2001—2018年长白山自然保护区生长季NDVI变化特征及其对气候变化的响应

为了解全球变化背景下东北亚温带森林的动态变化及其对气候变化的响应,基于MODIS 250 m分辨率遥感数据、1 km分辨率地表温度数据以及研究区内及周边气象站点数据,分析2001—2018年生长季长白山自然保护区的归一化植被指数(NDVI)变化情况及其与温度、降水的相关性。结果表明: 2001—2018年生长季,研究区NDVI均值为0.711,植被覆盖度较高,且呈逐年增加趋势(0.0025·a^-1);气温极显著增加(0.032 ℃·a^-1),增速高于全球平均;降水显著增加(5.54 mm·a^-1),但年际间变异加大。空间上,NDVI呈现西北部略高且随着海拔升高而降低的格局;研究期间,NDVI增加的区域占46.2%,主要集中在北部以及中南部高海拔地区,53.8%的区域基本无变化或微弱减少。研究区NDVI主要受温度影响;在年尺度上,NDVI与地表温度主要表现为正相关,正相关区域占90.2%,且有43.6%的区域相关性显著;在月尺度上,气温对NDVI的影响在生长季初和末期更为显著。

Variation characteristics of NDVI and its response to climatic change in the growing season of Changbai Mountain Nature Reserve during 2001 and 2018

To understand the dynamics of temperate forest in Northeast Asia and its response to climate change under the scenario of global change, we examined the temporal and spatial changes of normalized difference vegetation index (NDVI) and their correlation with temperature and precipitation of Changbai Mountain Nature Reserve in the growing season during 2001 and 2018, based on the remote sensing database of MODIS with a resolution of 250 m, land surface temperature data with a resolution of 1 km and meteorological data in the studied and surrounding area. The results showed that, in the growing season of 2001-2018, the averaged NDVI value of the study area was 0.711. Vegetation coverage was relatively high, increasing with a rate of 0.0025·a^-1. The temperature showed an extremely significantly increasing trend (0.032 ℃·a^-1), the rate of which was higher than that at global level. Precipitation also showed a significantly increasing trend (5.54 mm·a^-1) with increased interannual variation. Spatially, NDVI generally was higher in the northwest and decreased with elevation. During the study period, the area with increased NDVI accounted for 46.2%, mainly concentrated in the north and south central high-altitude areas, while 53.8% of total area remained unchanged or slightly decrease. NDVI of the study area was mainly affected by temperature. At the annual scale, NDVI and land surface temperature were positively correlated, with 90.2% presented positive correlation and 43.6% significantly correlated. At the monthly scale, the impact of temperature on NDVI was more significant at the beginning and the end of growing season.