关键词: 国家重点生态功能区, 气候变化, NDVI, 滞后性, 相关性, 新疆

Abstract:

Xinjiang Altai Mountain Forest and Prairie Ecological Functional Area (referred as Altai Ecological Function Area hereafter) is one of the eight key water conservation ecological function areas defined by the Major Function Oriented Zoning of China. Understanding the responses of vegetation growth to climate change in the area is extremely important due to the strong sensitivity and vulnerability of the vegetation ecosystem in the area. Weather (temperature and precipitation) and vegetation (coverage and type) data (1986-2015) that derived from 7 meteorological stations across the Altai Ecological Function Area and the remote sensing data were used in this study for identifying the response relationship of vegetation coverage to climate change in the area. The results show that:(1) During the period of 1986-2015, changes in mean annual temperature (MAT) in the area represented as a significant upward trend, with a tendency rate of 0.34℃·(10 a)^-1, while the mean annual precipitation (MAP) showed a cycle fluctuation increasing trend, with a tendency rate of 6.19 mm·(10 a)^-1; The mean annual normalized difference vegetation index (NDVI) showed a slow overall downward trend, with a small tendency rate of -0.001 (10 a)^-1; Meanwhile, the NDVI showed a significant upward trend during the growing season, with a tendency rate of 0.002 (10 a)^-1. (2) Vegetation coverage in the area remained stable over the period of 1986-2015. The areas with rate of NDVI change -0.001 (10 a)^-1 to 0.001 (10 a)^-1 covered approximately 60.4% of the study area; The areas with significantly-declined vegetation coverage[rate of NDVI change <-0.002 (10 a)^-1] covered approximately 3.1% of the area, and were mainly distributed in the northwestern parts of Altai Mountains; The areas with significantly-increased vegetation coverage[rate of NDVI change>0.002 (10 a)^-1] covered 2.1%, and were mainly distributed in the southeast and central regions of the study area. (3) Across the Altai Ecological Function Area, the responses of vegetation coverage to changes in precipitation are more sensitive than to temperature, however, the responses of changes in NDVI to changes in temperature and precipitation have a lagging effect that differed significantly for different time periods.

Key words: key national ecological function area, climate change, NDVI, time-lag, correlation, Xinjiang