Vegetation is the main component of the terrestrial ecosystem and plays a key role in global climate change. Remotely sensed vegetation indices are widely used to detect vegetation trends at large scales. To understan...Vegetation is the main component of the terrestrial ecosystem and plays a key role in global climate change. Remotely sensed vegetation indices are widely used to detect vegetation trends at large scales. To understand the trends of vegetation cover, this research examined the spatial-temporal trends of global vegetation by employing the normalized difference vegetation index(NDVI) from the Advanced Very High Resolution Radiometer(AVHRR) Global Inventory Modeling and Mapping Studies(GIMMS) time series(1982–2015). Ten samples were selected to test the temporal trend of NDVI, and the results show that in arid and semi-arid regions, NDVI showed a deceasing trend, while it showed a growing trend in other regions. Mann-Kendal(MK) trend test results indicate that 83.37% of NDVI pixels exhibited positive trends and that only 16.63% showed negative trends(P < 0.05) during the period from 1982 to 2015. The increasing NDVI trends primarily occurred in tree-covered regions because of forest growth and re-growth and also because of vegetation succession after a forest disturbance. The increasing trend of the NDVI in cropland regions was primarily because of the increasing cropland area and the improvement in planting techniques. This research describes the spatial vegetation trends at a global scale over the past 30+ years, especially for different land cover types.展开更多
Temperature and precipitation time series datasets from 1961 to 2005 at 65 meteorological stations were used to reveal the spatial and temporal trends of climate change in Xinjiang, China. Annual and seasonal mean air...Temperature and precipitation time series datasets from 1961 to 2005 at 65 meteorological stations were used to reveal the spatial and temporal trends of climate change in Xinjiang, China. Annual and seasonal mean air temperature and total precipitation were analyzed using Mann-Kendall （MK） test, inverse distance weighted （IDW） interpolation, and R/S methods. The results indicate that： （1） both temperature and precipitation increased in the past 45 years, but the increase in temperature is more obvious than that of precipitation; （2） for temperature increase, the higher the latitude and the higher the elevation the faster the increase, though the latitude has greater influence on the increase. Northern Xinjiang shows a faster warming than southern Xinjiang, especially in summer; （3） increase of precipitation occurs mainly in winter in northern Xinjiang and in summer in southern Xinjiang. lli, which has the most precipitation in Xinjiang, shows a weak increase of precipitation; （4） although both temperature and precipitation increased in general, the increase is different inside Xinjiang; （5） Hurst index （H） analysis indicates that climate change will continue the current trends.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41771179,41871103,41771138)the National Key Research and Development Project(No.2016YFA0602301)
文摘Vegetation is the main component of the terrestrial ecosystem and plays a key role in global climate change. Remotely sensed vegetation indices are widely used to detect vegetation trends at large scales. To understand the trends of vegetation cover, this research examined the spatial-temporal trends of global vegetation by employing the normalized difference vegetation index(NDVI) from the Advanced Very High Resolution Radiometer(AVHRR) Global Inventory Modeling and Mapping Studies(GIMMS) time series(1982–2015). Ten samples were selected to test the temporal trend of NDVI, and the results show that in arid and semi-arid regions, NDVI showed a deceasing trend, while it showed a growing trend in other regions. Mann-Kendal(MK) trend test results indicate that 83.37% of NDVI pixels exhibited positive trends and that only 16.63% showed negative trends(P < 0.05) during the period from 1982 to 2015. The increasing NDVI trends primarily occurred in tree-covered regions because of forest growth and re-growth and also because of vegetation succession after a forest disturbance. The increasing trend of the NDVI in cropland regions was primarily because of the increasing cropland area and the improvement in planting techniques. This research describes the spatial vegetation trends at a global scale over the past 30+ years, especially for different land cover types.
基金National Basic Research Program of China (973 Program), No.2010CB951003
文摘Temperature and precipitation time series datasets from 1961 to 2005 at 65 meteorological stations were used to reveal the spatial and temporal trends of climate change in Xinjiang, China. Annual and seasonal mean air temperature and total precipitation were analyzed using Mann-Kendall （MK） test, inverse distance weighted （IDW） interpolation, and R/S methods. The results indicate that： （1） both temperature and precipitation increased in the past 45 years, but the increase in temperature is more obvious than that of precipitation; （2） for temperature increase, the higher the latitude and the higher the elevation the faster the increase, though the latitude has greater influence on the increase. Northern Xinjiang shows a faster warming than southern Xinjiang, especially in summer; （3） increase of precipitation occurs mainly in winter in northern Xinjiang and in summer in southern Xinjiang. lli, which has the most precipitation in Xinjiang, shows a weak increase of precipitation; （4） although both temperature and precipitation increased in general, the increase is different inside Xinjiang; （5） Hurst index （H） analysis indicates that climate change will continue the current trends.
