## 3 Results and Discussion
### Vegetation Cover Persistence Analysis  
Using the R/S analysis method, a time-series analysis of the vegetation cover of the study area was conducted using MATLAB software on an image-by-image basis, and hierarchical statistics were performed to obtain the spatial distribution of the Hurst index for the study area from 1990 to 2020 (as shown in Figures 8 and 9).The variation trend is divided into three categories according to the different range of H value [25; 26]: anti-persistence, stochasticity and positive persistence. Because the FVC value of the three reservoirs and the Tarim River valley is zero, there is no definition in the calculation: it is null in the figure. As shown in Table 4, the Hurst value of the whole Reclamation area is 0.07-1, with the mean value of 0.63 and the standard deviation of 0.15. The significant anti-persistence areas with a Hurst index lower than 0.5 account for 18.3%, mainly concentrated in the human activity areas around three major reservoirs and the Tarim River valley; the areas with a Hurst index higher than 0.5 account for 81.7% and the areas with positive persistence H values are mainly concentrated in the newly built regiments such as the ninth, eleventh and twelfth regiments, alleviating desertification. It can be seen that the positive persistence trend is stronger than the anti-persistence trend, and the trend of vegetation coverage in Alar Reclamation area in the future is consistent with that in 1990-2020.  
The research area is a typical artificial desert oasis located in the north of Tarim Basin, studied from 2000 to 2020. The land use transfer matrix for the study area was calculated using arcgis software for the selected products of GLobeland 30 for the years 2000 and 2020. The land use types in the research area were converted to different degrees (as shown in Table 5 and Figure 9). Among them, the null value indicates that the ground feature types were not converted. It can be seen from the table that the grassland area increased by 32.2%, the cultivated land area increased by 21.2% and the forest land area decreased by 88% in the past 30 years; forest land has been converted into grassland, cultivated land and  
Figure 8: Spatial distribution of Hurst index and FVC in the future from 1990 to 2020.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**CV Variation Range** & **Degree of Variation** & **Number of Pixels** &
\begin{tabular}{c} **Image Area as a** \\ **Percentage** \\ \end{tabular} \\ \hline
0 \textless{} CV \textless{} 0.2 & Stable & 12,263,553 & 23.82\% \\
0.2 \textless{} CV \textless{} 0.5 & Relatively stable & 22,340,090 & 43.40\% \\
0.5 \textless{} CV \textless{} 0.8 & Weakly variable & 11,477,889 & 22.30\% \\
0.8 \textless{} CV \textless{} 2.13 & Highly variable & 5,396,171 & 10.48\% \\ \hline \hline \end{tabular}
\end{table}
Table 3: FVC change stability of Alar Reclamation area from 1990 to 2020.  
water bodies. The area of construction land increased by 64.4%, and the overall change in water body was relatively small, increasing by 13%. It can be said that the impact of human activities on vegetation coverage is far greater than that of natural factors. The promotion of urbanization and the implementation of ecological and environmental protection policies are the main driving factors for the spatial-temporal change in vegetation coverage in the research area.  
value in Alar from 2000 to 2020 increased by 21,952.82 billion yuan, the total forestry output value increased by 2901.8 million yuan, the cultivated area of food crops decreased by 88,500 hectares and the total sown area of crops increased by 884,400 hectares [28; 29]. This paper uses multiple linear regression, the coefficient of variation and Hurst index to explore and analyze the changes in vegetation cover in the Alar region in different years, adding multifactorial considerations to ensure that the research results are more objective and reasonable.