## 3 Results
### Forecasting Future Patterns in the Three Northern Protection Forest Project Area  
Figure 7 offers a meticulous analysis of the Hurst index for Net Ecosystem Productivity (NEP) across the study area, with values spanning from 0.07 to 0.98. This exhaustive evaluation synergistically combines the Hurst index with Theil-Sen trend analyses and Mann-Kendall test results, affording a multi-dimensional perspective on NEP dynamics throughout the entire time series. The analysis discloses that only a modest 2.49% of the study area demonstrates a decreasing NEP trend, while 10.78% shows an increasing trend. Notably, a substantial 86.73% of the area falls into a category indicative of uncertain future changes, emphasizing the inherent complexity and variability in projecting ecosystem productivity. Figure 6: The interplay between Net Ecosystem Productivity (NEP) and Land-Use and Land-Cover Changes (LUCC). In our analysis of regions exhibiting a consistent increase in Net Ecosystem Productivity (NEP), we identified that a notable 7.52% of these areas fall under the category of \"Weak Persistent-Significant Increase\". This trend is particularly evident across several provinces and autonomous regions, reflecting a diverse geographical spread. Specifically, the trend is observed in cities located in the eastern part of Gansu Province (such as Lanzhou City), throughout the Ningxia Hui Autonomous Region (including its capital, Yinchuan City, and other key cities), in various locations within the Inner Mongolia Autonomous Region (notably in its central and eastern parts), in the northern region of Hebei Province, and across several cities in the northeast. These areas, representing a mix of urban and rural landscapes, showcase the varied impact of environmental and climatic factors on ecosystem productivity. The findings from this analysis not only illuminate the present state and trajectories of NEP in these regions but also highlight the substantial proportion of areas where NEP is exhibiting an upward trend, surpassing those with declining trends. The spatial delineation of these trends is vital for comprehending regional ecosystem dynamics and for informing future environmental management and policy formulations. The discernible dominance of regions with increasing NEP trends, particularly those characterized by a weak but persistent significant increase, suggests an optimistic outlook for the ecological vitality and carbon sequestration capabilities of these areas. In this study, the category of \"Weak Persistent-Slight Increase\" in Net Ecosystem Productivity (NEP), covering 3.25% of the study area, is predominantly identified in specific regions of the Xinjiang Uyghur Autonomous Region, particularly in the Ili Kazakh  
Figure 7: NEP Hurst index and spatial patterns of long-term NEP changes. Autonomous Prefecture, Tacheng City, and Altay Prefecture. This trend is also observed in the Xilin Gol League of the Inner Mongolia Autonomous Region and in the northeast region, specifically in Shenyang City and Changchun City. Although the increase is modest, it indicates positive ecological developments in these areas. Conversely, the \"Weak Persistent-Slight Decrease\" category, representing 1.64% of the study area, is primarily found in the Bayingol Mongol Autonomous Prefecture and Turpan City in the Xinjiang Uyghur Autonomous Region, as well as in Zhangye City in Gansu Province. This slight downward trend in NEP highlights the need for targeted ecological management in these regions. Remarkably, a substantial portion of the Three Northern Protection Forest Project Area, constituting 86.73%, is characterized by uncertainty regarding future NEP trends. This prevalent uncertainty emphasizes the imperative for enhanced efforts toward stabilizing the ecosystems in these areas. It also sheds light on the complex challenges involved in ecological preservation and sustainable development across the region, underscoring the necessity for strategic measures to ensure future ecological equilibrium and sustainable resource management.