Gao Yang, Liu Jian, Wang Duojia, An Yu, Ma Hongyuan, Tong Shouzheng
Jilin Academy of Agricultural Sciences (Northeast Agricultural Research Center of China), Changchun, 130033, China.
State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102, China.
J Environ Manage. 2025 Jan;373:123877. doi: 10.1016/j.jenvman.2024.123877. Epub 2024 Dec 28.
Grazing exclusion is effective in restoring vegetation and ecological services in degraded grasslands within semi-arid regions. Variations in plant functional traits associated with the duration of grazing exclusion can indicate both ecological adaptability of plants and restoration processes of ecosystems. However, research on ecosystem multifunctionality (EMF) under grazing exclusion and restoration mechanisms mediated by plant functional traits is relatively limited. In this study, we calculated EMF based on plant species diversity, above-ground biomass (AGB), below-ground biomass (BGB), storages of soil organic carbon (TSOC), soil nitrogen (TSN), and soil phosphorus (TSP) in grasslands under varying durations of grazing exclusion in the semi-arid Songnen Plain, China, and investigated the trait-based pathways involved in forming EMF. The findings revealed irregular fluctuations in plant species diversity, while AGB, TSOC, TSN, and TSP exhibited a linear increase with grazing exclusion duration. Additionally, BGB initially increased but experienced a slight decline over the 17 years of grazing exclusion (GE17). Notably, EMF peaked at 0.778 in GE17 site. In particular, the proportions of AGB and TSOC in the EMF were higher in grazing exclusion sites than that in grazing site. Leaf area (LA) and leaf weight (LW) were lowest in grazing site and highest in GE17 site. Redundancy analysis indicated that the plant functional traits, including LA, leaf nitrogen content (LNC), and LW, collectively explained a substantial proportion of the variance (70.85%) in ecosystem function indicators. Structural equation modelling analysis revealed a direct impact of grazing exclusion on EMF (P < 0.05). However, EMF was remarkably and directly affected by the AGB (P < 0.01) that regulated by the trade-off between LW and LNC. In addition, the synergy between LW and LA had an impact on TSP (P < 0.01), and further enhance EMF (P < 0.05). These findings prominently emphasize the advantageous outcomes of proper grazing exclusion concerning the functional aspects of degraded grasslands. Moreover, they persuasively validate the crucial significance of plant functional traits in relation to the enhancement of EMF. Consequently, this study is capable of providing valuable information for revealing multiple driven mechanisms of grassland EMF in the semi-arid regions.
禁牧在恢复半干旱地区退化草原的植被和生态服务方面是有效的。与禁牧持续时间相关的植物功能性状变化，既可以表明植物的生态适应性，也能体现生态系统的恢复过程。然而，关于禁牧条件下的生态系统多功能性（EMF）以及由植物功能性状介导的恢复机制的研究相对有限。在本研究中，我们基于中国半干旱松嫩平原不同禁牧时长草地的植物物种多样性、地上生物量（AGB）、地下生物量（BGB）、土壤有机碳储量（TSOC）、土壤氮储量（TSN）和土壤磷储量（TSP）计算了EMF，并研究了形成EMF的基于性状的途径。研究结果显示，植物物种多样性呈现不规则波动，而AGB、TSOC、TSN和TSP则随着禁牧时长呈线性增加。此外，BGB最初增加，但在17年的禁牧期（GE17）内略有下降。值得注意的是，EMF在GE17样地达到峰值0.778。特别是，禁牧样地中AGB和TSOC在EMF中的占比高于放牧样地。叶面积（LA）和叶重（LW）在放牧样地最低，在GE17样地最高。冗余分析表明，包括LA、叶片氮含量（LNC）和LW在内的植物功能性状共同解释了生态系统功能指标中相当大比例（70.85%）的变异。结构方程模型分析显示禁牧对EMF有直接影响（P < 0.05）。然而，EMF受到由LW和LNC之间权衡所调节的AGB的显著直接影响（P < 0.01）。此外，LW和LA之间的协同作用对TSP有影响（P < 0.01），并进一步增强了EMF（P < 0.05）。这些发现突出强调了适当禁牧在退化草地功能方面的有利结果。此外，它们有说服力地验证了植物功能性状在增强EMF方面的关键意义。因此，本研究能够为揭示半干旱地区草地EMF的多种驱动机制提供有价值的信息。
