马尾松人工林不同营林措施下土壤微生物群落特征及其响应机制研究

发布时间：2018-04-03 03:11

本文选题：三峡库区　切入点：营林措施　出处：《中国林业科学研究院》2017年博士论文

【摘要】：森林地上部分和地下部分的群落结构具有强烈交互作用,土壤微生物在生物地球化学循环中起着重要的作用。微生物群落结构特征是表征森林生态系统物质循环、健康状况和生态服务功能的敏感指标。而不科学的森林经营会导致森林生产力的降低、养分流失、生物多样性降低。因此,本研究选取北亚热带典型马尾松人工林为研究对象,于2013年9月份于湖北省秭归县九岭头的典型马尾松人工林场进行典型采伐,设置3种营林措施和对照,每种营林方式设置6个10m×10m的固定样地,共24块固定样地,样地间距50-300 m。3种营林方式具体如下:除灌措施(SM)-对样地内灌丛地上部分全部清除;轻度采伐(LH)-对样地内胸径≥4 cm非马尾松(主要为光皮桦、漆树、杉木)和部分高大灌木(木姜子、火棘等)清除,按胸高断面积算强度为15%;重度采伐(HH)-对样地内胸径≥17.9cm马尾松清除,强度为70%。采伐树木移出样地,保留采伐的剩余物。本研究采用Illumina MiSeq高通量测序技术获得土壤微生物群落结构整体序列信息,通过数据库比对得到土壤微生物的群落组成、结构和功能特征,结合环境因子、功能家族特征、网络分子生态学模型和系统发育学特征,探究分析不同营林措施下土壤微生群落结构的稳定性和响应机制。主要研究结论如下:1)通过对土壤微生物生物量碳氮分析发现:土壤微生物生物量碳氮对营林干扰产生了显著响应,微生物生物量碳氮在营林干扰后显著降低;同时真菌较细菌具有较高微生物生物量碳氮比,说明真菌较细菌对营林干扰更加敏感。2)通过高通量测序获得微生物群落组成、结构、多样性特征表明:细菌和真菌的少数丰度较高的物种主导群落特征;在更细分类学水平上更能准确地反映微生物响应特征;营林措施导致了物种(OTU)总数降低,除灌和重度采伐的独有物种(OTU)百分比增高,而轻度采伐的独有物种(OTU)百分比降低;营林措施显著的改变了微生物群落结构(p0.05),同时轻度采伐的细菌真菌alpha多样性和丰度显著下降(p0.05)。3)通过PICRUSt预测细菌的功能家族特征,FUNGuild预测真菌营养功能特征,结果表明:营林干扰后细菌的功能家族呈现下降趋势,只有细胞通信和敏感系统显著下降(p0.05);真菌的功能团呈显著差异。结果同时说明细菌具有一定功能冗余,因此响应不显著,而真菌具有生长速率慢且宿主特异性,因此对营林干扰响应更灵敏。4)土壤微生物生物碳氮量、微生物群落结构与环境因子的多元逐步回归分析表明:环境因子是驱动土壤微生物的异质性主控因子;生物和非生物环境因子驱动微生物群落异质性,其中生物因子(细根生物量和凋落物产量)和非生物因子(含水量、PH、稳定和铵态氮)与微生物量碳显著相关,微生物量氮只和可溶性碳显著相关。综上表明环境对微生物群落特征起着决定作用,即符合生态位理论。5)通过微生物弱相互作用构建的分子生态学网络模型表明:营林措施改变了微生物的网络结构特征,微生物类群通过协作应对营林干扰导致的环境变化;细菌模块内部的重要关键物种(模块枢纽)显著下降,细菌模块之间的关键物种(连接者)也下降;同时,真菌网络模型模块(生态位)数量下降,且模块内部物种增多。综上可知:营林干扰显著降低了生态位的数量,相同生态位物种丰度增加,微生物群落内部竞争加剧,当受到外界环境干扰时,微生物群落结构不稳定;在微生物网络模型中环境因子起着关键作用,即符合生态位理论。6)通过微生物群落的系统发育特征进行分析表明:微生物系统发育学指数NRI、NTI0,生态位理论在微生物群落构建过程中起主导作用,环境是限制土壤微生物群落结构变化的主控因子;轻度采伐的生态位数量显著降低,这归因于轻度采伐导致微生物生存所需的养分和能量多样性降低;但是重度采伐的环境确定性作用显著降低,主要是因为重度采伐为其它物种的更新提供了大量生态位,中性理论的随机分布、扩散加强。综合上面主要研究结论发现:土壤微生物是营林干扰的敏感响应因子;营林措施不同程度改变了土壤微生物的群落特征;同时,营林干扰通过改变环境因子来改变土壤微生物的群落特征,环境因子是微生物群落结构变化的主控因子;营林措施导致土壤微生物网络模型发生了改变,土壤微生物的网络结构稳定性降低,微生物受到环境变化影响时,微生物群落结构就更加不稳定;营林措施导致土壤微生物的系统发育学特征发生改变,土壤微生物群落的生态位发生显著变化。环境因子是微生物群落的主控因子,即生态位理论;轻度采伐导致微生物的生态位降低,重度采伐为灌草更新提供生态位,即重度采伐有趋向于随机分布、扩散的中性理论趋势。
[Abstract]:Community structure and underground part of forest land has a strong interaction, soil microorganism plays an important role in the biogeochemical cycle. The microbial community structure is the material cycle of forest ecosystem characterization, sensitive indicators of health and ecological service function. Without scientific forest management will lead to reduced forest productivity the loss of nutrients, reducing biodiversity. Therefore, this study selected the typical tropical north of Masson pine plantation as the research object, the typical artificial Pinus massoniana forest farm in 2013 September in Hubei County of Zigui Province nine ridge head of typical logging, set up 3 kinds of silvicultural measures and control plots for each forest set 6 10m x 10m, a total of 24 fixed plots, 50-300 m.3 for afforestation plots as follows: in addition to irrigation interval (SM) - on the plots of shrub removal of light harvesting; (LH) - within the plot DBH over 4 cm non Masson (mainly for Betula luminifera, sumac, FIR) and some tall shrubs (Litsea, Pyracantha etc.) clear, according to the basal area of strength 15%; severe cutting (HH) - on the plots of Masson Pine DBH over 17.9cm removal the intensity of 70%. logging out plots, residue retention logging. This study used Illumina MiSeq high-throughput sequencing technology to obtain the overall sequence of soil microbial community structure information through the database on soil microbial community by composition, structure and function characteristics, combining with the environmental factors, the function of family characteristics, characteristics of development model and system of molecular network analysis on the stability of soil microbial ecology, community structure under different silvicultural measures and response mechanism. The main conclusions are as follows: 1) based on the soil microbial biomass carbon and nitrogen analysis: soil microbial biomass carbon and nitrogen Have a significant response to forest disturbance, microbial biomass carbon and nitrogen decreased significantly in the forest disturbance; and fungi than bacteria has higher microbial biomass carbon and nitrogen ratio, indicating fungi than bacteria are more sensitive to forest disturbance.2) by high-throughput sequencing to obtain microbial community composition, structure, shows that the diversity characteristics of bacteria and fungi a high abundance of species dominated community characteristics; in more subdivision level can accurately reflect the microbial response characteristics; silvicultural measures to reduce the total number of species (OTU), in addition to irrigation and harvesting of unique species of severe (OTU) and a higher percentage of light harvesting unique species (OTU) to reduce the percentage of silvicultural measures; significant changes in the microbial community structure (P0.05), and mild harvesting of bacterial and fungal diversity and abundance of alpha decreased significantly (P0.05).3) through the PICRUSt family of bacteria specific prediction function FUNGuild syndrome, predict fungal nutrition functional characteristics, the results show that the forest disturbance function family of bacteria showed a downward trend, only the cell communication and sensing system was significantly decreased (P0.05); functional groups of fungi showed significant differences. The results also show that bacteria have certain functional redundancy, so the response is not significant, but the growth rate is slow and the fungi have the host specificity, therefore more sensitive response to forest disturbance.4) microbial biomass carbon and nitrogen in soil, microbial community structure and environmental factors in the multivariate stepwise regression analysis showed that the environmental factor is the heterogeneity of the main control factors of driving soil microorganism; biological and non biological environmental factors driving microbial community heterogeneity, including biological factors (fine root the biomass and litter production) and non biological factors (water content, PH, and ammonium nitrogen) was significantly correlated with microbial biomass carbon, microbial biomass nitrogen and soluble carbon These results show that the environment significantly. It plays a decisive role on the microbial community characteristics, that is consistent with the theory of niche.5) through the weak interaction of microbial molecular ecology network model show that the silvicultural measures changed the network structure characteristics of microbial environment, microorganism change through cooperation to deal with interference in the forest; the key species of bacteria inside the module (hub module) decreased significantly, the key bacterial species between the modules (connected) also decreased; at the same time, fungal network model (niche) module and the module of a decline in the number of species increased. In summary: forest disturbance significantly reduced the number of niche, the same niche of species richness increased, microbial community internal competition when intensified, disturbance of environment, microbial community structure is not stable; in the network model of environmental microbial factor plays a key role in the match With the niche theory of.6) through the system of microbial community development characteristic analysis showed that: NRI index, the development of microbial system NTI0, niche theory plays a leading role in the process of building a microbial community environment is limited, soil microbial community structure change of main control factors; the number of mild ecological harvesting decreased significantly, this is due in the light harvesting cause microbial survival required nutrient and energy diversity decreased; but the environment uncertainty effects of severe harvesting decreased significantly, mainly because of severe cutting provides a lot of niche for other species update, random distribution, the neutral theory of diffusion strengthened. Conclusion above the main findings: soil microorganism is a sensitive response factor forest disturbance; different silvicultural measures changed soil microbial community characteristics; at the same time, by changing the environmental factors to forest disturbance Change of soil microbial community characteristics, environmental factors are the main control factors of the changes of microbial community structure; silvicultural measures due to the change of soil microbial network model, reduce network structure stability of soil microorganisms, microorganisms affected by climate change, microbial community structure is more stable; silvicultural measures lead to soil microbial system development characteristics change the niche of soil microbial community changed significantly. The environmental factors are main controlling factors of the microbial community, namely ecological niche theory; mild logging caused microbial reduction, severe harvesting for shrub and grass update provides a niche, which tend to have severe cutting random distribution theory of Neutral Trend diffusion.

【学位授予单位】：中国林业科学研究院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S714.3

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