寒旱牧区植被覆盖变化及气候因子驱动分析——以富蕴县为例

Spatial-temporal Changes in Vegetation Characteristics and Climate in Pastoral Area of Cold and Arid—A Case of Fuyun County

在全球气候变化的背景下,为探讨大陆性寒温带干旱气候的北疆牧区长时序地表生态空间变化及气候驱动特征,以新疆富蕴县为例,基于MODIS NDVI(2000~2018年)数据集,结合降雨量、气温数据,利用6~8月NDVI最大值合成、基于像元的NDVI随时间序列变化的斜率分析及显著性检验、NDVI与气候因子的相关性分析等方法,研究富蕴县近19年植被覆盖时空变化特征及对气候变化的响应关系。结果表明:研究区近19年平均植被覆盖年际变化在波动中呈现增加趋势,增速为0.0011·a^(-1)。植被覆盖显著增加和减小区域分别占研究区的14.48%和0.53%,增加区域集中在研究区北部的阿尔泰山南麓、乌伦古河沿岸及研究区南部边缘,零星减少区域集中在富蕴县城以西及额尔齐斯河沿岸。近19年6~8月总降雨量和平均气温出现较大波动但变化趋势不显著;NDVI与降雨量主要呈现正相关,与平均气温主要呈现负相关,且NDVI对前期一月降雨量和平均气温有一定的响应强度。研究区2000~2018年地表生态有明显的改善,气候因子(降雨量、气温)对植被生长影响显著。NDVI对降雨量和平均气温的响应强度受地形、土地利用类型、水资源来源等因素影响存在月际和空间差异。研究区北部阿尔泰山区及乌伦古河沿岸水资源丰富区域对气温变化更为敏感,而中部牧草区对降雨量变化更敏感。

Based on the global climate change,Fuyun County of Xinjiang was taken as the research object in order to explore the long-term land surface ecological spatial change and climate driving characteristics in the pastoral area of Northern Xinjiang under the condition of global climate change.According to MODIS NDVI(2000-2018)data set,combined with rainfall and temperature data,the spatial-temporal change characteristics of vegetation cover and its response to climate change in Fuyun County in recent 19 years were analyzed by using the methods of NDVI maximum synthesis in June,July and August,pixel-based slope analysis and significance test of NDVI changes with time series,and correlation analysis between NDVI and climate factors.In the study area,the interannual variation of average vegetation cover in recent 19 years showed an increasing trend,with the growth rate of 0.0011·a^(-1).The areas with significant increase and decrease of vegetation cover accounted for 14.48%and 0.53%of the study area.The areas with the significant increase of vegetation cover concentrated in the south foot of Altai mountain,along with the Bank of Wulungu River and the southern edge of the study area,and a small part of the reduced areas concentrated in the west of Fuyun county and along the Irtysh River.In recent 19 years,the total rainfall and average temperature fluctuated greatly in June,July and August,but the change trend was not significant.NDVI has a positive correlation with rainfall and a negative correlation with average temperature.NDVI has a certain response intensity to the rainfall and average temperature in the previous month.The surface ecology of the study area improved significantly from 2000 to 2018,and climate factors(rainfall and temperature)had remarkable effects on vegetation growth.The response intensity of NDVI to rainfall and average temperature is influenced by terrain,land use type,water resource and other factors,also there are inter-month and spatial differences.The water-rich areas along the Altai mountains and the Ulungur river in the north of the study area are more sensitive to temperature changes,while the grass area in the middle of the study area is more sensitive to rainfall changes.