锡林郭勒草原植被生长对降水响应的滞后性研究

Temporal lag of grassland vegetation growth response to precipitation in Xilinguolemeng

植被生长对气候因子变化的响应一直是全球气候变化研究的热点。NDVI作为植被生长的有效指示因子广泛的应用在植被遥感中。多数滞后性响应的研究基于月尺度或季节尺度的ND-VI,容易夸大或缩小滞后效应,不利于滞后时间的确定。为了揭示降水对草原植被生长的有效作用尺度,本研究以2001年至2007年MOD IS反射率数据和气象站点的降水为数据源,分析了时间间隔8天的内蒙古锡林郭勒盟草原生长季NDVI的变化特征以及NDVI与不同尺度的累积降水的相关关系。结果表明,年内生长期草原的NDVI变化呈单峰型,荒漠草原的NDVI变化没有草甸草原和典型草原明显。草原生长对降水存在明显的滞后,一般在50-60天,不同类型的草原滞后时间不同,但均无明显差异。同时,分析指出4-9月草原植被在不同时间段对降水响应的滞后时间分别为64、80、40、40、56和64天,特别是6月和7月份草原植被生长对降水变化的响应最为敏感。这为NDVI预测干旱提供参考。

It is a hot spot in global change studies to understand how vegetation growth responds to climate systems. Normalized Difference Vegetation Index （NDVI） widely used in remote sensing of vegetation. Most generally recognized as a good indicator of vegetation growth is of research on temporal lag response based on monthly or seasonal NDVI were easy to either exaggerate or reduce the lag effect and were disadvantage to determine the exact lag time.In order to reveal the effective scale of precipitation influencing on grassland vegetation growth, this article uses MODIS reflectance data and meteorological stations precipitation to analyze the eight-day interval NDVI dynamic characteristics during the grassland growing season in Xilinguolemeng, Inner Mongolia, China, as well as correlation relationship between NDVI and different schemes precipitation. The result reveals as follows：NDVI of grassland show a single peak during the growing season. However, dynamic of desert steppe is not as obvious as meadow steppe and typical steppe. A lag response time, about 50 to 60 days, exists obviously for grassland to precipitation and different type of grassland have different lag time, but not very significant. The result also reveals that the lag each month from the April to September, are, respectively, 64, 80,40,40,56 and 64 days and especially the response of vegetation growth to precipitation in June and July are more sensitive than other moths.