呼伦贝尔草地植被枯黄期变化及其对极端气候的响应

Changes of Grassland Vegetation End of Growing Season and Its Response to Extreme Climate in Hulun Buir

摘要: 草地生态系统是自然生态系统的重要组成部分，探讨植被物候变化与极端气候的关系，对草地生态系统保护及极端气候灾害预防具有重要意义。本文基于呼伦贝尔地区的2001~2017年MOD13Q1数据和日气象数据资料，选取S-G滤波法对NDVI时间序列数据拟合重建，采用动态阈值法提取草地植被枯黄期，并利用趋势分析、相关分析等方法分析呼伦贝尔草地植被枯黄期变化及其对极端气候的响应。结果表明：1) 枯黄期主要集中在260~290天，但各草地类型之间的物候参数具有差异性；年际变化趋势表现出微弱的提前趋势；在空间上，EOS提前区域主要分布在呼伦贝尔中部和西南地区，EOS推迟区域主要分布在中部偏西和东南地区。2) 近17a来，呼伦贝尔地区极端气温指数TX10P呈上升趋势，TX90P呈下降趋势，TNx、TXx、TNn和TXn总体呈减少趋势；极端降水指数CDD呈减少的趋势外，其他降水指数均呈上升趋势，表明该地区降水量增大。3) 不同草地植被类型枯黄期对于极端气温指数和极端降水指数的响应并不显著，且存在差异。该研究有助于加深草地植被物候对极端气候指数响应的认识，以期为维系生态平衡提供参考。

Abstract: Grassland ecosystems are an important part of natural ecosystems, it is of great significance to discuss the relationship between vegetation phenology changes and extreme climate for grassland ecosystem protection and extreme climate disaster prevention. In this paper, based on the MOD13Q1 data and daily meteorological data information in Hulun Buir area from 2001 to 2017, the S-G filter method was selected to fit and reconstruct the NDVI time series data, the dynamic threshold method was used to extract the grassland vegetation end of growing season, and the trend analysis and correlation analysis methods were used to analyze the changes of grassland vegetation end of growing season in Hulun Buir and its response to climate extremes. The results showed that: 1) The end of growing season was mainly concentrated in 260~290 days, but the phenological parameters of different grassland types were different; the interannual change trend showed a weak upward trend; spatially, the EOS advancement area was mainly distributed in the central and southwest areas of Hulun Buir, and the EOS delayed area was mainly distributed in the central west and southeast areas. 2) In the recent 17 years, the extreme temperature index TX10P in Hulun Buir area showed an upward trend, TX90P showed a downward trend, and TNx, TXx, TNn and TXn showed a downward trend in general. The extreme precipitation index CDD showed a downward trend, while other precipitation indexes showed an upward trend, which indicates that the precipitation in this area increased. 3) The responses of different grassland vegetation types to extreme temperature indices and extreme precipitation indices during end of growing season were not significant and differed. This study helps to deepen the understanding of the response of grassland vegetation phenology to extreme climate indices, with a view to providing a reference for maintaining ecological balance.