Fayi Li , Pingna Yin , Liangyu Lv , Shancun Bao , Zongcheng Cai , Shouquan Fu , Jianjun Shi
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引用次数: 0
Abstract
Alpine grasslands, as one of the typical ecosystem types of the Qinghai-Tibet Plateau, play a crucial ecological role in regional water conservation, carbon and nitrogen cycling, and forage production. However, in recent years, persistent human activity disturbances and the effects of climate change have led to widespread degradation of grasslands in this region, accompanied by declining soil functionality and inefficient utilization of water and nutrients by vegetation. These challenges impede efforts toward ecological restoration and sustainable management. In response to this issue, this study systematically analyzed the temporal and spatial variations of above-ground and below-ground biomass fresh-dry ratios, root-zone soil fresh-dry ratios of Carex parvula, plant δ13C and δ15N isotopic compositions, and soil physicochemical indicators (pH, SOC, TN, AN, TP, AP, TK, AK) across different restoration periods (2000s, 2006s, 2013s). The research focused on artificial grasslands, natural grasslands (AM), and degraded black soil beach ridges (BOBG), utilizing pearson correlation analysis and structural equation modeling (SEM) to investigate their interconnected relationships and underlying mechanisms. The results indicate that with increasing restoration time, the fresh-to-dry ratio of above ground biomass gradually decreases, while the fresh-dry ratio of below ground biomass gradually increases and stabilizes. Soil fresh-dry ratios and indicators such as Soc, TN, AN, TP, AP, TK, and AK progressively increase, while pH decreases significantly. The δ13C content decreases with increasing restoration time, while δ15N gradually increases. The correlation analysis reveals that soil functions are significantly positively associated with δ15N, below-ground biomass, and restoration stage, while being negatively associated with δ13C, above-ground biomass, and pH. Structural Equation Modeling further validated causal pathways among restoration period, soil functionality, and isotopes, indicating that enhanced soil functionality can increase δ15N supply and water acquisition capability, thereby reducing plant water use efficiency (WUE) and enhancing vegetation assimilation capacity. This study demonstrates that with extended restoration periods, the ecosystem components show increased structural stability and water use efficiency, while the coupling relationships between soil, vegetation, and isotopic signals become more interconnected. The study presents a comprehensive indicator system and theoretical framework for assessing grassland degradation and monitoring restoration outcomes in alpine grassland ecosystems, providing scientific support for optimizing grassland management strategies and establishing effective ecological monitoring systems.
期刊介绍:
Ecological engineering has been defined as the design of ecosystems for the mutual benefit of humans and nature. The journal is meant for ecologists who, because of their research interests or occupation, are involved in designing, monitoring, or restoring ecosystems, and can serve as a bridge between ecologists and engineers.
Specific topics covered in the journal include: habitat reconstruction; ecotechnology; synthetic ecology; bioengineering; restoration ecology; ecology conservation; ecosystem rehabilitation; stream and river restoration; reclamation ecology; non-renewable resource conservation. Descriptions of specific applications of ecological engineering are acceptable only when situated within context of adding novelty to current research and emphasizing ecosystem restoration. We do not accept purely descriptive reports on ecosystem structures (such as vegetation surveys), purely physical assessment of materials that can be used for ecological restoration, small-model studies carried out in the laboratory or greenhouse with artificial (waste)water or crop studies, or case studies on conventional wastewater treatment and eutrophication that do not offer an ecosystem restoration approach within the paper.