發(fā)布時(shí)間：2018-04-20 05:20

  本文選題：高山森林 + 林窗位置�。� 參考：《四川農(nóng)業(yè)大學(xué)》2016年博士論文

【摘要】：灌木是森林生態(tài)系統(tǒng)的基本組成部分,其凋落物分解在森林生態(tài)系統(tǒng)地力維持、碳吸存和養(yǎng)分循環(huán)等方面的作用將隨著林窗形成而發(fā)生變化。同時(shí),林窗對(duì)光照和降水的再分配可能改變不同關(guān)鍵時(shí)期林窗內(nèi)外的分解環(huán)境和分解者微生物群落,從而改變林窗內(nèi)外灌木凋落物分解過(guò)程。但迄今為止,有關(guān)灌木凋落物分解及其隨林窗位置的變化特征尚未受到關(guān)注。因此,本研究以受季節(jié)性雪被影響明顯的川西高山天然冷杉林(Abies faxoniana)生態(tài)系統(tǒng)為研究對(duì)象,通過(guò)2年的凋落葉分解袋實(shí)驗(yàn),研究了林窗中心到林下的華西箭竹(Fargeisia nitida)和康定柳(Salix paraplesia)凋落葉在5個(gè)關(guān)鍵時(shí)期(凍結(jié)初期、凍結(jié)期、融化期、生長(zhǎng)季節(jié)初期和生長(zhǎng)季節(jié)后期)的質(zhì)量損失、養(yǎng)分釋放以及木質(zhì)素、纖維素和酚類物質(zhì)降解及相關(guān)的微生物群落結(jié)構(gòu)動(dòng)態(tài),以期為高山森林生態(tài)系統(tǒng)管理提供理論依據(jù)。主要結(jié)果如下：(1)兩年分解過(guò)程中,兩種灌木凋落葉的質(zhì)量損失率在林窗中心位置表現(xiàn)較大。通過(guò)Olson模型指數(shù)回歸模擬,相比之下,林窗中心位置華西箭竹凋落葉的50%分解時(shí)間和95%分解時(shí)間分別縮短了0.44和1.89年,康定柳凋落葉的50%分解時(shí)間和95%分解時(shí)間分別縮短了0.11和0.49年。(2)經(jīng)過(guò)兩年的分解,在兩年的凍結(jié)初期、凍結(jié)期、融化期和生長(zhǎng)季節(jié)后期,兩種凋落葉的碳氮磷釋放率以及木質(zhì)素、纖維素和總酚降解率均表現(xiàn)出從林窗中心到林下依次降低的趨勢(shì),而在兩年的生長(zhǎng)季節(jié)初期,兩種凋落葉的碳氮磷釋放率以及木質(zhì)素、纖維素和總酚降解率均表現(xiàn)出從林窗中心到林下依次增加的趨勢(shì)(盡管從林窗中心到林下位置兩種凋落葉的氮和磷元素在第一年生長(zhǎng)季節(jié)初期和第二年融化期均表現(xiàn)出富集過(guò)程,但兩種凋落葉的氮和磷元素在第一年生長(zhǎng)季節(jié)初期的富集率有從林窗中心到林下逐漸增加的趨勢(shì),而兩種凋落葉的氮和磷元素在第二年融化期的富集率有從林窗中心到林下依次降低的趨勢(shì))。兩種凋落葉第一年冬季的碳氮磷釋放率、纖維素降解率以及總酚的降解率均占整個(gè)兩年釋放率(降解率)的重要比例,而華西箭竹凋落葉和康定柳凋落葉的木質(zhì)素降解則分別主要體現(xiàn)在第一年和第二年分解時(shí)期。(3)隨著分解時(shí)間的進(jìn)行,各林窗位置兩種凋落葉的C:N、C、Lignin/N和Lignin/P逐漸降低,N:P、Lignin/Cellulose和Lignin/Phenol逐漸升高。相較于林窗不同位置,兩種凋落葉的C:N、Lignin/N和Lignin/Cellulose表現(xiàn)出從林窗中心到林下依次升高的趨勢(shì),C:P、N:P、Lignin/P和Lignin/Phenol表現(xiàn)出從林窗中心到林下依次降低的趨勢(shì)。(4)在兩年的凍結(jié)初期、凍結(jié)期、融化期和生長(zhǎng)季節(jié)后期,兩種凋落葉的MBC、MBN、MBP、真菌數(shù)量和細(xì)菌數(shù)量有從林窗中心到林下依次降低的趨勢(shì),而在兩年的生長(zhǎng)季節(jié)初期,兩種凋落葉的MBC、MBN、MBP、真菌數(shù)量和細(xì)菌數(shù)量有從林窗中心到林下依次升高的趨勢(shì),且MBC、真菌數(shù)量和細(xì)菌數(shù)量在兩年各時(shí)期的這種趨勢(shì)更為顯著。MBC/MBN、MBC/MBP、MBN/MBP和Fungus/Bacteria在兩年的大部分時(shí)期均有從林窗中心到林下依次降低的趨勢(shì)。在兩年的凍結(jié)初期、凍結(jié)期、融化期和生長(zhǎng)季節(jié)后期,兩種凋落葉土壤真菌和土壤細(xì)菌的豐富度指數(shù)(S)以及香農(nóng)-維納指數(shù)(H)有從林窗中心到林下逐漸減小的趨勢(shì),兩種凋落葉土壤真菌和土壤細(xì)菌的辛普森指數(shù)(D)有從林窗中心到林下逐漸增大的趨勢(shì)；在兩年的生長(zhǎng)季節(jié)初期,兩種凋落葉土壤真菌和土壤細(xì)菌的豐富度指數(shù)(S)以及香農(nóng)-維納指數(shù)(H)有從林窗中心到林下逐漸增大的趨勢(shì),兩種凋落葉土壤真菌和土壤細(xì)菌的辛普森指數(shù)(D)有從林窗中心到林下逐漸減小的趨勢(shì)。(5)兩年各分解時(shí)期不同林窗位置總共檢測(cè)到了14類真菌：子囊菌綱(Ascomycetes)、座囊菌綱(Dothideomycetes)、錘舌菌綱(Leotiomycetes)、傘菌綱(Agaricomycetes)、酵母菌綱(Saccharomycetes)、散囊菌綱(Eurotiomycetes)、糞殼菌綱(Sordariomycetes)、盤菌綱(Pezizmycetes)、絲孢綱(Hyphpmycetes)、銀耳綱(Tremellomycetes)、昆蟲綱(Insecta)、卵菌綱(Oomycetes)、蜷絲球蟲綱(Filasterea)和中粘菌門(Mesomycetozoea),其中子囊菌綱、座囊菌綱、錘舌菌綱和傘菌綱這四大類群占各時(shí)期不同林窗位置兩種凋落葉土壤真菌群落的主體。共檢測(cè)到了10類細(xì)菌：擬桿菌綱(Bacteroidetes)、黃桿菌綱(Flavobacterial)、鞘脂桿菌綱(Sphingobacteria)、α變形菌綱(Alphaproteobacteria)、β變形菌綱(Betaproteobacteria)、ε變形菌綱(Epsilonproteobacteria)、γ變形菌綱(Gammaproteobacteria)、放線菌綱(Actinobacteria)、梭桿菌綱(Fusobacteria)和未培養(yǎng)細(xì)菌克隆(Unknown),其中擬桿菌綱、黃桿菌綱、鞘脂桿菌綱和α變形菌綱這四大類群占各時(shí)期不同林窗位置兩種凋落葉土壤細(xì)菌群落的主體。(6)兩種凋落葉兩年冬季凍結(jié)期的質(zhì)量損失率、碳釋放率、氮釋放率、磷釋放率、木質(zhì)素降解率和纖維素降解率以及第一年冬季凍結(jié)期的總酚降解率與平均溫度、雪被厚度、微生物生物量碳、真菌數(shù)量和細(xì)菌數(shù)量具有顯著正相關(guān)關(guān)系；兩種凋落葉兩年生長(zhǎng)季節(jié)初期的碳釋放率和纖維素降解率、第一年生長(zhǎng)季節(jié)初期的總酚降解率、第二年生長(zhǎng)季節(jié)初期的氮釋放率和磷釋放率以及康定柳凋落葉第二年生長(zhǎng)季節(jié)初期的質(zhì)量損失率均與平均溫度呈顯著負(fù)相關(guān)關(guān)系。其余各時(shí)期的凋落葉質(zhì)量損失率、養(yǎng)分釋放率以及木質(zhì)素、纖維素和總酚降解率與所調(diào)查的微環(huán)境因子和凋落葉基質(zhì)質(zhì)量變化部分存在顯著甚至極顯著的相關(guān)關(guān)系�？梢�(jiàn),高山森林林窗對(duì)光照和降水的再分配改變了不同位置的分解環(huán)境,從而影響到相關(guān)的微生物群落結(jié)構(gòu),促進(jìn)了凋落葉冬季及全年的質(zhì)量損失、碳氮磷釋放以及木質(zhì)素、纖維素和酚類物質(zhì)的降解。這意味著林窗更新消失將抑制凋落葉的分解過(guò)程。因此,進(jìn)一步理解灌木在森林生態(tài)系統(tǒng)物質(zhì)循環(huán)與能量轉(zhuǎn)換中的作用及其隨林窗更新的變化特征,不僅可以深入理解森林生態(tài)系統(tǒng)的物質(zhì)循環(huán)與能量流動(dòng),而且能夠?yàn)樯�林生態(tài)系統(tǒng)可持續(xù)經(jīng)營(yíng)與管理提供重要的科學(xué)依據(jù)。然而,本研究只涉及到高山森林林窗位置對(duì)兩種灌木凋落物分解及其微生物群落變化的影響,有關(guān)林窗更新與林下植物生長(zhǎng)發(fā)育、凋落物產(chǎn)量以及凋落物分解與土壤有機(jī)碳吸存等的生態(tài)聯(lián)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.

【學(xué)位授予單位】：四川農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：S718.5
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本文編號(hào)：1776418