Responses of net primary productivity to phenological dynamics in the Tibetan Plateau, China

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Quantifying the response of vegetation Net Primary Productivity (NPP) to phenological dynamics is critical to study climate change effects on ecosystem dynamics in the high-latitude, so investigating responses of NPP to phenological dynamics is becoming an increasing important way to identify and predict global ecosystem dynamics. In this study, we intend to quantifying the temporal trends and spatial variations of vegetation phenology and NPP across the Tibetan Plateau by calibrating and analyzing time series of the MODIS-derived normalized difference vegetation index (NDVI) during 2002–2012, and examining the mechanisms of vegetation NPP response to phenological dynamics over the plateau. Our results indicated that most of the plateau experienced a coninuous advancing trend in the beginning of vegetation growing season (BGS) and a delaying trend in the end of vegetation growing season (EGS), consequently a prolonged length of vegetation growing season (LGS). Accordingly, NPP also substantially increased in most parts of the plateau. Meanwhile, the spatial patterns of the BGS, EGS, LGS and NPP varied in accordcance with the heat and water gradient across the plateau. The response modes of the NPP to phenological shifs varied within different climatic regimes, and the spatiotemporal response patterns were primarily controlled by the local climatic and topographic conditions. Moreover, temperature and precipitation played different roles in diverse responses of NPP to phenological dynamics, implying a profound effect of climate on response mechanism of the NPP to phenological changes.