Miaogen Shen^a, Yanhong Tang^a, Jin Chen^b,∗, Xiaolin Zhu^c, Yinghua Zheng^d

a Environmental Biology Division, National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305-8506, Japan

b State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China

c Department of Geography, the Ohio State University, Columbus, OH 43210, USA

d Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China

Spatial variations in phenological responses to temperature have not been reported for grasslands of the Qinghai-Tibetan Plateau. Using satellite-derived normalized difference vegetation index and meteorological records from 1982 to 2006, we characterized the spatial patterns of grassland green-up onset in relation to air temperature and precipitation before the growing season (“preseason” henceforth) in the central and eastern plateau by combining linear programming with correlation analysis. Green-up onset near half of the meteorological stations was significantly correlated (p < 0.10) with precipitation and thermal spring onset (TSO) date based on the cumulative temperature less than 6 weeks before the onset. The green-up onset paralleled the advance in TSO in the southwestern, southeastern, eastern, and northeastern parts of the plateau. The TSO and preseason precipitation (PPT) explained part of the inter-annual phenological variations, with r2 varying between 0.05 and 0.55 and averaging 0.28, and did not explain delay of green-up onset in some areas. Increasing preseason temperature tended to advance green-up onset in relatively moist areas. PPT exerted a stronger influence on green-up onset in drier areas. These results indicate spatial differences in the key environmental influences on spring phenology. To improve the ability to predict onset, ground-based community-level phenological studies and spatial scaling-up of the phenology–climate relationship will be necessary..

 

Keywords: Alpine grassland; Climate change; NDVI; Qinghai-Tibetan Plateau; Land surface phenology