典型喀斯特峰丛洼地不同植被恢复对土壤养分含量和微生物多样性的影响

以桂西北典型喀斯特峰丛洼地植被恢复过程中草丛、灌丛、次生林、原生林4个植被恢复阶段为研究对象,通过测定优势种的根际与非根际的土壤p H、养分含量及微生物多样性,探讨不同恢复阶段根际土壤养分的富集效应及土壤微生物多样性的变化特征。研究结果表明:(1)4个恢复阶段的根际与非根际土壤养分均呈现显著差异;土壤有效态养分较全量养分对植物根际微小的变化响应更为灵敏;大多数养分表现出明显的富集效应,AP和AK在原生林的富集率明显高于其他恢复阶段;(2)4个恢复阶段细菌Shannon-Wiener指数(H)、丰富度指数(S)均高于真菌,根际土壤细菌与真菌Shannon-Wiener指数(H)、丰富度指数(S)与Pielou均匀度(EH)都高于非根际土壤;(3)4个恢复阶段土壤TN分别与p H、SOC、AN呈极显著正相关(P0.01),磷素、钾素与土壤微生物多样性呈显著相关(P0.05)。可研究结果为西南喀斯特脆弱区土壤生态功能恢复与植被恢复重建提供科学依据。

Dynamics of soil nutrient content and microbial diversity following vegetation restoration in a typical karst peak-cluster depression landscape

Understanding the dynamics of soil nutrients and microbial diversity following vegetation restoration is fundamentally important for promoting the recovery of soil ecological function and revegetation in degraded karst ecosystems of Southwest China. Here, the study selected four vegetation types which represent four stages of vegetation restoration in a typical karst peak-cluster depression in Mulun natural reservein northwest Guangxi, i.e., grassland, shrubland, secondary forest and primary forest, and investigated soil pH, nutrient content, and the diversity of microorganisms in non-rhizosphere and rhizosphere soil around the dominant species. Significant differences in soil nutrients were observed between rhizosphere and non-rhizosphere at the four vegetation restoration stages. Soil available nutrients respond more sensitively to subtle changes in the rhizosphere than total nutrients. There was an enrichment effect for most soil nutrients. In addition, a dramatically higher accumulation rate was observed for available phosphorous (AP) and available potassium (AK) at primary forest, as compared to other three stages. Both the Shannon-Wiener index (H) and the richness index (S) for bacteria were higher than those for fungi, and the Shannon-Wiener index (H), the richness index (S), and the Pielou evenness index (EH) of bacteria and fungi in the rhizosphere were also higher than those in the non-rhizosphere. Soil total nitrogen (TN) was strongly correlated with pH value, soil organic carbon (SOC), and available nitrogen (AN) (P < 0.01), and phosphorous and potassium correlated positively with the diversity of soil microorganisms.