In this study,we identified ecological pressures on grassland ecosystems and adaptive countermeasures in Northern China.Our research revealed that the main sources of these pressures included population growth,economi...In this study,we identified ecological pressures on grassland ecosystems and adaptive countermeasures in Northern China.Our research revealed that the main sources of these pressures included population growth,economic development,resources exploitation,and global climate change,with human-related activities being overriding factors.Overgrazing was an important reason for grassland imbalance,causing soil erosion and desertification,especially during the sensitive spring greening phase.In steppe zones,commercial coal mining was destructive to the ecological environment.Regarding long-term strategies,we recommend that policy-makers devote more consideration to a new conceptual approach for transforming grasslands through shifting the focus from die grassland's traditional production functions to meir ecological functions.Applying this concept,adaptive countermeasures should be developed to reduce human impacts based on the environmental capacities of grasslands.Moreover,we recommend the development of environment-friendly industries and reduction of pressures from human activities as effective measures for maintaining the balance between sustainable economic development and grassland conservation.Lastly,we suggest that restoration of degraded grasslands should conform to the principle of natural vegetation to further improve the ecological adaptability of plants and ecosystem stability.This study is expected to provide scientific support for policy-makers engaged in grassland protection.展开更多
Based on the model of grassland climate ecological productivity, the process of grassland degradation and its restoration mechanism in northern Tibetan Plateau were discussed by the model of food-chain in which the en...Based on the model of grassland climate ecological productivity, the process of grassland degradation and its restoration mechanism in northern Tibetan Plateau were discussed by the model of food-chain in which the environmental and human factors were corrected. The results of case study in Nierong County showed that:① the climate trend of becoming warmer, more droughts and gales were conflicted with the restoration of grassland degradation, even under level of perfect management the climate ecological productivity was declined from 89.3 kg/m 2 of 1983 to 71.8 kg/m 2 of 2003; ② from 1983 to 2003, the population increased fast, while the variation of livestock on hand was little, and the cost of its maintaining is rapid grassland degradation; ③ on the present condition of overgrazing, the livestock on hand can be maintained on the level of theoretical carrying capacity in 2033 by applying the mechanism of food-chain in grassland ecological system controlled with expected coefficients, so that to realize the policy of determining the quantity of livestock according to grass growth.展开更多
Overgrazing has been considered one of the major causes that trigger shrub encroachment of grassland.Proliferation of shrubs in grassland is recognized as an important indicator of grassland degradation and desertific...Overgrazing has been considered one of the major causes that trigger shrub encroachment of grassland.Proliferation of shrubs in grassland is recognized as an important indicator of grassland degradation and desertification.In China,various conservation measures,including enclosures to reduce livestock grazing,have been taken to reverse the trend of grassland desertification,yet shrubs have been reported to increase in the grasslands over the past decades.In late 2007,we set up a 400-m-by-50-m exclosure in a long-term overgrazed temperate grassland in Inner Mongolia,with the objective to quantify the spatiotemporal relationship between vegetation dynamics,soil variables,and grazing exclusion.Soil moisture was continuously monitored within the exclosure,and cover and aboveground biomass of the shrubs were measured inside the exclosure in 2007,2009,2010,2012,and 2013,and outside the exclosure in 2012 and 2013.We found the average shrub cover and biomass significantly increased in the six years by 103% and 120%,respectively.The result supported the hypothesis that releasing grazing pressure following long-term overgrazing tends to trigger shrub invasion into grassland.Our results,limited to a single gradient,suggest that any conservation measures with quick release of overgrazing pressure by enclosure or other similar means might do just the opposite to accelerate shrub encroachment in grassland.The changes in vegetation cover and biomass were regressed on the temporal average of the soil moisture content by means of the generalized least square technique to quantify the effect of the spatial autocorrelation.The result indicates that the grass cover and biomass significantly increased with the top,but decreased with the bottom layer soil moisture.The shrub cover and biomass,on the other hand,decreased with the top,but increased with bottom soil moisture,although the regression coefficients for the shrubs were not statistically significant.Hence this study supports the two-layered soil model which assumes grasses and shrubs use belowground resources in different depths.展开更多
近年来随着全球变暖,干旱事件的增加对植被的光合作用产生更加重要的影响,同时也严重影响了陆地生态系统的平衡。本文基于标准化降水蒸散指数(SPEI base v.2.7)和总初级生产力数据集(GOSIF GPP)研究了干旱对中国北方草原GPP的累积和时...近年来随着全球变暖,干旱事件的增加对植被的光合作用产生更加重要的影响,同时也严重影响了陆地生态系统的平衡。本文基于标准化降水蒸散指数(SPEI base v.2.7)和总初级生产力数据集(GOSIF GPP)研究了干旱对中国北方草原GPP的累积和时滞效应,利用Sen’s斜率、Mann-Kendall(MK)趋势检验、Mann-Kendall突变检验研究了GPP和SPEI在研究期内的时空变化,利用Pearson相关分析方法探究了干旱对北方草原GPP的累积和时滞效应。结果表明:(1)2001—2020年期间北方草原多年平均GPP呈现东北地区高、西南地区低的空间分布格局,多年平均SPEI呈现东北地区低、西南地区高的空间分布格局,且SPEI和GPP的年平均值都随时间变化呈现上升趋势。(2)干旱对北方草原84.99%的区域有累积效应,最长累积时间尺度主要集中在3~4个月,覆盖北方草原的39.82%;干旱对北方草原63.11%的区域有滞后效应,且主要发生在7个月,覆盖北方草原的19.73%。(3)通过对比不同水分条件下二者的变化趋势,发现干旱对草原GPP的累积效应强于时滞效应。展开更多
基金supported by the Reform initial projects of the Chinese Research Academy of Environmental Sciences[grant number 2012-YSGQ-06],and[grant number 2013-YSGQ-06]
文摘In this study,we identified ecological pressures on grassland ecosystems and adaptive countermeasures in Northern China.Our research revealed that the main sources of these pressures included population growth,economic development,resources exploitation,and global climate change,with human-related activities being overriding factors.Overgrazing was an important reason for grassland imbalance,causing soil erosion and desertification,especially during the sensitive spring greening phase.In steppe zones,commercial coal mining was destructive to the ecological environment.Regarding long-term strategies,we recommend that policy-makers devote more consideration to a new conceptual approach for transforming grasslands through shifting the focus from die grassland's traditional production functions to meir ecological functions.Applying this concept,adaptive countermeasures should be developed to reduce human impacts based on the environmental capacities of grasslands.Moreover,we recommend the development of environment-friendly industries and reduction of pressures from human activities as effective measures for maintaining the balance between sustainable economic development and grassland conservation.Lastly,we suggest that restoration of degraded grasslands should conform to the principle of natural vegetation to further improve the ecological adaptability of plants and ecosystem stability.This study is expected to provide scientific support for policy-makers engaged in grassland protection.
文摘Based on the model of grassland climate ecological productivity, the process of grassland degradation and its restoration mechanism in northern Tibetan Plateau were discussed by the model of food-chain in which the environmental and human factors were corrected. The results of case study in Nierong County showed that:① the climate trend of becoming warmer, more droughts and gales were conflicted with the restoration of grassland degradation, even under level of perfect management the climate ecological productivity was declined from 89.3 kg/m 2 of 1983 to 71.8 kg/m 2 of 2003; ② from 1983 to 2003, the population increased fast, while the variation of livestock on hand was little, and the cost of its maintaining is rapid grassland degradation; ③ on the present condition of overgrazing, the livestock on hand can be maintained on the level of theoretical carrying capacity in 2033 by applying the mechanism of food-chain in grassland ecological system controlled with expected coefficients, so that to realize the policy of determining the quantity of livestock according to grass growth.
基金supported by the National Science Foundations of China with Grant No.41171445
文摘Overgrazing has been considered one of the major causes that trigger shrub encroachment of grassland.Proliferation of shrubs in grassland is recognized as an important indicator of grassland degradation and desertification.In China,various conservation measures,including enclosures to reduce livestock grazing,have been taken to reverse the trend of grassland desertification,yet shrubs have been reported to increase in the grasslands over the past decades.In late 2007,we set up a 400-m-by-50-m exclosure in a long-term overgrazed temperate grassland in Inner Mongolia,with the objective to quantify the spatiotemporal relationship between vegetation dynamics,soil variables,and grazing exclusion.Soil moisture was continuously monitored within the exclosure,and cover and aboveground biomass of the shrubs were measured inside the exclosure in 2007,2009,2010,2012,and 2013,and outside the exclosure in 2012 and 2013.We found the average shrub cover and biomass significantly increased in the six years by 103% and 120%,respectively.The result supported the hypothesis that releasing grazing pressure following long-term overgrazing tends to trigger shrub invasion into grassland.Our results,limited to a single gradient,suggest that any conservation measures with quick release of overgrazing pressure by enclosure or other similar means might do just the opposite to accelerate shrub encroachment in grassland.The changes in vegetation cover and biomass were regressed on the temporal average of the soil moisture content by means of the generalized least square technique to quantify the effect of the spatial autocorrelation.The result indicates that the grass cover and biomass significantly increased with the top,but decreased with the bottom layer soil moisture.The shrub cover and biomass,on the other hand,decreased with the top,but increased with bottom soil moisture,although the regression coefficients for the shrubs were not statistically significant.Hence this study supports the two-layered soil model which assumes grasses and shrubs use belowground resources in different depths.
文摘近年来随着全球变暖,干旱事件的增加对植被的光合作用产生更加重要的影响,同时也严重影响了陆地生态系统的平衡。本文基于标准化降水蒸散指数(SPEI base v.2.7)和总初级生产力数据集(GOSIF GPP)研究了干旱对中国北方草原GPP的累积和时滞效应,利用Sen’s斜率、Mann-Kendall(MK)趋势检验、Mann-Kendall突变检验研究了GPP和SPEI在研究期内的时空变化,利用Pearson相关分析方法探究了干旱对北方草原GPP的累积和时滞效应。结果表明:(1)2001—2020年期间北方草原多年平均GPP呈现东北地区高、西南地区低的空间分布格局,多年平均SPEI呈现东北地区低、西南地区高的空间分布格局,且SPEI和GPP的年平均值都随时间变化呈现上升趋势。(2)干旱对北方草原84.99%的区域有累积效应,最长累积时间尺度主要集中在3~4个月,覆盖北方草原的39.82%;干旱对北方草原63.11%的区域有滞后效应,且主要发生在7个月,覆盖北方草原的19.73%。(3)通过对比不同水分条件下二者的变化趋势,发现干旱对草原GPP的累积效应强于时滞效应。
