From July 2008 to August 2008, 72 leaf samples from 22 species and 81 soil samples in the nine natural forest ecosystems were collected, from north to south along the North-South Transect of Eastern China （NSTEC）. B...From July 2008 to August 2008, 72 leaf samples from 22 species and 81 soil samples in the nine natural forest ecosystems were collected, from north to south along the North-South Transect of Eastern China （NSTEC）. Based on these samples, we studied the geographical distribution patterns of vegetable water use efficiency （WUE） and nitrogen use efficiency （NUE）, and analyzed their relationship with environmental factors. The vegetable WUE and NUE were calculated through the measurement of foliar δ 13C and C/N of predominant species, respectively. The results showed： （1） vegetable WUE, ranging from 2.13 to 28.67 mg C g-1 H2O, increased linearly from south to north in the representative forest ecosystems along the NSTEC, while vegetable NUE showed an opposite trend, increasing from north to south, ranging from 12.92 to 29.60 g C g-1 N. （2） Vegetable WUE and NUE were dominantly driven by climate and significantly affected by soil nutrient factors. Based on multiple stepwise regression analysis, mean annual temperature, soil phosphorus concentration, and soil nitrogen concentration were responding for 75.5% of the variations of WUE （p0.001）. While, mean annual precipitation and soil phosphorus concentration could explain 65.7% of the change in vegetable NUE （p0.001）. Moreover, vegetable WUE and NUE would also be seriously influenced by atmospheric nitrogen deposition in nitrogen saturated ecosystems. （3） There was a significant trade-off relationship between vegetable WUE and NUE in the typical forest ecosystems along the NSTEC （p0.001）, indicating a balanced strategy for vegetation in resource utilization in natural forest ecosystems along the NSTEC. This study suggests that global change would impact the resource use efficiency of forest ecosystems. However, vegetation could adapt to those changes by increasing the use efficiency of shortage resource while decreasing the relatively ample one. But extreme impacts, such as heavy nitrogen deposition, would break this trade-off mechanism and give a dramatic disturbance to the ecosystem biogeochemical cycle.展开更多
The time series NDVI distribution maps of the study area were calculated with AVHRR images acquired from May 1999 to April 2000 on the North-South transect of Eastern China. Based on the analysis of the characteristic...The time series NDVI distribution maps of the study area were calculated with AVHRR images acquired from May 1999 to April 2000 on the North-South transect of Eastern China. Based on the analysis of the characteristics and their contributions to NPP on the transect, the RS NPP distribution maps were created by zones and the quantitative models were established between NDVI maps and field measured NPP sample data collected from Central and South China for forest and cultivated land. Furthermore, the spatial distribution and quantitative result were obtained through an overlapping and fitting analysis between the NPP maps and DEM. The result shows that the NPP distribution features are not only distinguished on detail zonation of natural vegetation in vertical, latitudinal and longitudinal distribution but also reflected an obvious effect from the crop growing period of agricultural area. According to the results above, an opposite opinion was given that the NPP values for the forest and agricultural areas vary greatly in different regions, with the forest areas having a higher value than the agricultural areas in Southern China. In the Huang, Huai and Hai Plains, agricultural regions have higher NPP values than the surrounding low mountains. In Northeastern China, the NPP values form a gradient across the mid-to-high mountain forest zone to plains and low mountain areas. Further, for most of the agricultural areas, NPP values range between 25—35 t·hm2·a-1 and do not show significant areal differentiation.展开更多
A possible reason for the unreasonable simula- tion of maximum rainfall location, intensity and seasonal evolution over eastern China in CCM3 has been investigated. The analyses focus on the relationship between the s...A possible reason for the unreasonable simula- tion of maximum rainfall location, intensity and seasonal evolution over eastern China in CCM3 has been investigated. The analyses focus on the relationship between the simulated East Asian subtropical westerly jet biases and the seasonal evolution of rainbelt over eastern China. Comparisons of the simulated and observed precipitation distributions indicate that the simulated maximum rainfall location, intensity and seasonal evolution are inconsistent with reality. The simu- lated westerly jet center is located to the north of 40°N, which shifts eastward and northward and strengthens, com- pared with NCEP/NCAR reanalysis. The correlation analysis shows that there exists a significant positive correlation be- tween the maximum rainfall amount and zonal wind at 200 hPa over the Great Bend of the Huanghe River. Thus the simulated unrealistic heavy precipitation in the inland area of western China is related to the biases in the location and intensity of the East Asian subtropical westerly jet. Further analysis indicates that the temperature differences from south to north in the lower troposphere and the larger sensi- ble heating over the southeast Tibetan Plateau are responsi- ble for the westerly jet location and intensity biases. There- fore, much more attention should be paid to the accurate simulation of the surface heating near the Tibetan Plateau and the location and intensity of the East Asian subtropical westerly jet for the improvement of precipitation simulation over East Asia.展开更多
The north-south transect of tastern China (NSTEC) was a typical ecologcal region which was mostly driven by heat and varied with its vegetation along with latitude.In-depth knowing of the NSTEC will enhance our unders...The north-south transect of tastern China (NSTEC) was a typical ecologcal region which was mostly driven by heat and varied with its vegetation along with latitude.In-depth knowing of the NSTEC will enhance our understanding of global change along with global warming.In this paper,NOAA-AVHRR data was used to get the vegetation index across the NSTEC.Then a regression model was built to get the Net Primary Productivity (NPP) from it.Since the research area covered from 118°E to 128°E,40°N to 50°N,and from 108°E to 118°E,17.5°N to 40°N,to precisely acquire the NPP distribution pattern of the whole area,different vegetation indices were compared according to different land surface.Then three regression models were deduced for NPP.Finally,a NPP adjusting scheme was used to get a general NPP distribution map from the three regression results.The achievements well reflect the distribution character of NPP along the NSTEC and would support further analysis and simulation in land ecology system study and global change research.展开更多
基金National Natural Science Foundation of China No.30590381 No.31000211 National Basic Research Program of China No.2010CB833504
文摘From July 2008 to August 2008, 72 leaf samples from 22 species and 81 soil samples in the nine natural forest ecosystems were collected, from north to south along the North-South Transect of Eastern China （NSTEC）. Based on these samples, we studied the geographical distribution patterns of vegetable water use efficiency （WUE） and nitrogen use efficiency （NUE）, and analyzed their relationship with environmental factors. The vegetable WUE and NUE were calculated through the measurement of foliar δ 13C and C/N of predominant species, respectively. The results showed： （1） vegetable WUE, ranging from 2.13 to 28.67 mg C g-1 H2O, increased linearly from south to north in the representative forest ecosystems along the NSTEC, while vegetable NUE showed an opposite trend, increasing from north to south, ranging from 12.92 to 29.60 g C g-1 N. （2） Vegetable WUE and NUE were dominantly driven by climate and significantly affected by soil nutrient factors. Based on multiple stepwise regression analysis, mean annual temperature, soil phosphorus concentration, and soil nitrogen concentration were responding for 75.5% of the variations of WUE （p0.001）. While, mean annual precipitation and soil phosphorus concentration could explain 65.7% of the change in vegetable NUE （p0.001）. Moreover, vegetable WUE and NUE would also be seriously influenced by atmospheric nitrogen deposition in nitrogen saturated ecosystems. （3） There was a significant trade-off relationship between vegetable WUE and NUE in the typical forest ecosystems along the NSTEC （p0.001）, indicating a balanced strategy for vegetation in resource utilization in natural forest ecosystems along the NSTEC. This study suggests that global change would impact the resource use efficiency of forest ecosystems. However, vegetation could adapt to those changes by increasing the use efficiency of shortage resource while decreasing the relatively ample one. But extreme impacts, such as heavy nitrogen deposition, would break this trade-off mechanism and give a dramatic disturbance to the ecosystem biogeochemical cycle.
文摘The time series NDVI distribution maps of the study area were calculated with AVHRR images acquired from May 1999 to April 2000 on the North-South transect of Eastern China. Based on the analysis of the characteristics and their contributions to NPP on the transect, the RS NPP distribution maps were created by zones and the quantitative models were established between NDVI maps and field measured NPP sample data collected from Central and South China for forest and cultivated land. Furthermore, the spatial distribution and quantitative result were obtained through an overlapping and fitting analysis between the NPP maps and DEM. The result shows that the NPP distribution features are not only distinguished on detail zonation of natural vegetation in vertical, latitudinal and longitudinal distribution but also reflected an obvious effect from the crop growing period of agricultural area. According to the results above, an opposite opinion was given that the NPP values for the forest and agricultural areas vary greatly in different regions, with the forest areas having a higher value than the agricultural areas in Southern China. In the Huang, Huai and Hai Plains, agricultural regions have higher NPP values than the surrounding low mountains. In Northeastern China, the NPP values form a gradient across the mid-to-high mountain forest zone to plains and low mountain areas. Further, for most of the agricultural areas, NPP values range between 25—35 t·hm2·a-1 and do not show significant areal differentiation.
基金supported jointly by the National Natural Science Foundation of China(Grant No.40333026)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.ZKCX2-SW-210)
文摘A possible reason for the unreasonable simula- tion of maximum rainfall location, intensity and seasonal evolution over eastern China in CCM3 has been investigated. The analyses focus on the relationship between the simulated East Asian subtropical westerly jet biases and the seasonal evolution of rainbelt over eastern China. Comparisons of the simulated and observed precipitation distributions indicate that the simulated maximum rainfall location, intensity and seasonal evolution are inconsistent with reality. The simu- lated westerly jet center is located to the north of 40°N, which shifts eastward and northward and strengthens, com- pared with NCEP/NCAR reanalysis. The correlation analysis shows that there exists a significant positive correlation be- tween the maximum rainfall amount and zonal wind at 200 hPa over the Great Bend of the Huanghe River. Thus the simulated unrealistic heavy precipitation in the inland area of western China is related to the biases in the location and intensity of the East Asian subtropical westerly jet. Further analysis indicates that the temperature differences from south to north in the lower troposphere and the larger sensi- ble heating over the southeast Tibetan Plateau are responsi- ble for the westerly jet location and intensity biases. There- fore, much more attention should be paid to the accurate simulation of the surface heating near the Tibetan Plateau and the location and intensity of the East Asian subtropical westerly jet for the improvement of precipitation simulation over East Asia.
文摘The north-south transect of tastern China (NSTEC) was a typical ecologcal region which was mostly driven by heat and varied with its vegetation along with latitude.In-depth knowing of the NSTEC will enhance our understanding of global change along with global warming.In this paper,NOAA-AVHRR data was used to get the vegetation index across the NSTEC.Then a regression model was built to get the Net Primary Productivity (NPP) from it.Since the research area covered from 118°E to 128°E,40°N to 50°N,and from 108°E to 118°E,17.5°N to 40°N,to precisely acquire the NPP distribution pattern of the whole area,different vegetation indices were compared according to different land surface.Then three regression models were deduced for NPP.Finally,a NPP adjusting scheme was used to get a general NPP distribution map from the three regression results.The achievements well reflect the distribution character of NPP along the NSTEC and would support further analysis and simulation in land ecology system study and global change research.
