首页 > 分享 > 青藏高原高寒草地退化对土壤及微生物化学计量特征的影响

青藏高原高寒草地退化对土壤及微生物化学计量特征的影响

花匠小妙招
2024-11-23 22:44

摘要：

草地是我国陆地生态系统的重要组成部分, 具有重要的生产和生态功能。过去几十年来, 受气候变化和过度放牧等因素影响, 我国90%的天然草地发生不同程度退化。草地退化打破了土壤养分平衡, 影响草地生态系统的结构和功能。该研究以青藏高原高寒草地为研究对象, 基于三江源区多点采样和整个青藏高原高寒草地的meta分析相结合的手段, 解析了表层0-10 cm土壤和微生物碳氮磷含量及其化学计量特征随不同草地退化程度(未退化、中度和重度退化)的变化规律。结果显示, 草地退化整体上降低土壤有机碳、总氮和总磷含量及其化学计量比。土壤微生物碳氮含量随着退化程度的加剧而下降, 微生物磷含量不受退化的影响。微生物碳氮磷化学计量比沿退化梯度没有显著的变化规律, 且土壤和微生物元素化学计量比之间未呈现显著相关关系。以上结果表明, 草地退化致使土壤养分化学计量关系发生显著改变, 微生物群落自身却能维持一定的养分平衡。在长时间尺度上, 基于养分平衡的土壤质量提升技术可有效地促进退化高寒草地恢复, 改善其生态系统服务功能。

关键词: 草地退化, 养分限制, 化学计量内稳性, 土壤微生物, 青藏高原

Abstract:

Aims Grassland is an important component of the terrestrial ecosystems in China, and plays a vital role in ecosystem productivity and functioning. During the past decades, 90% of natural grasslands have been degraded as a result of climate change and anthropogenic activities. Grassland degradation altered soil nutrient balance, exerting substantial impacts on ecosystem structure and functions. Our objective was to explore the responses of soil and microbial carbon (C), nitrogen (N) and phosphorus (P) stoichiometry to grassland degradation across the Qingzang Plateau alpine grasslands.

Methods We collected soil samples (0-10 cm) along the degradation sequence (i.e., non-degradation, moderate degradation and heavy degradation) from five sites across the “Three-River Source” region. By determination of soil and microbial C, N and P, we examined the changes in their contents and stoichiometric ratios with grassland degradation. We further synthesized data from the whole Qingzang Plateau alpine grasslands to validate the measured results using a meta-analytical approach.

Important findings Grassland degradation significantly reduced soil organic C, total N and total P contents and their stoichiometric ratios. Although microbial C and N content declined with degradation, change in microbial P content was limited along the degradation gradient. The microbial C:N:P ratios showed minimal responses to degradation. No obvious relationships were observed among soil and microbial C:N:P ratios. The above results indicate that soil microbes have the ability to maintain a given elemental composition despite variation in soil elemental composition following grassland degradation. From a long-term perspective, the nutrient-balance based soil quality promotion technology is able to effectively enhance grassland restoration and improve ecosystem service.

Key words: grassland degradation, nutrient limitation, stoichiometric homoeostasis, soil microorganisms, Qingzang Plateau