大兴安岭森林区植被物候的纬度地带性

Latitudinal zonality of vegetation phenophases in Greater Khingan Range

全球气候变化可通过影响植被物候来影响生态系统过程,但人们对区域尺度植被物候如何响应气候变化却未形成共识。本研究在Google Earth Engine大数据平台支持下,以大兴安岭森林植被分布区为研究区,以2000—2020年系列MOD09GQ、MOD13Q1和MOD11A1卫星数据产品为数据源,分析了大兴安岭森林植被分布区植被物候的纬度地带性以及温度因子对其影响。结果表明:大兴安岭森林分布区植被物候在纬度梯度上呈现明显差异性,生长季开始时间SOS(start of growing season)呈提前趋势,纬度每升高1°,SOS提前0.34 d;生长季结束时间EOS(end of growing season)趋势与SOS相同,每升高1°,提前0.19 d;生长季长度LOS(length of growing season)变化具有阶段性,拐点在50°N,拐点之前每升高1°,LOS缩短1 d,拐点之后每升高1°,LOS延长0.57 d。从变化趋势来看,SOS和LOS对纬度变化的响应比EOS明显。其中,LOS延长主要缘于SOS提前的幅度明显大于EOS提前的幅度。温度因子对大兴安岭森林植被分布区物候变化有直接作用,其中对SOS和LOS的影响明显强于对EOS的影响,4月温度对于SOS和LOS作用明显,温度越高,SOS发生越早,LOS持续时间越长。LOS延长的主要贡献者是SOS的提前,而EOS在时间上的推后对LOS的贡献相对较小。大尺度植被物候研究对宏观理解全球气候变化对地表生态过程响应有重要补充意义,同时在区域林区森防工作分区管理上也具有一定参考价值。

Global climate change affects ecosystem processes by altering vegetation phenophases. However, there is few consensus on how vegetation phenophases respond to climate change at the regional scale. By using the Google Earth Engine platform and MOD09 GQ, MOD13 Q1 and MOD11 A1 satellite data products from 2000 to 2020, we analyzed the latitudinal zonality of vegetation phenophases and the influence of temperature on forest vegetation distribution in the Greater Khingan Range. The results showed that there were significant variations in the latitudinal gradient of vegetation phenophases in the study area, and that the start of growing season(SOS) advanced on average by 0.34 d for each degree of latitude increase. Similar to the SOS, the end of growing season(EOS) increased on average by 0.19 d for each degree of latitude increase. The length of growing season(LOS) exhibited a curvature change with an inflection point at around 50°N, and was shortened on average by 1 d for each degree of latitude increase before the point, and prolonged on averaged by 0.57 d for each degree of latitude increase after the point. SOS and LOS were more sensitive to latitude changes than EOS. Among them, the extension of LOS was mainly caused by the fact that the advance of SOS was more significantly than that of EOS. In addition, temperature directly affected vegetation phenophases in the study area, with stronger effect on SOS and LOS than on EOS. The effect of temperature in April on SOS and LOS was the most significant. The higher the temperature, the earlier SOS and the longer the LOS. The increase of LOS was mainly due to the advancement of SOS and the delay of EOS was relatively short in magnitude. The study of large-scale vegetation phenophases is principal supplementary for understanding the responses of ecological processes to climate change, with implications for forest zoning management.