Abstract:

Precipitation has an important impact on vegetation coverage in eastern desert regions of China. Understanding the response of vegetation coverage to precipitation changes is of importance to making strategies for vegetation restoration. Mu Us Sandy Land and Horqin Sandy Land， which are typical sandy lands in eastern China， were selected， the Landsat series data and MODIS data were used to obtain the normalized difference vegetation index （NDVI） data set in 2000-2020， and the pixel dichotomy method was used to compute the maximum vegetation coverage in each year and the average vegetation coverage in growing seasons. Then， the daily precipitation data observed by weather stations from 1999 to 2020 were combined with the data of the vegetation coverage to analyze the response of vegetation coverage to precipitation changes in different seasons. The results showed： （1） Both of the maximum vegetation coverage in a year and the average vegetation coverage in growing seasons appeared an increasing trend in Mu Us Sandy Land and Horqin Sandy Land， the increasing rate of the maximum vegetation coverage was 6.5%/10a and 4.1%/10a， respectively， and the increasing rate of the average vegetation coverage was 6.3%/10a and 3.6%/10a， respectively. Among them， the most significant increase with >30% of the average vegetation coverage in growing seasons was found in Mu Us Sandy Land， and that with >50% of the average vegetation coverage in growing seasons was found in Horqin Sandy Land. （2） The annual precipitation and the seasonal precipitation in the two sandy lands showed an increasing trend， the increasing rate was 50.4 mm/10a and 46.7 mm/10a， respectively. The precipitation was of the common characteristics of large variability and the largest summer increase. （3） Both of the yearly maximum vegetation coverage and the average vegetation coverage in growing seasons in Mu Us Sandy Land were most sensitive to the response of the summer precipitation in previous year， while those in Horqin Sandy Land were most sensitive to the response of the summer precipitation in the same year. （4） Different vegetation types have different lag times in response to precipitation changes.

Key words: yearly maximum vegetation coverage, average vegetation coverage, growing season, seasonal precipitation