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Table of Content

    18 January 2011, Volume 22 Issue 01
    Articles
    CO2 flux characteristics and their influence on the carbon budget of a larch plantation in Maoershan region of Northeast China
    2011, 22(01):  1-8. 
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    From January to December 2008, the CO2 flux in a larch plantation (Larix gmeilinii) in Maoershan region of Shangzhi County, Heilongjiang Province was measured by eddy covariance method, and the diurnal changes of leaf photosynthetic rate were measured in growth season (from May to October). There existed differences in the net ecosystem exchange (NEE) of the plantation in different time periods under the effects of environmental factors. In the afternoon (12:00-24:00), the NEE changed more slowly with the variation of vapor pressure deficit (VPD) than in the morning (0:00-12:00); and in the morning, the light use efficiency was 0.6284 mol·mol-1, 14% more than that in afternoon. The NEE increased with increasing temperature, and the increment in the morning was 50% higher than that in the afternoon (air temperature >15 ℃). These differences in responding to environmental changes led to 88% NEE implemented in the morning, and only 12% NEE implemented in the afternoon. The annual gross ecosystem productivity (GEP) in the morning took a percentage of 60%, and that in afternoon took 40%. These findings were supported by the observation at leaf level, i.e., on average of whole growth season, the leaf photosynthetic capacity in the morning was over 2-fold higher than that in afternoon. Generally, the annual NEE, ecosystem respiration (Re), and GEP of the plantation in 2008 were 263-264 g C·m-2, 718-725 g C·m-2, and 981-989 g C·m-2, respectively.
    Distribution patterns of Picea schrenkiana var. tianschanica population in Tianshan Mountains.
    2011, 22(01):  9-13. 
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    A vertical transect investigation on Picea schrenkiana var. tianschanica forests was conducted at five different longitudinal sites (Zhaosu, Gongliu, Wusu, Urumqi, and Hami) in Tianshan Mountains, and the distribution pattern of P. schrenkiana var. tianschanica population at each site was analyzed based on theoretical distribution model and aggregation intensity index. On the whole, the P. schrenkiana var. tianschanica population in Tianshan Mountains presented a clumped distribution, and the distribution pattern and clustering intensity were affected by the developmental stages of stem and the ranges of altitude to some degree. The clustering intensity increased with the increasing size (DBH) or developmental stage of stem, and had the highest values at high altitudes.
    Effects of thinning intensity on community stability of Quercus liaotungensis forest on Loess Plateau.
    2011, 22(01):  14-20. 
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    A sampling plot investigation was conducted on the Quercus liaotungensis forests on Loess Plateau, China under close-to-natural management thinning 13.4% (light thinning) and 30.0% (heavy thinning). Taking the un-thinned forest as the control, the population regeneration, woodland productivity, soil fertility, and species diversity of the forests after 5 years of thinning were studied, with the community stability evaluated by calculating the subordinate function values based on fuzzy comprehensive evaluation. Comparing with the control, the regeneration potential of the forests after light and heavy thinning promoted by 14.2% and 20.2%, arbor volume reduced by 9.0% and 23.8%, shrub biomass increased by 7.3% and 12.2%, and herb biomass increased by 10.5% and 31.6%, respectively. In addition, the soil fertility and species diversity indices were higher in thinning forests than in the control. The community stability showed the order of heavy thinning forest > light thinning forest > un-thinned forest, suggesting that the close-to-natural management thinning 30.0% was more suitable to the management of secondary Q. liaotungensis forest on Loess Plateau.
    Simulation of soil water dynamics in triploid Populus tomentosa root zone under subsurface drip irrigation.
    2011, 22(01):  21-28. 
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    Based on the observed data of triploid Populus tomentosa root distribution, a one-dimensional root water uptake model was proposed. Taking the root water uptake into account, the soil water dynamics in triploid P. tomentosa root zone under subsurface drip irrigation was simulated by using HYDRUS model, and the results were validated with field experiment. Besides, the HYDRUS model was used to study the effects of various irrigation technique parameters on soil wetting patterns. The RMAE for the simulated soil water content by the end of irrigation and approximately 24 h later was 7.8% and 6.0%, and the RMSE was 0.036 and 0.026 cm3·cm-3, respectively, illustrating that the HYDRUS model performed well in simulating the short-term soil water dynamics in triploid P. tomentosa root zone under drip irrigation, and the root water uptake model was reasonable. Comparing with 2 and 4 L·h-1 of drip discharge and continuous irrigation, both the 1 L·h-1 of drip discharge and the pulsed irrigation with water applied intermittently in 30 min periods could increase the volume of wetted soil and reduce deep percolation. It was concluded that the combination of 1 L·h-1 of drip discharge and pulsed irrigation should be the first choice when applying drip irrigation to triploid P. tomentosa root zone at the experiment site.
    Spatiotemporal variation of Populus euphratica’s radial increment at lower reaches of Tarim River after ecological water transfer.
    2011, 22(01):  29-34. 
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    Taking the Populus euphratica at lower reaches of Tarim River as test object, and by the methods of tree dendrohydrology, this paper studied the spatiotemporal variation of P. euphratic’s branch radial increment after ecological water transfer. There was a significant difference in the mean radial increment before and after ecological water transfer. The radial increment after the eco-water transfer was increased by 125%, compared with that before the water transfer. During the period of ecological water transfer, the radial increment was increased with increasing water transfer quantity, and there was a positive correlation between the annual radial increment and the total water transfer quantity (R2=0.394), suggesting that the radial increment of P. euphratica could be taken as the performance indicator of ecological water transfer. After the ecological water transfer, the radial increment changed greatly with the distance to the River, i.e., decreased significantly along with the increasing distance to the River (P=0.007). The P. euphratic’s branch radial increment also differed with stream segment (P=0.017), i.e., the closer to the head-water point (Daxihaizi Reservoir), the greater the branch radial increment. It was considered that the limited effect of the current ecological water transfer could scarcely change the continually deteriorating situation of the lower reaches of Tarim River.
    Distribution responses of Lespedeza davurica community on Loess Plateau to climate change.
    2011, 22(01):  35-40. 
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    Field survey and position monitoring were conducted from 2000 to 2009 to study the effects of climate change on the distribution and growth of Lespedeza davurica community on Loess Plateau. As affected by air temperature, the appropriate growth region of L. davurica community on the Plateau had an obvious zonal distribution from northwest to southeast. For the distribution of L. davurica community, the suitable air temperature was 7.4 ℃-10 ℃, average population density was 13.9 plants·m-2, and reproductive branch was averagely 11.4 per cluster. As affected by precipitation gradient, the horizontal distribution of L. davurica community changed from a constructive or predominant species in typical grassland region into a companion species in forest steppe region, and then, the community gradually became dominant species. The L. davurica community appeared as an occasional species on the half sunny slope of gullies and valleys and the sand dunes in desert steppe region, and extended gradually from its optimal region with yearly precipitation 300-500 mm to the region with yearly precipitation 270-600 mm. Also, the L. davurica community extended from its
     optimal altitude 1100-1700 m to 600-1950 m. Under the background of global climate change, the eco-breadth of L. davurica community expanded gradually.
    Spatiotemporal dynamics of forest carbon storage in Taihe County of Jiangxi Province in 1985-2030.
    2011, 22(01):  41-46. 
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    Based on the sixth forest inventory data of Taihe County, Jiangxi Province, this paper analyzed the curve relations between the carbon densities and ages of major forest types by using Logistic equation, and estimated the total amounts and change trends of the biomass and carbon storage of forest vegetation from 1985 to 2003 by the method of biomass expansion factor. The carbon storage in 2020 and 2030 was estimated by setting 2003 as the baseline year and assuming that the area of forest vegetation remained stable and without consideration of forest rotation. In 2003, the total forest area of Taihe County was 15.74×104 hm2, the total biomass was 6.71 Tg, the vegetation carbon storagewas 4.14 Tg C, and the average carbon density was 26.31 t C·hm-2. In 1985, 1994, 2003, 2020, and 2030, the forest carbon storage was 1.06, 2.83, 4.14, 5.65, and 6.35 Tg C, respectively. The carbon density of the forest vegetation in Taihe County decreased from the eastern and western regions to the central. Artificial afforestation contributed significantly to the increase of forest stand area, and consequently, to the improvement of forest carbon sequestration capacity.
    Quantitative driving analysis of forest biomass changes in Changbai Mountain forest region.
    2011, 22(01):  47-52. 
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    Based on the forest inventory data and single tree biomass model, the forest biomass in the sampling plots in Changbai Mountain forest region was calculated, and, by using the estimated forest biomass from four periods’ remote sensing data and based on high accuracy remote sensing models, the changes of regional forest biomass were analyzed. In the meanwhile, the driving factors such as meteorological factors, management factors, and socio-economic factors that caused forest biomass change were selected by bootstrap method, and the driving model of forest biomass change in different time period was set up by using partial least-squares method. The Variable Importance in Projection (VIP) values representing the importance of each of the factors affecting the forest biomass change in study region were calculated. The results showed that the influence of human activity factors (VIP values) on Changbai Mountain forest biomass changes was less than that of natural factors, suggesting that the national forest protection policy for forest regions had played an obvious role. Our research broadened the content of forest biomass change driving analysis, and the introduction of calculating VIP value, which can quantitatively represent the influence of driving factors to forest biomass change, provided a new way for the quantitative analysis on forest biomass change.
    Effects of strong solar UV-B radiation on photosynthesis and photosynthetic pigment contents of Saussurea superba on Qinghai-Tibet Plateau.
    2011, 22(01):  53-60. 
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    Taking the main companion species Saussurea superba in an alpine Kobresia humilis meadow on Qinghai-Tibet Plateau as test material, a UV-B
    exclusion experiment with UV-B excluding and UV-B transmitting filters was performed to study the effects of strong solar UV-B on the photosynthesis, photosynthetic pigments, and UV-B-absorbing compounds of S. superba, aimed to examine the adaptation capability of alpine plants to strong solar UV-B radiation. The removal of UV-B components from natural sunlight increased the net photosynthetic rate (P<0.05) and PSⅡ photochemistry efficiency of S. superba. The relatively increased leaf thickness under ambient UV-B could compensate the photo-oxidation of photosynthetic pigments, an inherent characteristic of alpine plants growing in intense UV-B. Short-term removal of UV-B radiation had no obvious effects on the UV-B absorbing compounds, suggesting that these compounds in epidermal layer of S. superba could hardly be affected by the environment. It was concluded that the increase of photosynthetic pigment contents due to the enhancement of leaf thickness was a specious phenomenon, but the strong solar UV-B radiation on Qinghai-Tibet Plateau still had a potential negative impact on the photo-physiological processes in alpine plant S. superba.
    Effects of litters and tannin on forest soil inorganic nitrogen.
    2011, 22(01):  61-65. 
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    A laboratory incubation test was conducted to study the effects of litters and tannin on forest soil nitrate- and ammonium N. The addition of litters and tannic acid made the soil nitrate-and ammonium N decreased. With the addition of fir litter, the nitrate- and ammonium N contents in red soil decreased by 6.1%-25.9% and 19.7%-68.6%, respectively, and the decrements in yellow-red soil were higher than those with the addition of bamboo litter, being significant for ammonium N. Compared with the control, the addition of tannin decreased the ammonium N content in yellow-red soil significantly, and there was a positive correlation between the concentration of added tannin and the decrement of soil ammonium N content. When the concentration of added tannin was high, the decrement of the ammonium N reached 31.9%-57.8%. With the addition of low concentration tannin, the soil nitrate N content decreased with time, and the decrement on the 84th day reached 4.5%. However, the addition of high concentration tannin increased the soil nitrate N content by 10.3%-18.5% in the first 7-28 days, but decreased it by 23.9% and 42.3% on the 56th and 85th day, respectively.
    Effects of low temperature stress during flowering period on pollen characters and flag leaf physiological and biochemical characteristics of rice.
    2011, 22(01):  66-72. 
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    Taking cold-tolerant rice cultivar 996 and cold-sensitive rice cultivar 4628 as test materials, a growth chamber experiment was conducted to investigate their pollen characters and flag leaf physiological and biochemical characteristics under the effects of low temperature stress. The plants were respectively treated with low temperature [19 ℃ (06:00-8:00;19:00-23:00)/21 ℃ (08:00-10:00;16:00-19:00)/23 ℃ (10:00-16:00)/17 ℃ (23:00-06:00)]and optimal temperature [24 ℃ (06:00-8:00; 19:00-23:00)/26 ℃ (08:00-10:00;16:00-19:00)/30 ℃ (10:00-16:00)/22 ℃ (23:00-06:00)] for seven days after heading. Low temperature stress decreased the anther dehiscence coefficient and pollen germination rate, as well as the sterile pollen rate of spikelets on middle and lower parts of panicles, with the anther dehiscence coefficient and pollen germination rate of cultivar 996 being significantly higher than those of cultivar 4628, indicating that coldtolerant cultivar 996 had the capability to keep better pollination and pollen germination. Under low temperature stress, the flag leaf soluble protein and free proline contents and their increments of cultivar 996 were significantly higher than those of cultivar 4628, while the MDA content and relative conductivity and their increment were in adverse, indicating that cold-tolerant cultivar 996 had more quick and strong protective responses, and was able to keep stable membrane structure and function.
    Effects of different application rates of water-retaining agent on root physiological characteristics of winter wheat at its different growth stages.
    2011, 22(01):  73-78. 
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    A field experiment was conducted at the Yuzhou Experimental Base of Henan Province to study the effects of different application rates (0, 30, 60, and
    90 kg·hm-2) of water-retaining agent (WRA) on the root physiological characteristics, biomass, and grain yield of two winter wheat cultivars Zhengmai-9694 and Aikang-58, aimed to probe into the action mechanisms of WRA on the root system of winter wheat at its different growth stages. The application of WRA decreased the root membrane permeability and soluble sugar content, and increased the root vigor. After the application of WRA, the Zhengmai-9694 at its different growth stages had a greater decrement of root membrane permeability, compared with Aikang-58. In all treatments except 90 kg·hm-2 of WRA, the root vigor of Aikang-58 was obviously higher than that of Zhengmai-9694. At booting and grain-filling stages, the root soluble sugar content of Zhengmai-9694 decreased much more than that of Aikang-58. In the whole growth period of the two cultivars, their root membrane permeability and soluble sugar content were the lowest in treatment 60 kg·hm-2 of WRA, and no significant differences were observed between treatments 60 and 90 kg·hm-2 of WRA. The root vigor of Zhengmai-9694 increased remarkably with the increasing rate of WRA application, while that of Aikang-58 was the highest in treatment 60 kg·hm-2 of WRA. The application of WRA also increased root biomass, and at jointing and booting stages, the root biomass of Aikang-58 was much higher than that of Zhengmai-9694. However, at grain-filling stage, the biomass of Aikang-58 in treatments 60 and 90 kg·hm-2 of WRA was lower than that of Zhengmai-9694. Treatment 60 kg·hm-2 of WRA had the highest grain yield of the two cultivars. It was concluded that WRA had more significant effects on Zhengmai-9694 than on Aikang-58, and applying 60 kg·hm-2 of WRA could obtain the best effect.
    Responses of winter wheat photosynthetic characteristics and chlorophyll content  to water retaining agent and N fertilizer.
    2011, 22(01):  79-85. 
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    The effects of water-retaining agent (60 kg·hm-2) and nitrogen fertilizer (0, 225, and 450 kg·hm-2) on the leaf photosynthetic characteristics, chlorophyll content, and water utilization of winter wheat at jointing and grain-filling stages were studied under field conditions. In all treatments, the net photosynthetic rate, stomata conductance, intercellular CO2 concentration, water use efficiency, and chlorophyll content were greater at grain-filling stage than at jointing stage. Under nitrogen fertilization but without water-retaining agent application, the water use efficiency (WUE) of single leaf at jointing stage increased with increasing nitrogen fertilization rate, while the net photosynthetic rate, stomata conductance, intercellular CO2 concentration, and transpiration rate decreased after an initial increase. The chlorophyll content was the highest under 225 kg·hm-2 nitrogen fertilization. In the treatments of water-retaining agent application, the intercellular CO2 concentration decreased with increasing nitrogen application rate, but the net photosynthetic rate, transpiration rate, and WUE increased. The application of water-retaining agent or its combination with nitrogen fertilization increased the chlorophyll content, but excessive nitrogen fertilization had lesser effects. At grain-filling stage, applying nitrogen fertilizer alone significantly increased the net photosynthetic rate and WUE, but decreased the stomata conductance, intercellular CO2 concentration, and transpiration rate. The chlorophyll content increased with increasing nitrogen application rate. After applying water-retaining agent and with the increase of nitrogen fertilization rate, the photosynthetic rate and WUE decreased after an initial increase, while the intercellular CO2 concentration and transpiration rate were in adverse but still lower than those without water-retaining agent application. The stomata conductance increased with increasing nitrogen fertilization rate. The chlorophyll content increased significantly under the application of water-retaining agent, but somewhat decreased under the combined application of water-retaining agent and nitrogen fertilizer. The application of both water-retaining agent and nitrogen fertilizer increased the 1000 grain mass, grain yield, and water production efficiency of winter whe at significantly, with the best effect in the treatment of water-retaining agent with 225 kg·hm-2 nitrogen fertilization.
    Effects of ground cover and water-retaining agent on winter wheat growth and precipitation utilization.
    2011, 22(01):  86-92. 
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    An investigation was made at a hilly upland in western Henan Province to understand the effects of water-retaining agent (0, 45, and 60 kg·hm-2), straw
    mulching (3000 and 6000 kg·hm-2), and plastic mulching (thickness <0.005 mm) on winter wheat growth, soil moisture and nutrition conditions, and precipitation use. All the three measures promoted winter wheat growth, enhanced grain yield and precipitation use efficiency, and improved soil moisture and nutritional regimes. These positive effects were more obvious when the straw- or plastic mulching was combined with the use of waterretaining agent. Comparing with the control, all the measures increased the soil moisture content at different growth stages by 0.1%-6.5%. Plastic film mulching had the best water-retention effect before jointing stage, whereas water-retaining agent showed its best effect after jointing stage. Soil moisture content was the lowest at flowering and grain-filling stages. Land cover increased the grain yield by 2.6%-20.1%. The yield increment was the greatest (14.2%-20.1%) by the combined use of straw mulching and water-retaining agent, followed by plastic mulching combined with water-retaining agent (11.9% on average). Land cover also improved the precipitation use efficiency (0.4-3.2 kg·mm-1·hm-2) in a similar trend as the grain yield. This study showed that land cover and water-retaining agent improved soil moisture and nutrition conditions and precipitation utilization, which in turn, promoted the tillering of winter wheat, and increased the grain number per ear and the 1000-grain mass.
    Effects of long-term application of organic fertilizer and superphosphate on accumulation and leaching of Olsen-P in Fluvo-aquic soil.
    2011, 22(01):  93-98. 
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    Based on a 20-year experiment of fertilization with organic and chemical fertilizers on a Fluvo-aquic soil under wheat-corn cropping system, this paper studied the relationships between Olsen-P concentration in plough layer and crop yields as well as the accumulation and vertical translocation of Olsen-P in soil profile. The results showed that when the Olsen-P concentration in plough layer maintained at 10-40 mg·kg-1, the grain yields of wheat and corn were higher, whereas when the concentration of Olsen-P in plough layer was higher than 40 mg·kg-1, it started to leach, which meant that in light loam Fluvo-aquic soil, the threshold value for P leaching might be 40 mg·kg-1. In the treatments of chemical fertilization (NPK) and corn straw returning (SNPK) with the P application rate of  77-90 kg·hm-2, the Olsen-P concentration in plough layer was increased by 0.63-0.72 mg·kg-1 per 100 kg·hm-2 of applied P, with an annual increment of 0.49-0.65 mg·kg-1 and needed 45-60 years for reaching the threshold value for P leaching. In the treatments of chemical fertilization combined with manure application (MNPK, MNPK2, and 1.5MNPK),  the formula of Olsen-P accumulation in 0-20 cm soil layer were YMNPK=3.1097x+6.9615 (R2=0.8562), YMNPK2=2.4765x+13.563(R2=0.9307), and Y1.5MNPK=4.506x+6.4464 (R2=0.8862). It might take 8 years to reach the threshold value for Olsen-P leaching when the P application rate in treatment 1.5MNPK was 210 kg·hm-2, 11 years when the P application rate in treatments MNPK2 and MNPK was 125 and 140 kg·hm-2. Organic fertilization combined with chemical fertilization increased the Olsen-P accumulation rate being 2.5 times higher than chemical fertilization. Excessive application of organic fertilizer could increase the accumulation and leaching of Olsen-P in soil profile.
    Effects of no-tillage on soil water content and physical properties of spring corn fields in semiarid region of northern China.
    2011, 22(01):  99-104. 
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    Field experiments were conducted in 2006-2008 to study the effects of no-tillage on the spatiotemporal dynamics of soil water content and related soil physical properties in spring corn fields in Beijing region during growth season. In study period, the water storage in 0-100 cm soil layer in tillage and no-tillage treatments had the same variation trend with time and precipitation, but the water storage at different time periods and under different precipitations was  2.7%-30.3% higher in no-tillage treatment than in tillage treatment. When the precipitation was relatively abundant, the increment of soil water storage was somewhat increased, but no-tillage was still worth to be popularized in the regions relatively deficit in precipitation. Under no-tillage, the average water storage in 0-100 cm soil layer during the three growth seasons in 2006-2008 was 3.4%-12.8% higher than that under conventional tillage, and the increment of the water storage in 0-20 cm and 80-100 cm soil layers under no-tillage was higher than that in intermediate layer, with the highest increment reached 22.2%. No-tillage improved soil water-holding capacity and water use efficiency via decreasing soil bulk density, increasing soil porosity, and promoting the formation of soil water-stable aggregates, and thereby, promoted crop yielding. After 3 years no-tillage, the soil water use efficiency and spring corn yield were increased by 13.3% and 16.4%, respectively, compared with those under convent
    ional tillage.
    Simulation on the restoration effect of soil moisture in alfalfa (Medicago sativa)-grain rotation system in semi-arid and drought-prone regions of Loess Plateau.
    2011, 22(01):  105-113. 
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    With the combination of field survey and EPIC modeling, this paper simulated the restoration effect of soil moisture in different alfalfa (Medicago sativa) -grain rotation systems in semi-arid and drought-prone regions of Loess Plateau. In perennial alfalfa field and in grain crop field after alfalfa, the correlation coefficients between the simulated and observed values of soil moisture content in 0-10 m layer were larger than 0.9 (P<0.01), and their relative root mean square errors were between 0.05 and 0.16, with the relative errors less than 10%. The dynamic changes of the simulated soil moisture contents in different soil layers were consistent with those of the observed values. In the study regions, it was difficult for the restoration of soil moisture in the deep soil layers of alfalfa field. During the cultivation of alfalfa, the soil moisture content in the layers at 8-10 m depth should not be less than 5.7%. Considering the sustainable development of agricultural production, the appropriate cultivation duration of alfalfa should be 4-6 years and no more than 8 years. For the restoration of soil moisture after alfalfa cultivation in the study regions, the rotation system potato (Solanum tuberosum) → potato → spring wheat (Triticum aestivum) could be adopted, and alfalfa could be cultivated again after 32-33 years.
    Effect of plantation of transgenic Bt cotton on the amount of rhizospheric soil microorganism and bacterial diversity in the cotton region of Yellow River basin.
    2011, 22(01):  114-120. 
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    Traditional culture-dependent method and PCR-DGGE were adopted to investigate the amount of microorganism and bacterial diversity in rhizospheric soil of transgenic Bt cotton in four provinces of  Yellow River basin at four growth stages, i.e., 30, 60, 90, and 120 days after sowing. In the same province and at the same growth stage, no significant difference was observed in the amount of microorganism in rhizospheric soils of transgenic and non-transgenic Bt cottons. Within the same province the amount of  microorganism was mainly affected by growth stage; while in different provinces, it was greatly affected by regional conditions.In the four provinces, the bacterial diversity in rhizospheric soil of transgenic Bt cotton was abundant; and in the same province and at the same growth stage, there were no significant differences in the Shannon index, evenness, and richness of bacteria in rhizospheric soils of transgenic and non-transgenic Bt cottons. In different provinces, the bacterial diversity in rhizospheric soils was dependent on regional conditions, but the difference was rather small.
    Spatial variation of soil properties and quality evaluation for arable Ustic Cambosols in central Henan Province.
    2011, 22(01):  121-128. 
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    A GIS-based 500 m×500 m soil sampling point arrangement was set on 248 points at Wenshu Town of Yuzhou County in central Henan Province, where the typical Ustic Cambosols locates. By using soil digital data, the spatial database was established, from which, all the needed latitude and longitude data of the sampling points were produced for the field GPS guide. Soil samples (0-20 cm) were collected from 202 points, of which, bulk density measurement were conducted for randomly selected 34 points, and the ten soil property items used as the factors for soil quality assessment, including organic matter, available K, available P, pH, total N, total P, soil texture, cation exchange capacity (CEC), slowly available K, and bulk density, were analyzed for the other points. The soil property items were checked by statistic tools, and then, classified with standard criteria at home and abroad. The factor weight was given by analytic hierarchy process (AHP) method, and the spatial variation of the major 10 soil properties as well as the soil quality classes and their occupied areas were worked out by Kriging interpolation maps. The results showed that the arable Ustic Cambosols in
    study area was of good quality soil, over 95% of which ranked in good and medium classes and only less than 5% were in poor class.
    GIS-based evaluation of farmland soil fertility and its relationships with soil profile configuration pattern.
    2011, 22(01):  129-136. 
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    Taking the mid and low yielding fields in Yanjin County, Henan Province as a case, and selecting soil organic matter, total N, total P, total K, available N, available P, available K, pH value, and cation exchange capacity as indicators, a comprehensive evaluation on soil fertility was conducted by the method of fuzzy mathematics and using software ArcGIS 9.2. Based on this evaluation,the differences in the soil fertility level under different soil profile configuration pattern were analyzed. In the study region, soils were slightly alkaline,poorer in total N, total P, available N, cation exchange capacity, organic matter, and available K, and medium in available P and total K. The integrated fertility index was 0.14-0.63, indicating that the soil fertility in the region was on the whole at a lower level. There existed significant differences in all indicators except available P and total K under different soil profile  configuration patterns (P<0.05), suggesting the close relationship between soil fertility and soil profile  configuration. The soil profile loamy in surface soil and clayey in subsurface soil had a higher level of soil fertility, followed by that loamy in surface soil and sandy in subsurface soil, and sandy in both surface and surface soil. Overall, the soils in the region were bad in profile  configuration, poor in water and nutrient conservation, and needed to be ameliorated aiming at these features.
    Three-dimensional morphological modeling and visualization of wheat root system.
    2011, 22(01):  137-143. 
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    Crop three-dimensional (3D) morphological modeling and visualization is an important part of digital plant study. This paper aimed to develop a 3D morphological model of wheat root system based on the parameters of wheat root morphological features, and to realize the visualization of wheat root growth. According to the framework of visualization technology for wheat root growth, a 3D visualization model of wheat root axis, including root axis growth model, branch geometric model, and root axis curve model, was developed firstly. Then, by integrating root topology, the corresponding pixel was determined, and the whole wheat root system was threedimensionally reconstructed by using the morphological feature parameters in the root morphological model. Finally, based on the platform of OpenGL, and by integrating the technologies of texture mapping, lighting rendering, and collision detection, the 3D visualization of wheat root growth was realized. The 3D output of wheat root system from the model  was vivid, which could realize the 3D root system visualization of different wheat cultivars under different water regimes and nitrogen application rates. This study could lay a technical foundation for further development of an integral visualization system of wheat plant.
    Effects of canal-lining project on groundwater and ecological environment in Hetao Irrigation District of Inner Mongolia.
    2011, 22(01):  144-150. 
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    The canal-lining project in Hetao Irrigation District (HID) for water-saving irrigation has been implemented for many years. By using statistical method, ordinary Kriging, and software ArcGIS 9.0, this paper analyzed the spatiotemporal variation of groundwater table depth and salinity in HID in September, 2001 and 2009. In the meantime, the vegetation distribution on the both shores of the lining part and non-lining part of Yangjiahe channel was also investigated.After the many years implementation of the project, the water diversion amount in HID in 2009 was reduced to 44.5×108 m3. The region area of groundwater table with a depth of 2.5-3.0 m was increased from 1.2×104 hm2 in 2001 to 9.11×104 hm2 in 2009. The region area of groundwater table with a depth of 2.0-2.5 m in 2009 took 80% of the total area of HID. In the northwestern region of HID, the groundwater salinity had reduced from 5000-10000 mg·L-1 to 3000-5000 mg·L-1. In Wulate irrigation region, the areas of salt water belt and half-salt water belt were increasing. After the canal-lining of Yangjiahe channel, the plant species and diversity index on both shores reduced, and some herbaceous plants with shallow roots showed degradation signs. The implementation of the project and the reduction of water diversion for irrigation did not exert negative effects on the maintenance of water surface area of Wuliangsuhai Lake.
    Spatiotemporal distribution characteristics of rainfall erosivity in Three Gorges Reservoir Area.
    2011, 22(01):  151-158. 
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    Based on the 1976-2005 daily rainfall records from 25 weather stations in the Three Gorges Reservoir Area and its surrounding regions, this paper studied the spatiotemporal distribution characteristics of rainfall erosivity in the Area, with the focus on the annual and inter-annual trends of the rainfall erosivity around seven main weather stations. In 1976-2005, the average annual rainfall erosivity (R) in the Area was from 4389.0 to 8021.0 MJ·mm·hm-2·h-1·a-1, being increased first from the northeast to the southwest, reached the peak in the central, and then decreased. The annual rainfall erosivity around the seven main weather stations mostly concentrated in the period from April to October, with the R value increased first from April, reached the highest in June or July, and then decreased. The maximum rainfall erosivity in consecutive three months around each of the seven weather stations accounted for 54.2%-60.7% of the total annual rainfall erosivity. In the study period, the coefficients of variation of the annual rainfall erosivity around the seven main weather stations varied moderately from 0.278 to 0.387, and the tendency rate ranged from -431.1 to 263.5 MJ·mm·hm-2·h-1·(10 a)-1.However, the coefficients of tendency did not pass the confidence test with 5% level of significance, and the changes of annual rainfall erosivity showed random fluctuation. The variation degree of monthly rainfall erosivity was larger than the variation of annual rainfall erosivity, but only showed an obvious climate trend in a few months around parts of the weather stations.
    Fractal characteristics of daily discharge in different scales watersheds.
    2011, 22(01):  159-164. 
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    Based on the fractal theory and the long-term daily discharge records, this paper analyzed the fractal characteristics of daily discharge in mid-scale watershed (Wushui watershed) and small-scale watersheds (Zhenfu and Shuangxi watersheds). Under the same time scales and different threshold values of daily runoff, the fractal characteristics of daily discharge in the watersheds of different spatial scales and of same spatial scales were evident, and existed self-similarity. With the increase of the threshold values of daily runoff, the fractal dimensions of the daily discharge of different space-scale watersheds decreased gradually. The set of fractal dimensions of the daily discharge in different space-scale watersheds tended to be saturated when the time scale was 120-150 days, and the critical threshold values of daily runoff might appear when the time scale exceeded this number of days.  
    Spatiotemporal variation of urban heat island in Zhengzhou City based on RS.
    2011, 22(01):  165-170. 
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    By using two Landsat remote sensing images (May 14, 1988 by TM sensor and May 10, 2001 by ETM+ sensor) and local meteorological data, this paper analyzed the causes and harms of urban heat island (UHI) in Zhengzhou City. The brightness temperatures of the images were calculated by mono-window algorithm, and related thematic maps were figured out. The results showed that with the expanding urban area of Zhengzhou City, the UHI effect was growing. Comparing with that in 1988, the high-temperature region of the City in 2001 had a clear shift and expansion towards northeast and southwest, being similar to the change trends of the low vegetation coverage area and urban land area. In order to alleviate the growing UHI effect, attentions should be paid on the urban greening work and the choice of reasonable greening patterns in the process of urbanization.
    Landscape pattern gradient dynamics and desakota features in rapid urbanization area: A case study in Panyu of Guangzhou.
    2011, 22(01):  171-180. 
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    In order to understand the landscape pattern gradient dynamics and desakota features in rapid urbanization area, this paper took the rapidly urbanizing Panyu District of Guangzhou City as a case, and analyzed its land use and land cover data, based on four Landsat TM images from 1990 to 2008. With the combination of gradient analysis and landscape pattern analysis, and by using the landscape indices in both class and landscape scales, the spatial dynamics and desakota feature of this rapidly urbanizing district were quantified. In the study district, there was a significant change in the landscape pattern, and a typical desakota feature presented along buffer gradient zones. Urban landscape increased and expanded annually, accompanied with serious fragmentation of agricultural landscape. The indices patch density, contagion, and landscape diversity, etc., changed regularly in the urbanization gradient, and the peak of landscape indices appeared in the gradient zone of 4-6 km away from the urban center. The landscape patterns at time series also reflected the differences among the dynamics in different gradient zones. The landscape pattern in desakota region was characterized by complex patch shape, high landscape diversity and fragmentation, and remarkable landscape dynamics. The peaks of landscape indices spread from the urban center to border areas, and desakota region was expanding gradually. The general trend of spatiotemporal dynamics in desakota region and its driving forces were discussed, which could be benefit to the regional land use policy-making and sustainable development planning.
    Health assessment on aquatic ecosystem in Liaohe River of Liaoning Province.
    2011, 22(01):  181-188. 
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    Based on the investigation of the hydrology, water quality, periphytic algae, and habitat conditions of 20 hydrologic sections in the Tieling, Shenyang, and Panjin reaches of Liaohe River from June to August 2009, the indicators and their weights for the health assessment of aquatic ecosystem in the River were screened and determined by the method of principal component analysis, and the River’s health assessment indicator system and health assessment standard system were constructed. The modified gray correlative degree method was also used to evaluate the aquatic ecosystem health condition at six sections of the River. Among the sections evaluated, three of them had a fair health level, two were worse or worst, and only one reached subhealth degree, suggesting that the aquatic ecosystem in the River was seriously degraded. Special attention should be paid to the ecological recovery of the river system, and comprehensive measures should be taken to control the River’s water pollution.
    Ecological security assessment of Baishan City in Jilin Province based on DPSIR.
    2011, 22(01):  189-195. 
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    This paper explored the main driving forces and stresses contributing to the eco-environmental changes of Baishan City in Jilin Province, through the analysis of the ecological security problems in the City. The framework of DPSIR was applied to establish an ecological security assessment index system, and further, to create an ecological security assessment model suitable for mountain areas. By using the 1989, 1999, and 2006 TM images, and in combining with the DEM data and field survey data, the interpretation of the land cover in Baishan City was conducted, and the landscape classification was carried out. With the support of Fragstats, the important ecological indicators were extracted. Then, the situations of ecological security in various districts and counties of Baishan City were assessed. The results indicated that there was an obvious regional difference in the ecological security of Baishan City, with a deteriorating trend of the overall ecological security situation. Human activities had deeper influence on the land cover pattern and species habitat distribution, and even, became the main driving force of the pattern changes in ecological security.
    Effects of organic fertilization on arsenic absorption of pakchoi (Brassica chinensis) on arsenic-contaminated red soil.
    2011, 22(01):  196-200. 
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    A pot experiment with arsenic-contaminated red soil was conducted to study the effects of applying pig dung and chicken manure on the growth and arsenic absorption of pakchoi (Brassica chinensis), and on soil available arsenic. Applying pig dung and chicken manure to the arsenic- contaminated red soil increased the biomass of pakchoi to some extent. Comparing with the control, applying pig dung increased the pakchoi biomass significantly (P<0.05). The soil available arsenic content after applying pig dung increased by 394.9%-1033.6% (P<0.05), and that after applying chicken manure increased by 30.4%-94.1%. Organic fertilization promoted the arsenic absorption of pakchoi, with the arsenic uptake after applying pig dung increased by 20.7%-53.9%. The application of pig dung and chicken manure to arsenic-contaminated red soil could somewhat increase the soil available arsenic content and the arsenic uptake by crops,and thus, increase the risks of agricultural product quality and environment.
    Concentration and speciation of arsenic in greenhouse vegetable soil in Shouguang County of Shandong Province.
    2011, 22(01):  201-205. 
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    A sampling survey was conducted in the typical areas in Shouguang County of Shandong Province to study the characteristics of arsenic (As) concentration and speciation in greenhouse vegetable soil. The total As concentration in the surface (0-20 cm) and subsurface (20-40 cm) soil was averagely 8.27 and 7.93 mg·kg-1, being 19% and 23% higher than that of the control (open field soil), and the soluble As (AE-As) concentration was 0.13 and 0.06 mg·kg-1, 63% and 200%  higher than that of the control, respectively. The ratio of residual As (O-As) to total arsenic reached more than 63.0%, and the concentrations of different As speciation decreased in the order of O-As > iron-bound As (Fe-As) > calcium bound As (Ca-As) > aluminum bound As (Al-As) > AE-As. With the increasing planting years, the AE-As concentration enhanced significantly, and the Al-As concentration also increased to some degree. After 15 years planting, the AE-As concentration in surface and subsurface soil increased by 75.0% and 150.0%, and Al-As concentration increased by 51.6% and 190.4%, respectively, while the concentrations of Fe-As and Ca-As all decreased to some degree.
    Minimum amounts of suitable habitat for wheat aphid, parasitoid, and hyperparasitoid in facility-based agricultural landscapes.
    2011, 22(01):  206-214. 
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    Minimum amount of suitable habitat (MASH) is the minimum habitat area that a population requires to persist in a given environmental setting for a long time, being an important aspect of population viability analysis (PVA). In this paper, we estimated the MASH for wheat aphids, parasitoids, and hyperparasitoids in facility-based agricultural landscapes in Yinchuan Plain of Northwest China, based on the relationships between population density and habitat area, and by using regression analysis. It was found that the population density and growth rate were consistently inversely related to area, but the exact mathematical functions varied with different species, especially those at different trophic levels. The MASH values for Macrosiphum avenae, Schizaphis graminum, Aphidius avenae, Aphidius gifuensis, and Pachyneuron aphidis were estimated with a polynormal regression model of density-area relationship, and the results were similar to those estimated from an inverse relationship between population and area. The differences of MASH between trophic levels were significant. It was concluded that these species had different values of MASH, which reflected their different habitat requirements and their differences in body size, migration, trophic position, and habitat quality. For parasitoids, the highest parasitic rates always took place at a spatial scale of 800-1000 m2, which could be considered as the base of aphids control with parasitoids, while the difference of MASH among trophic levels could be used to suppress the pest population.
    Effects of perfluorooctane sulfonate on acute lethality and avoidance behavior of earthworm.
    2011, 22(01):  215-220. 
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    As a new kind of persistent organic pollutants, perfluorooctane sulfonate (PFOS) has become a research spot of environmental science and toxicology. Its impacts on ecological environment should be deeply studied. In this paper, standard contact filter paper test of OECD, artificial soil test, and natural soil test were adopted to study the effects of PFOS on the acute lethality and avoidance behavior of earthworm. The results showed that the acute toxicity of PFOS on earthworm was related to the toxicant exposure time and concentration. The LC50,48 h in filter paper test, LC50,14 d in artificial soil test, andLC50,14 d in natural soil test were 13.64 μg·cm-2, 955.28 mg·kg-1, and 542.08 mg·kg-1, respectively. At the maximum test concentration of 160
     mg·kg-1, the earthworm in artificial soil and natural soil showed significant avoidance behavior, which proved that earthworm could perceive and avoid the soil contaminated by a higher concentration of PFOS. To assess PFOS-contaminated soils, the avoidance endpoint was more sensitive than the mortality endpoint. PFOS had higher acute toxicity on earthworm in natural soil than in artificial soil. Meanwhile, more significant avoidance reaction was observed in natural soil than in artificial soil at the same concentrations of PFOS.
    Longevity and emergence rhythm of adult parasitoids of Coccobius asumai Tachikawa (Hymenoptera: Aphelinidae) introduced from Japan.
    2011, 22(01):  221-228. 
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    A series of feeding experiment and regular observation were conducted in laboratory to explore the effects of diet and temperature on the longevity of
    Coccobius azumai adults and their temporal rhythm of emergence. Diet had significant effects on the longevity of the adults. Without any diet supply, the mean longevity of the females and males was 1.5 d; but with the supplement of 20% honey water and of 20% honey water + fresh pine needles, the mean longevity reached 14.8 d and 11.3 d, and 17.3 d and 12.3 d, respectively. Temperature also played an important role on the longevity of the adults fed with 20% honey water. At 23 ℃ and 26 ℃, the longevity of the females and males was obviously longer; while at 32 ℃, the longevity was the shortest. At same temperatures, the mean longevity of the females was significantly longer than that of the males. In their circadian cycle, most of the females emerged from 11:00 to 15:00, but most males emerged from 9:00 to 12:00. Few females emerged after 18:00, and few males after 17:00. Most of the adult parasitoids enclosed from July to September. The amount of emerged adults peaked in July, and showed a fluctuant and descending trend in the subsequent August and September. Over 80% of the emerged adults were female in most days, and the males were always fluctuating in a low level in this period. A separate experiment showed that in the collection of the adult parasitoids, cloth shed was more superior to paper box. This study showed that limited energy was conserved in the parasitoids before adult emergence, and thus, supplementing suitable diet to newly emerged adults before release was necessary for prolonging their longevity and improving the efficiency of biological control. In Fujian and Guandong of China, there would be some potential disadvantage factors against the continuation of the parasitoid population, e.g., high temperature in summer, lack of temporal synchronization between the adult parasitoid females and their hosts (adult females of pine armored scale), and greatly high proportion of parasitoid females. Cloth shed benefited the collection of large amount of the parasitoids, being available in the biological control activities.
    Monopolization of honeydew sources by Crematogaster macaoensis and its effects on lac production.
    2011, 22(01):  229-234. 
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    From October 2008 to May 2010, an investigation was made in a lac plantation in Yayi region of Mojiang County, Yunnan Province, China, aimed to understand the behavior of the monopolization of honeydew sources by ant Crematogaster macaoensis, and its effects on the sex ratio, mortality, fecundity, and lac production of Yunnan lac insect Kerria yunnanensis. The results showed that C. macaoensis fed and monopolized the honeydews around the clock during the whole life cycle of K. yunnanensis on the sticklac, and the average number of visiting C. macaoensis ranged from 16.8±2.3 to 39.3±10.0 per 10 cm length of the stick-lac. C. macaoensis constructed shelters to prevent other animals from visiting the lac insect. C. macaoensis monopolization reduced the lac production of individual K. yunnanensi significantly, but had no significant effects on the lac production of whole lac insect colony. In addition, C. macaoensis monopolization reduced the mortality of K. yunnanensis significantly, and increased the percentage of K. yunnanensis females and the adult female fecundity. It was concluded that ant monopolization of the lac insect honeydew seemed to be beneficial to the lac production by the Yunnan lac insect.
    Phytoplankton in Yangtze River estuary and its adjacent waters in spring in 2009: Species composition and size-fractionated chlorophyll a.
    2011, 22(01):  235-242. 
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    Based on the multidisciplinary cruise investigation in the Yangtze River estuary and its adjacent waters in April 2009, the phytoplankton species and
    their abundance were analyzed by the Utermöhl method, and the size-fractionated chlorophyll a concentrations were determined. In the meantime, the relationships between the dominant phytoplankton species and environmental physicochemical factors were explored by Canonical Correspondence Analysis (CCA). A total of 3 phyla, 46 genera, and 64 species (not including uncertain species) were found, mostly diatoms and dinoflagellates, with diatoms dominant. Most of these species were temperate and coastal, but a few brackish and oceanic species also presented. There were 33 diatom genera including 45 species. The dominant species were Skeletonema dohrnii, Paralia sulcata, Thalassionema nitzschioides, Pseudo-nitzschia pungens, Melosira granulata var. angustissima, Pseudo-nitzschia delicatissima, and Guinardia delicatula. The phytoplankton cell abundance ranged
    from 0.3 to 13447.7 cells·ml-1, with an average of 1142.385 cells·ml-1. Concerning the horizontal distribution, cell abundance was the highest in the middle-northern part of the survey area, with S. dohrnii dominant. The phytoplankton cell abundance was high in the surface layer water, and decreased with increasing depth. The Shannon diversity index and Pielou evenness index were consistently low in the middlenorthern part of the survey area, in contrast to the trend of phytoplankton cell abundance. The chlorophyll a concentrations ranged from 0.34 to 29 g·L-1, with an average of 3.3 g·L-1, consistent with the cell abundance distribution. Size-fractionated chlorophyll a results showed that the biomass in the middle-northern part of the survey area was mainly composed of microphytoplankton (>20 μm), while that in offshore waters was mainly composed of nanophytoplankton (2-20 μm) and picophytoplankton (<2 μm). The CCA showed that the distribution of predominant species S. dohrnii was mainly affected by the water nitrate content, pH value, and microzooplankton grazing. On the contrary, the distribution of other common species including dinoflagellates was mainly associated with water salinity, and phosphate and silicate contents. The paper also compared the differences in the methods of phytoplankton quantification used by the present study and by the previous studies based on net samples. It was suggested that in future work, the autecological study of genus Skeletonema in the Yangtze River estuary and its adjacent waters should be strengthened.
    Precipitation pulses and ecosystem responses in arid and semiarid regions: A review.
    2011, 22(01):  243-249. 
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    Precipitation events in arid/semi-arid environment are usually occurred in “pulses”, with highly variable arrival time, duration, and intensity. These discrete and largely unpredictable features may lead to the pulsed availability of soil water and nutrients in space and time. Resources pulses can affect the life history traits and behaviors at individual level, numerous responses at population level, and indirect effects at community level. This paper reviewed the most recent research advances in the related fields from the aspects of the effects of resources pulses and the responses of ecosystems. It was emphasized that the following issues are still open, e.g., the effects of the pulsed features of resources availability on ecosystems, the discrepancy among the effects of resources pulses in different ecosystems, the eco-hydrological mechanisms that determine the persistence of pulsed resources effects, and the effects of the pulsed resources availability on ecosystem processes.Given the potential global climate and precipitation pattern change, an important research direction in the future is to determine how the resources pulses affect the ecosystem responses at different scales under different climate scenarios.
    Affecting factors of plant stomatal traits variability and relevant investigation methods.
    2011, 22(01):  250-256. 
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    Stoma is the main routeway for water and gas exchange in terrestrial plants, playing an important role on the global water and carbon cycles. Stomatal traits, including stomatal density, stomatal shape, stomatal size, and stomatal index, are the long term adaptation result of plants to environmental factors during evolution, and sensitive to the changes of environmental factors. This paper reviewed the last 30 years research advances in the relationships between stomatal traits and environmental factors (e.g., air CO2 concentration, temperature, water, and light, etc.) and the main relevant investigation methods, and proposed the main directions of future research in stomatal traits in context of climate change.
    Methods and applications of population viability analysis (PVA): A review.
    2011, 22(01):  257-267. 
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    With the accelerating human consumption of natural resources, the problems associated with endangered species caused by habitat loss and fragmentation have become greater and more urgent than ever. Conceptually associated with the theories of island biogeography, population viability analysis (PVA) has been one of the most important approaches in studying and protecting endangered species, and this methodology has occupied a central place in conservation biology and ecology in the past several decades.  PVA has been widely used and proven effective in many cases, but its predictive ability and accuracy are still in question. Also, its application needs expand. To overcome some of the problems, we believe that PVA needs to incorporate some principles and methods from other fields, particularly landscape ecology and sustainability science. Integrating landscape pattern and socioeconomic factors into PVA will make the approach theoretically more comprehensive and practically more useful. Here, we reviewed the history, basic conception, research methods, and modeling applications and their accuracies of PVA, and proposed the perspective in this field.
    Effects of climate factors on the epidemic of apple Marssonina blotch in Shaanxi Province and related prediction models.
    2011, 22(01):  268-272. 
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    Based on the long term (1999-2008) monitoring of air temperature and relative humidity and of the occurrence and epidemiological trend of Marssonina blotch in the main apple-production area of Shaanxi Province, this paper analyzed the occurrence time, pathogenesis regularity, and epidemiological level of Marssonina blotch, with the 1- and 3-dimensional models for predicting Marssonina blotch under effects of ten-day mean air temperature (T) and relative humidity (Hm) constructed. In study area, the development of Marssonina blotch was mainly affected by environment factors. This disease spread rapidly in field in July and August, causing orchard defoliation, and the harm persisted until September. After the first frost, new disease spots no longer developed. The data of T and Hm in the models showed a good fitting with field condition. The 3-dimensional dynamic prediction model of Marssonina blotch was f(T,Hm)=-0.0172T3+0.9497T2-16.2209T+88.9923-0.00001Hm3+0.00354Hm2-0.15554Hm+2.36578, where f(T,Hm) was disease index. The modeling results showed that the T  for the occurrence of Marssonina blotch in field was 15 ℃, and the disease would have an epidemic peak when the T and Hm in July and August reached 23 ℃ and ≥90%, respectively.