Data Sheet 1_Long-term Kentucky bluegrass cultivation enhances soil quality and microbial communities on the Qinghai-Tibet Plateau.docx

IntroductionNature-based Solutions (NbS) provide a comprehensive strategy for environmental management, focusing on the protection, sustainable use, and restoration of natural and modified ecosystems. Cultivated grasslands are a form of NbS, offering benefits such as increased biodiversity, improved soil fertility, and greater ecosystem resilience. They are widely acknowledged for their positive impact on restoring degraded grasslands. Kentucky bluegrass (Poa pratensis L.) is widely used for restoring degraded grasslands on the Qinghai-Tibet Plateau. However, long-term cultivation of Kentucky bluegrass can lead to above-ground degradation, which challenges its effectiveness in restoring ecosystem health.
MethodsThis study investigates the impacts of Kentucky bluegrass cultivation on soil quality, focusing on soil nutrients, enzyme activities, and microbial communities across different recovery stages. Field experiments were conducted to analyze soil quality dynamics during early (2nd year), mid (6th year), and late (10th year) succession stages of cultivated grasslands on the Qinghai-Tibet Plateau. Our results show that in the early and mid-stages, soil total nitrogen, total phosphorus, and organic carbon storage were significantly lower compared to undegraded grasslands, with the lowest soil quality observed in the early stage (P< 0.05). However, by the late stage, soil quality significantly improved, with total nitrogen, total phosphorus, and organic carbon contents exceeding those of undegraded grasslands by 14.59%. These improvements were driven by enhanced microbial community dynamics and increased nitrogen and carbon cycling enzyme activities, which promoted nutrient utilization and organic matter decomposition. This process was accompanied by a rise in microbial diversity, supporting soil resilience and ecosystem function. Soil total nitrogen emerged as a key determinant of soil quality in both natural and cultivated grasslands, and appropriate nitrogen fertilization strategies were found to effectively enhance grassland productivity and ecosystem health.
DiscussionOverall, this study highlights the potential of Kentucky bluegrass in restoring degraded grasslands by improving soil fertility and microbial community structure over time, providing insights into sustainable management practices to maintain soil fertility and ecosystem services on the Qinghai-Tibet Plateau.

引言
基于自然的解决方案（Nature-based Solutions, NbS）是一套综合性环境管理策略，核心聚焦于自然及受干扰生态系统的保护、可持续利用与修复。人工草地是基于自然的解决方案的应用形式之一，可带来生物多样性提升、土壤肥力改善以及生态系统韧性增强等多重效益，其在退化草地修复中的积极作用已得到广泛认可。草地早熟禾（Poa pratensis L.）是青藏高原退化草地修复中广泛应用的物种，但长期种植该草种会引发地上部分退化，这对其维持生态系统健康的修复效果构成挑战。

方法
本研究以青藏高原人工草地不同恢复阶段的土壤为研究对象，探讨草地早熟禾种植对土壤质量的影响，重点关注土壤养分、酶活性及微生物群落特征。本研究设置野外定位试验，分析青藏高原人工草地早期（种植第2年）、中期（种植第6年）与晚期（种植第10年）演替阶段的土壤质量动态变化。
研究结果显示，在早期与中期演替阶段，土壤全氮、全磷及有机碳储量均显著低于未退化草地，且早期阶段的土壤质量最低（P<0.05）。但至晚期演替阶段，土壤质量得到显著改善，全氮、全磷及有机碳含量较未退化草地提升14.59%。该改善得益于微生物群落动态的增强以及氮、碳循环相关酶活性的提升，进而促进了养分利用与有机质分解；此过程伴随微生物多样性的升高，助力土壤韧性与生态系统功能维持。研究发现，土壤全氮是天然与人工草地土壤质量的关键调控因子，而合理的氮肥施用策略可有效提升草地生产力与生态系统健康水平。

讨论
综上，本研究揭示了草地早熟禾通过随时间推移改善土壤肥力与微生物群落结构，从而助力青藏高原退化草地修复的潜力，为青藏高原地区维持土壤肥力与生态系统服务功能的可持续管理实践提供了理论参考。