[Objective] The aim was to study the environment evolution of Shanbei Loess landscape under the background of global climate changes.[Method] The annual and monthly temperature and precipitation in Yulin area in north...[Objective] The aim was to study the environment evolution of Shanbei Loess landscape under the background of global climate changes.[Method] The annual and monthly temperature and precipitation in Yulin area in north Shaanxi from 1952 to 2009 were selected,and by dint of linear regression and M-K mutation,the Loess land form evolution under the global climate change was studied.[Result] The temperature in Yulin area showed increasing tendency from 1952 to 2009 at a speed of 0.287℃/10 a.The year 1994 was a year of mutation of temperature;precipitation decreased at speed of 8.262 mm/10 a and the precipitation fluctuated largely in 1960s,and stably in 1970s,1980s and 1990s.It showed drying tendency.The climate in north Shanxi was becoming warmer.The extreme dry and flood incident,especially the rising drought occurrence frequency had more serious endangerment to the fragile ecological environment.The ' warmer drought' of climate worsened the environment in north Shaanxi,with temperature rising and worsening drought;reduction of precipitation made the wind and sand more active;the frequency of sandstorm increased;desertification of land furthered;the water and soil losses in Loess was serious and might led to degradation of land in north Shaanxi.[Conclusion] The study provided theoretical basis for the ecological and environmental construction in the region.展开更多
The Tianshan Mountains is a high and huge mountain body lying across the central part of Xinjiang, China, and is also the main area where the runoff forms in Xinjiang. In this paper, a set of RS-based study methods is...The Tianshan Mountains is a high and huge mountain body lying across the central part of Xinjiang, China, and is also the main area where the runoff forms in Xinjiang. In this paper, a set of RS-based study methods is put forward for deriving the information about the natural change of the ecology in arid areas, and the relationship between the climate change trend and the corresponding ecological response on the northern slope of the Tianshan Mountains since recent 40 years is analyzed from the scales of the land cover ecosystems and landscapes based on the observed data of climate, hydrology, modern glaciers and lakes on the northern slopes of the Tianshan Mountains since recent 40 years and the satellite RS data since recent 10 years by using the RS and GIS technologies. The results are as follows: (1) The overall trend of climate change on the northern slope of the Tianshan Mountains since recent 40 years is that both air temperature and precipitation are increased, especially the increase amplitudes of air tempera-ture, precipitation and annual runoff volume are high since the decade of the 1990s; (2) the in-tegrated indexes of the vegetation in all the geographical divisions on the northern slope of the Tianshan Mountains are obviously increased since recent 10 years, especially in the artificial oases and the foothill belts, such a change trend is advantageous for improving the vegetation ecology; and (3) the vegetation ecology in the arid areas is extremely sensitive to the climate change, the vegetation coverage and the biomass on the northern slope of the Tianshan Moun-tains are continuously increased because of the climate change since recent 10 years, their in-crease amplitudes in the plains and during the late stage are obviously higher than that in the mountainous regions and during the early stage.展开更多
The ＂Grain for Green Project＂ initiated by the governments since 1999 were the dominant contributors to the vegetation restoration in the agro-pastoral transitional zone of northern China. Climate change and human a...The ＂Grain for Green Project＂ initiated by the governments since 1999 were the dominant contributors to the vegetation restoration in the agro-pastoral transitional zone of northern China. Climate change and human activities are responsible for the improvement and degradation to a certain degree. In order to monitor the vegetation variations and clarify the causes of rehabilitation in the Shaanxi-Gansu-Ningxia Region, this paper, based on the MODIS-NDVI and climate data during the period of 2000-2009, analyzes the main charac- teristics, spatial-temporal distribution and reasons of vegetation restoration, using methods of linear regression, the Hurst Exponent, standard deviation and other methods. Results are shown as follows. （1） From 2000 to 2009, the NDVI of the study area was improved progres- sively, with a linear tendency being 0.032/10a, faster than the growth of the Three-North Shelter Forest Program （0.007/10a） from 1982 to 2006. （2） The vegetation restoration is characterized by two fast-growing periods, with an ＂S-shaped＂ increasing curve. （3） The largest proportion of the contribution to vegetation restoration was observed in the slightly improved area, followed by the moderate and the significantly improved area; the degraded area is distributed sporadically over southern part of Ningxia Hui Autonomous Region as well as eastern Dingbian of Shaanxi province, Huanxian and Zhengyuan of Gansu province. （4） Climate change and human activities are two driving forces in vegetation restoration; more- over anthropogenic factors such as ＂Grain for Green Project＂ were the main causes leading to an increasing trend of NDVI on local scale. However, its influencing mechanism remains to be further investigated. （5） The Hurst Exponent of NDVI time series shows that the vegetation restoration was sustainable. It is expected that improvement in vegetation cover will expand to the most parts of the region.展开更多
Vegetation dynamics could lead to changes in the global carbon and hydrology cycle,as well as feedbacks to climate change.This paper reviews the response of forest dynamics to climate change.Based on palaeoecological ...Vegetation dynamics could lead to changes in the global carbon and hydrology cycle,as well as feedbacks to climate change.This paper reviews the response of forest dynamics to climate change.Based on palaeoecological studies,we summarized the features and modes of vegetation response to climate change and categorized the impacts of climate change on vegetation dynamics as three types:climate stress on vegetation,buffer effects by non-climatic factors,and perturbation of the vegetation distribution by stochastic events.Due to the openness of the vegetation system and the integrated effects of both climatic and non-climatic factors,the vegetation-climate relationship deviates far from its equilibrium.The vegetation distribution shows a non-linear response to climate change,which also makes it difficult to quantify the modern vegetation distribution in terms of specific climatic factors.Past analog,space-for-time-substitution and Dynamic Global Vegetation Models(DGVMs)are three approaches to predicting the future vegetation distribution,but they have all been established on the assumption of vegetation-climate equilibrium.We propose that improving DGVMs is a future task for studies of vegetation dynamics because these are process-based models incorporating both disturbance(e.g.fire)and the variability in Plant Functional Types(PFTs).However,palaeoecological results should be used to test the models,and issues like spatial and temporal scale,complexity of climate change,effects of non-climatic factors,vegetation-climate feedback,and human regulation on vegetation dynamics are suggested as topics for future studies.展开更多
We developed a vegetation geo-climatic zonation incorporating the zonal concept, gradient and discriminant analysis in Wasatch Range, northern Utah, USA. Mountainous forest ecosystems were sampled and described by veg...We developed a vegetation geo-climatic zonation incorporating the zonal concept, gradient and discriminant analysis in Wasatch Range, northern Utah, USA. Mountainous forest ecosystems were sampled and described by vegetation, physiographic features and soil properties. The Snowpack Telemetry and National Weather Service Cooperative Observer Program weather station networks were used to approximate the climate of sample plots. We analysed vegetation and environmental data using clustering, ordination, classification, and ANOVA techniques to reveal environmental gradients affecting a broad vegetation pattern and discriminate these gradients. The specific objective was to assess and classify the response of the complex vegetation to those environmental factors operating at a coarse-scale climatic level. Ordination revealed the dominant role of regional, altitude-based climate in the area. Based on vegetation physiognomy, represented by five tree species, climatic data and taxonomic classification of zonal soils, we identified two vegetation geo-climatic zones:(1) a montane zone, with Rocky Mountain juniper and Douglas-fir; and(2) a subalpine zone, with Engelmann spruce and subalpine fir as climatic climax species. Aspen was excluded from the zonation due to its great ecological amplitude. We found significant differences between the zones in regional climate and landformgeomorphology/soils. Regional climate was represented by elevation, precipitation, and air and soil temperatures; and geomorphology by soil types. This coarse-scale vegetation geo-climatic zonation provides a framework for a comprehensive ecosystem survey, which is missing in the central Rocky Mountains of the United States. The vegetation-geoclimatic zonation represents a conceptual improvement on earlier classifications. This framework explicitly accounts for the influence of the physical environment on the distribution of vegetation within a complex landscape typical of the central Rocky Mountains and in mountain ranges elsewhere.展开更多
文摘[Objective] The aim was to study the environment evolution of Shanbei Loess landscape under the background of global climate changes.[Method] The annual and monthly temperature and precipitation in Yulin area in north Shaanxi from 1952 to 2009 were selected,and by dint of linear regression and M-K mutation,the Loess land form evolution under the global climate change was studied.[Result] The temperature in Yulin area showed increasing tendency from 1952 to 2009 at a speed of 0.287℃/10 a.The year 1994 was a year of mutation of temperature;precipitation decreased at speed of 8.262 mm/10 a and the precipitation fluctuated largely in 1960s,and stably in 1970s,1980s and 1990s.It showed drying tendency.The climate in north Shanxi was becoming warmer.The extreme dry and flood incident,especially the rising drought occurrence frequency had more serious endangerment to the fragile ecological environment.The ' warmer drought' of climate worsened the environment in north Shaanxi,with temperature rising and worsening drought;reduction of precipitation made the wind and sand more active;the frequency of sandstorm increased;desertification of land furthered;the water and soil losses in Loess was serious and might led to degradation of land in north Shaanxi.[Conclusion] The study provided theoretical basis for the ecological and environmental construction in the region.
基金the important orientation program of the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX3-SW-327).
文摘The Tianshan Mountains is a high and huge mountain body lying across the central part of Xinjiang, China, and is also the main area where the runoff forms in Xinjiang. In this paper, a set of RS-based study methods is put forward for deriving the information about the natural change of the ecology in arid areas, and the relationship between the climate change trend and the corresponding ecological response on the northern slope of the Tianshan Mountains since recent 40 years is analyzed from the scales of the land cover ecosystems and landscapes based on the observed data of climate, hydrology, modern glaciers and lakes on the northern slopes of the Tianshan Mountains since recent 40 years and the satellite RS data since recent 10 years by using the RS and GIS technologies. The results are as follows: (1) The overall trend of climate change on the northern slope of the Tianshan Mountains since recent 40 years is that both air temperature and precipitation are increased, especially the increase amplitudes of air tempera-ture, precipitation and annual runoff volume are high since the decade of the 1990s; (2) the in-tegrated indexes of the vegetation in all the geographical divisions on the northern slope of the Tianshan Mountains are obviously increased since recent 10 years, especially in the artificial oases and the foothill belts, such a change trend is advantageous for improving the vegetation ecology; and (3) the vegetation ecology in the arid areas is extremely sensitive to the climate change, the vegetation coverage and the biomass on the northern slope of the Tianshan Moun-tains are continuously increased because of the climate change since recent 10 years, their in-crease amplitudes in the plains and during the late stage are obviously higher than that in the mountainous regions and during the early stage.
基金National Natural Science Foundation of China, No.41171090 No.40871052
文摘The ＂Grain for Green Project＂ initiated by the governments since 1999 were the dominant contributors to the vegetation restoration in the agro-pastoral transitional zone of northern China. Climate change and human activities are responsible for the improvement and degradation to a certain degree. In order to monitor the vegetation variations and clarify the causes of rehabilitation in the Shaanxi-Gansu-Ningxia Region, this paper, based on the MODIS-NDVI and climate data during the period of 2000-2009, analyzes the main charac- teristics, spatial-temporal distribution and reasons of vegetation restoration, using methods of linear regression, the Hurst Exponent, standard deviation and other methods. Results are shown as follows. （1） From 2000 to 2009, the NDVI of the study area was improved progres- sively, with a linear tendency being 0.032/10a, faster than the growth of the Three-North Shelter Forest Program （0.007/10a） from 1982 to 2006. （2） The vegetation restoration is characterized by two fast-growing periods, with an ＂S-shaped＂ increasing curve. （3） The largest proportion of the contribution to vegetation restoration was observed in the slightly improved area, followed by the moderate and the significantly improved area; the degraded area is distributed sporadically over southern part of Ningxia Hui Autonomous Region as well as eastern Dingbian of Shaanxi province, Huanxian and Zhengyuan of Gansu province. （4） Climate change and human activities are two driving forces in vegetation restoration; more- over anthropogenic factors such as ＂Grain for Green Project＂ were the main causes leading to an increasing trend of NDVI on local scale. However, its influencing mechanism remains to be further investigated. （5） The Hurst Exponent of NDVI time series shows that the vegetation restoration was sustainable. It is expected that improvement in vegetation cover will expand to the most parts of the region.
基金supported by the National Natural Science Foundation of China(41071124 and 31021001)
文摘Vegetation dynamics could lead to changes in the global carbon and hydrology cycle,as well as feedbacks to climate change.This paper reviews the response of forest dynamics to climate change.Based on palaeoecological studies,we summarized the features and modes of vegetation response to climate change and categorized the impacts of climate change on vegetation dynamics as three types:climate stress on vegetation,buffer effects by non-climatic factors,and perturbation of the vegetation distribution by stochastic events.Due to the openness of the vegetation system and the integrated effects of both climatic and non-climatic factors,the vegetation-climate relationship deviates far from its equilibrium.The vegetation distribution shows a non-linear response to climate change,which also makes it difficult to quantify the modern vegetation distribution in terms of specific climatic factors.Past analog,space-for-time-substitution and Dynamic Global Vegetation Models(DGVMs)are three approaches to predicting the future vegetation distribution,but they have all been established on the assumption of vegetation-climate equilibrium.We propose that improving DGVMs is a future task for studies of vegetation dynamics because these are process-based models incorporating both disturbance(e.g.fire)and the variability in Plant Functional Types(PFTs).However,palaeoecological results should be used to test the models,and issues like spatial and temporal scale,complexity of climate change,effects of non-climatic factors,vegetation-climate feedback,and human regulation on vegetation dynamics are suggested as topics for future studies.
基金supported in part by the Ecology Center, United States Department of Agriculture (USDA) Forest Service, Wasatch-Cache National Forest, Forest Supervisor’s Office, and the Utah Agricultural Experiment Station, Utah State University,USA and approved as journal paper no. 8235
文摘We developed a vegetation geo-climatic zonation incorporating the zonal concept, gradient and discriminant analysis in Wasatch Range, northern Utah, USA. Mountainous forest ecosystems were sampled and described by vegetation, physiographic features and soil properties. The Snowpack Telemetry and National Weather Service Cooperative Observer Program weather station networks were used to approximate the climate of sample plots. We analysed vegetation and environmental data using clustering, ordination, classification, and ANOVA techniques to reveal environmental gradients affecting a broad vegetation pattern and discriminate these gradients. The specific objective was to assess and classify the response of the complex vegetation to those environmental factors operating at a coarse-scale climatic level. Ordination revealed the dominant role of regional, altitude-based climate in the area. Based on vegetation physiognomy, represented by five tree species, climatic data and taxonomic classification of zonal soils, we identified two vegetation geo-climatic zones:(1) a montane zone, with Rocky Mountain juniper and Douglas-fir; and(2) a subalpine zone, with Engelmann spruce and subalpine fir as climatic climax species. Aspen was excluded from the zonation due to its great ecological amplitude. We found significant differences between the zones in regional climate and landformgeomorphology/soils. Regional climate was represented by elevation, precipitation, and air and soil temperatures; and geomorphology by soil types. This coarse-scale vegetation geo-climatic zonation provides a framework for a comprehensive ecosystem survey, which is missing in the central Rocky Mountains of the United States. The vegetation-geoclimatic zonation represents a conceptual improvement on earlier classifications. This framework explicitly accounts for the influence of the physical environment on the distribution of vegetation within a complex landscape typical of the central Rocky Mountains and in mountain ranges elsewhere.
