荒漠区不同植被类型NDVI变化特征分析——以内蒙古阿拉善盟为例

Analysis of NDVI Variation Characteristics of Different Vegetation Types in Desert Areas——A Case Study of Alxa League,Inner Mongolia

以内蒙古自治区阿拉善盟为研究区,基于1981~2019年NDVI数字影像、植被类型数据以及气象台站数据资料,运用GIS以及相关分析方法对阿拉善盟植被NDVI变化进行分析,探讨阿拉善盟植被NDVI对温度和降水量的响应特征。结果表明:阿拉善盟NDVI呈典型的东南高西北低的空间分布格局,且空间分布不均匀。1981~2019年阿拉善盟NDVI年平均值仅为0.028,植被覆盖度不高。阿拉善盟长期较为稳定的典型草原、典型荒漠、草原化荒漠、极旱荒漠、荒漠草原、固定沙丘、灌丛、草甸8种天然植被类型中,典型草原、草原化荒漠、固定沙丘和灌丛植被覆盖度增加,其余植被类型覆盖度呈下降趋势。阿拉善盟各种植被覆盖类型NDVI均与温度呈负相关关系,其中极旱荒漠与温度呈显著负相关关系(P<0.05),典型草原、荒漠草原、草原化荒漠、固定沙丘植被NDVI与年降水量呈显著或极显著正相关关系(P<0.05或P<0.01)。

Based on the NDVI digital images,vegetation type data and meteorological station data from 1981 to 2019,this study used GIS and related analysis methods to analyze the changes of vegetation NDVI in Alxa League,Inner Mongolia,and discussed the response characteristics of NDVI in Alxa League to temperature and precipitation.The results showed that the vegetation NDVI of Alxa League showed a typical spatial distribution pattern of high in the southeast and low in the northwest,and the spatial distribution was uneven.The annual average value of NDVI in Alxa League from 1981 to 2019 was only 0.028,and the vegetation coverage was not high.Among the eight natural vegetation types of typical grassland,typical desert,grassland desertification,extremely arid desert,desert grassland,fixed sand dune vegetation,shrub and meadow that had been relatively stable for a long time in Alxa League,the vegetation coverage of typical grassland,grassland desertification,fixed sand dune and shrub had improved,and the coverage of other vegetation types showed a downward trend.NDVI of all vegetation cover types in Alxa had a negative correlation with temperature,in which extremely arid desert had a significant negative correlation with temperature(P<0.05),and NDVI of typical grassland,desert grassland,grassland desert and fixed dune vegetation had a significant positive correlation with annual precipitation(P<0.05 or 0.01).