai plateau.

WANG De-xuan; SONG Chang-chun; WANG Yi-yong; ZHAO Zhi-chun

2008, 19(02):  285-289 . 

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With closed chamber and GC technique, a comparative study was conducted on the CO₂ fluxes in mire and grassland on Ruoergai plateau during the plant growth period in 2003-2005. The results showed that the mean value of the CO₂ fluxes in the three years was 203.22 mg·m^-2·h^-1 in mire and 323.03 mg·m^-2·h^-1 in grassland, with the former being only about 60% of the latter. The perennially waterlogging of mire limited the decomposition of plant residues, roots and organic substances, resulting in a lower CO₂ flux in mire than in grassland. The seasonal changes of CO₂ fluxes in mire and grassland were positively correlated with air temperature, the peak value being usually appeared in July or August, and the diurnal changes of the CO₂ fluxes were also positively correlated with air temperature, the peak value being usually appeared between 11:00 and 17:00. The CO₂ fluxes had a higher correlation with the soil temperature at the depth of 5 cm than at the depths of 10 cm and 15 cm.

Comparison of eddy covariance and static chamber/gas chromatogram methods in measuring ecosystem respiration.

ZHENG Ze-mei^1,2; YU Gui-rui¹; SUN Xiao-min¹; CAO Guang-min³; WANG Yue-si⁴; DU Ming-yuan⁵; LI Jun1; LI Ying-nian³

2008, 19(02):  290-298 . 

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Based on the measurement of carbon flux by the methods of eddy covariance and static chamber/gas chromatogram, a comparison was made between the two methods in evaluating ecosystem respiration over winter wheat (Triticum aestivum)-summer maize (Zea mays) double cropland and Kobresia humilis alpine meadow. The results showed that under the conditions of obtained data having good quality, nighttime ecosystem respiration from eddy covariance measurement was significantly agreed with that from static chamber/gas chromatogram measurement, with the correlation coefficients ranging from 0.95 to 0.98, and the daytime ecosystem respiration from these two measurements also had a good consistency though the static chamber/gas chromatogram measurement often produced higher values. The daily mean value of ecosystem respiration was significantly different between these two measurements, but the seasonal pattern was similar. For winter wheatsummer maize double cropland, the difference of mean air temperature inside and outside the chamber was 1.8 ℃, and the daily mean value of ecosystem respiration across the whole study period was 30.3% lower in eddy covariance measurement than in static chamber/gas chromatogram measurement; while for alpine meadow, the difference of the mean air temperature was 1.9 ℃, and the daily mean value of ecosystem respiration was 31.4% lower in eddy covariance measurement than in static chamber/gas chromatogram measurement. The variance between the daily mean values of ecosystem respiration obtained from the two measurements was higher in growing season than in dormant season.

Stem sap flow of grape under different drip irrigation patterns and its relationships with environmental factors in arid oasis region of Shiyang River basin.

DU Tai-sheng¹; KANG Shao-zhong¹; ZHANG Bao-zhong¹; LI Si-en¹; YANG Xiu-ying²

2008, 19(02):  299-305 . 

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This paper studied the stem sap flow of grape in arid oasis region of Shiyang River basin under conventional drip irrigation (CDI), alternate drip irrigation (ADI), and fixed drip irrigation (FDI), and its relationships with meteorological conditions and soil moisture content. The results showed that the stem sap flow of grape had an obvious day-night rhythm synchronous with solar radiation, and was significantly higher under CDI than under ADI and FDI during new branch growth and flowering stages. Solar radiation and air temperature were the main meteorological factors affecting the hourly sap flow, and the daily stem sap flow had linear relationships with daily air temperature and wind speed. The correlation coefficients between the stem sap flow and the meteorological factors ranked in the order of CDI>ADI>FDI. There was a significant correlation between daily stem sap flow and reference crop evapotranspiration (ET₀). Compared with CDI, ADI could save 50% of irrigation water while the stem sap flow only reduced by 6.56%, and an obvious compensation effect between stem sap flow and hydraulic conductivity was observed.

Physiological and biochemical responses of different scion/rootstock combinations grapevine to partial rootzone drought.

QI Wei^1，3; LI En-mao^1，2; ZHAI Heng^1，2; WANG Xiao-fang¹; DU Yuan-peng¹ 

2008, 19(02):  306-310 . 

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By using self-made wooden boxes with two separated zones, the grapevine Vitis vinifera cv. Malvasia (M) grafted on rootstocks 3309C, 420A and 110R, respectively, was planted, and the physiological and biochemical responses of these scion/rootstock combinations to bilateral alternative irrigation (AI) and unilateral irrigation (UI) were studied. The results showed that in treatments AI and UI, the average leaf ABA content of test scion/rootstock combinations increased by 267.5% and 394.7%, respectively, while stomatal conduction and transpiration decreased markedly. In treatment UI, the leaf SOD and CAT activities and Pro content were notably enhanced, with the greatest increment in M/110R and followed by in M/420A and M/3309C; while in treatment AI, the leaf SOD and CAT activities of test scion/rootstock combinations enhanced slightly and Pro content increased markedly. UI induced a remarkable increase of leaf relative electronic conductivity and MDA and H₂O₂ contents, with the highest increment in M/3309C and the lowest in M/110R. In summary, the drought resistance of different scion/rootstock combinations grapevine mainly depended on the variety of rootstock. 110R had a higher drought-resistance than 420A and 3309C. Comparing with unilateral irrigation, bilateral alternative irrigation had lesser damage to grapevine, being a profitable water-saving irrigation technique.

Effects of temperature and illumination on flag leaf photosynthetic characteristics and senescence of wheat cultivars with different grain quality.

ZHANG Li-ping; JING Qi; DAI Ting-bo; JIANG Dong; CAO Wei-xing 

2008, 19(02):  311-316 . 

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Taking wheat cultivars Yumai 34 (high protein content in grain) and Yangmai 9 (low protein content in grain) as test materials, and by the method of growth chamber, this paper studied the effects of different combinations of temperature and illumination on the photosynthetic characteristics and senescence of their flag leaves at grain-filling stage. The results showed that both high temperature and low illumination had negative effects on the photosynthesis. They decreased the net photosynthetic rate (P_n), photochemical efficiency (F_v/F_m), and actual photochemical efficiency (Φ_PSⅡ) significantly, but their action mechanisms were differed. High temperature mainly decreased the chlorophyll content (SPAD value) and P_n, while low illumination mainly decreased the chlorophyll fluorescence parameters F_v/F_m and Φ_PSⅡ, and thus, inhibited the activity of PSⅡ. High temperature increased the MDA content and decreased the soluble protein content and SOD activity, resulting in the acceleration of senescence, while low illumination increased the SOD activity and slowed down the senescence. Yumai 34 was more sensitive to high temperature and low illumination than Yangmai 9.

Effects of water-nitrogen interaction on the contents and components of protein and starch in wheat grains.

FU Xue-li^1,3; WANG Chen-yang^1,2;GUO Tian-cai^1,2; ZHU Yun-ji¹; MA Dong-yun^1,2; WANG Yong-hua^1,2 

2008, 19(02):  317-322 . 

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With wheat cultivars Yumai 34 (strong-gluten wheat) and Yumai 50 (weak-gluten wheat) as test materials, a field experiment was conducted to study the effects of three irrigation treatments (irrigation at jointing stage, at jointing and grain-filling stages, and at jointing, grain-filling, and pre-maturing stages), three nitrogen application rates (0, 150, and 270 kg·hm^-2), and their combinations on the contents and components of protein and starch in wheat grains. The results showed that for strong-gluten wheat cultivar Yumai 34, applying 270 kg·hm^-2 of N increased the total content of protein and the contents of albumin, gliadin and glutelin, and enhanced the glutelin/gliadin ratio. This application rate of nitrogen also increased the total content of starch and the content of amylopectin, and decreased the amylose/amylopetin ratio. For weak-gluten wheat cultivar Yumai 50, applying 150 kg·hm^-2 of N increased the contents of albumin and gliadin, and decreased the contents of globulin and glutelin and the glutelin/gliadin ratio. The amylopectin and starch contents also increased when the N application rate was 150 kg·hm^-2. NonN fertilization or applying 270 kg·hm^-2 of N decreased the accumulation of protein and starch, and resulted in a decrease of grain yield. Among the irrigation treatments, irrigation at jointing and grain-filling stages promoted the accumulation of protein and starch in grains and increased the grain yield, while the other two treatments were unbeneficial to the accumulation of protein and starch and decreased the grain yield. Applying 270 kg·hm^-2and 150 kg·hm^-2of N combined with irrigation at jointing and grain-filling stages was the ideal management regime for the high yield and good quality of strong and weak-gluten wheat cultivars, respectively.

Effects of maize plant type and planting width on the early morphological characters and yield of relayplanted soybean.

WANG Zhu¹; YANG Wen-yu²; WU Xiao-yan²; WU Qi-lin² 

2008, 19(02):  323-329 . 

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This paper studied the effects of different maize plant type and planting width on the early morphological characters and yield of relayplanted soybean under wheat/maize/soybean relayplanting. The results showed that different maize plant type led to different micro-climate in soybean planting strip, which was a direct factor affecting the changes in morphological characters and tissue structure of soybean. Large planting width and relay cropping with erect maize resulted in the short plant, thick main stem, large accumulation of dry matter, higher LAI and SLM, and high yield of soybean, while small planting width and relay cropping with flat maize led to the undergrowth of leaf and stem, overgrowth of plant, thin and lodgingsusceptible stem, and low yield of soybean. From the tissue sections of soybean leaf and stem at early blossoming stage under conditions of planted with different maize plant type and 1.17 m/0.83 m (soybean/maize) of planting width, it was found that under more shading, the leaf thickness decreased, epidermis cells became larger, cuticle became thinner, differentiation of palisade tissue and spongy tissue was inconspicuous, space between cells was large, epidermis and secondary xylem of stem all became thinner, parenchyma cells were loose, formulation of vessel delayed, and phloem fibers were less developed. It was concluded that relayplanting soybean with erect maize in a planting width of 1.17 m/0.83 m (soybean/maize) could be the best field combination in ensuring high yield and high efficiency all the year round.

Regulation effect of exogenous salicylic acid on weed suppression and molecular physiological characteristics of allelopathic rice.

QIU Long^1,2; WANG Hai-bin^1,2; XIONG Jun^1,2; FANG Chang-xun^1,2; WU Wen-xiang^1,2; HE Hai-bin^1,2; LIN Wen-xiong^1,2 (

2008, 19(02):  330-336 . 

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To investigate the feasibility of using exogenous salicylic acid (SA) to regulate the allelopathic weed suppression of rice, this paper studied the effects of different concentrations exogenous SA on the weed-suppression and physiological-biochemical characteristics of allelopathic rice PI312777, and the relative expression quantity of gene ZB8 in the rice by real time quantitative RT-PCR (FQ-PCR). The results showed that exogenous SA induced the enhancement of the allelopathic potential of donor rice in suppressing target weed plants, and this inducing effect was SA dose and treatment time dependent. After foliar spraying SA, the inhibitory effect of PI312777 on barnyardgrass increased significantly, and the root vigor and superoxide dismutase (SOD) and perocidase (POD) activities of PI312777 increased, while its catalase (CAT) activity decreased. The reverse was true for the target weed barnyardgrass. At the same time, the phenylalanine ammonia-lyase (PAL) activity of PI312777 increased significantly, leading to an increase of the total content of phenols. Among the test concentrations of SA, 0.2 mmol·L^-1 had the best inducing effect, under which, the relative expression quantity of ZB8 increased first and decreased then, with a peak at 24 hours after treatment.

Quantitative relationships between leaf total nitrogen concentration and canopy reflectance spectra of rice.

ZHOU Dong-qin; TIAN Yong-chao; YAO Xia; ZHU Yan; CAO Wei-xing 

2008, 19(02):  337-344 . 

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By the method of statistics, this paper approached the quantitative relationships between leaf total nitrogen concentration (LNC) and canopy reflectance spectra of rice, based on the data from 5-year field experiments involving different varieties and nitrogen fertilization rates. The results showed that the LNC had higher correlations with the key spectral parameters of two bands than of single band. The relative, differential, and normalized difference vegetation indices (RVI, DVI, NDVI) of the bands in near infrared (760-1 220 nm) and visible light 510 nm, 560 nm, 680 nm and 710 nm all showed significantly positive correlations to LNC, and NDVI showed the best. All the parameters having significant correlations with LNC were selected to compare the R² and SE in the regression equations with LNC, which confirmed that the NDVI of R₁₂₂₀and R₇₁₀ was the best parameter for predicting the LNC. The quantitative equation LNC=3.2708 × NDVI (1220, 710) + 0.8654 was tested by the data from other three field experiments with different rice cultivars, water conditions and nitrogen fertilization rates, and the estimated R², slope, and RMSEwere ranged in 0.674-0.862, 0.908-1.010 and 11.315%-19.491%, respectively, indicating a good fit between the predicted and observed values of LNCs, which suggested that this model was feasible for predicting the LNC of rice under different cultivation conditions.

Effects of maize and rice straw amendment on the pH, CO₂, and exchangeable NH₄⁺ of submerged soil.

YE Wen-pei^1,4; WANG Kai-rong^1,2; Johnson SE³; XIE Xiao-li¹

2008, 19(02):  345-350 . 

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A greenhouse incubation test was conducted to study the effects of amendment with different amounts of maize and rice straws on the soil pH, CO₂, and exchangeable NH₄⁺ under continuous flooded condition. The results showed that in a near-neutral soil, straw amendment could decrease soil pH, with a significant difference (P＜0.05) between the treatments of 4 g straws·kg^-1 and control (CK), but no significant difference (P＞0.05) between the treatments of 1 g straws·kg^-1and CK. The CO₂ content in soil solution increased with increasing rate of straw amendment, with the peak value being 35.9% and 31.9% (v/v) in the treatments of 1 g maize straw·kg^-1and 1 g rice straw·kg^-1, respectively. These two treatments had significantly higher CO₂ contents (P＜0.05) than CK, but no obvious difference between themselves (P＞0.05). In treatments 4 g maize straw·kg^-1 and 4 g rice straw·kg^-1, the peak value of CO₂ content was 54.2% and 41.8% (v/v), respectively, being significantly higher than that of CK (P＜0.01), and significantly different between themselves (P＜0.05). Under nonN fertilization, soil NH₄⁺N concentration decreased after straw amendment, and the increase of the amendment rate caused a further decrease of soil NH₄⁺N concentration, with a significant difference (P＜0.05) between the doses of 1 and 4 g straw·kg^-1. Under N fertilization, soil NH₄⁺N concentration increased after 1 g straw·kg^-1amendment, but decreased after amendment with 4 g straw·kg^-1. No significant differences were observed between maize straw and rice straw amendment regardless with or without N fertilization (P＞0.05).

Effects of heavy machinery operation on the structural characters of cultivated soils in black soil region of Northeast China.

WANG En-heng, CHAI Ya-fan, CHEN Xiang-wei

2008, 19(02):  351-356 . 

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With the cultivated soils in black soil region of Northeast China as test objects, this paper measured their structural characters such as soil strength, bulk density, and non-capillary porosity/capillary porosity (NCP/CP) ratio before and after heavy and mediumsized machinery operation, aimed to study the effects of machinery operation on the physical properties of test soils. The results showed that after machinery operation, there existed three distinct layers from top to bottom in the soil profiles, i.e., plowed layer, cumulative compacted layer, and non-affected layer, according to the changes of soil strength. Under medium-sized machinery operation, these three layers were shallower, and there was a new plow pan at the depth between 17.5 and 30 cm. Heavy machinery operation had significant positive effects on the improvement of topsoil structure (P＜0.05). After subsoiling and harvesting with heavy machinery, the bulk density of topsoil decreased by 7.2% and 3.5%, respectively, and NCP/CP increased by 556.6% after subsoiling, which would benefit water infiltration, reinforce water storage, and weaken the threat of soil erosion. The main action of heavy machinery operation was soil loosening, while that of mediumsized machinery operation was soil compacting.

Development process of crust in black soil of Northeast China.

BU Chong-feng¹; WU Shu-fang³; ZHANG Xing-chang¹; CAI Qiang-guo²

2008, 19(02):  357-362 . 

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In a simulated rainfall experiment, the microstructure, bulk density, and shear strength of black soil were determined to study the development process of crust during rainfall, and the effects of the crust on soil infiltration. The results showed that with the process of rainfall, surface soil layer became compact, soil shear strength and bulk density increased, and infiltration decreased. In a period of 120 minutes rainfall, a stable crust layer in 3-4 mm thickness formed, whose bulk density increased by 14.13% and porosity decreased by 6.45%. The removal of raindrop beat weakened the development of crust, with soil porosity decreased by 3.27%, bulk density increased by 7.11%, and accumulated infiltration increased by 41.1%. The black soil in Northeast China had a stable soil structure, and raindrop beat was the dominant factor resulting in the development of crust. During the process of rainfall, no obvious eluviation was observed.

Characteristics of water infiltration in urban soils of Nanjing City.

YANG Jin-ling; ZHANG Gan-lin;YUAN Da-gang

2008, 19(02):  363-368 . 

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By using dual-ring method, this paper measured the water infiltration rate in urban soils under representative land use patterns in Nanjing City, and studied the characteristics of water infiltration in the soils with different compaction degree. The results showed that there was a great difference in the infiltration rate among the soils with different compactness. Soil infiltration rate decreased with increasing bulk density and decreasing porosity, and the water-transport-limiting layer existed in heavily compacted soils resulted in a dramatic decrease of final stabilized infiltration rate. There was a significant linear relationship between the initial and final infiltration rates in the same soil though their absolute values had a great difference. The urban soils in Nanjing City had a wide range of final infiltration rate varied from 1 mm·h^-1 to 679 mm·h^-1, which was highly related to the soil compactness, structural status, and skeleton grain contents. The decrease of urban soil infiltration rate could induce the increase of runoff and of the probability and intensity of flooding.

Effects of manure application on organic carbon in aggregates of black soil.

AN Ting-ting¹; WANG Jing-kuan¹; LI Shuang-yi¹; YU Shu¹; ZHU Ping²

2008, 19(02):  369-373 . 

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In this paper, black soil samples were separated into four sizes (>2 000, 2 000-250, 250-53, and <53 μm) of aggregates by wet sieving, and their free light fraction (free LF) and intraaggregate particulate organic matter (iPOM) were isolated by density fractionation, aimed to evaluate the effects of manure application on the organic carbon in different sizes of aggregates in black soil. The results showed that compared with the control, applying manure improved soil aggregation significantly, and compensated the disturbance of tillage and slowed down the turnover of aggregates to some degree. After applying manure, the content of fine iPOM-C was significantly higher than that of coarse iPOM-C, suggesting that manure application was beneficial to the accumulation of fine iPOM-C, which is the main form of carbon sequestration in the aggregates of black soil.

Dynamic changes of nitrogen forms in livestock manure during composting and relevant evaluation indices of compost maturity.

BAO Yan-yu¹; ZHOU Qi-xing^1,3; YAN Li²; GUAN Lian-zhu²

2008, 19(02):  374-380 . 

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In this paper, the dynamic changes of nitrogen (N) forms in different livestock manures were investigated during composting, and the relevant N evaluation indices of compost maturity were approached. The results indicated that during composting, the total nitrogen (TN) concentration in dairy cattle manure increased first and became steady then, but in other five test manures, it decreased first and became steady then. For all test manures, their hydrolizable nitrogen (HN) decreased after an initial increase, NH₄⁺-N ecreased first and became steady then, while NO₃--N had a persistent increase. Among the N indices of compost maturity, HN/TN and NH₄⁺-N/TN could be selected as the adaptable parameters to evaluate the maturity, while NO₃^--N/TN could be only used as a universal one. According to the required standard of compost maturity based on the comprehensive index GI (seed germination index), i.e., GI>0.50, it was suggested that for the livestock manures except young pig manure, the basic requirements of their compost maturity were HN/TN <20.77％, NH₄⁺-N/TN <10.06％, and NO₃^--N/TN>0.8％.

Index system and fuzzy synthetic assessment in landscape evaluation of ornamental grasses.

WANG Qing-hai; YUAN Xiao-huan; WU Ju-ying; TENG Wen-jun 

2008, 19(02):  381-386 . 

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A composite index system for landscape evaluation of ornamental grasses was built from the aspects of ecological constraints, resources requirement and aesthetic values, and the ornamental grass landscapes in Beijing Botanical Garden and in Nanzhongzhou public green spaces were evaluated by fuzzy synthetic assessment (FSA) method. The results showed that the scores of “very apt” for the ornamental grasses in Beijing Botanical Garden and in Nanzhongzhou public green spaces were 0.459 and 0.413, respectively, while those of “apt” for the two landscapes were 0.302 and 0.301, respectively. The evaluation results were consistent with the public feedbacks, suggesting that the composite index system and FSA method were applicable for the landscape evaluation of ornamental grasses.

Adaptive optimized technologies for ecological sanitation and their complex ecological benefits.

ZHOU Chuan-bin; WANG Ru-song; YANG Wen-rui; JIN Jia-sheng 

2008, 19(02):  387-393 . 

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Aiming at the ecological characters of the cities in central and west China, several ecological sanitary (ecosan) technologies with different adaptability were integrated, and five adaptive optimized technologies were established. The environmental effects, resources recyclable potential, economic benefits, management difficulties, and public acceptance of each of the technologies were studied, with the possible complex eco-benefits of the technical improvement assessed. The results showed that decentralized ecosan technologies had the advantages of conserving water, recycling nutrients and saving cost, but also had the problems in management and public acceptance. Centralized ecosan technologies had the advantages in management and public acceptance, but were short in high cost and low recycling potential. If the sanitary system was improved through applying ecosan technologies, the greenhouse gases emission (CO₂ equivalent) and water pollution (calculated as BOD₅) could be reduced by 70% and 30%, respectively, while recycled nutrients (the sum of N, P, K) could be increased by 15 times. The optimized system could supply 3% of domestic energy, 10% of domestic water, and 15% of food demand, and the total cost could be reduced by 56% when the resource-recycling benefits were taken into account.

Evaluation on a demonstration project of ecological restoration of ditches at Qianwei Village of Chongming County, Shanghai.

ZHOU Xiang-xiang^1,2; ZHANG Li-quan^1,2; YUAN Lian-qi^1,2

2008, 19(02):  394-400 . 

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By using biological slope-protection techniques, oxidation pond system, and zeolite treatment system, a demonstration project of ecological restoration of ditches at the Qianwei Village of Chongming County in Shanghai was implemented, and an evaluation on the project was made via a runoff simulation experiment and the measurements of the parameters soil shear strength, biodiversity, and ditch water quality. The results showed that covering the dich slopes with shrub could significantly increase soil shear strength, compactness and moisture content, and the formed vegetation had significant effects on retarding runoff and removing TSS (P<0.05). Applying live fascines could significantly increase soil shear strength and TSS removal rate (P<0.05), but its effects on increasing soil compactness and moisture content and retaining runoff were not significant. After the implement of the demonstration project, the total N and P concentrations in ditch water decreased significantly, habitat quality and aesthetic value of ditch slope improved, and biodiversity enhanced greatly. The integration of the biological techniques with other ecological restoration measures could stabilize ditch slope, improve ditch habitat quality, and restore the ecological environment of the ditches.

Low dose benzo(a)pyrene up-regulated the transcription of HSP70 and HSP90 in Eisenia fetida. 

ZHENG Sen-lin^1,2,3; SUN Tie-heng¹; XIAO Hong¹; QIU Xiao-yan⁴; SONG Yu-fang¹ 

2008, 19(02):  401-406 . 

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To search for the molecular biomarkers of sub-lethal polycyclic aromatic hydrocarbons (PAHs)-contamination of soil, the subtractive cDNA libraries of earthworm Eisenia fetida exposed to benzo(a)pyrene (BaP) in artificial soil were constructed by suppression subtractive hybridization. After sequencing and analyzing with basic local alignment search tool (BLAST), two clones matching heat shock protein 70 k Da (HSP70) and one clone matching heat shock protein 90 k Da (HSP90) were isolated from the upregulated library, and subsequently, the up-regulation of HSP70 and HSP90 was verified by real-time PCR in E. fetida exposed to 0.1 mg·kg^-1 and 1.0 mg·kg^-1 BaP. It was indicated that these two newly identified HSPs in E. fetida were the potential molecular biomarkers for soil contamination monitoring.

Insitu remediation of polluted water body by planting hydrophytes.

FANG Yun-ying¹ ;YANG Xiao-e¹ ;CHANG Hui-qing² ;PU Pei-min^1,3 

2008, 19(02):  407-412 . 

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In an experimental enclosure system, floating plant Eichhornia crassipes was planted in summer and submersed plant Elodea nutalli was planted in winter to reestablish water ecosystem, and to investigate the effects of the hydrophytes on the removal of nitrogen and phosphorus from polluted water body and the improvement of water transparency. The results showed that compared with the control and native pond water, the water body planted with hydrophytes had a low level of nutrients. E. crassipes had a fast growth, with its covered area increased from 100 m² to 470 m² in the first 15 days, and to 65 % of the water area after 44 days. The total nitrogen, ammonium nitrogen, nitrite nitrogen, COD_Mn and chlorophyll a decreased to a lower level, and the water transparency increased significantly, reaching to a depth of 1.7-1.8 m (i.e., to the bottom of the pond). After October, the total phosphorus kept on about 0.1 mg·L^-1. Due to the increased water transparency, E. nutalli became the dominant species and covered 1/3 of the water area, playing an important role in purifying water quality, keeping water physicochemical properties in good status, and improving water transparency. It was concluded that planting hydrophytes in polluted water body could efficiently reduce its nutrients level and control the overgrowth of algae, being an important way in improving the water quality of eutrophicated water body.

Responses of Arabidopsis thaliana to oxidative stress induced by polycyclic aromatic hydrocarbon fluoranthene.

LIU Hong¹; YE Yuan-bei¹; CUI Bo²; ZHENG Li-min¹; HUANG Yan-he¹; WANG Zong-hua²

2008, 19(02):  413-418 . 

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With the seedlings of model plant Arabidopsis thaliana and the polycyclic aromatic hydrocarbon fluoranthene as test materials, this paper studied the physiological responses of plants to polycyclic aromatic hydrocarbons from the aspects of antioxidases and membrane protection system that are tightly related to abiotic stresses. The results showed that under fluoranthene stress, the seedlings experienced oxidative stress and membranelipid peroxidization. At 0.75 mmol·L^-1 of fluoranthene, the photosynthetic process was inhibited; at 1.00 mmol·L^-1of fluoranthene, the malonaldehydic acid (MDA) content increased and the ascorbate peroxidase (APX) activity decreased significantly, indicating an accelerated membrane-lipid peroxidization; and at 1.25 mmol·L^-1 of fluoranthene, the peroxidase (POD) activity decreased significantly and H₂O₂ had a high accumulation, making the seedlings injured severely.

Effects of salinity fluctuation on the molt, growth, and energy budget of juvenile Fenneropenaeus chinensis.

DING Sen; WANG Fang; GUO Biao; LI Xing-sheng

2008, 19(02):  419-423 . 

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By the methods of experimental ecology, this paper studied the effects of 4 salinity fluctuation amplitudes (2, 4, 6, and 8 PSU) on the molt and growth of juvenile Fenneropenaeus chinensis cultured in the seawater with salinity of 20. The results showed that the proportion of molted F. chinensisranged from 13.3% to 15.4%, with no significant differences among different treatments. When the salinity fluctuation amplitude was 4 PSU, the specific growth rate and the energy consumption for the growth were the highest while the energy consumption for respiration was the lowest, resulting in the rapid growth of F. chinensis. At 2 PSU, the feeding rate was the lowest; but at 2 and 4 PSU, the feed conversion efficiency was the highest. No significant difference in energy allocation for molt was observed between the four treatments. It was revealed that too large salinity fluctuation was unbeneficial to the growth, but had less effect on the molt of juvenile F. chinensis.

Nutrient management strategy of paddy rice-upland crop rotation system.

FAN Ming-sheng¹; JIANG Rong-feng¹; ZHANG Fu-suo¹; LV Shi-hua²; LIU Xue-jun¹ 

2008, 19(02):  424-432 . 

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Paddy rice-upland crop rotation system is a major cropping system in China, and practiced widely along the Yangtze River basin. A unique feature of this system is the annual conversion of soil from aerobic to anaerobic and then back to aerobic condition, which can result in the changes of soil physical, chemical, and biological prosperities among seasons, making a special agroecosystem. The major challenges faced by this system include declining or stagnating productivity, increasing shortage of irrigation water, improper management of nutrients, low efficiency of resource utilization, and environmental pollution. Based on an overview of the characteristics and problems of paddy rice-upland crop rotation system, this paper put forward a strategy of practicing integrated nutrient management to solve the contradictions between nutrient input, crop production and environmental risk. The key points of this strategy included nutrient management from the whole rotation system perspective, integrated use of nutrients from various sources (chemical fertilizers, organic fertilizers, and nutrients from the environment), synchronization of nutrient supply and crop nutrient demand, application of different management technologies based on the characteristics of different nutrient resources, and integration of nutrient management with other cropping system technologies like water saving and high-yielding cultivation, etc.

Research advance in rare and endemic plant Tetraena mongolica Maxim.

ZHEN Jiang-hong^1,2; LIU Guo-hou¹

2008, 19(02):  433-440 . 

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In this paper, the research advance in rare and endemic plant Tetraena mongolica Maxim. was summarized from the aspects of morphology, anatomy, palynology, cytology, seed-coat micro-morphology, embryology, physiology, biology, ecology, genetic diversity, chemical constituents, endangered causes, and conservation approaches, and the further research directions were prospected. It was considered that population viability, idioplasm conservation and artificial renewal, molecular biology of ecological adaptability, and assessment of habitat suitability should be the main aspects for the future study of T. mongolica.

Enantioselective interaction between plants and chiral compounds.

LIU Wei-ping^1,2; YE Jing¹; ZHANG An-ping²; QIAN Hai-feng² 

2008, 19(02):  441-448 . 

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There exists a close relationship between plants and chiral compounds. On one hand, plants can secrete and synthesize some chiral compounds such as glucosides, enzymes, terpenoids, organic acids and phytohormones that play important roles in plant physiological and biochemical processes, and on the other hand, artificial synthetic chiral compounds, especially pesticides, had enantioselective interactions with plants. The pesticides can enantioselectively inhibit the growth of plants, or can be enantioselectively absorbed and metabolized by plants. Therefore, in the exploitation, production and application of chiral compounds, it’s needed to consider the enantioselective interaction between plants and chiral compounds. In the meanwhile, choosing appropriate plants to ameliorate the environment polluted by chiral compounds is of practical significance. In this review, the enantioselective interaction between plants and chiral compounds was summarized, and the amelioration of chiral compounds-polluted environment by plants was prospected.

Thermal tolerance of some marine copepods.

LIAO Yi-bo¹; CHEN Quan-zhen¹; ZENG Jiang-ning^1,2; XU Xiao-qun¹; SHOU Lu¹; LIU Jing-jing¹; JIANG Zhi-bing¹; ZHENG Ping²

2008, 19(02):  449-452 . 

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By using experimental ecological methods, the 24 hours semi-lethal temperature (24 h LT₅₀) of typical copepods living in the coastal area of East China Sea was determined to elucidate the effects of thermal discharge from power station on the coastal ecosystem. The results indicated that different copepods at same natural acclimated temperature and specific copepod at different initial acclimated temperature had different thermal tolerance capability. The 24h LT₅₀ of Calanus sinicusand Sinocalanus tenellusat natural acclimated temperature 13.5 ℃ was 26.9 ℃ and 25.4 ℃, of Acartiella sinensis and Corycaeus affinis at natural acclimated temperature 14.2 ℃ was 26.7 ℃ and 30.5 ℃, and of Centropages dorsispinatus, Paracalanus crassirostris, Acartia spinicaudaand Euterpina acutifrons at natural acclimated temperature 28.0 ℃ was 34.0 ℃, 34.3 ℃, 35.7 ℃ and 36.0 ℃, respectively. The 24h LT₅₀ of S. tenellus at natural acclimated temperature 13.5 ℃ and 23.5 ℃ was 25.4 ℃ and 33.0 ℃, respectively.

Land use/cover change during lately 50 years in Three Gorges Reservoir Area.

SHAO Huai-yong¹; XIAN Wei²; YANG Wu-nian¹; ZHOU Wan-cun³ 

2008, 19(02):  453-458 . 

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Based on the topographic maps (1∶50 000) in 1955, MSS images in 1972, and TM images in 1986 and 2000, the dynamic changes of land use during lately 50 years in Three Gorges Reservoir Area were quantitatively analyzed, with their driving forces discussed. The results showed that during lately 50 years, the structure of land use in the study area changed obviously, with a decrease of woodland, water area and unused land, and an increase of cultivated land, grassland and construction land. During the periods of 1955-1972, 1972-1986 and 1986-2000, woodland had a persistent and gradual decrease, grassland and cultivated land underwent a process of increase-decreaseincrease and of increase-increase-decrease, respectively, construction land increased continually, while water area and unused land kept decreasing. Policy, economic development, and population growth were the main driving factors of the land use change in the study area.