大九湖泥炭藓沼泽植被指数时空变化研究

Spatio-temporal Variation of Vegetation Index of Sphagnum Swamp in Dajiu Lake

基于Landsat系列卫星数据,计算大九湖泥炭藓沼泽地区1986-2021年的归一化植被指数(NDVI),利用Theil-Sen median趋势分析和Mann-Kendall显著性检验方法,结合研究区气象资料,分析近36 a来植被指数的时空演变规律。结果表明:①植被指数变化在2005年存在明显的拐点。1986-2005年总体呈退化趋势,显著和微显著退化的面积占比约60.38%;2006-2021年则总体呈改善趋势,显著和微显著改善的面积占比约81.5%。②泥炭藓斑块与沼泽区域植被指数的变化基本一致,但前期退化的幅度明显高于后期的改善幅度。③研究区植被指数相比气温和降水存在明显的滞后性,NDVI滞后于气温一个月,滞后于降水3个月。④1986-2020年,研究区NDVI对降水的响应更稳定,且集中在中部泥炭藓覆盖度较高区域,这与泥炭藓植被的生态特性基本一致。

Based on Landsat satellite data,we calculated the normalized vegetation index(NDVI)of sphagnum swamp in Dajiu Lake area from 1986 to 2021,and analyzed the spatio-temporal evolution of vegetation index in the past 36 years.The results showed that①there was an obvious inflection point in the change of vegetation index in 2005.From 1986 to 2005,the overall trend was degraded,and the area with significant and slightly degraded areas accounted for about 60.38%.From 2006 to 2021,there was an overall improvement trend,and the area with significant and slightly significant improvement accounted for about 81.5%.②The changes of vegetation index of sphagnum patches and sphagnum swamp areas were basically the same,but the decline in the early stage was significantly higher than the increase in the later stage.③Compared with temperature and precipitation,the vegetation index in the study area has a significant lag.NDVI lags behind the temperature by one month and the precipitation by three months.④From 1986 to 2020,the response of NDVI to precipitation in the study area was more stable and concentrated in the central area with higher coverage of sphagnum,which is basically consistent with the ecological characteristics of sphagnum vegetation.