發(fā)布時間：2018-05-29 22:09

  本文選題：氮沉降 + 殘落物��； 參考：《江西農(nóng)業(yè)大學(xué)》2017年碩士論文

【摘要】：氮(N)沉降是全球性的重大環(huán)境問題之一,中國已成為繼歐美之后的第三大N沉降區(qū),N沉降對森林生態(tài)系統(tǒng)的影響是當(dāng)前的研究熱點和科學(xué)前沿。森林殘落物是森林生態(tài)系統(tǒng)重要的碳庫和養(yǎng)分庫,對維持森林生態(tài)系統(tǒng)結(jié)構(gòu)和功能至關(guān)重要。開展N沉降對森林殘落物分解速率和養(yǎng)分動態(tài)的影響研究,可為深入探討N沉降對森林生態(tài)系統(tǒng)物質(zhì)循環(huán)和能量流動提供科學(xué)參考。本研究選取了亞熱帶6種不同質(zhì)量(C:N:P化學(xué)計量比)殘落物為對象,采用實驗室微宇宙法,開展為期720天的分解試驗,比較N沉降對不同類型殘落物分解速率與養(yǎng)分動態(tài)的影響。與此同時,采用了99.99%~(15)N同位素示蹤技術(shù)監(jiān)測殘落物對N沉降的固持量,利用Saiya-Cork的微孔板熒光法測定5種酶活性,以期揭示N沉降對殘落物分解過程的影響及其N沉降本身的去向和酶活性的響應(yīng)機制。主要研究結(jié)果如下:(1)6種殘落物初始化學(xué)組成及其化學(xué)計量比差異顯著(P0.05),初始C/N比從高到低的順序為:合歡(Albizia julibrissin)凋落葉(AJL)、楓香(Liquidambar formosana)凋落葉(LQL)、杉木(Cunninghamia lanceolata)+楓香混合凋落葉(CLL+LQL)、苔蘚(Bryophyte)殘體(BRL)、杉木凋落葉(CLL)、馬尾松(Pinus massoniana)木屑(PWL),初始N、P濃度為CLL+LQL、LQL和AJL高于PWL、BRL和CLL,各殘落物分解速率與其初始C、N、P濃度及其化學(xué)計量比等指標(biāo)中2個或2個以上顯著相關(guān)。(2)N添加處理總體顯著降低各殘落物的分解速率。經(jīng)過720d的分解試驗,對照處理殘落物的重量殘留率為:BRL(82.07%)、PWL(81.95%)CLL(54.97%)CLL+LQL(41.87%)、LQL(41.48%)AJL(27.77%),N添加處理的各殘落物重量殘留率為:PWL(86.03%)BRL(84.23%)CLL(78.62%)CLL+LQL(70.38%)LQL(62.00%)AJL(33.51%)。(3)與對照處理相比,N添加處理減緩了PWL、BRL、CLL和CLL+LQL的C釋放,促進(jìn)了LQL和AJL的C釋放;N添加處理除對AJL分解過程N凈釋放影響不顯著外,對其它5種殘落物N凈固持與釋放影響顯著;N添加處理降低各殘落物的P濃度,不同程度地加快PWL、BRL、CLL+LQL、LQL和AJL的P凈釋放。(4)N添加處理各殘落物~(15)N豐度變化趨勢基本一致,前期或中期呈上升趨勢,中期或后期呈下降趨勢;PWL、CLL、BRL、CLL+LQL、LQL和AJL固持~(15)N的豐度分別為6.73‰、13.15‰、11.37‰、13.65‰、14.30‰和5.81‰,而釋放則分別為8.35‰、19.24‰、17.55‰、14.52‰、15.95‰和5.81‰,可見,不同殘落物對外源N的固持與釋放的強度及其轉(zhuǎn)換規(guī)律各異,與其質(zhì)量(C/N、C/P和N/P)有關(guān)。(5)N添加處理對殘落物分解的5種酶活性的影響因殘落物類型而各異,整體提高了各殘落物酸性磷酸酶和L-亮氨酸基態(tài)酶的活性,降低了β-1,4-葡萄糖苷酶、半纖維素酶和乙酰葡萄胺糖苷酶的活性。綜上所述,N添加處理對殘落物分解速率與養(yǎng)分動態(tài)的影響以及外源N的去向與殘落物質(zhì)量、分解階段、酶活性等因素有關(guān)。殘落物初始C/N和C/P比及其隨分解過程的動態(tài)變化是解釋N沉降影響效應(yīng)的關(guān)鍵特征。N沉降對亞熱帶森林生態(tài)系統(tǒng)殘落物分解及養(yǎng)分的歸還仍需加強原位的模擬研究。
[Abstract]:Nitrogen (N) settlement is one of the most important environmental problems in the world. China has become the third largest N settlement area after Europe and America. The impact of N settlement on forest ecosystem is the current research hotspot and scientific frontier. Forest residues are important carbon and nutrient storage in forest ecosystem, and it is critical to maintain the structure and function of forest ecosystem. The study on the effect of N settlement on the decomposition rate and nutrient dynamics of forest residues can provide a scientific reference for the material circulation and energy flow of the forest ecosystem by N settlement. This study selected 6 subtropical mass (C:N:P stoichiometric) residues as the object, and carried out a 720 laboratory microcosm method. The effect of N deposition on the decomposition rate and nutrient dynamics of different types of residues was compared. At the same time, the 99.99%~ (15) N isotope tracer technique was used to monitor the retention of the residues on the N settlement, and the activity of the 5 enzymes was measured by the Saiya-Cork microplate fluorescence method, in order to reveal the effect of N settlement on the decomposition process of the residue and the effect of the precipitation on the decomposition process of the residues. The main results are as follows: (1) the initial chemical composition and stoichiometry of 6 species of residues are significant (P0.05), and the order of initial C/N ratio from high to low is: Albizia julibrissin (AJL), maple (Liquidambar formosana) litter (LQL), and Sugiki (Cunninghamia LAN) Ceolata) + CLL+LQL, moss (Bryophyte) residue (BRL), Chinese fir litter (CLL), Pinus massoniana (Pinus massoniana) wood chip (PWL), initial N, P concentration is CLL+LQL, LQL and other residues are higher than those of 2 or more than 2. (2) The decomposition rate of the residue was significantly reduced by the addition treatment. After the 720d decomposition test, the residual weight residue rate of the controlled residue was BRL (82.07%), PWL (81.95%) CLL (54.97%) CLL+LQL (41.87%), LQL (41.48%) AJL (27.77%), and the residue of N addition treated residues was PWL (86.03%) BRL (84.23%) CLL (78.62%) CLL+LQL (70.38%)). 62%) AJL (33.51%). (3) compared with the control treatment, N addition treatment slowed down the C release of PWL, BRL, CLL and CLL+LQL, and promoted the release of LQL and AJL C; N addition treatment had no significant influence on the net release of the AJL decomposition process, and had a significant effect on the other 5 residues. To accelerate the net release of P in PWL, BRL, CLL+LQL, LQL and AJL. (4) the variation trend of ~ (15) N abundances in N addition treatment was basically consistent, in the early or middle period, the trend was rising, and in the middle or later period, the trend was decreasing; PWL, CLL, BRL, CLL+LQL, 13.15, 11.37, 13.65, 14.30 and 5.81 per thousand, respectively, for the abundance of PWL, CLL, BRL, CLL+LQL, 11.37, 13.65, and 13.65. It is 8.35 per thousand, 19.24 per thousand, 17.55 per thousand, 14.52 per thousand, 15.95 per thousand and 5.81 per thousand. It can be seen that the strength and conversion of different residues on the fixation and release of exogenous N are different, and their mass (C/N, C/P and N/P). (5) the effects of N addition treatment on the viability of the 5 enzymes in the residues are different from the residue types, and the whole residues are improved as a whole. The activity of acid phosphatase and L- leucine Base State Enzyme reduced the activity of glucosidase, hemicellulase and acetylglucosidase in beta -1,4-. In summary, the effects of N addition on the decomposition rate and nutrient dynamics of the residues and the quality of residue, decomposition stage, enzyme activity and other factors were related to the origin of exogenous N. The C/N and C/P ratio and the dynamic changes with the decomposition process are the key characteristics to explain the effect of N deposition..N deposition in the subtropical forest ecosystem residue decomposition and the return of nutrients still need to be strengthened in situ.
【學(xué)位授予單位】：江西農(nóng)業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S714

【參考文獻(xiàn)】

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本文編號：1952622