期刊
FRONTIERS OF EARTH SCIENCE
卷 10, 期 4, 页码 784-793出版社
SPRINGER
DOI: 10.1007/s11707-016-0566-3
关键词
normalized difference vegetation index (NDVI); Tibetan Plateau; inter-annual variations; alpine grasslands; exponential model
资金
- National Natural Science Foundation of China [41271118, 41471227, 41371013]
- Strategic Priority Research Program of the Chinese Academy of Sciences [XDA05050209]
Clarifying the spatial and temporal variations in precipitation-use efficiency (PUE) is helpful for advancing our knowledge of carbon and water cycles in Tibetan grassland ecosystems. Here we use an integrated remote sensing normalized difference vegetation index (NDVI) and in-situ above-ground net primary production (ANPP) measurements to establish an empirical exponential model to estimate spatial ANPP across the entire Tibetan Plateau. The spatial and temporal variations in PUE (the ratio of ANPP to mean annual precipitation (MAP)), as well as the relationships between PUE and other controls, were then investigated during the 2001-2012 study period. At a regional scale, PUE increased from west to east. PUE anomalies increased significantly (> 0.1 g center dot m(-2)center dot mm(-1)/10 yr) in the southern areas of the Tibetan Plateau yet decreased (> 0.02 g center dot m(-2)center dot mm(-1)/10 yr) in the northeastern areas. For alpine meadow, we obtained an obvious breaking point in trend of PUE against elevation gradients at 3600 m above the sea level, which showed a contrasting relationship. At the inter-annual scale, PUE anomalies were smaller in alpine steppe than in alpine meadow. The results show that PUE of Tibetan grasslands is generally high in dry years and low in wet years.
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