亚热带4种树种凋落叶降解和养分释放特征

发布时间：2018-04-30 02:00

本文选题：亚热带森林 + 凋落叶分解　；参考：《中南林业科技大学》2016年硕士论文

【摘要】：森林凋落物是森林生态系统重要的碳库和养分库,对维持森林生态系统结构和功能具有极其重要的作用。凋落物分解影响着土壤碳储量、有机养分矿化、无机养分含量和碳平衡。研究森林凋落叶在分解过程中质量、养分的动态特征,探寻凋落物对森林生态系统养分循环、碳流动的影响机制,可为深入研究森林生态系统物质循环、能量流动提供科学参考。本研究以中亚热带4种优势树种：针叶树马尾松(Pinus massonana)、杉木(Cunninghamia lanceolata)、落叶阔叶树枫香(Liquidambar formosana)、常绿阔叶树青冈(Cyclobalanopsis glauca)的凋落叶为对象,采用野外分解网袋法,在南酸枣(Choerospondia axillaris)落叶阔叶林1ha固定样地进行分解试验,比较研究不同树种凋落叶分解速率及其养分释放特征。主要结果为：(1)4种树种凋落叶初始化学组成及其C/N、C/P、N/P化学计量比值存在较明显的差异,阔叶树种凋落叶初始N、P含量高于针叶树种,而针叶树种凋落叶初始C含量高于阔叶树种；除C、N含量外,落叶阔叶树种凋落叶初始组成含量高于常绿阔叶树种。(2)经过24个月的分解,4种树种凋落叶质量残留率由高到低为：马尾松(PM)(45.78%)杉木(CL)(42.31%)枫香(LF)(37.24%)青冈(LG)(29.11%),4种树种凋落叶质量残留率差异不明显。凋落叶分解速率分为3个阶段：分解初期(0-10个月)速率较慢,分解中期较快(10-18个月),后期(18-24个月)最慢。凋落叶分解系数常数k值依次是：青冈(0.0525)枫香(0.0447)杉木(0.0370)马尾松(0.0365)。青冈凋落叶分解最快,t50%为1.18 a,t95%为4.84 a,马尾松凋落叶分解最慢,t50%为1.60 a,t95%为6.79 a,枫香凋落叶t50%为1.38 a,t95%为5.67 a,杉木凋落叶t50%为1.44 a,t95%为6.70 a。(3)经过24个月的分解,C释放量由高到低依次为：杉木青冈马尾松枫香,N释放量为：青冈枫香杉木马尾松,P释放量：为枫香青冈杉木马尾松,可溶性糖释放量为：杉木枫香青冈马尾松,淀粉释放量为：杉木枫香马尾松青冈。4种树种凋落叶的C、N、P化学计量比均表现为下降的趋势,但不同树种的变化趋势有差异。(4)4种树种凋落叶C均表现为淋溶—富集—淋溶模式,4种树种凋落叶C分解模型除了青冈为线性衰减方式以外,其余3种树种均为负指数衰减方式,拟合曲线较符合实际情况。4种树种凋落叶N、P均表现为富集—释放模式,其中枫香凋落叶的N出现4次富集—释放,马尾松凋落叶出现3次,青冈凋落叶出现2,枫香、杉木拟合曲线为线性方程,青冈为三次方程,马尾松为负指数衰减模型,均达到极显著水平；枫香、青冈、马尾松凋落叶P出现2次富集—释放,杉木凋落叶P一直处于富集状态,仅枫香为负指数衰减模型且达到极显著水平。4种树种凋落叶可溶性糖、淀粉均释放特征与C相似,马尾松、青冈凋落叶的可溶性糖与淀粉均呈负指数衰减,杉木呈三次方程衰减,而枫香可溶性糖呈三次方程衰减,淀粉为负指数衰减模式。(5)凋落叶的C含量、C/N比、C/P比和N/P比越高,凋落叶分解速率越慢,相反,凋落叶的N、P含量越高,越有利于凋落叶的分解,说明凋落叶化学组成是影响其分解速率的重要因素。凋落叶N、P含量高,有利于养分的释放,而C含量、C/N比、C/P比、N/P比高不利于养分的释放。
[Abstract]:Forest litter is an important carbon pool and nutrient Library of forest ecosystem, which plays an extremely important role in maintaining the structure and function of forest ecosystem. Litter decomposition affects soil carbon storage, organic nutrient mineralization, inorganic nutrient content and carbon balance. The quality of forest litter in decomposition process and the dynamic characteristics of nutrients are explored. The effects of litter on the nutrient cycle of forest ecosystem and the mechanism of carbon flow can provide a scientific reference for the deep study of the material circulation and energy flow in the forest ecosystem. This study is based on 4 dominant species in the middle subtropics: Coniferous pine (Pinus massonana), Chinese fir (Cunninghamia lanceolata), deciduous broadleaf tree maple (Liquidambar Formos) ANA), the leaf litter of Cyclobalanopsis glauca in evergreen broad-leaved tree (Cyclobalanopsis glauca) was taken as the object. The field decomposition net bag method was used to decompose the 1ha fixed plots in the deciduous broadleaf forest of the South sour jujube (Choerospondia axillaris). The decomposition rate and nutrient release characteristics of the leaves of different species were compared. The main results were as follows: (1) 4 species of leaf litter. The chemical composition of the initial chemical composition and the ratio of C/N, C/P and N/P to the chemical stoichiometric ratio of the broadleaf tree species were higher than that of the conifers, but the initial C content of the leaves of the conifers was higher than that of the broadleaved tree species. In addition to the C and N content, the content of the litters in deciduous broadleaf trees was higher than that of the evergreen broad-leaved trees. (2) after 24 months' score, the content of the leaves of deciduous broadleaved tree species was higher than that of the broadleaved tree species. The residue rate of 4 species of tree species was from high to low, including PM (45.78%) Chinese fir (CL) (42.31%) Feng Xiang (LF) (37.24%) green ridge (LG) (29.11%), and there was no significant difference in the residual rate of litter in 4 species of tree species. The rate of litter decomposition was divided into 3 stages: the rate of early decomposition (0-10 months) was slower, and the decomposition rate was faster (10-18 months), and 1 8-24 months) the slowest. The K value of the decomposition coefficient constant of the deciduous leaf is: green hill (0.0525) Feng Xiang (0.0447) Cunninghamia lanceolata (0.0370) masson pine (0.0365). The leaf litter decomposition is the fastest, t50% is 1.18 a, t95% is 4.84 a, the litter decomposition of Masson pine is the slowest, t50% is 1.60 a, t95% is 6.79 a, and the t50% of Feng Xiang litter t50% is 1.38 a, t95% is 5.67 traditions, Chinese fir leaf litter. For 1.44 a, t95% to 6.70 A. (3) after 24 months of decomposition, the release of C from high to low in turn: Sugiki Aookamaomatsukaedeka, N release amount: Aooka Kaedekasugikimayomatsu, P release amount: Maple cedar Cunninghamia lanceolata masson pine, the release amount of soluble sugar: Sugiki Kaedeka Pinus massoniana, starch release amount: Sugiki Kaedeka Masson Pine The chemical stoichiometric ratio of C, N and P in the leaves of.4 species in Qinggang was decreased, but the variation trend of different tree species was different. (4) the C of 4 species of tree species was leached and enriched and leaching model, and the C decomposition model of 4 species of tree species litter, except for the linear attenuation method, the other 3 species of tree species were negative exponential decay methods. The fitting curves were in accordance with the actual conditions of the.4 species N, P showed the enrichment and release pattern, in which the N of the leaves of maple leaf litter had 4 enrichment and release, 3 times, 2 of the litterfall leaves of Pinus massoniana, the linear equation of the fitting curve of maple and Cunninghamia lanceolata, the three equations of Cunninghamia lanceolata, and the negative exponential attenuation model of Masson pine. Very significant level, 2 concentration and release of P in the leaves of maple, Qinggang and Pinus massoniana leaves, and the P of fir litter has been in the state of enrichment. Only the maple root is a negative exponential decay model, and the soluble sugar of.4 species is very significant. The release characteristics of starch are similar to that of C. Exponential decay, Cunninghamia lanceolata was decaying three times, while the soluble sugar of maple was three attenuation and starch was negative exponential decay. (5) the C content of the litter, C/N ratio, C/P ratio and N/P ratio, the slower the decomposition rate of litter, the higher the N and P content of litter, the more beneficial to the decomposition of litter leaves, which indicated that the chemical composition of litter leaves was affected. An important factor of decomposition rate is that the high content of N and P in litters leaves is beneficial to nutrient release, while C content, C/N ratio, C/P ratio and N/P ratio are not conducive to nutrient release.

【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S714

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