川西亞高山森林林冠對凋落葉分解過程中微生物群落結(jié)構(gòu)的影響
發(fā)布時間：2018-08-01 08:10
【摘要】：森林凋落物分解普遍受到分解環(huán)境、分解者生物群落和凋落物基質(zhì)質(zhì)量的影響,而森林林冠可能從兩方面控制著森林地表生態(tài)系統(tǒng)物質(zhì)循環(huán)和能量流動過程。一方面,林冠決定著凋落物產(chǎn)量、凋落動態(tài)和凋落物基質(zhì)質(zhì)量；另一方面,林冠通過對光照和降水的再分配影響到森林地表的分解環(huán)境和分解者生物群落的結(jié)構(gòu)和功能。因此,研究森林林冠對凋落物分解過程中微生物群落結(jié)構(gòu)和功能的影響,有助于深刻理解森林生態(tài)系統(tǒng)物質(zhì)循環(huán)和能量轉(zhuǎn)換機(jī)制,為森林生態(tài)系統(tǒng)可持續(xù)經(jīng)營與管理提供科學(xué)依據(jù)。但迄今為止,有關(guān)森林林冠對森林地表凋落物分解過程中微生物群落的影響研究尚未見報道。為此,本研究以地處長江上游和青藏高原東緣、生態(tài)戰(zhàn)略地位突出、受季節(jié)性雪被影響顯著、森林更新以林窗為主要方式的川西亞高山針葉林為研究對象,通過5年的凋落物分解實(shí)驗(yàn),研究了林下、擴(kuò)展林窗、林冠林窗、林窗中心北側(cè)和林窗中心南側(cè)上四川紅杉(Larix mastersiana)、岷江冷杉(Abies faxoniana)、方枝柏(Sabina saltuaria)和紅樺(Betula albo-sinensis)凋落物微生物數(shù)量、群落結(jié)構(gòu)和類群在5個關(guān)鍵時期(初凍期、深凍期、融化期、生長季初期及生長季末期)的變化特征,從而為亞高山森林生態(tài)系統(tǒng)管理提供了一定的理論依據(jù)。主要結(jié)果如下：(1)林冠缺失形成的林窗改變了森林地表的水熱動態(tài)。受季節(jié)性雪被的影響,冬季和生長季節(jié)的土壤水熱動態(tài)對林窗形成的響應(yīng)截然不同。在冬季,受林冠對降雪分配的影響,從林下到林窗中心,雪被厚度依次增加,地表溫度依次升高,而在生長季節(jié),由于太陽輻射程度不同,地表溫度也同樣依次升高。這意味著,受季節(jié)性雪被影響明顯的區(qū)域,生長季節(jié)與非生長季節(jié),森林林冠對地表分解環(huán)境存在顯著不同的影響,從而影響地表凋落物分解者生物群落的結(jié)構(gòu)和動態(tài)。(2)林冠顯著影響了四種凋落葉分解過程中細(xì)菌的16S rDNA基因拷貝數(shù)和真菌18S rDNA基因拷貝數(shù)。隨著凋落葉的分解,微生物群落的細(xì)菌和真菌豐度呈現(xiàn)下降趨勢。生長季節(jié)與非生長季節(jié)相比,生長季節(jié)的凋落葉具有相對較高的微生物數(shù)量；在冬季的不同關(guān)鍵時期,深凍期的凋落葉具有最低的細(xì)菌和真菌數(shù)量,融化期的凋落葉則具有最高的細(xì)菌數(shù)量,而初凍期的凋落葉具有最高的真菌數(shù)量。生長季節(jié)與非生長季節(jié)相比,冬季的凋落葉具有最高的細(xì)菌/真菌數(shù)量比,在冬季的不同關(guān)鍵時期,深凍期的凋落葉具有最高的細(xì)菌/真菌數(shù)量比,初凍期的凋落葉具有最低的細(xì)菌/真菌數(shù)量比,這說明冬季凋落葉中的細(xì)菌對冬季的低溫耐受性和適應(yīng)性更強(qiáng)。從林冠下到林窗中心,冬季林冠下的凋落葉具有較低的微生物數(shù)量,而林冠下的凋落葉在生長季具有較高的微生物數(shù)量；初凍期的林冠下,凋落葉具有較低的細(xì)菌／真菌數(shù)量比,而深凍期和融化期的凋落葉具有較高的細(xì)菌／真菌數(shù)量比,說明微生物對林冠格局改變的響應(yīng)敏感,但細(xì)菌和真菌對林冠格局改變的響應(yīng)存在一定差異。(3)林冠顯著影響了四種凋落葉分解過程中微生物群落結(jié)構(gòu)和多樣性指數(shù)。隨著凋落葉的分解,微生物群落結(jié)構(gòu)發(fā)生改變,多樣性指數(shù)呈現(xiàn)波動的變化趨勢。生長季節(jié)與非生長季節(jié)相比,生長季初期的凋落葉具有相對較高的Shannon-Wiener指數(shù)和較低的Simpson指數(shù)；冬季的凋落葉Shannon-Wiener指數(shù)性先降低后升高、Simpson指數(shù)先升高后降低。這說明冬季相對嚴(yán)酷的環(huán)境改變了微生物群落結(jié)構(gòu),提高了微生物群落的優(yōu)勢度,降低了微生物群落的多樣性。從林冠下到林窗中心,除生長季初期外,林下和擴(kuò)展林窗下的凋落葉微生物Shannon-Wiener指數(shù)更低而Simpson指數(shù)更高。這說明林冠格局的改變對冬季相對嚴(yán)酷的環(huán)境中微生物群落結(jié)構(gòu)有明顯影響,進(jìn)而可能作用于凋落葉分解過程。(4)凋落葉分解過程中不同關(guān)鍵時期的微生物類群也存在明顯差異。隨著凋落葉的分解,微生物群落中的優(yōu)勢類群發(fā)生了改變。生長季和非生長季相比,冬季的細(xì)菌以Y變形菌綱(Gammaproteobacteria)和鞘脂桿菌綱(Sphingobacteria)為主,生長季的細(xì)菌類群更為豐富,優(yōu)勢類群不明顯；冬季的真菌以座囊菌綱(Dothideomycetes)為主,生長季則以座囊菌綱和傘菌綱(Agaricomycetes)為主要類群。這說明冬季相對嚴(yán)酷的環(huán)境改變了微生物類群組成,耐受性和適應(yīng)性更強(qiáng)的微生物類群成為冬季微生物群落的主要組成部分。而從林冠下到林窗中心,微生物主要類群沒有明顯差異。微生物類群和凋落葉質(zhì)量損失和元素釋放相關(guān)。細(xì)菌類群y變形菌綱與磷元素釋放正相關(guān),黃桿菌綱(Flavobacteria)和放線菌綱(Actinobacteria)與木質(zhì)素降解相關(guān)；真菌類群傘菌綱與纖維素分解相關(guān),錘舌菌綱(Leotiomycetes)與木質(zhì)素及纖維素分解過程有關(guān)。這說明不同微生物類群對凋落葉分解起到不一樣的作用,可能對理解亞高山森林生態(tài)系統(tǒng)物質(zhì)循環(huán)和能量流動具有重要意義。綜上所述,亞高山森林林冠格局的改變,改變了凋落葉分解的微環(huán)境,其對凋落葉分解過程中不同時期的微生物數(shù)量及群落結(jié)構(gòu)具有一定影響,本研究結(jié)果對更深入理解該區(qū)域復(fù)雜多變的氣候環(huán)境條件下(如季節(jié)性雪被斑塊和凍融循環(huán)),凋落物分解這一生態(tài)過程提供了一定的基礎(chǔ)數(shù)據(jù)。
[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.
【學(xué)位授予單位】：四川農(nóng)業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：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.
【學(xué)位授予單位】：四川農(nóng)業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：S714
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