青藏高原三江源地区藏嵩草沼泽化草地退化与植被特征的变化

Degradation and vegetation characteristics of Kobresia tibetica swamp meadow in the Sanjiangyuan area

摘要:

【目的】 探究青藏高原三江源藏嵩草沼泽化草地退化与植被特征的变化对保障三江源地区生态安全的重要意义。【方法】 对青海省果洛州玛沁县、玉树州曲麻莱县样地进行调查与数据收集，研究三江源地区藏嵩草沼泽化草地退化与植被特征的变化。【结果】 1）三江源地区藏嵩草沼泽化草地植物有15科37属54种植物，其中地面芽植物较多，共41种；2）藏嵩草（Kobresia tibetica）在4个不同退化草地阶段均为优势种，群落调查指标（高度、盖度、地上生物量）受草地退化程度的影响而产生了明显的变化，其平均高度由26.2 cm下降到11.9 cm，盖度由76%下降到43%，地上生物量由1 061.6 g/m2下降到196.8 g/m2；3）藏嵩草优势种随着草地退化程度的加剧，所占的比例越来越低；莎草科和禾本科生物量在重度退化草地占比最少，其他科植物在重度退化草地中生物量占比较大；4）物种丰富度指数和多样性指数表现为中度退化草地与轻度退化草地物种最丰富；均匀度指数表现为，重度退化＞中度退化＞轻度退化＞未退化；优势度指数在4种不同退化阶段的草地中无明显差别。【结论】 藏嵩草在4个不同退化阶段草地中始终保持着优势种的地位，但随着草地退化程度的加剧，其竞争能力和所占比重呈现下降的趋势，藏嵩草的平均高度、盖度、地上生物量也明显下降。草地的退化表现在群落中的优势物种的衰退。

Abstract:

【Objective】 The Kobresia tibetica swampy meadow in the Sanjiangyuan region has undergone significant changes due to global climate change and human activities，resulting in a series of ecological and environmental issues. Exploring the degradation of K. tibetica meadows and changes in the vegetation characteristics is crucial for ensuring ecological security of the Sanjiangyuan region.【Method】 infield surveys and data collection were conducted in Maqin County，Guoluo Prefecture，and Qumalai County，Yushu Prefecture，Qinghai Province，to investigate degradation and vegetation characteristics of K. tibetica swampy meadows.【Result】 （1） K. tibetica was the dominant species across four different stages of degradation，but its quantitative traits （height，cover，and aboveground plant volume） significantly declined with increasing degradation. Average height decreased from 26. 2 cm to 11. 9 cm，cover dropped from 76% to 43%，and aboveground plant volume decreased from 1 061. 6 g/m2 to 196. 8 g/m2.（2） As degradation intensified，the proportion of K. tibetica grass within the plant community decreased. Plant volume contribution from Salicaceae and Gramineae were minimal under sever degradation，while other plant families contributed for a higher proportion.（3） The species richness index and diversity index showed that the most abundant species were in the middle degradation and light degradation； the evenness index ranked as heavyily＞moderately＞lightly＞non degraded. The dominance index showed no significant differences across the four different degradation stages. 【Conclusion】 Although K. tibetica retained its status as the dominant species across all degradation stages its competitive ability and the proportional share declined with increasing degradation. The degradation of K. tibetica meadows is characterized by reductions in average plant height，cover，and aboveground biomass，reflecting a broader decline in the community’s dominant species.