Collage of Agriculture and Animal Husbandry, Qinghai University, Xining 810016, China; CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China.
Collage of Agriculture and Animal Husbandry, Qinghai University, Xining 810016, China.
Sci Total Environ. 2021 Dec 1;798:149362. doi: 10.1016/j.scitotenv.2021.149362. Epub 2021 Jul 31.
The alpine meadow ecosystem, as the main ecosystem of the Qinghai-Tibet Plateau, has been heavily degraded over the past several decades due to overgrazing and climate change. Although soil microorganisms play key roles in the stability and succession of grassland ecosystems, their response to grassland degradation has not been investigated at spatial scale. Here, we systematically analyzed the spatial turnover rates of soil prokaryotic and fungal communities in degraded and undegraded meadows through distance-decay relationship (DDR) and species area relationship (SAR), as well as the community assembly mechanisms behind them. Although the composition and structure of both fungal and prokaryotic communities showed significant changes between undegraded and degraded meadows, steeper spatial turnover rates were only observed in fungi (Degraded Alpine Meadow β = 0.0142, Undegraded Alpine Meadow β = 0.0077, P < 0.05). Mantel tests indicated that edaphic variables and vegetation factors showed significant correlations to the β diversity of fungal community only in degraded meadow, suggesting soil and vegetation heterogeneity both contributed to the variation of fungal community in that system. Correspondingly, a novel phylogenetic null model analysis demonstrated that environmental selection was enhanced in the fungal community assembly process during meadow degradation. Interestingly, dispersal limitation was also enhanced for the fungal community in the degraded meadow, and its relative contribution to other assembly process (i.e. selection and drift) showed a significant linear increase with spatial distance, suggesting that dispersal limitation played a greater role as distance increased. Our findings indicated the spatial scaling of the fungal community is altered during meadow degradation by both niche selection and dispersal limitation. This study provides a new perspective for the assessment of soil microbial responses to vegetation changes in alpine areas.
高山草甸生态系统作为青藏高原的主要生态系统，在过去几十年中由于过度放牧和气候变化而严重退化。尽管土壤微生物在草地生态系统的稳定性和演替中起着关键作用，但它们对草地退化的响应在空间尺度上尚未得到研究。在这里，我们通过距离衰减关系（DDR）和物种面积关系（SAR）系统地分析了退化和未退化草地中土壤原核生物和真菌群落的空间周转率，以及它们背后的群落组装机制。尽管真菌和原核生物群落的组成和结构在未退化和退化草地之间均发生了显著变化，但仅在真菌中观察到更陡峭的空间周转率（退化高山草甸β=0.0142，未退化高山草甸β=0.0077，P<0.05）。Mantel 检验表明，土壤变量和植被因素仅与退化草地中真菌群落的β多样性显著相关，这表明土壤和植被异质性都对该系统中真菌群落的变异有贡献。相应地，一种新颖的系统发育零模型分析表明，在草地退化过程中，环境选择增强了真菌群落的组装过程。有趣的是，在退化草地中，真菌群落的扩散限制也增强了，其对其他组装过程（即选择和漂移）的相对贡献随空间距离呈显著线性增加，这表明随着距离的增加，扩散限制发挥了更大的作用。我们的研究结果表明，在草地退化过程中，真菌群落的空间尺度受到生态位选择和扩散限制的共同作用。这项研究为评估高寒地区土壤微生物对植被变化的响应提供了新的视角。
