喀斯特峰丛洼地植物与土壤微生物时空互作机制

Plant and soil microorganism are key elements to controlling rocky desertification in depressions between karst hills, and their interactions have been hot issues in restoration ecology. However, it is still debated that whether there are "combined succession" effects between them and spatial distribution of vegetation and soil microorganism. The project plans to establish 84 quadrats based on the grid of 1 × 1 in longitude-latitude, four dynamic monitoring plots according to CTFS standard and 80 supplementary quadrats at four successional stages (i.e., grass, shrub, secondary forest, and primary forest) in depressions between karst hills. Based on the investigation and analysis of vegetation, soil microorganism, litter, soil physicochemical properties, topography, and human activity, the project intends to explore the dynamic relationships between vegetation and soil microorganism and to reveal spatial heterogeneity of vegetation and soil microorganism and degree of association between them at landscape and regional scales, and then to draw spatial distribution maps of them; to clarify the effects of typical plants on rhizospheric microorganism and to find out the main factors influencing spatial distribution pattern of vegetation and soil microorganism by principal component analysis (PCA); to demonstrate the relationships between plant/soil microorganism and groups of soil, litter, topography, and human activities, and to quantify the contribution ratios of each group to plant/soil microorganism by Canonical correlation analysis (CCA) and variation patitioning, respectively; to represent vegetation distribution along ecological environment gradients by detrended canonical correspondence analysis (DCCA), and to test the hypothesis proposed by us that plants evolve cooperatively with soil main nutrients, mineral nutrients, and soil microorganism. Finally, intrinsic mechanism of soil microorganism facilitating vegetation recovery will be revealed. The research would enrich biogeographic theory and provide a scientific basis for ecological restruction in karst areas.

植物和土壤微生物是喀斯特峰丛洼地石漠化治理的关键，二者的相互作用也是目前恢复生态学研究热点，但土壤微生物与植物是否存在"共演替"效应和相应空间分布格局的争议很大。本项目在西南喀斯特峰丛洼地按0.1 经纬网格设置84块石山林样方，并选择草丛、灌丛、次生林和原生林4个演替阶段及20个典型群落，建立4块动态监测样地和80块辅助样方。分析喀斯特峰丛洼地典型植物对根际微生物的影响，探讨植物和土壤微生物随群落演替的动态变化，揭示其景观和区域尺度的空间异质性和关联度，绘制空间分布图；进一步用PCA、CCA、DCCA等方法阐明植物和土壤微生物及与土壤、凋落物、地形、干扰各集团因子之间的耦合关系和相互贡献率，找出主导因子，表征其沿生态环境梯度的分布，验证我们提出的"植物和土壤主要养分、矿质养分、微生物协同演变"假设，揭示土壤微生物促进植被恢复的内在机制，为丰富生物地理学理论和喀斯特地区生态重建提供科学依据。

植物和土壤微生物是喀斯特峰丛洼地石漠化治理的关键，二者的相互作用一直是生态学研究的热点，但两者是否存在“共演替”效应的争议很大。本项目基于群落样方和动态监测样地的系统调查与分析，获得结论如下：.1）不同植被演替阶段、同一植被演替阶段不同植物群落、同一植物群落根际与非根际土壤细菌与真菌群落结构均不同；植物群落对土壤细菌群落多样性影响不同，但对非根际土壤真菌群落多样性的影响显著；土壤TN和TK是分别是影响细菌shannon-wiener指数、丰富度和均匀度的主要土壤因子。.2）沿植物群落的顺向演替发展，重要值＞10.00的科、属、种及物种多样性最大值出现在次生林，群落结构最佳值出现在原生林；各生态系统影响因子不同，土壤微生物处于主导地位，其次为灌丛；植物多样性与土壤氮素、Al2O3、Fe2O3、MBC、真菌和细菌关系密切。.3）随着森林类型的退化，土壤微生物MBC、MBN急剧减少，土壤微生物MBP有小幅下降；土壤微生物3大类群总数基本保持不变，真菌所占比例很小，放线菌比例提高，细菌比例下降；土壤微生物空间分布明显，不同森林类型呈现不同空间格局；不同森林类型土壤微生物的影响因素不同，土壤C、N是影响土壤微生物的最主要因素。.4）喀斯特森林样地内胸径≥1 cm的木本植物独立个体共10，9728株，隶属于227种59科144属，以热带区系成分为主；所有木本植物径级分布和物种相对频度均呈倒“J”型分布，主要优势树种均呈明显聚集型分布，且形成互补；物种多样性表现出较强的区域性分布特征，具有尺度依赖性。.5）喀斯特森林土壤细菌和真菌门、纲主要类群相对丰度均存在空间依赖性，变程除变形菌门、厚壁菌门、α-变形菌纲和接合菌纲外均在取样范围内，空间分布复杂，呈现不同甚至相反的空间格局。.发表论文34篇，其中SCI/EI 5篇；编写专著1部；申请专利3项，授权1项；培养研究生16名。.建议：加强较大尺度上土壤微生物多样性和群落组成的研究，综合考虑空间、土壤、植物、地形等环境因素，揭示产生和维持微生物多样性的内在机制。