本文選題：土壤呼吸　切入點：微生物呼吸　出處：《中南林業(yè)科技大學》2017年碩士論文　論文類型：學位論文

【摘要】：土壤呼吸是陸地生態(tài)系統(tǒng)碳循環(huán)的最重要的環(huán)節(jié)之一,是土壤碳庫的主要輸出途徑和大氣cO2的重要來源,其微小的變化就會顯著地減緩或加劇大氣中CO2的增加,進而影響氣候變化,森林土壤碳庫是全球土壤碳庫的重要組成部分,其比例約為73%。因此對森林土壤呼吸的研究是研究碳失匯現(xiàn)象以及包括全球變化在內等一系列重大環(huán)境問題的重要組成部分。本研究以湖南會同杉木林生態(tài)系統(tǒng)國家野外科學觀測研究站試驗基地的杉木人工林為對象,分別設立對照組、干旱組、低氮組和高氮組,共12塊實驗樣地。每個樣地內設去凋落物觀測點、去根觀測點、無處理觀測點各3個,定期監(jiān)測各觀測點土壤總呼吸速率以及土壤呼吸組分(根呼吸和微生物呼吸速率),以探究杉木人工林土壤呼吸及各組分對干旱及氮沉降的響應機理,并對未來森林土壤呼吸情況,全球碳循環(huán)預測等其他相關研究提供科學研究數(shù)據(jù),主要研究結果為:1.模擬氮沉降時,土壤總呼吸年平均速率為對照組1.53μmol/(m2·s)高氮組1.46μmol/(m2·s)低氮組1.24μmol/(m2·s)。從趨勢來看模擬不同水平的氮沉降處理均會對杉木人工林土壤總呼吸產(chǎn)生抑制效果,在模擬低水平氮沉降時效果更明顯,模擬不同水平的氮沉降處理均會對土壤呼吸組分的比例發(fā)生變化,使得微生物呼吸上升,植物根系呼吸下降,在低氮水平下,這種提升達到了 30.1%。2.隔離降雨總體上使得土壤總呼吸速率1.43μmol/(m2·s)比對照組l.53μmol/(m2·s)低,但差異不顯著,但在隔離降雨10個月后,土壤總呼吸及各組分呼吸均表現(xiàn)出上升趨勢。而去除凋落物對杉木人工林土壤呼吸的影響極為微小。3.土壤溫度是影響實驗地杉木人工林土壤呼吸的主要因素,溫度可以解釋實驗地土壤總呼吸62.4-73.9%的變異,土壤微生物呼吸55.1-69.5%的變異,在模擬高水平氮沉降的條件下,土壤總呼吸的Q10值有所上升,而模擬低水平氮沉降和模擬干旱條件下,土壤總呼吸的Q10值有所下降。模擬氮沉降和干旱均使得土壤微生物呼吸的Q10值上升。土壤濕度對實驗地杉木人工林土壤呼吸的影響較小,僅能解釋土壤總呼吸的6.2%到22.9%的變異,土壤微生物呼吸11.1-24.7%的變異,模擬氮沉降和干旱處理后,土壤濕度與土壤微生物呼吸的關系進一步削弱。而低氮水平下土壤濕度與土壤總呼吸的關系有所加強。
[Abstract]:Soil respiration is one of the most important processes of terrestrial ecosystem carbon cycle, and it is the main output pathway of soil carbon pool and the important source of atmospheric cO2. The small change of soil respiration will significantly slow or aggravate the increase of CO2 in the atmosphere. Thus affecting climate change, forest soil carbon pool is an important component of global soil carbon pool, Therefore, the study of forest soil respiration is an important part of the study of carbon sequestration and a series of major environmental problems, including global change. The Cunninghamia lanceolata plantation in the experimental base of the field scientific observation and research station, Control group, drought group, low nitrogen group and high nitrogen group were set up with 12 experimental plots. Soil total respiration rate and soil respiration components (root respiration and microbial respiration rate) were monitored regularly in order to explore the mechanism of soil respiration and its response to drought and nitrogen deposition in Chinese fir plantation. And provide scientific data for future forest soil respiration, global carbon cycle prediction and other related studies. The main results are: 1. When simulating nitrogen deposition, The annual average rate of soil total respiration was 1.53 渭 mol/(m2 路s in control group (1.46 渭 mol/(m2 路s) in high nitrogen group (1.46 渭 mol/(m2 路s)) in low nitrogen group (1.24 渭 mol/(m2 路s). According to the trend, nitrogen deposition at different levels could inhibit soil total respiration in Chinese fir plantation, especially when simulating low nitrogen deposition. Simulation of nitrogen deposition at different levels will change the proportion of soil respiration components, resulting in the increase of microbial respiration, the decline of plant root respiration, and the decrease of plant root respiration at low nitrogen level. The total respiration rate of the soil was lower than that of the control group (1.43 渭 mol/(m2 路s), but the difference was not significant, but after 10 months of isolated rainfall, the total respiration rate of the soil was lower than that of the control group (1.43 渭 mol/(m2 路s). Soil total respiration and components respiration showed an upward trend, while the effect of litter removal on soil respiration of Chinese fir plantation was very small. 3. Soil temperature was the main factor affecting soil respiration in Chinese fir plantation. The temperature can explain 62.4-73.9% variation of soil total respiration and 55.1-69.5% variation of soil microbial respiration. Under the condition of simulating high nitrogen deposition, the Q10 value of soil total respiration increased, but under simulated low level nitrogen deposition and simulated drought condition, Q10 value of soil total respiration increased. The Q10 value of soil total respiration decreased. Simulated nitrogen deposition and drought increased the soil microbial respiration Q10 value. Soil moisture had little effect on soil respiration of Chinese fir plantation, which could only explain the variation of soil total respiration between 6.2% and 22.9%. The variation of soil microbial respiration was 11.1-24.7%. After simulated nitrogen deposition and drought treatment, the relationship between soil moisture and soil microbial respiration was further weakened, but the relationship between soil moisture and soil total respiration was strengthened at low nitrogen level.
【學位授予單位】：中南林業(yè)科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：S714
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本文編號：1643623