【摘要】：杉木(Cunninghamia lanceolata)是我國(guó)南方最重要的速生用材樹(shù)種,由于長(zhǎng)期不合理的強(qiáng)度經(jīng)營(yíng),導(dǎo)致杉木林地力衰退嚴(yán)重,如何維持杉木人工林的長(zhǎng)期生產(chǎn)力是林業(yè)部門(mén)亟待解決的重要科學(xué)問(wèn)題。林下植物和凋落物是森林生態(tài)系統(tǒng)的重要組成部分。傳統(tǒng)觀點(diǎn)認(rèn)為,林下植物與喬木競(jìng)爭(zhēng)養(yǎng)分和水分,不利于目標(biāo)樹(shù)種的生長(zhǎng),往往被移除,然而林下植物在森林生態(tài)系統(tǒng)中的生態(tài)功能尚不是很明確;凋落物分解是生態(tài)系統(tǒng)養(yǎng)分的重要來(lái)源,凋落物的積累對(duì)生態(tài)系統(tǒng)過(guò)程,特別是土壤生態(tài)過(guò)程的影響是研究熱點(diǎn)。本研究以杉木人工林為對(duì)研究象,布設(shè)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)和對(duì)照(CK)四種處理4次重復(fù)的完全隨機(jī)區(qū)組設(shè)計(jì)試驗(yàn),監(jiān)測(cè)土壤養(yǎng)分狀況、凋落物分解狀況、土壤呼吸狀況、氮礦化狀況的變化,闡明林下植物去除和凋落物添加對(duì)杉木人工林土壤關(guān)鍵生態(tài)過(guò)程的影響機(jī)制,為杉木林可持續(xù)經(jīng)營(yíng)提供理論支撐。主要結(jié)果如下:(1)林下植被去除(UR)顯著降低土壤全氮(P=0.021)、全磷(P=0.009)及可溶性碳(P=0.013)含量;UR顯著降低土壤真菌的量(P=0.02)。凋落物添加(LA)顯著增加土壤有機(jī)碳(P=0.003)、無(wú)機(jī)氮(P0.001)的含量和土壤pH值(P=0.007);LA顯著增加真菌的量(P=0.007)和真菌/細(xì)菌的比值(P0.001)。林下植被去除和凋落物添加對(duì)土壤有機(jī)碳(P=0.013)、細(xì)菌(P=0.035)及總微生物的量(P=0.04)交互作用顯著。(2)UR和LA均顯著抑制凋落物的分解速率,且UR抑制作用強(qiáng)于LA。在凋落物分解過(guò)程中,磷元素濃度始終處于富集狀態(tài),不同處理下凋落枝葉分解至480天時(shí)磷殘余量均高于初始值;氮元素濃度則表現(xiàn)為釋放-富集交替波動(dòng)的模式,UR處理下的凋落葉分解至480天時(shí)氮?dú)堄嗔繛槌跏贾档?3%;凋落枝分解過(guò)程中,UR和LA處理下的氮?dú)堄嗔渴冀K高于初始值,表現(xiàn)為對(duì)氮的富積;凋落葉碳?xì)堄嗔拷橛?6.16%-31.04%之間,凋落枝碳?xì)堄嗔拷橛?0.31%-49.75%之間。(3)UR顯著增加土壤呼吸速率,總呼吸和異養(yǎng)呼吸分別增加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對(duì)土壤呼吸影響的交互作用不顯著。根系呼吸占總呼吸的比例表現(xiàn)為UR最大(41.85%),CK次之(32.32%),LA和LUR最小(16.60%和14.92%)。(4)UR對(duì)土壤氮礦化速率的影響不顯著。LA顯著增加土壤氨化速率和總氮礦化速率。UR和LA的交互作用顯著增加了土壤氮礦化速率。綜上,林下植物去除降低土壤養(yǎng)分含量,降低真菌的量,抑制凋落物的分解,減緩養(yǎng)分歸還速率,建議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,減少土壤碳的排放,在全球氣候持續(xù)變化,刺激森林生態(tài)系統(tǒng)凋落物增加的背景下,促進(jìn)生態(tài)系統(tǒng)對(duì)土壤碳截獲,增強(qiáng)生態(tài)系統(tǒng)的碳匯功能。
[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.
【學(xué)位授予單位】：江西農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：S714

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