川西亚高山森林林冠对凋落叶分解过程中微生物群落结构的影响
发布时间：2018-08-01 08:10
【摘要】：森林凋落物分解普遍受到分解环境、分解者生物群落和凋落物基质质量的影响,而森林林冠可能从两方面控制着森林地表生态系统物质循环和能量流动过程。一方面,林冠决定着凋落物产量、凋落动态和凋落物基质质量；另一方面,林冠通过对光照和降水的再分配影响到森林地表的分解环境和分解者生物群落的结构和功能。因此,研究森林林冠对凋落物分解过程中微生物群落结构和功能的影响,有助于深刻理解森林生态系统物质循环和能量转换机制,为森林生态系统可持续经营与管理提供科学依据。但迄今为止,有关森林林冠对森林地表凋落物分解过程中微生物群落的影响研究尚未见报道。为此,本研究以地处长江上游和青藏高原东缘、生态战略地位突出、受季节性雪被影响显著、森林更新以林窗为主要方式的川西亚高山针叶林为研究对象,通过5年的凋落物分解实验,研究了林下、扩展林窗、林冠林窗、林窗中心北侧和林窗中心南侧上四川红杉(Larix mastersiana)、岷江冷杉(Abies faxoniana)、方枝柏(Sabina saltuaria)和红桦(Betula albo-sinensis)凋落物微生物数量、群落结构和类群在5个关键时期(初冻期、深冻期、融化期、生长季初期及生长季末期)的变化特征,从而为亚高山森林生态系统管理提供了一定的理论依据。主要结果如下：(1)林冠缺失形成的林窗改变了森林地表的水热动态。受季节性雪被的影响,冬季和生长季节的土壤水热动态对林窗形成的响应截然不同。在冬季,受林冠对降雪分配的影响,从林下到林窗中心,雪被厚度依次增加,地表温度依次升高,而在生长季节,由于太阳辐射程度不同,地表温度也同样依次升高。这意味着,受季节性雪被影响明显的区域,生长季节与非生长季节,森林林冠对地表分解环境存在显著不同的影响,从而影响地表凋落物分解者生物群落的结构和动态。(2)林冠显著影响了四种凋落叶分解过程中细菌的16S rDNA基因拷贝数和真菌18S rDNA基因拷贝数。随着凋落叶的分解,微生物群落的细菌和真菌丰度呈现下降趋势。生长季节与非生长季节相比,生长季节的凋落叶具有相对较高的微生物数量；在冬季的不同关键时期,深冻期的凋落叶具有最低的细菌和真菌数量,融化期的凋落叶则具有最高的细菌数量,而初冻期的凋落叶具有最高的真菌数量。生长季节与非生长季节相比,冬季的凋落叶具有最高的细菌/真菌数量比,在冬季的不同关键时期,深冻期的凋落叶具有最高的细菌/真菌数量比,初冻期的凋落叶具有最低的细菌/真菌数量比,这说明冬季凋落叶中的细菌对冬季的低温耐受性和适应性更强。从林冠下到林窗中心,冬季林冠下的凋落叶具有较低的微生物数量,而林冠下的凋落叶在生长季具有较高的微生物数量；初冻期的林冠下,凋落叶具有较低的细菌／真菌数量比,而深冻期和融化期的凋落叶具有较高的细菌／真菌数量比,说明微生物对林冠格局改变的响应敏感,但细菌和真菌对林冠格局改变的响应存在一定差异。(3)林冠显著影响了四种凋落叶分解过程中微生物群落结构和多样性指数。随着凋落叶的分解,微生物群落结构发生改变,多样性指数呈现波动的变化趋势。生长季节与非生长季节相比,生长季初期的凋落叶具有相对较高的Shannon-Wiener指数和较低的Simpson指数；冬季的凋落叶Shannon-Wiener指数性先降低后升高、Simpson指数先升高后降低。这说明冬季相对严酷的环境改变了微生物群落结构,提高了微生物群落的优势度,降低了微生物群落的多样性。从林冠下到林窗中心,除生长季初期外,林下和扩展林窗下的凋落叶微生物Shannon-Wiener指数更低而Simpson指数更高。这说明林冠格局的改变对冬季相对严酷的环境中微生物群落结构有明显影响,进而可能作用于凋落叶分解过程。(4)凋落叶分解过程中不同关键时期的微生物类群也存在明显差异。随着凋落叶的分解,微生物群落中的优势类群发生了改变。生长季和非生长季相比,冬季的细菌以Y变形菌纲(Gammaproteobacteria)和鞘脂杆菌纲(Sphingobacteria)为主,生长季的细菌类群更为丰富,优势类群不明显；冬季的真菌以座囊菌纲(Dothideomycetes)为主,生长季则以座囊菌纲和伞菌纲(Agaricomycetes)为主要类群。这说明冬季相对严酷的环境改变了微生物类群组成,耐受性和适应性更强的微生物类群成为冬季微生物群落的主要组成部分。而从林冠下到林窗中心,微生物主要类群没有明显差异。微生物类群和凋落叶质量损失和元素释放相关。细菌类群y变形菌纲与磷元素释放正相关,黄杆菌纲(Flavobacteria)和放线菌纲(Actinobacteria)与木质素降解相关；真菌类群伞菌纲与纤维素分解相关,锤舌菌纲(Leotiomycetes)与木质素及纤维素分解过程有关。这说明不同微生物类群对凋落叶分解起到不一样的作用,可能对理解亚高山森林生态系统物质循环和能量流动具有重要意义。综上所述,亚高山森林林冠格局的改变,改变了凋落叶分解的微环境,其对凋落叶分解过程中不同时期的微生物数量及群落结构具有一定影响,本研究结果对更深入理解该区域复杂多变的气候环境条件下(如季节性雪被斑块和冻融循环),凋落物分解这一生态过程提供了一定的基础数据。
[Abstract]:Forest litter decomposition is generally influenced by the decomposition environment, the decomposers' biological community and the mass of litter matrix, and the forest canopy may control the material circulation and the energy flow process in the forest surface ecosystem from two aspects. On the one hand, the canopy determines the litter yield, the litter dynamics and the litter matrix quality; on the other hand, forest canopy It affects the decomposition environment of forest surface and the structure and function of the decomposer biological community by redistribution of light and precipitation. Therefore, the study of the influence of forest canopy on the structure and function of microbial community during litter decomposition helps to understand the mechanism of material circulation and energy conversion in forest ecosystem, and for forest ecology. A scientific basis for the sustainable management and management of the system is provided. However, the effect of forest canopy on the microbial community in the decomposition process of forest ground litter has not been reported so far. The forest window is the main way to study the subalpine coniferous forest in Western Sichuan. Through 5 years of litter decomposition experiment, we studied the undergrowth, the expanded forest window, the canopy forest window, the Sichuan Redwood (Larix mastersiana), the Abies faxoniana, Fang Zhibai (Sabina saltuaria) and the birch (Betula albo-sinen) on the southern side of the center of the forest window center and the south side of the forest window center. SIS) changes in the number of litter microbes, community structure and groups in the 5 critical periods (early freezing, deep freezing, melting, early growing and end of growth), thus providing a certain theoretical basis for the management of subalpine forest ecosystems. The main results are as follows: (1) forest canopy gaps formed by forest canopy gaps change the forest surface. Water thermal dynamics. Influenced by seasonal snow cover, the response of Soil Hydrothermal dynamics to the formation of forest windows in winter and growing season is very different. In winter, the influence of the canopy to snow distribution, from under forest to the center of the forest window, is increasing in turn and the surface temperature in turn, but in the growing season, due to the different degree of solar radiation, the surface temperature is different. The degree also increased in turn. This means that the seasonal snow is affected obviously, the growing season and the non growing season, the forest canopy has significant different influence on the surface decomposition environment, thus affecting the structure and dynamics of the biological community of the litter decomposer. (2) the forest crown significantly affects the bacteria in the decomposition process of the four species of litter. The copy number of the 16S rDNA gene and the copy number of the fungal 18S rDNA gene. With the decomposition of the litter, the bacterial and fungal abundance of the microbial community showed a downward trend. The growing season compared with the non growing season, the leaf litter of the growing season had relatively high microbial number; in different critical periods in winter, the litterleaf with deep freezing period was in the growing season. With the lowest number of bacteria and fungi, the litterleaf of the melting period had the highest number of bacteria, while the litterleaf in the early freezing period had the highest number of fungi. The growing season compared with the non growing season, with the highest number of bacteria / fungi in winter, the highest in the different critical period in winter and the highest in the deep freezing period. The number ratio of bacteria / fungi and the lowest number of bacteria / fungi in the litters during the early freezing period showed that the bacteria in the litterleaf in winter were more tolerant and more adaptable to winter. From canopy to window center, the number of microbes under the canopy of winter forest was lower, and the litter under canopy was higher in the growing season. The number of microbes; under the first freezing period of the canopy, the litter had a lower number of bacteria / fungi, while the number of bacteria / fungi in the deep freeze and melted leaves had a higher number of bacteria / fungi, indicating that microbes were sensitive to the response of the canopy pattern change, but the response of the bacteria and fungi to the canopy pattern change was different. (3) Lin Guanxian The microbial community structure and diversity index were affected by the decomposition of four species of litter. With the decomposition of the litter, the microbial community structure changed and the diversity index fluctuated. Compared with the non growing season, the leaves of the early growing season were relatively high Shannon-Wiener index and lower. In winter, the index of Simpson index, Shannon-Wiener exponent decreased first and then increased, and the Simpson index increased first and then decreased. This indicated that the relatively harsh environment in winter changed the microbial community structure, improved the dominance of microbial community and reduced the diversity of microbial community. From canopy to window center, except for the early growing season. In addition, the Shannon-Wiener index was lower and the Simpson index was higher under the under and under the forest. This indicates that the canopy pattern changes have a significant influence on the microbial community structure in the relatively harsh environment in winter, and may act on the decomposition process of the litter. (4) the microorganism at different critical stages during the decomposition process of the litter. The dominant groups in the microbial community changed with the decomposition of litter. Compared with the growing season of Ji Hefei, the bacteria in winter were mainly Y Proteus (Gammaproteobacteria) and sphingobacteria (Sphingobacteria), and the bacterial groups were more abundant in the growing season, and the dominant groups were not obvious. The main fungi are the Dothideomycetes, and the main groups are the cystomycetes and the Agaricomycetes in the growing season. This indicates that the relatively harsh environment in winter has changed the composition of the microorganism group. The tolerant and more adaptable microbial groups are the main components of the microbiological community in winter. There were no significant differences in the main groups of microbes. Microbial groups were related to the loss of litter mass and the release of elements. Bacterial group y Proteus was positively related to phosphorus release, and Flavobacteria and actinomycetes (Actinobacteria) were related to lignin degradation; fungal groups were related to cellulose decomposition and hammered. Leotiomycetes is related to lignin and cellulose decomposition process, which indicates that different microbial groups play a different role in litter decomposition and may be of great significance to understanding the material circulation and energy flow of subalpine forest ecosystems. The microenvironment of the solution has a certain influence on the number of microbes and the community structure of the litter decomposition in the process of litter decomposition. The results of this study provide some basic data for understanding the ecological process of litter decomposition, such as seasonal snow patches and freezing and thawing cycles in the complex and changeable climatic and environmental conditions of the region.
【学位授予单位】：四川农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S714
[Abstract]:Forest litter decomposition is generally influenced by the decomposition environment, the decomposers' biological community and the mass of litter matrix, and the forest canopy may control the material circulation and the energy flow process in the forest surface ecosystem from two aspects. On the one hand, the canopy determines the litter yield, the litter dynamics and the litter matrix quality; on the other hand, forest canopy It affects the decomposition environment of forest surface and the structure and function of the decomposer biological community by redistribution of light and precipitation. Therefore, the study of the influence of forest canopy on the structure and function of microbial community during litter decomposition helps to understand the mechanism of material circulation and energy conversion in forest ecosystem, and for forest ecology. A scientific basis for the sustainable management and management of the system is provided. However, the effect of forest canopy on the microbial community in the decomposition process of forest ground litter has not been reported so far. The forest window is the main way to study the subalpine coniferous forest in Western Sichuan. Through 5 years of litter decomposition experiment, we studied the undergrowth, the expanded forest window, the canopy forest window, the Sichuan Redwood (Larix mastersiana), the Abies faxoniana, Fang Zhibai (Sabina saltuaria) and the birch (Betula albo-sinen) on the southern side of the center of the forest window center and the south side of the forest window center. SIS) changes in the number of litter microbes, community structure and groups in the 5 critical periods (early freezing, deep freezing, melting, early growing and end of growth), thus providing a certain theoretical basis for the management of subalpine forest ecosystems. The main results are as follows: (1) forest canopy gaps formed by forest canopy gaps change the forest surface. Water thermal dynamics. Influenced by seasonal snow cover, the response of Soil Hydrothermal dynamics to the formation of forest windows in winter and growing season is very different. In winter, the influence of the canopy to snow distribution, from under forest to the center of the forest window, is increasing in turn and the surface temperature in turn, but in the growing season, due to the different degree of solar radiation, the surface temperature is different. The degree also increased in turn. This means that the seasonal snow is affected obviously, the growing season and the non growing season, the forest canopy has significant different influence on the surface decomposition environment, thus affecting the structure and dynamics of the biological community of the litter decomposer. (2) the forest crown significantly affects the bacteria in the decomposition process of the four species of litter. The copy number of the 16S rDNA gene and the copy number of the fungal 18S rDNA gene. With the decomposition of the litter, the bacterial and fungal abundance of the microbial community showed a downward trend. The growing season compared with the non growing season, the leaf litter of the growing season had relatively high microbial number; in different critical periods in winter, the litterleaf with deep freezing period was in the growing season. With the lowest number of bacteria and fungi, the litterleaf of the melting period had the highest number of bacteria, while the litterleaf in the early freezing period had the highest number of fungi. The growing season compared with the non growing season, with the highest number of bacteria / fungi in winter, the highest in the different critical period in winter and the highest in the deep freezing period. The number ratio of bacteria / fungi and the lowest number of bacteria / fungi in the litters during the early freezing period showed that the bacteria in the litterleaf in winter were more tolerant and more adaptable to winter. From canopy to window center, the number of microbes under the canopy of winter forest was lower, and the litter under canopy was higher in the growing season. The number of microbes; under the first freezing period of the canopy, the litter had a lower number of bacteria / fungi, while the number of bacteria / fungi in the deep freeze and melted leaves had a higher number of bacteria / fungi, indicating that microbes were sensitive to the response of the canopy pattern change, but the response of the bacteria and fungi to the canopy pattern change was different. (3) Lin Guanxian The microbial community structure and diversity index were affected by the decomposition of four species of litter. With the decomposition of the litter, the microbial community structure changed and the diversity index fluctuated. Compared with the non growing season, the leaves of the early growing season were relatively high Shannon-Wiener index and lower. In winter, the index of Simpson index, Shannon-Wiener exponent decreased first and then increased, and the Simpson index increased first and then decreased. This indicated that the relatively harsh environment in winter changed the microbial community structure, improved the dominance of microbial community and reduced the diversity of microbial community. From canopy to window center, except for the early growing season. In addition, the Shannon-Wiener index was lower and the Simpson index was higher under the under and under the forest. This indicates that the canopy pattern changes have a significant influence on the microbial community structure in the relatively harsh environment in winter, and may act on the decomposition process of the litter. (4) the microorganism at different critical stages during the decomposition process of the litter. The dominant groups in the microbial community changed with the decomposition of litter. Compared with the growing season of Ji Hefei, the bacteria in winter were mainly Y Proteus (Gammaproteobacteria) and sphingobacteria (Sphingobacteria), and the bacterial groups were more abundant in the growing season, and the dominant groups were not obvious. The main fungi are the Dothideomycetes, and the main groups are the cystomycetes and the Agaricomycetes in the growing season. This indicates that the relatively harsh environment in winter has changed the composition of the microorganism group. The tolerant and more adaptable microbial groups are the main components of the microbiological community in winter. There were no significant differences in the main groups of microbes. Microbial groups were related to the loss of litter mass and the release of elements. Bacterial group y Proteus was positively related to phosphorus release, and Flavobacteria and actinomycetes (Actinobacteria) were related to lignin degradation; fungal groups were related to cellulose decomposition and hammered. Leotiomycetes is related to lignin and cellulose decomposition process, which indicates that different microbial groups play a different role in litter decomposition and may be of great significance to understanding the material circulation and energy flow of subalpine forest ecosystems. The microenvironment of the solution has a certain influence on the number of microbes and the community structure of the litter decomposition in the process of litter decomposition. The results of this study provide some basic data for understanding the ecological process of litter decomposition, such as seasonal snow patches and freezing and thawing cycles in the complex and changeable climatic and environmental conditions of the region.
【学位授予单位】：四川农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S714
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