2001-2014年博斯腾湖流域植被物候时空变化及其驱动因子

以博斯腾湖流域为研究对象，利用MODIS的MCD12Q2和LST产品、GHCN_CAMS气温观测/再分析资料与气象数据，采取趋势分析与相关性分析法探求了博斯腾湖流域2001-2014年植被物候的时空变化及其影响因素的相对作用，对博斯腾湖流域植被物候分区不同的驱动区域。结果表明：①在研究期内，整个研究区植被物候始期在第76-168天，末期在第172-295天；物候始期自南向北逐渐推迟、而末期逐渐提前，物候的空间分布特征与该区海拔高度的分布保持了较好的一致性；②2001-2014年植被始期和末期有明显提前趋势（提前3-6d），主要分布在流域的盆地和平原绿洲区，表示研究区植被物候受到人类活动的影响。③植被物候始期与末期变化受气候因子驱动影响的区域占比分别为57.10%和51.30%，主要分布在黄水沟流域，清水河流域，孔雀河流域，大尤路都斯盆地和小尤路都斯盆地周围地区；而非气候因子占42.90%和48.70%，主要位于博斯腾湖周围绿洲和库尔勒绿洲等地势较低的区域。④由植被生长季物候与降水、气温的偏相关性关系和复相关性关系可以得出，多年物候始期和末期与气温有关；而且随海拔升高，气温的敏感幅度越高。博斯腾湖流域植被物候的时空变化不仅是受气候变化的影响，还主要受人类活动和海拔高度差异等影响因素的共同作用。

Temporal and spatial variation of vegetation phenology and its driving factor analysis in the Bosten Lake Drainage Basin from 2001 to 2014

Vegetation phenology is widely used as an independent measure and powerful indicator of primary net productivity, crop yields, insect emergence, bird migration, climate change, carbon balance and cycle, and fundamental ecosystem function and is influenced at the local and global scales by climatic factors (including precipitation, temperature) and human activities. Studies of vegetation phenology are important, as solutions are needed to overcome issues such as environmental change, sustainable management, and biodiversity conservation. Hence, an in-depth understanding of the spatio-temporal variations and driving factors of vegetation phenology are important in the currently changing environment. The Bosten Lake Drainage Basin is located in northwest China and covers a vast area with a complicated terrain, including most of the middle Tianshan Mountains in the northwest, whole Yanqi basin, and northeast part of the Tarim basin in the south, which are characterized by distinctive distribution patterns of temperature, precipitation, and human activities. Here, based on the MCD12Q2, GHCN_CAMS air temperature, Digital Elevation Model(DEM), and metrological observed data, we established monthly geographical weighted regression (GWR) models and measured the near surface air temperature. Next, spatio-temporal evolution characteristics and driving factors of vegetation phenology in the Bosten Lake Drainage Basin were studied by determining slope, partial correlation, and multiple correlations. The results demonstrated that:(1) the start of growth season (SOG) was concentrated in 76-168 Julian days, whereas the end of growth season (EOS) was in 172-295 Julian days; the SOG was delayed and EOS was gradually advanced from north to south. Elevation played an important role in the regional differentiation of vegetation phenology; with increasing altitude, SOG was significantly delayed, EOG was advanced, and the length of the growth season (LOG) was significantly shortened. (2) SOG and EOG advanced synchronously in the plane oasis area during 2001 and 2014 because of the influence of human activities. (3) Climatic factors affected the area of SOG and BOG accounted for 57.10% and 51.30%, respectively, and was mainly located in the Huangshuigou river watershed, Qingshui river watershed, Konqi river watershed, Qongyultuz basin, and around the Kiqikyultuz basin. Non-climatic factors affected the area of SOG and BOG, accounting for 42.90% and 48.70%, and were located in low-altitude regions including the oasis around Bosten lake and the Korla oasis. (4) The correlation between vegetation phenology and climatic factors by partial correlation and multiple correlations demonstrated that variations in inter-annual SOG and BOG were mostly affected by air temperature. As altitude increased, vegetation showed obvious sensitivity of phenology to temperature. In summary, spatio-temporal variations in vegetation phenology in the Bosten Lake Drainage Basin are not only influenced by climate change, but are also influenced by the combined effects of human activities and altitude.