伊犁地区不同草地类型植被指数与气候因子的关系

Relationships Between Different Types of Grasslands Vegetation Index and Climatic Factors in the Yili Region

基于2006—2012年主要生长季(5—9月)MODIS旬最大值合成NDVI数据,结合同期气温、降水插值栅格资料,采用均值法、线性回归法、相关系数法分析了伊犁河谷地区七大不同草地类型NDVI的时空变化规律及其对气象因子响应的敏感性及滞后性。结果表明:(1)伊犁河谷草地植被NDVI整体呈微弱增加趋势,其中,温性荒漠类草地的增加趋势略高于其他几种类型。(2)温性草甸草原、温性草原、温性荒漠草原、高寒草原、低平地草甸的NDVI主要受降水影响,即NDVI与生长季平均降水量呈极显著正相关,且平均降水量每增加1 mm,其NDVI分别增加0.005、0.006、0.007、0.004、0.003。(3)不同草地类型与气温、降水存在不同的滞后响应,多数草地类型5月气温、降水与7月NDVI表现出显著相关性。其中,温性草甸草原、温性草原、温性荒漠草原NDVI受气温和降水共同影响,气温每升高1℃,NDVI分别减少0.020、0.028、0.027,降水每增加1 mm,NDVI分别增加0.002、0.003、0.003;高寒草原主要受降水影响,降水每增加1 mm,NDVI增加0.003;低平地草甸主要受气温影响,气温每升高1℃,NDVI减少0.016;温性荒漠、沼泽与气温、降水没有明显相关性。不同草地类型对水热因子的需求不同,是产生这种结果的主要原因。

Based on averaging method and linear regression method, MODIS growing season maximum NDVI datasets from 2006 to 2012 were used to analyze vegetation dynamics of Yili area different grasslands. Integrated with the same period of temperature and precipitation raster datasets, correlation coefficients were computed to characterize different grasslands in meteorological factors sensitivity and hysteresis. The results showed that： （1）A slight addition occurred in Yili area grasslands from 2006 to 2012. The temperate deserts increased slightly higher than other types. （2） The NDVI of temperate meadow grasslands, temperate grasslands, temperate desert grasslands, alpine meadow, lowland meadow showed a significant correlation with precipitation in growing season, when the average precipitation increased 1 ram, each type NDVI increased repectively by 0.005, 0.006, 0.007,0.004,0.003. （3） The NDVI of temperate meadow grasslands, temperate grasslands, temperate desert grasslands in July showed greater sensitivity to the interaction of temperature and precipitation in May. Temperature rose 1 degrees,each type NDVI decreased repectively by 0.020,0.028,0.027;precipitation increased 1 mm,NDVI increased repectively by 0.002,0.003,0.003. The precipitation in May affected alpine meadow NDVI in July. Precipitation increased 1 ram, NDVI increased 0.003. The temperature in May affected lowland meadow NDVI in July. Temperature rose 1 degrees, NDVI decreased 0.003. Other grassland types showed no significant correlation with temperature and precipitation. The main reasons for the results were that different grasslands had different requirements for hydrothermal factors.