模拟N沉降下不同林龄马尾松林凋落叶分解-土壤C、N化学计量特征

发布时间：2018-06-12 23:28

本文选题：马尾松林 + 模拟N沉降　；参考：《生态学报》2017年04期

【摘要】：模拟N沉降对森林生态系统的影响是当今全球变化生态学研究的一个热点问题,土壤碳库对N沉降比较敏感,N沉降增加了凋落叶分解过程中外源N含量,间接影响凋落叶分解的化学过程并改变凋落叶分解速率,因此,研究模拟N沉降下凋落叶分解-土壤C-N关系对预测森林C吸存有重要意义。利用原位分解袋法研究了模拟N沉降下三峡库区不同林龄马尾松林(Pinus massoniana)凋落叶分解过程中凋落叶-土壤C、N化学计量响应及其关系;N沉降水平分对照(CK,0 g m~(-2)a~(-1))、低氮(LN,5 g m~(-2)a~(-1))、中氮(MN,10 g m~(-2)a~(-1))和高氮(HN,15 g m~(-2)a~(-1))。结果表明:分解540 d后,N沉降促进20年生和30年生马尾松林凋落叶分解,46年生马尾松林中仅低氮处理促进凋落叶分解,4种处理均是30年生分解最快,说明同一树种起始N含量低的凋落叶对N沉降呈正响应,N沉降处理促进起始N含量低的凋落叶分解,起始N含量高的凋落叶分解过程中易达到"N饱和"。N沉降抑制20年生和46年生凋落叶C释放(低于对照0.62%—6.69%),促进30年生C释放(高于对照0.28%—5.55%);30年生和46年生林分N固持量均高于对照(高于对照0.15%—21.34%),20年生则低于对照(5.70%—13.87%),说明模拟N沉降处理促进起始C含量低的凋落叶C释放和起始N含量低的凋落叶N固持。N沉降处理下仅30年生马尾松林土壤有机碳较对照增加,且土壤有机质与凋落叶C、N和分解速率呈正相关,与凋落叶C/N比呈显著负相关;土壤总氮与凋落叶分解速率、凋落叶N含量呈正相关,土壤有机碳/总氮比与凋落叶C、N含量呈正相关;对照处理中凋落叶分解指标对土壤养分影响顺序是分解速率凋落物C含量凋落物C/N比凋落物N含量,低、中、高氮处理中则是凋落物C含量分解速率凋落物N含量凋落物C/N比。研究表明低土壤养分含量马尾松林对N沉降呈正响应,N沉降促进低土壤养分马尾松林凋落叶分解并提高土壤肥力;凋落叶质量和土壤养分含量低的生态系统土壤C对N沉降响应更显著。
[Abstract]:Simulating the effects of N deposition on forest ecosystem is a hot issue in global change ecology. Soil carbon pool is sensitive to N deposition and N deposition increases the exogenous N content in the decomposition process of litter leaves. The chemical process of leaf decomposition is indirectly affected and the decomposition rate of litter is changed. Therefore, it is important to study the relationship between litter decomposition and soil C-N under simulated N deposition in predicting forest C uptake. In situ decomposition bag method was used to study the stoichiometric response of foliage to soil Con N during leaf decomposition of Pinus massoniana, Pinus massoniana at different forest ages in the three Gorges Reservoir area under simulated N deposition. The results were as follows: (1) MN (10 g MN) and 15 g (HN ~ (2) ~ (1) ~ (1) and 15 g ~ (?) ~ (-2) ~ (?) ~ (1) ~ (1) ~ (?) ~ (1) ~ (-1), and ~ (2) A ~ (1) ~ (1) ~ (-1) ~ (-1). The results showed that N deposition promoted litter decomposition of Pinus massoniana forest in 20 years old and 30 years old after 540 d decomposition, and only low nitrogen treatment promoted litter decomposition in 46 years old Pinus massoniana forest, which was the fastest in 30 years old Pinus massoniana forest. The results showed that the litter leaves with low initial N content of the same tree species had a positive response to N deposition. It is easy to reach "N saturation" .N deposition during leaf decomposition with high N content to inhibit C release from litter leaves of 20 years old and 46 years old (lower than that of control 0.62 -6.69C, promote C release of 30-year old forest (higher than control 0.28-5.55g; 30-year-old and 46-year-old forest). The N sequestration capacity was higher than that of the control (0.15-21.34g), and the 20-year old was lower than the control (5.70-13.87g), which indicated that simulated N deposition could promote C release from litter leaves with low initial C content and N sequestration in litter leaves with low initial N content. The soil organic carbon of Pinus massoniana forest was higher than that of the control. Soil organic matter was positively correlated with Con N and decomposition rate, and negatively correlated with C / N ratio of littered leaves, and soil total nitrogen was positively correlated with litter decomposition rate and leaf N content. There was a positive correlation between soil organic carbon / total nitrogen ratio and Con N content in litter leaves, and the order of litter decomposition index on soil nutrient was that C / N content of litter was lower and lower than that of litter N in control treatment. The decomposition rate of C content in litter was C / N ratio of litter N content in litter. The results showed that the low soil nutrient content of Pinus massoniana forest was positive response to N deposition and N deposition promoted litter decomposition and improved soil fertility of Pinus massoniana forest with low soil nutrient content. The response of soil C to N deposition was more significant in ecosystem with low leaf quality and soil nutrient content.
【作者单位】：中国林业科学研究院亚热带林业研究所;中国林业科学研究院森林生态环境与保护研究所国家林业局森林生态环境重点实验室;中国林业科学研究院森林生态环境与保护研究所国家林业局森林生态环境重点实验室;南京林业大学南方现代林业协同创新中心;国家林业局秭归森林生态系统定位观测研究站;
【基金】：国家自然科学基金资助项目(31400531) 中央级公益性科研院所基本科研业务费专项资助项目(CAFYBB2014QB033)
【分类号】：S714

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