Strong impacts of daily minimum temperature on the green-up date and summer greenness of the Tibetan Plateau.
Understanding vegetation responses to climate change on the Tibetan Plateau (TP) helps in elucidating the land-atmosphere energy exchange, which affects air mass movement over and around the TP. Although the TP is one of the world's most sensitive regions in terms of climatic warming, little is known about how the vegetation responds. Here, we focus on how spring phenology and summertime greenness respond to the asymmetric warming, that is, stronger warming during nighttime than during daytime. Using both in situ and satellite observations, we found that vegetation green-up date showed a stronger negative partial correlation with daily minimum temperature (Tmin ) than with maximum temperature (Tmax ) before the growing season ('preseason' henceforth). Summer vegetation greenness was strongly positively correlated with summer Tmin , but negatively with Tmax . A 1-K increase in preseason Tmin advanced green-up date by 4 days (P < 0.05) and in summer enhanced greenness by 3.6% relative to the mean greenness during 2000-2004 (P < 0.01). In contrast, increases in preseason Tmax did not advance green-up date (P > 0.10) and higher summer Tmax even reduced greenness by 2.6% K(-1) (P < 0.05). The stimulating effects of increasing Tmin were likely caused by reduced low temperature constraints, and the apparent negative effects of higher Tmax on greenness were probably due to the accompanying decline in water availability. The dominant enhancing effect of nighttime warming indicates that climatic warming will probably have stronger impact on TP ecosystems than on apparently similar Arctic ecosystems where vegetation is controlled mainly by Tmax . Our results are crucial for future improvements of dynamic vegetation models embedded in the Earth System Models which are being used to describe the behavior of the Asian monsoon. The results are significant because the state of the vegetation on the TP plays an important role in steering the monsoon.
Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, 16 Lincui Road, Chaoyang District, Beijing, 100101, China.|CAS Center for Excellence in Tibetan Plateau Earth Sciences, 16 Lincui Road, Chaoyang District, Beijing, 100101, China.
Miaogen
M
Shen
Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, 16 Lincui Road, Chaoyang District, Beijing, 100101, China.|CAS Center for Excellence in Tibetan Plateau Earth Sciences, 16 Lincui Road, Chaoyang District, Beijing, 100101, China.|College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China.
Shilong
S
Piao
College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China.
Xiaoqiu
X
Chen
College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China.
Shuai
S
An
College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China.|Department of Biology, Centre of Excellence PLECO (Plant and Vegetation Ecology), University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium.
Yongshuo H
YH
Fu
Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, 16 Lincui Road, Chaoyang District, Beijing, 100101, China.|CAS Center for Excellence in Tibetan Plateau Earth Sciences, 16 Lincui Road, Chaoyang District, Beijing, 100101, China.
Shiping
S
Wang
Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, 16 Lincui Road, Chaoyang District, Beijing, 100101, China.
Nan
N
Cong
Department of Biology, Centre of Excellence PLECO (Plant and Vegetation Ecology), University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium.
Ivan A
IA
Janssens
D001110:Arctic Regions; D057231:Climate Change; D010944:Plants; D012621:Seasons; D013696:Temperature; D018609:Tibet
Tibetan Plateau; alpine vegetation; asymmetric warming; climate change; plant phenology; vegetation growth