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    近15年锡林郭勒盟植被变化时空特征及其对气候的响应

    Spatiotemporal characteristics of vegetation variation in Xilin Gol League in recent 15 years and its response to climate

    • 摘要: 全球变化背景下,植被动态变化及其与气候的关系研究,是当前国际社会十分关注的科学问题。研究植被NDVI 时空变化特征及其对气候的响应,对调节生态过程、改善生态环境质量具有重要的理论和实际意义。基于锡林郭勒盟2001—2015 年MODIS NDVI 数据及该地区气温、降水数据,利用Sen 斜率估计与Mann Kendall 统计检验、相关分析等方法,探讨了其植被时空变化特征及其对气候因子的响应。结果表明:1)锡林郭勒盟2001—2015 年平均植被NDVI 呈波动上升趋势,其变化过程出现了2 次较明显的波动,2 个波峰分别出现在2003 和2012 年,其中2008 年植被NDVI 出现了1 次明显的增加。2)锡林郭勒盟NDVI 大体呈现出“东高西低冶的空间分布特征,变化趋势总体表现为上升,具体为先下降后上升;空间分布上,太仆寺旗、多伦县增加趋势显著,西部苏尼特左旗、二连浩特市下降趋势明显;草原类型上,显著上升面积从大到小依次为草甸草原、典型草原和荒漠草原。3)NDVI 出现峰值的年份与同年降水量波峰相对应,但区域植被变化对气候因子的响应及其相关关系因季节和植被类型而异。植被状况改善与降水量关系密切,只有结合区域气候要素,开展相关生态工程,才能充分发挥生态保护的效益。

       

      Abstract: Background Under the background of global change, vegetation dynamics and research on its relationship with climate is one of the focuses of the current international scientific problems. The study on the trend of vegetation coverage and response to climate is of great significance for global research, furthermore, it also benefits to global ecological processes and global ecological environment. Methods The annual and seasonal change trends of vegetation coverage were examined by employing MODIS-NDVI datasets in Xilin Gol League from 2001 to 2010, and then using Sen + Mann-Kendall model to analyze the significant level of the vegetation change further. In the end, based on the region of the meteorological data, mainly including the local temperature and precipitation, and using correlation analysis, the patterns of spatiotemporal variation of vegetation and its response to climate in Xilin Gol League during the period 2001—2015 was investigated. Results 1) The average vegetation NDVI showed a trend of greater volatility during 2001 to 2015 in the studied area, the change trend of process presented two waves, and the two higher values appeared in 2003 and 2012, of which 2008 vegetation NDVI appeared a temporary rise. Meanwhile, this highly correlated with the precipitation peak, it suggested that the increase of precipitation was a main reason of Xilin Gol League area vegetation to be improved. 2) The NDVI generally presented the distribution characteristics of “high in west and low in east冶, and this kind of distribution characteristics were consistent with the distribution of grassland type, from west to east in the order of desert grassland > typical steppe > meadow steppe. In terms of temporal characteristics, the overall trend was in rise, in detail, the trend was first rising after falling. The spatial distribution showed that NDVI increased significantly in southern and declined significantly in western. Significant increase in size for the grassland types was in the order of meadow steppe > typical steppe > desert grassland. 3) The peaks of NDVI were corresponding to the peaks of precipitation, but because of space differences in geographical location and climate conditions, the correlation between vegetation change and climate were different in each season and vegetation type, the vegetation variations were mostly influenced by precipitation in spring and summer, while it was controlled by temperature in autumn. Conclusions The improvement of vegetation conditions in the studied area was closely associated with precipitation, although ecological measures like returning farming to forest benefited to the growing of vegetation, plenty of rainfall may guarantee the increase of vegetation coverage. Thus, only comprehending regional climate condition may play maximum function in ecological engineering.

       

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