# The Response of Vegetation Dynamics to Climate in Xinjiang from 1991 to 2018
## 5 Conclusions  
This study investigated the spatiotemporal changes in vegetation in Xinjiang from 1991 to 2018 and the vegetation's response to climate. Using multiple vegetation datasets (NDVI, LAI, and GPP), the spatial distribution and trends of vegetation during the study period were analyzed, and the variations in vegetation reflected by each index were compared. Additionally, land use data from 1991 to 2018 were used to analyze changes in vegetation types and areas in Xinjiang. Furthermore, temperature and precipitation data were combined to study the vegetation response to climate change. From 1991 to 2018, NDVI, LAI, and GPP values in Xinjiang showed a distribution pattern of being higher in the north and lower in the south, with long-term averages of 0.28, 0.34, and 274.0 g C m\({}^{-2}\) yr\({}^{-1}\), respectively. The annual average distributions of NDVI, LAI, and GPP were mainly influenced by vegetation patterns during the growing season. The high annual average values for all indices were distributed similarly. In northern Xinjiang, high values were concentrated in the Tianshan Mountains, Altai Mountains, and the northwest of the Junggar Basin, while in southern Xinjiang, they were mainly distributed around the Tarim Basin. During the study period, the annual averages of NDVI, LAI, and GPP all showed increasing trends, with _slopes_ of 0.52, 0.14 and 1.19; however, the spatial distributions of these trends differed slightly. Areas with consistent upward trends for all three indices were primarily located in the southern and northwestern parts of the Junggar Basin and around the Tarim Basin, while areas with consistent downward trends were mainly in central Tianshan. Overall, vegetation in Xinjiang had gradually improved. The net increase in vegetation area was 24,345.8 km\({}^{2}\). Grassland has the largest area increase, accounting for 88.7% of the total area increase. The increase in grassland mainly resulted from the conversion of bare/desert. During the study period, both precipitation and temperature in Xinjiang showed upward trends, but the correlations between these climate factors and the different vegetation indices varied significantly. The proportions of positive correlations between NDVI, LAI, GPP, and temperature were all around 50%, with a less than 5% difference in the positive correlation proportions among the three indices. In contrast, the proportions of positive correlations with precipitation varied greatly, with 50.3% for NDVI, 85.5% for LAI, and 74.3% for GPP in detail. Due to the distribution characteristics of vegetation data, the data in areas without vegetation caused this variation. Especially in desert areas, there was a negative correlation between NDVI and climate factors. Increased precipitation favored vegetation growth. The areas where each index had positive correlations with precipitation were largely consistent with the regions of high annual averages for these indices. In contrast, the effect of temperature on vegetation was less pronounced. Among the three indices, GPP indicated weak correlations with both precipitation and temperature, while NDVI and LAI generally showed positive correlations with climate factors, though these correlations were influenced by factors such as vegetation type and elevation. Although all three indices could represent vegetation conditions, they showed great differences when analyzing the impact of climate on vegetation, leading to varying results. Therefore, careful selection of vegetation data was essential when conducting attribution analysis for vegetation changes in a given region. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/f15122065/s1](https://www.mdpi.com/article/10.3390/f15122065/s1)]([https://www.mdpi.com/article/10.3390/f15122065/s1](https://www.mdpi.com/article/10.3390/f15122065/s1)), Figure S1. Characteristics of land use change during the study period. (a) represents increased areas from 1991 to 2018, (b) represents decreased areas from 1991 to 2018.