模拟氮沉降对瓦屋山次生常绿阔叶林不同凋落物组分输入量和养分归还的影响

发布时间：2018-04-23 06:51

本文选题：氮沉降 + 凋落物量　；参考：《四川农业大学》2016年硕士论文

【摘要】：从工业革命以来,由于人类活动制造了大量的活性氮(N),使得大气N沉降的含量成比例的增加。N沉降其来源和分布迅速地扩张到全世界,并不断地沉降到陆地和水生生态系统。中国已经成为全球继欧洲和美国之外第三大N沉降集中区。过量的N沉降已经引起了水体富营养化、土壤和水体酸化、陆地生态系统N饱和、营养元素失衡等一系列的生态问题。凋落物作为森林生态系统中物质循环和能量流动的重要组成部分,它在维持植物生产力、土壤肥力、微生物活性以及森林生态系统碳循环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沉降对凋落物及其养分动态的影响显得极为重要。次生林(secondary forest)作为为中国乃至世界森林资源的上体,在全球物质循环和能量流动中具有重要作用。因此,在N沉降全球化的背景下,研究该常绿阔叶次生林凋落物归还对N沉降增加的响应,为该区域森林生态系统的物质循环和能量流动提供理论基础和数据支撑,进而为更加合理高效的解决全球过量N沉降的环境问题提供科学依据。本研究选取四川瓦屋山次生常绿阔叶林为研究对象,运用模拟N沉降的试验方法(2013年4月至2015年6月),用NH4NO3进行N沉降处理,设置3种N添加水平：对照(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沉降对凋落量、凋落物养分含量和元素归还量的影响。实验地树种主要分为：扁刺栲、中华木荷、硬壳柯、细梗吴茱萸五加和野桐等,其中扁刺栲、中华木荷和硬壳柯为主要树种,因此本实验将凋落物分为：扁刺栲、中华木荷、硬壳柯、其它树种和枝条花果5个部分。得到以下结论。(1)模拟N沉降对凋落量的影响未达统计学显著水平,但表现出增加凋落物凋落量的趋势,LN和HN处理下凋落量增幅分别为4%和17%。凋落物年凋落量为明显的双峰型,峰值大抵出现在5月份和11月份左右,N沉降未改变凋落量的月动态变化。凋落叶占总凋落量的84.2%-86.9%,其中其它树种凋落叶中华木荷凋落叶扁刺栲凋落叶硬壳柯凋落叶。(2)模拟N沉降处理下,N、K、Ca和Mg等养分元素含量表现为增加的趋势,P养分元素含量表现为减少的趋势。氮沉降显著增加了LN和HN处理扁刺栲凋落叶K元素含量。其余组分和元素指标均未表现出处理间的显著差异。各个凋落物组分各养分元素含量均存在显著的季节变化。(3)自然状态下(未施氮),凋落物中K、N、Ca、Mg和P元素归还量分别为10.12、9.06、8.75、4.68和1.14 kg·hm-2。氮沉降处理显著增加了N元素归还量,由9.06 kg·hm-2增加为13.93 kg·hm-2和15.22kg·hm-2,增幅分别为54%和68%。氮沉降也明显增加了钾元素归还量,增幅为12%和35%。各组分凋落物元素归还量存在显著季节变化。
[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.
【学位授予单位】：四川农业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S714

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