缙云山自然保护区代表性树种凋落叶分解特征研究

发布时间：2018-03-05 04:26

本文选题：凋落叶　切入点：分解　出处：《重庆师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：凋落叶是森林生态系统生产力重要的构成部分之一,其分解是养分生物循环的关键环节,是沟通生物地球化学循环的桥梁和纽带。凋落叶分解过程深刻地影响着森林土壤的物理化学性质,制约着林地的生物量和生产力。为了弄清凋落叶在不同条件下的分解状况,采集缙云山国家级自然保护区内代表性树种的凋落叶(四川山矾、白毛新木姜子、马尾松),运用凋落物分解袋法,研究凋落叶在常绿阔叶林和针阔混交林内三种设置条件下(地表无覆盖层、凋落物层、地下5cm层),凋落叶分解过程中干重损失动态以及养分动态变化。经过一年的野外分解实验得出以下结论:(1)各林分下三种树种凋落叶分解过程中累计干重损失率均逐月增加,且累计干重损失率存在ⅡⅠⅢ即凋落物层地表无覆盖层地下5cm层。研究期内5月、6月和9月为凋落叶干重损失率的高峰期。同种树种的三种处理方式下,针阔混交林的四川山矾累计干重损失率高于常绿阔叶林。(2)在不同设置条件下三种树种凋落叶月净损失率变化过程基本一致,均经历了逐步上升-迅速下降-小幅度上升-下降的过程,但同种树种凋落叶的每月净损失情况各有不同。同时,同种设置条件下,不同树种的月损失率也有所不同,其中针叶树种马尾松的损失率明显低于阔叶树种四川山矾和白毛新木姜子。(3)通过修正后的Olson指数模型拟合,得出四川山矾、白毛新木姜子和马尾松在不同设置条件下分解常数ⅡⅠⅢ。同种设置条件下,三种树种的分解常数表现出四川山矾白毛新木姜子马尾松,且针阔混交林内下的四川山矾分解速率快于常绿阔叶林内的分解速率。(4)通过单因素方差分析比较同树种,同取样月的不同设置条件下凋落叶分解过程中的残留率可见:绝大多数月份(主要为2016年5月~2016年11月)四川山矾、白毛新木姜子和马尾松凋落叶的残留率在三种处理方式下彼此之间都存在明显差异;研究期初期Ⅰ和Ⅲ号样地残留率差异不显著;在同一设置条件下,各月间的凋落叶残留率均存在显著差异性。(5)方差分析结果显示,三种树种凋落叶初始养分元素含量存在显著性差异,马尾松凋落叶的C和P含量明显高于四川山矾和白毛新木姜子。四川山矾拥有最高的K、Ca和Mg含量,白毛新木姜子的C/N和C/P明显高于另两个树种。(6)三种树种凋落叶分解过程中,养分元素C、N、P、K、Ca和Mg的含量和残留率均呈现出波动性变化,不同树种凋落叶分解过程中的养分元素动态变化各有不同。三种设置条件下分解过程中各元素含量和残留率变化过程大体一致,但波动的幅度有所差异。C、K、Ca和Mg元素在整个研究期内总体上表现出一定的释放。其中,C残留率在变化过程中较为明显的存在地下层地表无覆盖层凋落物层,而白毛新木姜子Mg元素的释放不明显。K元素含量随分解的进行呈明显的下降趋势,并表现出释放的特征。N元素在整个研究期内基本处于相对富集状态。三种树种凋落叶P释放状况各有不同。在两种林分下,四川山矾凋落叶分解过程中的P、Ca和Mg元素在常绿阔叶林和针阔混交林中呈现略微不同的变化过程。
[Abstract]:Litter in forest ecosystem is one of the most important part of productivity, the decomposition is a key link in nutrient cycling, is the bridge and link of the biogeochemical cycle. Litter decomposition process affects the physical and chemical properties of forest soils, restricting the biomass and productivity of forest land. In order to clarify the decomposition of leaf litter under different conditions, the representative species of leaf litter collected in Jinyun Mountain National Nature Reserve (Sichuan, Symplocos, Neolitsea, Masson), using the litter bag method, study on leaf litter in the evergreen broad-leaved forest and coniferous forest in three conditions (no land cover, litter underground layer, 5cm layer), leaf litter decomposition and nutrient dynamics of heavy loss dynamic changes of dry process. After a year of field decomposition experiment obtained the following conclusions: (1) the three species of forest litter The decomposition of leaf dry weight loss rate was the cumulative monthly increase in the process, and the cumulative rate of loss in weight is that the litter I II III surface intectate underground 5cm layer. The study period of May, June and September for the dry weight loss rate of leaf litter peak. Three kinds of treatment methods of the same species, conifer the mixed forest of Sichuan total dry weight loss rate is higher than the major evergreen broad-leaved forest. (2) in the litter Yuejing loss rate change process under three kinds of different setting conditions are basically the same, have experienced a gradual rise in rapid decline - small amplitude increase decrease, but the net loss per month the same species of leaf litter in the there are different. At the same time, the same set of conditions, different species may have different loss rate, the loss rate of Pinus massoniana was significantly lower than that of broadleaf species in Sichuan and Symplocos Neolitsea. (3) through the Olson exponent modified model Come to Sichuan, Symplocos, Neolitsea Masson and decomposition constant II I-III in different setting conditions. The same set under the condition of constant shows Sichuan pine Symplocos Neolitsea decomposition of three species, and coniferous forest in Sichuan under the decomposition rate of Symplocos in evergreen broad-leaved forests decomposition rate. (4) through the single factor analysis of variance compared with the same month in different species, sampling set under the condition of leaf litter decomposition in the process of the residual rate of visible: most month (mainly for the May 2016 ~2016 year in November) Sichuan Symplocos rate in three ways, there are obvious differences between each other under the new white wood residue ginger and pine litter; on early stage I and III sample residual rate was not significantly different; in the same conditions, each month between leaf litter residual rate. There were significant differences (5) the results of analysis of variance Show that there is a significant difference between the nutrient elements in the leaves of three species of initial litter, C and P content of Masson pine leaf litter was significantly higher than that of Sichuan and Symplocos Neolitsea Symplocos. Sichuan had the highest K, Ca and Mg content, Neolitsea C/N and C/P was significantly higher than that of the other two species (. 6) three species of leaf litter decomposition, nutrient elements C, N, P, K, Ca and Mg content and residual rate showed changes in volatility, dynamic changes of nutrient elements in different species of leaf litter decomposition process is different. The content of each element decomposition process of three kinds of conditions and settings the residual rate of change is largely the same, but the fluctuation of the difference of.C, K, Ca and Mg elements show certain release during the whole study period in general. Among them, the residual rate of C in the process of changing obviously exist underground without overburden layer of surface litter layer, and white wood Ginger Mg element release is not obvious.K content significantly decreased with the decomposition of a, and show the characteristics of.N release is relatively enriched in the entire study period. Three species of leaf litter P release was different. In two plantations, in the decomposition process of P in Sichuan mountain alum leaffall, Ca and Mg elements changed slightly different process in evergreen broad-leaved forest and coniferous forest.

【学位授予单位】：重庆师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714

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