青藏高原退化高寒草甸植被群落与土壤养分变化特征

Characterization of vegetation communities and soil nutrient changes in degraded alpine meadows on the Qinghai‐Tibetan Plateau

摘要:

【目的】 以三江源区中度退化高寒草甸为研究对象，分析退化高寒草甸的植物群落特征和土壤养分的动态变化及其差异性，揭示影响植物群落特征的驱动因子，为青藏高原退化高寒草甸的科学管理及资源的合理利用提供基础数据。【方法】 于2020-2022年的7、8和9月在青海省玉树州退化高寒草甸测定植物的高度、盖度、Patrick指数、Pielous指数、Shannon-Wiener指数和总生物量以及土壤的全氮、铵态氮、硝态氮、速效氮、有机碳、全磷和全钾含量等指标。对植物和土壤的指标进行单因素分析，分析植物群落特征与土壤养分之间的相关性，采用Canoco 5.0软件对植被特征和土壤理化性质进行冗余分析。【结果】 高寒草甸植物Patrick指数、Pielous指数和总生物量没有统一的月际动态变化，但月际间差异显著；植物功能群生物量表现出增加的月际动态变化，其变化趋势基本一致（除2022年杂类草）；土壤全氮、铵态氮、硝态氮、速效氮和有机碳含量整体上反映出相似的变化规律，均在8月达到峰值；土壤全磷和全钾含量与植物总生物量、高度和Pielous指数呈极显著正相关，与Patrick指数呈极显著负相关。植物盖度与土壤全氮和有机碳呈极显著正相关；Shannon-Wiener指数和总生物量与土壤硝态氮含量呈显著正相关。【结论】 退化草甸植物群落特征和功能群生物量没有统一的变化规律，整体表现为8月有最大值。土壤养分与植物群落间存在显著正相关，对植被特征影响最大的土壤因子是土壤有机碳和全氮含量。

Abstract:

【Objective】 Taking the moderately degraded alpine meadows in Sanjiangyuan area as the research ob ject，we analyzed the dynamic changes of plant community characteristics，soil nutrients，and their variability in de graded alpine meadows. This investigation aims to explore the relationship between the two，and to identify the key factors affecting plant community characteristics. The findings provide the basic data for the scientific management and sustainable utilization of degraded alpine meadows in Qinghai‐Tibetan Plateau.【Method】 Field measurements were conducted in Yushu Prefecture，Qinghai Province，in the months of July，August，and September from 2020 to 2022. Plant height，cover，Patrick index，Pielou’s evenness index，Shannon‐Wiener index，and total biomass of plants were recorded. Soil samples were analyzed for total nitrogen，ammonium nitrogen，nitrate nitrogen，quick nitrogen，or ganic carbon，total phosphorus，and total potassium. The one-way analysis of plant and soil indicators was used to analyze the correlation between plant community characteristics and soil nutrients. The RDA analysis of vegetation characteristics and soil physicochemical properties was performed using Canoco 5. 0 software to evaluate the relation ship between vegetation traits and soil physiochemical properties.【Result】 The Patrick index，Pielou’s index，and to tal biomass displayed significant monthly variation but no consistent seasonal trend. In contrast，the biomass of plant functional groups generally increased over time，with consistent patterns across years （except for miscellaneous grasses in 2022）. Soil total nitrogen，ammonium nitrogen，nitrate nitrogen，quick nitrogen and organic carbon peaked in August. Soil total phosphorus and total potassium showed strong positive correlations with total plant biomass， height，and Pielou’s index，and significant negative correlations with the Patrick index. Plant cover was positively cor related with soil total nitrogen and organic carbon，while the Shannon‐Wiener index and total biomass were positively correlated with soil nitrate nitrogen.【Conclusion】 Plant community characteristics and functional group biomass in de graded alpine meadows exhibited variable seasonal patterns，with most indicators peaking in August. There was a sig nificant positive correlation between soil nutrients and plant communities，with soil organic carbon and total nitrogen being the most influential factor.