基于1982~2011年第三代GIMMS NDVI数据,利用累计NDVI的Logistic曲线曲率极值法、Logistic曲线曲率变化率法和NDVI变化率法等方法,识别了蒙古高原植被生长季开始日期(Start of Growing Season,SOS)、生长季结束日期(End of Growing Seaso...基于1982~2011年第三代GIMMS NDVI数据,利用累计NDVI的Logistic曲线曲率极值法、Logistic曲线曲率变化率法和NDVI变化率法等方法,识别了蒙古高原植被生长季开始日期(Start of Growing Season,SOS)、生长季结束日期(End of Growing Season,EOS)和生长季长度(Length of Growing Season,LOS)等物候参数,并分析了其时空变化特征。结果表明:累计NDVI的Logistic曲线曲率极值法和NDVI变化率法在蒙古高原植被区具有较好的物候识别能力,对两种方法识别的物候参数求平均一定程度上可提高研究区物候参数的识别精度。蒙古高原植被SOS一般从4月中旬到5月下旬开始,到9月下旬至10月中旬结束,生长季长度主要集中在125~175d之间。在空间上,蒙古高原湿润半湿润地区的SOS较早、EOS较晚和LOS更长,而干旱半干旱地区的SOS较晚、EOS更早和LOS更短。时间变化分析表明,在30a的观测尺度,约占研究区51.6%和33.9%地区的SOS分别呈提前和推迟趋势,其中21.2%和12.4%地区的变化为显著;约占研究区35.6%和49.8%的地区EOS分别呈推迟和提前趋势,其中8.2%和12.0%地区的变化为显著。受SOS和EOS的影响,40.3%的地区(17.8%为显著)主要以缩短为主,44.8%的地区(18.9%为显著)主要以延长为主。展开更多
This study analyzed the spatial and temporal variations in the Normalized Difference Vegetation Index(NDVI) on the Mongolian Plateau from 1982–2013 using Global Inventory Modeling and Mapping Studies(GIMMS) NDVI3 g d...This study analyzed the spatial and temporal variations in the Normalized Difference Vegetation Index(NDVI) on the Mongolian Plateau from 1982–2013 using Global Inventory Modeling and Mapping Studies(GIMMS) NDVI3 g data and explored the effects of climate factors and human activities on vegetation. The results indicate that NDVI has slight upward trend in the Mongolian Plateau over the last 32 years. The area in which NDVI increased was much larger than that in which it decreased. Increased NDVI was primarily distributed in the southern part of the plateau, especially in the agro-pastoral ecotone of Inner Mongolia. Improvement in the vegetative cover is predicted for a larger area compared to that in which degradation is predicted based on Hurst exponent analysis. The NDVI-indicated vegetation growth in the Mongolian Plateau is a combined result of climate variations and human activities. Specifically, the precipitation has been the dominant factor and the recent human effort in protecting the ecological environments has left readily detectable imprints in the NDVI data series.展开更多
Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we es- tablished the Tariat-Xilin Gol transect from northwest to southeast across the Mongolian Plateau, and selected seven s...Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we es- tablished the Tariat-Xilin Gol transect from northwest to southeast across the Mongolian Plateau, and selected seven sampling sites along the transect. We then estimated the soil wind erosion rates by using the ^(137)Cs tracing technique and examined their spatial dynamics. Our results showed that the ^(137)Cs inventories of sampling sites ranged from 265.63±44.91 to 1279.54±166.53 Bq·m^(-2), and the wind erosion rates varied from 64.58 to 419.63 t·km^(-2)·a^(-1) accordingly. In the Mongolia section of the transect (from Tariat to Sainshand), the wind erosion rate increased gradually with vegetation type and climatic regimes; the wind erosion process was controlled by physical factors such as annual precipitation and vegetation coverage, etc., and the impact of human activities was negligible. While in the China section of the transect (Inner Mongolia), the wind erosion rates of Xilin Hot and Zhengxiangbai Banner were thrice as much as those of Bayannur of Mongolia, although these three sites were all dominated by typical steppe. Besides the physical factors, higher population density and livestock carrying level should be responsible for the higher wind erosion rates in these two regions of Inner Mongolia.展开更多
文摘基于1982~2011年第三代GIMMS NDVI数据,利用累计NDVI的Logistic曲线曲率极值法、Logistic曲线曲率变化率法和NDVI变化率法等方法,识别了蒙古高原植被生长季开始日期(Start of Growing Season,SOS)、生长季结束日期(End of Growing Season,EOS)和生长季长度(Length of Growing Season,LOS)等物候参数,并分析了其时空变化特征。结果表明:累计NDVI的Logistic曲线曲率极值法和NDVI变化率法在蒙古高原植被区具有较好的物候识别能力,对两种方法识别的物候参数求平均一定程度上可提高研究区物候参数的识别精度。蒙古高原植被SOS一般从4月中旬到5月下旬开始,到9月下旬至10月中旬结束,生长季长度主要集中在125~175d之间。在空间上,蒙古高原湿润半湿润地区的SOS较早、EOS较晚和LOS更长,而干旱半干旱地区的SOS较晚、EOS更早和LOS更短。时间变化分析表明,在30a的观测尺度,约占研究区51.6%和33.9%地区的SOS分别呈提前和推迟趋势,其中21.2%和12.4%地区的变化为显著;约占研究区35.6%和49.8%的地区EOS分别呈推迟和提前趋势,其中8.2%和12.0%地区的变化为显著。受SOS和EOS的影响,40.3%的地区(17.8%为显著)主要以缩短为主,44.8%的地区(18.9%为显著)主要以延长为主。
基金National Key Technology R&D Program of China,No.2013BAK05B01,No.2013BAK05B02National Natural Science Foundation of China,No.41571491,No.61631011Program of Introducing Talents of Discipline to Universities,No.B16011
文摘This study analyzed the spatial and temporal variations in the Normalized Difference Vegetation Index(NDVI) on the Mongolian Plateau from 1982–2013 using Global Inventory Modeling and Mapping Studies(GIMMS) NDVI3 g data and explored the effects of climate factors and human activities on vegetation. The results indicate that NDVI has slight upward trend in the Mongolian Plateau over the last 32 years. The area in which NDVI increased was much larger than that in which it decreased. Increased NDVI was primarily distributed in the southern part of the plateau, especially in the agro-pastoral ecotone of Inner Mongolia. Improvement in the vegetative cover is predicted for a larger area compared to that in which degradation is predicted based on Hurst exponent analysis. The NDVI-indicated vegetation growth in the Mongolian Plateau is a combined result of climate variations and human activities. Specifically, the precipitation has been the dominant factor and the recent human effort in protecting the ecological environments has left readily detectable imprints in the NDVI data series.
基金Supported by the National Natural Science Foundation of China (Grant No. 40571130)the Key Project of International Cooperation, CAS (Grant No. GJHZ06)+1 种基金the Director Foundation of Institute of Geographic Sciences and Resources Research, CAS (Grant Nos. 06W60000SZ and 06W60001SZ)the Open Foundation of Key Laboratory of Water Cycle & Related Land Surface Processes, CAS (Grant No. WL2005001)
文摘Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we es- tablished the Tariat-Xilin Gol transect from northwest to southeast across the Mongolian Plateau, and selected seven sampling sites along the transect. We then estimated the soil wind erosion rates by using the ^(137)Cs tracing technique and examined their spatial dynamics. Our results showed that the ^(137)Cs inventories of sampling sites ranged from 265.63±44.91 to 1279.54±166.53 Bq·m^(-2), and the wind erosion rates varied from 64.58 to 419.63 t·km^(-2)·a^(-1) accordingly. In the Mongolia section of the transect (from Tariat to Sainshand), the wind erosion rate increased gradually with vegetation type and climatic regimes; the wind erosion process was controlled by physical factors such as annual precipitation and vegetation coverage, etc., and the impact of human activities was negligible. While in the China section of the transect (Inner Mongolia), the wind erosion rates of Xilin Hot and Zhengxiangbai Banner were thrice as much as those of Bayannur of Mongolia, although these three sites were all dominated by typical steppe. Besides the physical factors, higher population density and livestock carrying level should be responsible for the higher wind erosion rates in these two regions of Inner Mongolia.
