Applied Sciences  
Progress and Prospects in Assessing the Multidimensional Environmental Impacts of Global Vegetation Restoration  
[PERSON] 1,2\({}^{\copyright}\)  
1 State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling 712100, China; [EMAIL_ADDRESS]  
2 State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and the Ministry of Water Resources, Yangling 712100, China  
The restoration of degraded vegetation and ecosystems is a critical tool for mitigating biodiversity losses, stabilizing soils, improving water quality, sequestering carbon, and providing other ecosystem services. The goals of vegetation restoration include reestablishing native plant communities, restoring ecological processes and functions, and repairing human impacts to the landscape [1]. However, the environmental impacts of vegetation restoration practices remain inadequately understood. Recent research has aimed to elucidate restoration outcomes across multiple ecological indicators and provide guidance for maximizing benefits while minimizing unintended consequences. The significance of vegetation restoration stems primarily from widespread ecosystem degradation and biodiversity declines worldwide [2]. Up to 2 billion hectares globally may be suitable for restoration [2], presenting major opportunities for ecological enhancement. Degradation reduces the ability of ecosystems to provide services that are foundational for human wellbeing, such as climate regulation, water provisioning, and nutrient cycling [3]. Restoration goals thus center on increasing vegetation cover, richness, structural complexity, and native species abundances to recover these ecosystem functions [4]. Successful restoration can generate numerous ecosystem service benefits, including enhanced carbon storage, soil development, hydrologic regulation, nutrient cycling, habitat provisioning, and resilience to climate change [3, 5, 6]. However, restoration practices may also have unintended environmental tradeoffs that require careful evaluation [4]. Environmental impacts may also change over time as restored systems develop along ecological successional trajectories [7]. Considerable research in recent years has examined the environmental impacts of vegetation restoration across various biomes and ecological indicators. Multiple meta-analyses indicate that restoration effectively increases species diversity and richness on average, but long-term trajectories may continue diverging from reference ecosystems even after decades [8, 9]. A closer examination reveals that biodiversity responses vary across biomes, with larger gains seen in wetland and forest restoration compared to grassland and shrubland projects [8]. Nevertheless, specific geographic regions within these biomes, such as tropical forests in Sub-Saharan Africa and Southeast Asia, remain understudied [9, 10]. Focused research expanding across these tropical regions could provide new insights into restoration outcomes and context dependencies. Temporal studies tracking soil nutrients, microbial communities, and enzymatic activities demonstrate successful changes during restoration [11, 12, 13], but more long-term data are needed [7, 14]. Soil carbon accumulation is commonly enhanced by restoration, but the magnitude depends on climate, soil type, previous land use, and restoration methods [3, 15]. Modeling studies project continuing soil carbon accrual over decades to centuries as restored systems aggrade [16, 17]. Potential tradeoffs exist between increased water yield from reforestation and reduced storm flow buffers [18]. Assessments using multiple ecosystem service indicators highlight both synergies and tradeoffs among hydrologic regulation, biodiversity enhancement, carbon storage, and sustainability outcomes [9, 19]. Several reviews synthesize the state of knowledge on vegetation restoration outcomes. [PERSON] et al.