Abstract:

In order to learn about features of vegetation change in the middle south of Ningxia on the monthly average, seasonal average, the annual average and decadal time, including the change of green and brown waves, and its relationship with climate variables, the author used the monthly GIMMS Normalized Difference Vegetation Index (NDVI) data and the data of precipitation and temperature in the middle south of Ningxia between 1982 and 2006, found that the annual mean of NDVI was getting better continuously, although there were undulations in vegetation cover over past 25 years in this region. The dynamic variations of NDVI on a seasonal basis obvious increases occurred except summer. The change of green and brown waves revealed that NDVI had significantly seasonal and regional variation. From the statistical analysis, the result showed that the seasonal annual NDVI showed a positive correlation with precipitation, and a negative correlation with surface air temperature Moreover there was a significant positive correlation between spring mean precipitation and following summer, fall and annual mean NDVI, suggesting that spring rainfall was a key factor to determine the distribution of vegetation in the middle south of Ningxia. In summary, relationships between annual variation of seasonal vegetation and climatic factors represented temporal rhythm controls of temperature and precipitation on grass growth, and dynamic monitoring of the vegetation variation could reflect the trend of climate change to some extent.