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Responses of Litter Decomposition and Soil Organic Carbon to Simulated Nitrogen and Sulphur Combined Deposition in Necsinocalamus Affinis Plantation

Author: WangXiaoJun
Tutor: HuangCongDe
School: Sichuan Agricultural University
Course: Forest Management
Keywords: N deposition S deposition NS combined deposition Necsinocalamusaffinis plantation litter decomposition soil organic carbon
CLC: S718.5
Type: Master's thesis
Year: 2012
Downloads: 50
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Abstract


Since Industrial Revolution, a large amount of nitrogen and sulfur compounds (NOx and SO2major) caused intensification of human activities and the burning of fossil fuels released into the atmosphere. Through a series of physical and chemical process, most of emissions as rainfall components form acid rain. Acid rain has become the world’s environmental problems. Countries have in the research work of acid rain. Increasing acid subsidence will have great influence on the carbon cycle of the global forest ecological system. As important component of forest ecological system, Bamboo forest ecological system has been important carbon sink and carbon source, and it contributes about5.1%of Carbon stock to forest ecosystems in China. So the bamboo forest plays an important role in the national and global carbon cycle. Sichuan is the centre of Necsinocalamus affinis plantation distribution and cultivation. The cultivation time is long and area is big. Therefore, this thesis studies Responses of litter decomposition and soil organic carbon to simulated nitrogen(N) and sulphur(S) combined deposition in Necsinocalamus affinis plantation in Rainy Area of West China, and discusses the contribution of litter decomposition to soil organic carbon fixation. Simulation scheme as follows:LN, MN, HN, LS, MS, HS, HNLS, LNLS, MNLS, MNHS, LNMS, HNMS, HNHS, MNMS and LNHS shows low-N(5g.m-2.a-1), medium-N(15g.m-2.a-1), high-N(30g.m-2.a-1), low-S (2.4g.m-2.a-1), medium-S(3.6g.m-2.a-1), and high-S (4.8g.m-2.a-1) and N-S combined deposition. The main results are as follows:(1) Simulation of N deposition in a year, the effects of N deposition to Necsinocalamus affinis plantation litter decomposition presents inhibitory action at first, and then facilitation on the whole. LN and HN treatments show inhibitory action at first, and then facilitation, and HN significantly improve litter decomposition later in the settlement (p<0.05); MN display certain inhibition, and the function gradually decreasing with time and the accumulation of N. Simulation of S deposition in a year, LS and MS treatments stimulate litter decomposition, the effects are notable in12months (p<0.05). That suggests that low and high S deposition can promote litter decomposition, but HS treatment restrain litter decomposition persistently, the impact is growing with time. Simulation of NS combined deposition3months later, the effects of various treatments are not apparent; Simulation in a year, HNLS, LNLS and MNLS treatments promote litter decomposition, HNLS promote strongest. The other combined treatments all show restrain inhibitory action, LNHS suppression strongest.(2)Under the simulation of N and S combined deposition, the litter organic carbon content of Necsinocalamus affinis plantation shows complex changes in a year, and it around the initial value fluctuate. Simulation of N deposition and NS combined deposition one year later, there is a downturn in the litter organic carbon content. Simulation of S deposition one year later, there is a ascending trend of litter organic carbon content.(3) Simulation of N deposition in a year, as a whole, there is a declining trend of total N content with the increasing of the concentration of settlement concerning Necsinocalamus affinis plantation litter. Simulation of S deposition in a year, LS and HS restrain litter N release, MS reveal facilitation. Simulation of NS combined deposition in one year, MNLS and MNMS reduce total N content firstly, and increase observably follow on(p<0.05); the rest of the settlement reduce litter total N early, have rising volatility in the middle period, and all decrease later.(4) Simulation of N deposition in a year, impacts of each settlement to Necsinocalamus affinis plantation litter C/N are not significant during the first half of the year, and the effects from various treatments to C/N are different. As a whole, LN and MN have no obvious effect tendency to litter C/N, but significantly reduce litter C/N after12months (p<0.05). HN bring about C/N gradually increasing, achieving significant level after12months (p<0.05). Simulation of S deposition a year later, LS and HS lessen litter C/N, but MS increase litter C/N obviously (p<0.05). Simulation of NS combined deposition in one year, various treatments have complicated affects to litter C/N, and the change law is not apparent. (5) A year later of Simulated N deposition, there is an increasing trend of soil organic carbon in Necsinocalamus affinis plantation, but not significantly. During one year’s simulated deposition of S, LS treatment increase soil organic carbon content, and the increasing effects weakened gradually over time; MS and HS treatments reduce soil organic carbon content, and reducing effect is enhanced with increasing S concentration. Simulation of NS compound deposition treatments within one year, under the low concentration of N treatment, S deposition increase soil organic carbon content, and increasing effect is decreased with rising S concentration; under the middle concentration of N treatment, the low and middle concentration of sulfur treatment can both increase soil organic carbon content; under the high concentration of N treatment, the middle and high concentration of S sedimentation have reduced the soil organic carbon content; under the low concentration of S treatment, the various concentration of N deposition all have increased soil organic carbon content; under the high concentration of S deposition, all concentration of N deposition decrease soil organic carbon content.(6) Through different concentration of N, S and NS composite deposition settlement, the results show Necsinocalamus affinis plantation litter decomposition effect on soil organic carbon content is much more complex. For the most of the deposition settlements, the increase or decrease of litter mass loss have aroused the same changes of soil organic carbon fixation, but the same law does not exist in the MS, MNMS and MNHS treatments. Obviously, under the N, S and NS compound Settlements, the litter decomposition have a certain impact on soil organic carbon fixation, but the impact mechanism is extremely complex. The specific mechanism of action needs long-term in-depth observational study.

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