To investigate the climate change effects on spring phenology at a spatial-temporal scale in Tibetan Plateau, an algorithm of dynamic threshold was applied to extract start of season (SOS) based on MODIS 250 m 16-days NDVI products. Then, the phenological responses to climate change were assessed by the linear regression of phenological dates against the current monthly temperature from 2000 to 2009. The vegetation ecosystems are sensitive to climate warming in Tibetan Plateau (2.72-9.72 days℃-1). The SOS of meadow and steppe were advanced by up to 8.17 days℃-1 and 5.69 days ℃-1 under climate warming. Finally, we investigated the impact of altitude on the spring phenology dates for steppe and meadow in 2000 and 2009, respectively. For each degree warming along with the altitude, the spring phenology was advanced by about 2.04 days and 1.8 days for steppe and meadow, respectively. Compared to the spring phenology variation adapted to local climate gradient (along with altitude gradient), the spring phenology on the Tibetan Plateau under climate warming is more sensitive, with about 3 times larger response amplitude.
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机译：为了研究青藏高原气候变化在时空尺度上对春季物候的影响，基于MODIS 250 m 16天NDVI产品，应用动态阈值算法提取季节开始（SOS）。然后，通过物候日期相对于当前2000-2009年当前月温度的线性回归，评估了对气候变化的物候响应。青藏高原（2.72-9.72 days℃-1）的植被生态系统对气候变暖敏感。在气候变暖的条件下，草地和草原的SOS分别升高了8.17天-1和5.69天-1。最后，我们分别调查了海拔对2000年和2009年草原和草甸春季物候日期的影响。随着海拔的升高，草原和草甸的春季物候分别增加了约2.04天和1.8天。与适应局部气候梯度（以及海拔梯度）的春季物候变化相比，青藏高原气候变暖下的春季物候更为敏感，响应幅度大约是其三倍。
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