Spatial and Temporal Pattern of Ecological Requirement of Natural Vegetation on the Qinghai–Tibet Plateau From 1991 to 2020.

The Qinghai–Tibet Plateau is a globally significant ecological barrier, and its ecological water requirement (EWR) is of great importance for the stability of regional ecosystems and water resource management. Based on meteorological data, this study employed the Penman–Monteith method, combined with the vegetation coefficient (Kc) and soil moisture limitation coefficient (Ks), to estimate the EWR and ecological water deficit (EWD) for the entire Qinghai–Tibet Plateau and its 11 climate zones from 1991 to 2020. The spatiotemporal variation patterns were also analyzed. The results indicate: 

(1) Among the seven major vegetation types, low cover grassland has the highest EWR (7.28 × 1010 m³), while other forest land has the lowest (0.04 × 1010 m³). 

(2) In the wet year (2014), normal water year (2016), and dry year (2012), vegetation growth across the Qinghai–Tibet Plateau generally shows a water surplus, with the wet year having a greater surplus than the dry year. 

(3) Except for the Qaidam region (HD1) and the northern Tibet region (HD2), the other nine climate zones show a water surplus. (4) The peak EWR for different zones and vegetation types occurs during the mid-growth period. The most severe water deficit in HD1 and HD2 regions occurs during the early growth stage, with precipitation addressing 12.59% and 26.08% of the deficit, respectively. This study provides a scientific basis for water resource management on the Qinghai–Tibet Plateau.

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