林下植被去除和凋落物添加对杉木林土壤关键生态过程的影响
发布时间：2018-11-24 14:26
【摘要】：杉木(Cunninghamia lanceolata)是我国南方最重要的速生用材树种,由于长期不合理的强度经营,导致杉木林地力衰退严重,如何维持杉木人工林的长期生产力是林业部门亟待解决的重要科学问题。林下植物和凋落物是森林生态系统的重要组成部分。传统观点认为,林下植物与乔木竞争养分和水分,不利于目标树种的生长,往往被移除,然而林下植物在森林生态系统中的生态功能尚不是很明确;凋落物分解是生态系统养分的重要来源,凋落物的积累对生态系统过程,特别是土壤生态过程的影响是研究热点。本研究以杉木人工林为对研究象,布设林下植被去除(UR)、凋落物添加(LA)、凋落物添加+林下植被去除(LUR)和对照(CK)四种处理4次重复的完全随机区组设计试验,监测土壤养分状况、凋落物分解状况、土壤呼吸状况、氮矿化状况的变化,阐明林下植物去除和凋落物添加对杉木人工林土壤关键生态过程的影响机制,为杉木林可持续经营提供理论支撑。主要结果如下:(1)林下植被去除(UR)显著降低土壤全氮(P=0.021)、全磷(P=0.009)及可溶性碳(P=0.013)含量;UR显著降低土壤真菌的量(P=0.02)。凋落物添加(LA)显著增加土壤有机碳(P=0.003)、无机氮(P0.001)的含量和土壤pH值(P=0.007);LA显著增加真菌的量(P=0.007)和真菌/细菌的比值(P0.001)。林下植被去除和凋落物添加对土壤有机碳(P=0.013)、细菌(P=0.035)及总微生物的量(P=0.04)交互作用显著。(2)UR和LA均显著抑制凋落物的分解速率,且UR抑制作用强于LA。在凋落物分解过程中,磷元素浓度始终处于富集状态,不同处理下凋落枝叶分解至480天时磷残余量均高于初始值;氮元素浓度则表现为释放-富集交替波动的模式,UR处理下的凋落叶分解至480天时氮残余量为初始值的83%;凋落枝分解过程中,UR和LA处理下的氮残余量始终高于初始值,表现为对氮的富积;凋落叶碳残余量介于26.16%-31.04%之间,凋落枝碳残余量介于40.31%-49.75%之间。(3)UR显著增加土壤呼吸速率,总呼吸和异养呼吸分别增加33.13%和14.91%;凋落物添加(LA)降低土壤呼吸速率的17.95%;UR和LA对土壤呼吸影响的交互作用不显著。根系呼吸占总呼吸的比例表现为UR最大(41.85%),CK次之(32.32%),LA和LUR最小(16.60%和14.92%)。(4)UR对土壤氮矿化速率的影响不显著。LA显著增加土壤氨化速率和总氮矿化速率。UR和LA的交互作用显著增加了土壤氮矿化速率。综上,林下植物去除降低土壤养分含量,降低真菌的量,抑制凋落物的分解,减缓养分归还速率,建议杉木人工林中保留林下植物。凋落物的添加抑制凋落物的分解速率,减少土壤碳的排放,在全球气候持续变化,刺激森林生态系统凋落物增加的背景下,促进生态系统对土壤碳截获,增强生态系统的碳汇功能。
[Abstract]:Chinese fir (Cunninghamia lanceolata (Cunninghamia lanceolata) is one of the most important fast-growing timber species in southern China. How to maintain the long-term productivity of Chinese fir plantation is an important scientific problem to be solved urgently. Undergrowth and litter are important components of forest ecosystem. According to the traditional view, the competition of nutrients and water between undergrowth plants and trees is not conducive to the growth of target tree species and is often removed. However, the ecological function of undergrowth plants in forest ecosystem is not clear. Litter decomposition is an important source of nutrients in ecosystem, and the effect of litter accumulation on ecosystem processes, especially soil ecological processes, is a hot topic. In this study, four repeated complete randomized block design experiments of four treatments of Chinese fir plantation (Chinese fir plantation) were carried out to remove (UR), litter and (LA), litter plus (LUR) removal and control (CK) treatment. The changes of soil nutrient status, litter decomposition, soil respiration and nitrogen mineralization were monitored, and the influence mechanism of plant removal and litter addition on the key ecological processes of Chinese fir plantation was clarified. To provide theoretical support for sustainable management of Chinese fir forest. The main results were as follows: (1) removal of (UR) significantly decreased soil total nitrogen (P0. 021), total phosphorus (P0. 009) and soluble carbon (P0. 013), and UR significantly decreased the amount of soil fungi (P0. 02). The addition of (LA) to litter significantly increased soil organic carbon (P0. 003), inorganic nitrogen (P0. 001) and soil pH (P0. 007); LA) significantly increased the fungal content (P0. 007) and the ratio of fungi to bacteria (P0. 001). The interaction of vegetation removal and litter addition on soil organic carbon (P0. 013), bacteria (P0. 035) and total microbial biomass (P0. 04) was significant. (2) UR and LA significantly inhibited the decomposition rate of litter. The inhibitory effect of UR is stronger than that of LA.. In the process of litter decomposition, the concentration of phosphorus was always in the enrichment state, and the residual phosphorus content was higher than the initial value at 480 days after the decomposition of litter leaves and branches under different treatments. The nitrogen concentration fluctuated alternately between release and enrichment, and the litter leaves under UR treatment were decomposed to 833% of the initial value at 480 days. During the decomposition of litter branches, the nitrogen residues under UR and LA treatments were always higher than the initial values, showing the accumulation of para-nitrogen. The residual carbon content of littered leaves ranged from 26.16% to 31.04%, and that of branches ranged from 40.31% to 49.75%. (3) UR significantly increased soil respiration rate. Total respiration and heterotrophic respiration increased 33.13% and 14.91%, respectively. The effect of (LA) on soil respiration was not significant when litter was added to (LA). The effects of LA and UR on soil respiration were not significant. The proportion of root respiration to total respiration was the highest in UR (41.85%), CK, 32.32%). The minimum LA and LUR (16.60% and 14.92%). (4) UR had no significant effect on soil nitrogen mineralization rate. LA significantly increased soil ammoniation rate and total nitrogen mineralization rate. The interaction of UR and LA significantly increased soil nitrogen mineralization rate. In conclusion, the removal of undergrowth plants can reduce the soil nutrient content, reduce the amount of fungi, inhibit the decomposition of litter and slow down the rate of nutrient return. It is suggested that Chinese fir plantations should be retained in the plantation. The addition of litter inhibits the decomposition rate of litter, reduces soil carbon emissions, and promotes the interception of soil carbon by ecosystem against the background of global climate change and the increase of litter in forest ecosystem. Enhance the carbon sink function of the ecosystem.
【学位授予单位】：江西农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714
本文编号：2354068
[Abstract]:Chinese fir (Cunninghamia lanceolata (Cunninghamia lanceolata) is one of the most important fast-growing timber species in southern China. How to maintain the long-term productivity of Chinese fir plantation is an important scientific problem to be solved urgently. Undergrowth and litter are important components of forest ecosystem. According to the traditional view, the competition of nutrients and water between undergrowth plants and trees is not conducive to the growth of target tree species and is often removed. However, the ecological function of undergrowth plants in forest ecosystem is not clear. Litter decomposition is an important source of nutrients in ecosystem, and the effect of litter accumulation on ecosystem processes, especially soil ecological processes, is a hot topic. In this study, four repeated complete randomized block design experiments of four treatments of Chinese fir plantation (Chinese fir plantation) were carried out to remove (UR), litter and (LA), litter plus (LUR) removal and control (CK) treatment. The changes of soil nutrient status, litter decomposition, soil respiration and nitrogen mineralization were monitored, and the influence mechanism of plant removal and litter addition on the key ecological processes of Chinese fir plantation was clarified. To provide theoretical support for sustainable management of Chinese fir forest. The main results were as follows: (1) removal of (UR) significantly decreased soil total nitrogen (P0. 021), total phosphorus (P0. 009) and soluble carbon (P0. 013), and UR significantly decreased the amount of soil fungi (P0. 02). The addition of (LA) to litter significantly increased soil organic carbon (P0. 003), inorganic nitrogen (P0. 001) and soil pH (P0. 007); LA) significantly increased the fungal content (P0. 007) and the ratio of fungi to bacteria (P0. 001). The interaction of vegetation removal and litter addition on soil organic carbon (P0. 013), bacteria (P0. 035) and total microbial biomass (P0. 04) was significant. (2) UR and LA significantly inhibited the decomposition rate of litter. The inhibitory effect of UR is stronger than that of LA.. In the process of litter decomposition, the concentration of phosphorus was always in the enrichment state, and the residual phosphorus content was higher than the initial value at 480 days after the decomposition of litter leaves and branches under different treatments. The nitrogen concentration fluctuated alternately between release and enrichment, and the litter leaves under UR treatment were decomposed to 833% of the initial value at 480 days. During the decomposition of litter branches, the nitrogen residues under UR and LA treatments were always higher than the initial values, showing the accumulation of para-nitrogen. The residual carbon content of littered leaves ranged from 26.16% to 31.04%, and that of branches ranged from 40.31% to 49.75%. (3) UR significantly increased soil respiration rate. Total respiration and heterotrophic respiration increased 33.13% and 14.91%, respectively. The effect of (LA) on soil respiration was not significant when litter was added to (LA). The effects of LA and UR on soil respiration were not significant. The proportion of root respiration to total respiration was the highest in UR (41.85%), CK, 32.32%). The minimum LA and LUR (16.60% and 14.92%). (4) UR had no significant effect on soil nitrogen mineralization rate. LA significantly increased soil ammoniation rate and total nitrogen mineralization rate. The interaction of UR and LA significantly increased soil nitrogen mineralization rate. In conclusion, the removal of undergrowth plants can reduce the soil nutrient content, reduce the amount of fungi, inhibit the decomposition of litter and slow down the rate of nutrient return. It is suggested that Chinese fir plantations should be retained in the plantation. The addition of litter inhibits the decomposition rate of litter, reduces soil carbon emissions, and promotes the interception of soil carbon by ecosystem against the background of global climate change and the increase of litter in forest ecosystem. Enhance the carbon sink function of the ecosystem.
【学位授予单位】：江西农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714
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