菌根微生态域构建对大青山困难立地植被恢复影响的研究

The relationships between community structure and function of soil microorganism, and vegetation restoration of degraded ecosystem are the research focus in the field ofecological restoration. Vegetation restoration in difficult sites of Daqingshan Mountains is regarded as pointcut in this project. We attempt to reconstruct the vanished local mycorrhizal fungi by methods of monoculture, planted together of each two species, and mixed plantation of different native shrub species with different orders. The objectives of this project are to construct the mycorrhizal niche, which ensure the vegetation restore in difficult sites of Daqingshan Mountains. Four survived native shrub species will be selected, including Clematis fruticosa, Pruns mongolica, Spiraea pubescens, and Ostriopsis davidiana, in the arid sunny slopes of Daqingshan Mountains. And mycorrhizal seedlings will be cultivated by inoculating four local dominant mycorrhizal fungi in sterile substrates under greenhouse conditions. After investigating the characteristics of soil and mycorrhizal fungal diversity in the field samples, the experiment will be carried out under natural conditions in the field sites. The mycorrhizal and non-mycorrrhizal seedlings of C. fruticosa, P. mongolica, and S. pubescens will be planted in individual holes, separated between them in different plant regeneration pattern subareas, respectively. Soil physicochemical properties, seedling survival rate, mycorrhizal colonization rate, mycorrhizal morphology, spore density and mycorrhizal fungal diversity will be investigated yearly. Finally, mycorrhizal and non-mycorrhizal seedlings of O. davidiana will be planted in different regeneration sites, respectively. By the combined soil and mycorrhizal fungal results, the best planting pattern will be selected. The results of this project will provide the important practical significance for accelerating the vegetation restoration in difficult sites of western China.

土壤微生物群落结构及其功能与退化生态系统植被恢复关系的研究是当今生态恢复研究的热点。项目拟以大青山困难立地植被恢复为切入点，试图采用不同乡土植物单栽，两两共栽，不同先后顺序混栽等方式，重建土壤生态系统中已流失的乡土菌根菌，构建主栽树种赖以生存的菌根微生态域，最终实现大青山困难立地植被恢复目标。研究拟对大青山干旱阳坡4种残存乡土植物（灌木铁线莲、蒙古扁桃、土庄绣线菊、虎榛子）在温室内采用混合接种4种乡土优势菌根菌的方式在盆栽灭菌基质内育苗。在栽植前调查样地土壤理化指标、菌根菌多样性的基础上，将前3种灌木菌根与非菌根苗在设定的裸地上分区不同方式栽植，形成不同植物复栽组合，每年调查土壤理化性质、苗木成活率、菌根侵染率、菌根形态、及菌根菌孢子密度、多样性。最后在不同复栽样地上分别栽虎榛子菌根苗和非菌根苗，并检测其上述指标，分析选出最佳复栽模式。研究成果将对加速西部困难立地植被恢复进程具有重要意义。

土壤微生物群落结构及其功能与退化生态系统植被恢复关系的研究是当今生态恢复研究的热点。项目以大青山困难立地植被恢复为切入点，试图采用不同乡土植物单栽，两两共栽，不同先后顺序混栽等方式，重建土壤生态系统中已流失的乡土菌根菌，构建主栽树种赖以生存的菌根微生态域，最终实现大青山困难立地植被恢复目标。项目在大青山干旱阳坡选取了灌木铁线莲（Clematis fruticosa）、蒙古扁桃（Pruns mongolica）、土庄绣线菊（Spiraea pubescens）3种乡土灌木。选择2种优势丛枝菌根真菌（摩西斗管囊霉（Funneliformis mosseae）、根内根孢囊霉（Rhizophagus intraradices））为接种菌剂，开展了菌根苗与非菌根苗培育。在野外样地上进行不同模式乡土植被的复栽研究，将3种植物菌根化与非菌根化苗木分别在所设置的样地内进行人工栽植（单栽、不同顺序的共栽），测定不同栽植模式下苗木的成活率、生物量、孢子密度、菌根真菌多样性、土壤理化指标等，通过生物信息学分析菌根真菌群落演替规律。主要研究结果：大青山干旱阳坡3种乡土灌木不同栽植模式中先栽灌木铁线莲后栽土庄绣线菊根际土壤丛枝菌根真菌多样性达到最大，同时接菌处理对丛枝菌根真菌多样性的增加有促进作用。混栽模式较单栽模式根际土壤与碳、氮、磷相关的酶活性增加，有利于土壤养分活化。本研究揭示了不同灌木接种AMF后，根际土壤中酶化学计量特征和微生物养分限制的响应规律。酶化学计量特征受土壤中碳和氮有效性的影响，且与接种AMF后的养分化学计量特征密切相关。接种AMF增加了宿主植物根际土壤中微生物的碳限制。接种AMF后，灌木根际土壤微生物磷限制的主要影响因素是土壤磷有效性。本研究从根际微生态环境调控角度阐明了混栽模式较单栽模式增加干旱半干旱区生态系统稳定性的机制，且接种丛枝菌根真菌可调节宿主植物根际土壤中微生物的养分限制。灌木树种生态位的相似性影响树种共栽模式的根际微生态环境的构建。以上研究结果为菌根真菌在干旱区植被恢复中调控土壤微环境变化提供了理论依据。