川西高原植被物候及其对气候变化的响应

Phenology of Vegetation and Its Response to Climate Change inthe Western Sichuan Plateau

为探究2001-2020年川西高原植被物候时空变化及其对气候变化的响应,利用MODIS NDVI数据、植被区划数据、数字高程数据以及气象数据,通过Savitzky-Golay滤波以及动态阈值法,提取了川西高原2001-2020年植被生长季始期(SOS)、生长季末期(EOS)以及生长季长度(LOS),结合月平均气温与降水量,探讨了植被物候与气候因子(月平均气温、降水量)之间的关系。结果表明:(1)川西高原植被SOS主要集中在第90-第130天,EOS主要集中在第260-第290天,LOS主要为130~190 d;随着海拔不断升高,植被SOS呈提前趋势、EOS呈推迟趋势、LOS呈延长趋势。(2)植被SOS呈提前趋势的面积占60.56%;植被EOS呈推迟趋势的面积占51.21%;植被LOS呈延长趋势的面积占60.75%,其中7.19%呈显著延长趋势。(3)川西高原植被SOS与春季2-4月份平均气温呈负相关,且存在较大的时空差异性;植被EOS与10月份平均温度、11月份降水量呈显著正相关;6月份平均气温和8月份降水对LOS的正向影响较大。整体来说,川西高原植被物候在不同植被区划具有明显的分布规律。研究成果可为高原地区植被物候变化规律研究提供参考。

The aim of this research is to investigate the spatiotemporal changes in vegetation phenology and their response to climate change in the Western Sichuan Plateau from 2001 to 2020 and provide insights for the study of vegetation phenology changes in the plateau.Based on MODIS NDVI data,vegetation zoning data,digital elevation data,and meteorological data,we extracted the SOS(start of the growing season),EOS(end of the growing season),and LOS(length of growing season)of vegetation by using the Savitzky-Golay filter and dynamic threshold method.We then explored the relationship between vegetation phenology and climatic factors,such as monthly mean temperature and precipitation.Results indicate that 1)the SOS,EOS,and LOS of vegetation in the Western Sichuan Plateau were mainly concentrated in the 90 th to 130 th days,260 th to 290 th days,and 130-190 d,respectively.As altitude increased,the SOS trended towards an advance,while EOS trended towards a delay,and LOS trended towards an extension.2)Specifically,60.56%of the vegetation area exhibited an advanced SOS trend,51.21%a delayed EOS,and 60.75%a prolonged LOS,of which 7.19%showing a significant prolonged LOS trend.3)The SOS of vegetation was negatively correlated with mean temperature from February to April,displaying significant spatio-temporal differences.Additionally,a significant positive correlation was found between EOS and average temperature in October,and precipitation in November.Moreover,average temperature in June and precipitation in August had a significant positive effect on LOS.Overall,the phenology of vegetation in the Western Sichuan Plateau displayed distinct distribution rules in different vegetation divisions.