摘要
土壤氮转化过程是森林生态系统氮循环的重要组成部分,调控着土壤可利用氮的含量,决定了土壤氮素的存留状况。大气氮沉降增加是全球变化研究领域的重点问题之一,氮和磷作为影响植物生长最主要的矿质元素,人类活动加剧造成的氮磷养分输入的变化已经成为影响森林生态系统土壤氮循环的重要因素之一。截至目前,国内外已开展了大量关于氮磷输入对森林生态系统土壤氮转化影响的研究,但仍缺乏对该问题的统一结论和整体认知,这在相对"氮富集"、"磷限制"的热带森林尤为突出。本文综述了国内外关于热带森林土壤氮转化和氮损失对氮磷养分添加响应的研究结果,以期概述该问题的普遍规律并揭示其潜在机理。目前的研究趋于认为,长期氮输入使热带森林土壤氮转化过程加速,进而提高了土壤有效氮含量以及增强生态系统氮损失(通过气态排放和液态淋溶);磷添加则趋向于刺激植物-土壤之间的养分循环,降低热带森林土壤氮素损失速率,从而有利于土壤氮素的存留;氮磷同时添加对热带森林土壤氮转化过程可能不存在交互作用。在氮磷添加下,土壤环境条件、土壤有机质、凋落物性质、微生物群落组成等的变化可能是造成热带森林土壤氮转化速率大小和方向发生改变的潜在机理。同时,结合已有研究现状,指出了当前相关研究存在的问题及未来研究方向。
Soil nitrogen(N)transformation is a key component of N cycling in forest ecosystems.Soil organic N and subsequent mineral N(NH4+and NO3-)transformations in forest ecosystems drive forest productivity and control soil mineral N concentrations and their relative abundance(the ratio of NH4+to NO3-).Increasing atmospheric N deposition is a key issue in the research area of global change.Nitrogen and phosphorus(P)are generally considered as the most important mineral nutrients for plant growth.The rapidly increasing N deposition by anthropogenic activities may increase soil N availability,and cause P deficiency in tropical regions,leading to imbalances in soil mineral nutrition.Changes in N and P inputs caused by intensified human activities have become one of the important factors affecting soil N cycling of forest ecosystems.Therefore,knowledge on the responses of soil N transformation processes to N and P inputs is crucial for understanding soil N dynamics under increasing N deposition.Numerous studies have been conducted over the past decades to examine the effects of N and P inputs on soil N transformation in forests,but without a unified conclusion and overall understanding of this issue,which is particularly prominent in tropical forests with N enrichment and P limitation.Here,we synthesized the studies on soil N transformation and loss following N and P addition in tropical forests,in order to outline the general understanding of this issue and identify the underlying mechanisms.We found that long-term N addition tends to accelerate soil N transformation in tropical forests,increases available N concentration and enhances N loss(through gaseous emissions and leaching),and weakens microbial N retention by decreasing microbial biomass.By contrast,P addition tends to simulate nutrient cycling between plants and soil,reduces the rate of soil N loss,and thus facilitates N retention in tropical forest.We found that N and P addition may not have an interactive effect on soil N transformations in tropical forests.We identified the major possible mechanisms driving changes in soil N transformation by N and/or P addition.Nitrogen and P addition can affect soil N cycling by directly altering the quality of soil organic matter and litterfall,soil conditions,and microbial communities(e.g.,biomass,community composition,enzyme activity).In addition,we pointed out the limitations of the previous studies and proposed further research direction on soil N transformation in tropical forests.
作者
郭亚兵
毛晋花
王聪
王森浩
李安迪
朱怡静
莫江明
张炜
GUO Ya-bing;MAO Jin-hua;WANG Cong;WANG Sen-hao;LI An-di;ZHU Yi-jing;MO Jiang-ming;ZHANG Wei(South China Botanical Garden,Chinese Academy of Sciences,Guangzhou 510650,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《生态学杂志》
CAS
CSCD
北大核心
2021年第10期3339-3354,共16页
Chinese Journal of Ecology
基金
国家自然科学基金项目(41731176和42077311)资助。
关键词
养分添加
森林土壤
热带森林
氮转化
nutrient addition
forest soil
tropical forest
nitrogen transformation
