祁连山区植被物候遥感监测与变化趋势

基于1982-2006年GIMMS NDVI时间序列数据,利用Double Logistic拟合方法提取了祁连山区植被的生长季始期、生长季末期和生长季长度参数,分析了植被物候期的时间变化趋势及空间分异特征。结果表明:祁连山植被从东南向西北逐渐变绿,而从西北到东南逐渐变黄,植被生长季呈现出东南地区比西北地区长、河谷地区比高山地区长的特征。25年内植被年生长季始期呈提前趋势,提前幅度为0.044 d·a^-1,年代趋势为延迟-提前-延迟;年生长季末期也呈提前趋势,提前幅度为0.059 d·a^-1,年代趋势为延迟-提前;生长季长度略有缩短,缩短幅度为0.015 d·a^-1,年代趋势为缩短-延长-缩短。25年内祁连山区植被生长季始期、末期提前不明显的区域主要为高山地区,分别占51.46%、42.77%;生长季始期、末期推迟不明显区域主要为河谷地区,分别占44.41%、52.91%;植被生长季高山地区延长不明显,河谷地区缩短不明显,总体上植被物候没有出现明显变化。

Monitoring and Change Trends of Phenological Phase in the Qilian Mountains Based on Remote Sensing

Based on GIMMS NDVI data during 1982-2006, the spatial pattern of the start of growing season (SOS), the end of growing season (EOS) and the length of growing season (LOS) were extracted to analyze the average spatial distribution, change trends as well as its spatial distribution characteristics of phenological phase by using double logistic model in Qilian Mountains. The results show that: vegetation in the Qilian Mountains from southeast to northwest gradually turn green, and gradually turn yellow from the northwest to the southeast. The LOS of vegetation is longer in southeast area than that in northwest area, and LOS is longer in valley area than that in the alpine area. During 1982 to 2006, the inter annual variation trend of SOS dates shows earlier by the rate of 0.044 days per year, in which the variation trend in different decadal years of the SOS shows delay-advance-delay. The inter annual variation trend of EOS dates also shows earlier by the rate of 0.059 days per year, in which the variation trend in different decadal years of the EOS shows delay-advance. The LOS of Vegetation becomes slightly shorter by the rate of 0.015 days per year, in which the variation trend in different decadal years of the LOS shows shorter-longer-shorter. The regions without earlier SOS and EOS during 1982-2006 were mainly located in alpine area with 51.46% and 42.77%, respectively. But the regions without postponed SOS and EOS were located in valley area with 44.41% and 52.91%, respectively. The LOS of vegetation in alpine is shortened unobvious, while that of prolonged unobvious area is in valley area. Generally, there is no significant variation existed in the vegetation phenology in the study area.