川西高山森林林窗位置对两种灌木凋落叶分解的影响

发布时间：2018-04-20 05:20

  本文选题：高山森林 + 林窗位置　； 参考：《四川农业大学》2016年博士论文

【摘要】：灌木是森林生态系统的基本组成部分,其凋落物分解在森林生态系统地力维持、碳吸存和养分循环等方面的作用将随着林窗形成而发生变化。同时,林窗对光照和降水的再分配可能改变不同关键时期林窗内外的分解环境和分解者微生物群落,从而改变林窗内外灌木凋落物分解过程。但迄今为止,有关灌木凋落物分解及其随林窗位置的变化特征尚未受到关注。因此,本研究以受季节性雪被影响明显的川西高山天然冷杉林(Abies faxoniana)生态系统为研究对象,通过2年的凋落叶分解袋实验,研究了林窗中心到林下的华西箭竹(Fargeisia nitida)和康定柳(Salix paraplesia)凋落叶在5个关键时期(冻结初期、冻结期、融化期、生长季节初期和生长季节后期)的质量损失、养分释放以及木质素、纤维素和酚类物质降解及相关的微生物群落结构动态,以期为高山森林生态系统管理提供理论依据。主要结果如下：(1)两年分解过程中,两种灌木凋落叶的质量损失率在林窗中心位置表现较大。通过Olson模型指数回归模拟,相比之下,林窗中心位置华西箭竹凋落叶的50%分解时间和95%分解时间分别缩短了0.44和1.89年,康定柳凋落叶的50%分解时间和95%分解时间分别缩短了0.11和0.49年。(2)经过两年的分解,在两年的冻结初期、冻结期、融化期和生长季节后期,两种凋落叶的碳氮磷释放率以及木质素、纤维素和总酚降解率均表现出从林窗中心到林下依次降低的趋势,而在两年的生长季节初期,两种凋落叶的碳氮磷释放率以及木质素、纤维素和总酚降解率均表现出从林窗中心到林下依次增加的趋势(尽管从林窗中心到林下位置两种凋落叶的氮和磷元素在第一年生长季节初期和第二年融化期均表现出富集过程,但两种凋落叶的氮和磷元素在第一年生长季节初期的富集率有从林窗中心到林下逐渐增加的趋势,而两种凋落叶的氮和磷元素在第二年融化期的富集率有从林窗中心到林下依次降低的趋势)。两种凋落叶第一年冬季的碳氮磷释放率、纤维素降解率以及总酚的降解率均占整个两年释放率(降解率)的重要比例,而华西箭竹凋落叶和康定柳凋落叶的木质素降解则分别主要体现在第一年和第二年分解时期。(3)随着分解时间的进行,各林窗位置两种凋落叶的C:N、C、Lignin/N和Lignin/P逐渐降低,N:P、Lignin/Cellulose和Lignin/Phenol逐渐升高。相较于林窗不同位置,两种凋落叶的C:N、Lignin/N和Lignin/Cellulose表现出从林窗中心到林下依次升高的趋势,C:P、N:P、Lignin/P和Lignin/Phenol表现出从林窗中心到林下依次降低的趋势。(4)在两年的冻结初期、冻结期、融化期和生长季节后期,两种凋落叶的MBC、MBN、MBP、真菌数量和细菌数量有从林窗中心到林下依次降低的趋势,而在两年的生长季节初期,两种凋落叶的MBC、MBN、MBP、真菌数量和细菌数量有从林窗中心到林下依次升高的趋势,且MBC、真菌数量和细菌数量在两年各时期的这种趋势更为显著。MBC/MBN、MBC/MBP、MBN/MBP和Fungus/Bacteria在两年的大部分时期均有从林窗中心到林下依次降低的趋势。在两年的冻结初期、冻结期、融化期和生长季节后期,两种凋落叶土壤真菌和土壤细菌的丰富度指数(S)以及香农-维纳指数(H)有从林窗中心到林下逐渐减小的趋势,两种凋落叶土壤真菌和土壤细菌的辛普森指数(D)有从林窗中心到林下逐渐增大的趋势；在两年的生长季节初期,两种凋落叶土壤真菌和土壤细菌的丰富度指数(S)以及香农-维纳指数(H)有从林窗中心到林下逐渐增大的趋势,两种凋落叶土壤真菌和土壤细菌的辛普森指数(D)有从林窗中心到林下逐渐减小的趋势。(5)两年各分解时期不同林窗位置总共检测到了14类真菌：子囊菌纲(Ascomycetes)、座囊菌纲(Dothideomycetes)、锤舌菌纲(Leotiomycetes)、伞菌纲(Agaricomycetes)、酵母菌纲(Saccharomycetes)、散囊菌纲(Eurotiomycetes)、粪壳菌纲(Sordariomycetes)、盘菌纲(Pezizmycetes)、丝孢纲(Hyphpmycetes)、银耳纲(Tremellomycetes)、昆虫纲(Insecta)、卵菌纲(Oomycetes)、蜷丝球虫纲(Filasterea)和中粘菌门(Mesomycetozoea),其中子囊菌纲、座囊菌纲、锤舌菌纲和伞菌纲这四大类群占各时期不同林窗位置两种凋落叶土壤真菌群落的主体。共检测到了10类细菌：拟杆菌纲(Bacteroidetes)、黄杆菌纲(Flavobacterial)、鞘脂杆菌纲(Sphingobacteria)、α变形菌纲(Alphaproteobacteria)、β变形菌纲(Betaproteobacteria)、ε变形菌纲(Epsilonproteobacteria)、γ变形菌纲(Gammaproteobacteria)、放线菌纲(Actinobacteria)、梭杆菌纲(Fusobacteria)和未培养细菌克隆(Unknown),其中拟杆菌纲、黄杆菌纲、鞘脂杆菌纲和α变形菌纲这四大类群占各时期不同林窗位置两种凋落叶土壤细菌群落的主体。(6)两种凋落叶两年冬季冻结期的质量损失率、碳释放率、氮释放率、磷释放率、木质素降解率和纤维素降解率以及第一年冬季冻结期的总酚降解率与平均温度、雪被厚度、微生物生物量碳、真菌数量和细菌数量具有显著正相关关系；两种凋落叶两年生长季节初期的碳释放率和纤维素降解率、第一年生长季节初期的总酚降解率、第二年生长季节初期的氮释放率和磷释放率以及康定柳凋落叶第二年生长季节初期的质量损失率均与平均温度呈显著负相关关系。其余各时期的凋落叶质量损失率、养分释放率以及木质素、纤维素和总酚降解率与所调查的微环境因子和凋落叶基质质量变化部分存在显著甚至极显著的相关关系。可见,高山森林林窗对光照和降水的再分配改变了不同位置的分解环境,从而影响到相关的微生物群落结构,促进了凋落叶冬季及全年的质量损失、碳氮磷释放以及木质素、纤维素和酚类物质的降解。这意味着林窗更新消失将抑制凋落叶的分解过程。因此,进一步理解灌木在森林生态系统物质循环与能量转换中的作用及其随林窗更新的变化特征,不仅可以深入理解森林生态系统的物质循环与能量流动,而且能够为森林生态系统可持续经营与管理提供重要的科学依据。然而,本研究只涉及到高山森林林窗位置对两种灌木凋落物分解及其微生物群落变化的影响,有关林窗更新与林下植物生长发育、凋落物产量以及凋落物分解与土壤有机碳吸存等的生态联系亟待深入研究。
[Abstract]:Shrubs are the basic components of forest ecosystem, and their litter decomposition is maintained in the forest ecosystem. The effects of carbon storage and nutrient cycling will change with the formation of forest windows. Meanwhile, the redistribution of light and precipitation in the forest window may change the decomposition environment and the decomposer of the forest windows at different critical periods. So far, the decomposition of shrubs and the changes in the location of the shrubs have not been paid attention to. Therefore, this study is based on the Abies faxoniana ecosystem, which is obviously affected by seasonal snow in the Western Sichuan Alpine natural fir forest (Abies). The mass loss, nutrient release and lignin degradation and degradation of cellulose and phenols were studied in the litter decomposition bag experiment in 5 key periods (freezing, freezing, melting, growing season and late growing season) of the withered leaves of Fargeisia nitida and Kangding willow (Salix paraplesia). The related microbial community structure is dynamic to provide a theoretical basis for the management of the alpine forest ecosystem. The main results are as follows: (1) during the two-year decomposition process, the loss rate of the two shrubs was larger in the center of the forest window. By the Olson model index regression model, in contrast, the position of Western Huaxi bamboo litter in the center of the forest window was withered. The 50% decomposition time and the 95% decomposition time of the leaves were shortened by 0.44 and 1.89 years respectively. The 50% decomposition and 95% decomposition times of the leaves of Kangding willow litter were shortened by 0.11 and 0.49 years respectively. (2) after two years of decomposition, the carbon and nitrogen and phosphorus release rates of two species of litter and the lignin, fiber and fiber in the early freezing period, the freezing period, the thawing period and the late growth season, and the fiber were reduced. The degradation rate of vitamin and total phenol decreased from the center of the forest window to the undergrowth. In the early growing season, the carbon, nitrogen and phosphorus release rates of two species of litter and the degradation rate of lignin, cellulose and total phenol all showed an increasing trend from the center of the forest window to the forest (two kinds of litter from the center of the forest window to the undergrowth. " The accumulation of nitrogen and phosphorus in the deciduous leaves during the first year of the first year of growth and the second year melting period showed that the enrichment rate of the nitrogen and phosphorus elements in the first year of the first year of the two species of litter was gradually increased from the center of the forest window to the undergrowth, while the enrichment rate of the nitrogen and phosphorus elements of the two species of litter in the second year melting period was found. The rate of carbon, nitrogen and phosphorus release, cellulose degradation rate and total phenol degradation rate in the first year of two species of litter accounted for an important proportion of the whole two year release rate (degradation rate), while the lignin degradation of the leaves of Western Huaxi bamboo litter and Kangding willow litter were mainly reflected in the first year and the first year. Two years of decomposition period. (3) with the time of decomposition, the C:N, C, Lignin/N and Lignin/P gradually decreased, and N:P, Lignin/Cellulose and Lignin/Phenol gradually increased. Compared with the different positions of the forest windows, the C:N of two species of litter, Lignin/N and Lignin /Cellulose showed an ascending trend from the center of the window to the forest. Potential, C:P, N:P, Lignin/P and Lignin/Phenol showed a downward trend from the center of the forest window to the undergrowth. (4) in the early freezing period, the freezing period, the melting period and the late growth season, the two species of MBC, MBN, MBP, the number of fungi and the number of bacteria decreased from the heart to the forest in the forest window, but in the early growing season of two years. The number of MBC, MBN, MBP, the number of fungi and the number of bacteria in the two species of litter increased from the center of the forest window to the forest, and the number of fungi and the number of bacteria were more.MBC/MBN in the two years. MBC/MBP, MBN/MBP and Fungus/Bacteria decreased from the center of the window to the forest for the most part of the two years. In the early freezing period, the freezing period, the melting period and the late growth season, the abundance index (S) and the Shannon Wiener index (H) of the fungi and the Shannon Wiener index (H) decreased gradually from the center of the forest window to the forest, and the Simpson index (D) of the fungi and soil bacteria in the litter soil was from the center of the forest window. In the early growing season, the richness index (S) of fungi and soil bacteria and the Shannon Wiener index (H) of the two species of litter soil increased gradually from the center of the forest window to the forest, and the Simpson index (D) of the two species of litter soil fungi and the soil microbacteria (D) were from the center of the forest window to the undergrowth in the early growing season. Gradually decreasing trend. (5) 14 types of fungi were detected in different forest window positions during the two years of decomposition: Ascomycetes, Dothideomycetes, Leotiomycetes, Agaricomycetes, Saccharomycetes, Eurotiomycetes, Sordariomycetes, and disc bacteria. Pezizmycetes, Hyphpmycetes, Tremellomycetes, Insecta, oomycetes (Oomycetes), Filasterea and Mesomycetozoea, in which the four groups of cysts, cysts, mallet and agaricomycetes account for two species of litter soil fungi at different forest window positions in each period A total of 10 types of bacteria were detected: Bacteroidetes, Flavobacterial, Sphingobacteria, Alphaproteobacteria, Betaproteobacteria, Epsilonproteobacteria, Gammaproteobacteria, and actinomycetes (Actinobac). Teria), Clostridium (Fusobacteria) and uncultured bacterial clone (Unknown), among which four groups of bacteriobacteria, bacilli, sphingomyelin and alpha deformia accounted for the main body of bacterial community of two species of litter in different forest windows in each period. (6) the mass loss rate, carbon release rate and nitrogen release of two species of litter in the freezing period of two years in winter. Rate, phosphorus release rate, lignin degradation rate and cellulose degradation rate and the total phenol degradation rate of the first year winter freezing period and the average temperature, snow thickness, microbial biomass carbon, fungi quantity and bacteria number have significant positive correlation; the carbon release rate and cellulose degradation rate in the first year of two species of litter growth season, the first year The total phenol degradation rate at the beginning of the growing season, the nitrogen release rate and the release rate of phosphorus in the early second year growth season and the mass loss rate in the early growth season of the second year growing season of Kangding willow litter were all negatively correlated with the average temperature. The loss rate of leaf litter, the nutrient release rate and the lignin, cellulose and total phenol in the rest of the season. There is a significant or even significant correlation between the degradation rate and the variation of the microenvironmental factors and the variation of the litter matrix. It is obvious that the redistribution of light and precipitation in the forest windows of the alpine forest changes the decomposition environment in different locations, thus affecting the related microbial community structure and promoting the quality of the leaves in winter and the whole year. Loss, release of carbon, nitrogen and phosphorus, and degradation of lignin, cellulose and phenolic compounds. This means that the regeneration and disappearance of the forest window will inhibit the decomposition process of the litter. Therefore, further understanding of the role of shrubs in the material cycle and energy conversion of forest ecosystems and the change characteristics with the forest window renewal can not only be understood in depth in forest ecology. The material circulation and energy flow of the system can provide an important scientific basis for the sustainable management and management of forest ecosystems. However, this study only involves the effect of the position of the forest window on the decomposition of two shrubs and the changes of the microbial community. And the ecological relationship between litter decomposition and soil organic carbon sequestration needs to be further studied.

【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】：S718.5
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本文编号：1776418