Breeding Base for State Key Lab. of Land Degradation and Ecological Restoration in northwestern China/Key Lab. of Restoration and Reconstruction of Degraded Ecosystems in northwestern China of Ministry of Education, Ningxia University, Yinchuan, Ningxia 750021, China; State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Soil and Water Conservation Science and Engineering (Institute of Soil and Water Conservation), Northwest A&F University, Yangling, Shaanxi 712100, China.
Breeding Base for State Key Lab. of Land Degradation and Ecological Restoration in northwestern China/Key Lab. of Restoration and Reconstruction of Degraded Ecosystems in northwestern China of Ministry of Education, Ningxia University, Yinchuan, Ningxia 750021, China; College of Forestry and Prataculture, Ningxia University, Yinchuan 750021, China.
Sci Total Environ. 2024 Dec 1;954:176474. doi: 10.1016/j.scitotenv.2024.176474. Epub 2024 Sep 26.
Livestock removal (LR) is considered an effective strategy for recovering ecosystem functions in degraded grasslands. Carbon (C), nitrogen (N), and phosphorus (P), as well as their ratios in plants and microorganisms, act as key regulators of ecosystem stability and nutrient limitation during grassland succession. However, few studies have comprehensively evaluated plant and microbial nutrient limitations through C:N:P stoichiometry following LR over different durations. Here, our study explored the C, N, P contents, and C:N, C:P and N:P ratios of green and senescent leaves, microbial biomass and extracellular enzymes after 33 years of LR on the Loess Plateau, China. The results showed that LR increased the C, N, and P contents of plant and microbial communities. LR (>26 years) enhanced C, N, P contents of green leaves by 364.7 %, 232.2 %, 134.6 %, and C, N, P contents of senescent leaves by 164.8 %, 230.8 %, 86.3 %, respectively. LR also increased plant C:P and N:P ratios and the P reabsorption efficiency, indicating that the plant communities shifted from N to P-limitation during grassland restoration. Compared with the grazing sites, LR26 increased C, N, P contents, C:P and N:P ratios of soil microbial biomass, whereas reduced soil N-acquiring enzyme activity and enzymatic N:P ratio, indicating that the microbial community experienced higher P limitation than that of grazing sites. Plant and microbial communities showed strong plastic relationships with soil resource. Vegetation cover and productivity played strong roles in altering the plant and microbial C:N:P stoichiometry following LR. These findings indicate that long-term LR (>26 years) will exacerbate plant and microbial P limitation during grassland succession.
家畜移除（LR）被认为是恢复退化草地生态系统功能的有效策略。碳（C）、氮（N）和磷（P）以及它们在植物和微生物中的比值，是草地演替过程中生态系统稳定性和养分限制的关键调节因子。然而，很少有研究综合评估 LR 后不同时间内通过 C:N:P 化学计量比植物和微生物的养分限制。在这里，我们的研究探讨了 33 年来黄土高原 LR 对植物和微生物生物量以及胞外酶的绿色和衰老叶片、微生物生物量和胞外酶的 C、N、P 含量以及 C:N、C:P 和 N:P 比的影响。结果表明，LR 增加了植物和微生物群落的 C、N 和 P 含量。LR（>26 年）分别使绿叶的 C、N、P 含量增加了 364.7%、232.2%、134.6%，衰老叶片的 C、N、P 含量增加了 164.8%、230.8%、86.3%。LR 还增加了植物 C:P 和 N:P 比和 P 再吸收效率，表明在草地恢复过程中，植物群落从 N 限制转变为 P 限制。与放牧地相比，LR26 增加了土壤微生物生物量的 C、N、P 含量、C:P 和 N:P 比，而降低了土壤获取 N 的酶活性和酶 N:P 比，表明微生物群落比放牧地面临更高的 P 限制。植物和微生物群落与土壤资源表现出强烈的可塑性关系。植被覆盖度和生产力在改变 LR 后植物和微生物 C:N:P 化学计量比方面发挥了重要作用。这些发现表明，长期 LR（>26 年）将加剧草地演替过程中植物和微生物的 P 限制。
