Vegetation phenology is a sensitive indicator of global warming,especially on the Tibetan Plateau.However,whether climate warming has enhanced the advance of grassland phenology since 2000 remains debated and little i...Vegetation phenology is a sensitive indicator of global warming,especially on the Tibetan Plateau.However,whether climate warming has enhanced the advance of grassland phenology since 2000 remains debated and little is known about the warming effect on semiarid grassland phenology and interactions with early growing season precipitation.In this study,we extracted phenological changes from average NDVI in the growing season（GNDVI） to analyze the relationship between changes in NDVI,phenology and climate in the Northern Tibetan Damxung grassland from 2000 to 2014.The GNDVI of the grassland declined.Interannual variation of GNDVI was mainly affected by mean temperature from late May to July and precipitation from April to August.The length of the growing season was significantly shortened due to a delay in the beginning of the growing season and no advancement of the end of the growing season,largely caused by climate warming and enhanced by decreasing precipitation in spring.Water availability was the major determinant of grass growth in the study area.Warming increased demand for water when the growth limitation of temperature to grass was exceeded in the growing season.Decreased precipitation likely further exacerbated the effect of warming on vegetation phenology in recent decades due to increasing evapotranspiration and water limitations.The comprehensive effects of global warming and decreasing precipitation may delay the phenological responses of semiarid alpine grasslands.展开更多
Elevation dependency amongst climate change signals has been found in major mountain ranges around the world,but the main factors causing this dependency have not been clarified.In this study,four different datasets o...Elevation dependency amongst climate change signals has been found in major mountain ranges around the world,but the main factors causing this dependency have not been clarified.In this study,four different datasets of observation and reanalysis for China were used to examine the elevation dependency of climate change.A lack of consistency was found in dependency between warming magnitude and elevation across the Tibetan Plateau and China.However,a dependency of climate change on water vapor was detected whereby the temperature trend initially increased at low specific humidity,and then decreased as specific humidity increased.At ground level the maximum trend in temperature appeared in the specific humidity range 2.0–3.0 g kg^（-1）.This suggests that water vapor is a mediator of climate change and may be responsible for elevation-dependent climate change.展开更多
基金National Natural Science Foundation of China(41271067)National key research and development program(2016YFC0502001)
文摘Vegetation phenology is a sensitive indicator of global warming,especially on the Tibetan Plateau.However,whether climate warming has enhanced the advance of grassland phenology since 2000 remains debated and little is known about the warming effect on semiarid grassland phenology and interactions with early growing season precipitation.In this study,we extracted phenological changes from average NDVI in the growing season（GNDVI） to analyze the relationship between changes in NDVI,phenology and climate in the Northern Tibetan Damxung grassland from 2000 to 2014.The GNDVI of the grassland declined.Interannual variation of GNDVI was mainly affected by mean temperature from late May to July and precipitation from April to August.The length of the growing season was significantly shortened due to a delay in the beginning of the growing season and no advancement of the end of the growing season,largely caused by climate warming and enhanced by decreasing precipitation in spring.Water availability was the major determinant of grass growth in the study area.Warming increased demand for water when the growth limitation of temperature to grass was exceeded in the growing season.Decreased precipitation likely further exacerbated the effect of warming on vegetation phenology in recent decades due to increasing evapotranspiration and water limitations.The comprehensive effects of global warming and decreasing precipitation may delay the phenological responses of semiarid alpine grasslands.
基金National Natural Science Foundation of China(41571042,41271067)National Key Research and Development Program(2016YFC0502001)
文摘Elevation dependency amongst climate change signals has been found in major mountain ranges around the world,but the main factors causing this dependency have not been clarified.In this study,four different datasets of observation and reanalysis for China were used to examine the elevation dependency of climate change.A lack of consistency was found in dependency between warming magnitude and elevation across the Tibetan Plateau and China.However,a dependency of climate change on water vapor was detected whereby the temperature trend initially increased at low specific humidity,and then decreased as specific humidity increased.At ground level the maximum trend in temperature appeared in the specific humidity range 2.0–3.0 g kg^（-1）.This suggests that water vapor is a mediator of climate change and may be responsible for elevation-dependent climate change.
