本文選題：氮沉降 + 凋落物量　； 參考：《四川農(nóng)業(yè)大學(xué)》2016年碩士論文

【摘要】：從工業(yè)革命以來(lái),由于人類活動(dòng)制造了大量的活性氮(N),使得大氣N沉降的含量成比例的增加。N沉降其來(lái)源和分布迅速地?cái)U(kuò)張到全世界,并不斷地沉降到陸地和水生生態(tài)系統(tǒng)。中國(guó)已經(jīng)成為全球繼歐洲和美國(guó)之外第三大N沉降集中區(qū)。過(guò)量的N沉降已經(jīng)引起了水體富營(yíng)養(yǎng)化、土壤和水體酸化、陸地生態(tài)系統(tǒng)N飽和、營(yíng)養(yǎng)元素失衡等一系列的生態(tài)問(wèn)題。凋落物作為森林生態(tài)系統(tǒng)中物質(zhì)循環(huán)和能量流動(dòng)的重要組成部分,它在維持植物生產(chǎn)力、土壤肥力、微生物活性以及森林生態(tài)系統(tǒng)碳循環(huán)等方面都有重要作用。因此,在N沉降全球化的背景下,研究N沉降對(duì)凋落物及其養(yǎng)分動(dòng)態(tài)的影響顯得極為重要。次生林(secondary forest)作為為中國(guó)乃至世界森林資源的上體,在全球物質(zhì)循環(huán)和能量流動(dòng)中具有重要作用。因此,在N沉降全球化的背景下,研究該常綠闊葉次生林凋落物歸還對(duì)N沉降增加的響應(yīng),為該區(qū)域森林生態(tài)系統(tǒng)的物質(zhì)循環(huán)和能量流動(dòng)提供理論基礎(chǔ)和數(shù)據(jù)支撐,進(jìn)而為更加合理高效的解決全球過(guò)量N沉降的環(huán)境問(wèn)題提供科學(xué)依據(jù)。本研究選取四川瓦屋山次生常綠闊葉林為研究對(duì)象,運(yùn)用模擬N沉降的試驗(yàn)方法(2013年4月至2015年6月),用NH4NO3進(jìn)行N沉降處理,設(shè)置3種N添加水平：對(duì)照(CK, 0gNm-1·a-1),低N(IN,5 g N m-2.a-1),高N(HN,15gNm-2·a-1),研究N沉降對(duì)凋落量、凋落物養(yǎng)分含量和元素歸還量的影響。實(shí)驗(yàn)地樹(shù)種主要分為：扁刺栲、中華木荷、硬殼柯、細(xì)梗吳茱萸五加和野桐等,其中扁刺栲、中華木荷和硬殼柯為主要樹(shù)種,因此本實(shí)驗(yàn)將凋落物分為：扁刺栲、中華木荷、硬殼柯、其它樹(shù)種和枝條花果5個(gè)部分。得到以下結(jié)論。(1)模擬N沉降對(duì)凋落量的影響未達(dá)統(tǒng)計(jì)學(xué)顯著水平,但表現(xiàn)出增加凋落物凋落量的趨勢(shì),LN和HN處理下凋落量增幅分別為4%和17%。凋落物年凋落量為明顯的雙峰型,峰值大抵出現(xiàn)在5月份和11月份左右,N沉降未改變凋落量的月動(dòng)態(tài)變化。凋落葉占總凋落量的84.2%-86.9%,其中其它樹(shù)種凋落葉中華木荷凋落葉扁刺栲凋落葉硬殼柯凋落葉。(2)模擬N沉降處理下,N、K、Ca和Mg等養(yǎng)分元素含量表現(xiàn)為增加的趨勢(shì),P養(yǎng)分元素含量表現(xiàn)為減少的趨勢(shì)。氮沉降顯著增加了LN和HN處理扁刺栲凋落葉K元素含量。其余組分和元素指標(biāo)均未表現(xiàn)出處理間的顯著差異。各個(gè)凋落物組分各養(yǎng)分元素含量均存在顯著的季節(jié)變化。(3)自然狀態(tài)下(未施氮),凋落物中K、N、Ca、Mg和P元素歸還量分別為10.12、9.06、8.75、4.68和1.14 kg·hm-2。氮沉降處理顯著增加了N元素歸還量,由9.06 kg·hm-2增加為13.93 kg·hm-2和15.22kg·hm-2,增幅分別為54%和68%。氮沉降也明顯增加了鉀元素歸還量,增幅為12%和35%。各組分凋落物元素歸還量存在顯著季節(jié)變化。
[Abstract]:Since the Industrial Revolution, human activities have produced a large number of active nitrogen nitrides, which make atmospheric N deposition increase proportionally. The source and distribution of atmospheric N deposition are rapidly expanded to the whole world, and continue to sink to land and aquatic ecosystems. China has become the third largest concentration area of nitrogen deposition in the world after Europe and the United States. Excessive N deposition has caused a series of ecological problems, such as eutrophication of water, acidification of soil and water, N saturation in terrestrial ecosystem, imbalance of nutrient elements, and so on. Litter, as an important component of material circulation and energy flow in forest ecosystem, plays an important role in maintaining plant productivity, soil fertility, microbial activity and carbon cycle in forest ecosystem. Therefore, under the background of the globalization of N deposition, it is very important to study the effect of N deposition on litter and its nutrient dynamics. Secondary forestas the upper body of forest resources in China and the world, and play an important role in the global material circulation and energy flow. Therefore, under the background of the globalization of N deposition, the response of litter return of evergreen broadleaved secondary forest to the increase of N deposition is studied, which provides the theoretical basis and data support for the material cycle and energy flow of forest ecosystem in this region. It provides a scientific basis for solving the environmental problem of excessive N deposition in the world more reasonably and efficiently. In this study, the secondary evergreen broad-leaved forest in Wawushan Mountain, Sichuan Province was selected as the research object, and the experiment method of simulating N deposition was used (from April 2013 to June 2015, NH4NO3 was used to deal with N deposition). The effects of N deposition on litter amount, nutrient content and element return of litter were studied by setting up three levels of N addition: CK, 0gNm-1 a-1, 5 g Nm-2.a-1N, and 15g Nm-2 ~ (-1) A ~ (-1). The tree species were mainly divided into four species: Castanopsis fargesii, Schima sinensis, Cortex Hardshell, Evodia rutaecarpa and Paulownia, among which Castanopsis fargesii, Schima sinensis and Cortex Hardshurica were the main species. Therefore, the litter was divided into Castanopsis fargesii, Castanopsis chinensis and Schima sinensis in this experiment. Hardenhead, other tree species and branches, flowers and fruits 5 parts. The results showed that the simulated N deposition had no significant effect on litter amount, but showed a trend of increasing litter litterfall under LN and HN treatments, which increased by 4% and 17%, respectively. The annual litter amount of litter was obviously bimodal, and the peak appeared in May and November, and the monthly dynamic change of litter was not changed. 84.2% -86.9% of the total litter amount, among which other tree species litter leaves, Castanopsis fargesii littered leaves, hardshells, coca litter leaves. 2) under N sedimentation treatment, the contents of nutrient elements such as N, N, K, C, Ca, mg and so on, showed the increasing trend of P nutrient elements, such as the content of N, N, K, K, Ca, mg, etc., in the litter leaves of Castanopsis fargesii. The content shows a decreasing trend. Nitrogen deposition significantly increased K content in littered leaves of Castanopsis fargesii treated with LN and HN. There was no significant difference between the other components and elements. There was significant seasonal variation of nutrient element contents in all litter components. (without nitrogen application, the return of mg and P elements in litter were 10.129.06.8.754.68 and 1.14kg / h ~ (-2) 路h ~ (-2), respectively), and the contents of K ~ (2 +) N ~ (2 +) mg and P in litter were 1.14 kg 路h ~ (-2) 路m ~ (-2), respectively. Nitrogen deposition significantly increased the amount of N element return from 9.06 kg hm-2 to 13.93 kg hm-2 and 15.22kg hm-2, an increase of 54% and 68%, respectively. Nitrogen deposition also increased the return of potassium by 12% and 35%. There was a significant seasonal variation in the return of litter elements in each component.
【學(xué)位授予單位】：四川農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：S714

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