氮沉降对森林凋落物分解的影响

氮沉降增加作为全球变化的重要现象之一,已经并将继续对森林凋落物分解产生影响.综述了国内外氮沉降对森林凋落物分解影响及其机理的研究现状.氮沉降对凋落物分解的影响可分为直接影响和间接影响.氮沉降通过影响森林地被物组成和凋落物化学成分,间接影响凋落物分解.氮沉降对凋落物分解的直接影响表现为促进、无影响和抑制3种效果.分析了产生以上影响效果的作用机理,介绍了氮沉降对森林凋落物分解影响的研究方法,探讨了目前研究存在的问题,讨论了未来该方面研究的重点和方向.

Effects of nitrogen deposition on forest litter decomposition

Human activities such as combustion of fossil fuels, intensive agriculture and stockbreeding, have significantly altered the global nitrogen cycle in the last several decades, resulting in increases in the concentrations of nitrogenous compounds in the atmosphere and increases in N deposition several fold. Chronically elevated N deposition to forests can lead to changes in tree growth, mortality, species composition, and to possible decline in soil fertility and drainage water quality. A large number of experiments have been carried out in Europe and Northern America to identify the specific role of N deposition on changes observed in water quality and tree health. Chronically elevated N deposition also affects litter decomposition, a critical processes controlling nutrient cycling, soil humus formation, soil fertility, and primary productivity. Based on available scientific evidence the effects of N deposition on forest litter decomposition are reviewed in this paper. Nitrogen deposition can have indirect and direct effects on forest litter decomposition. By changing the composition of the forest floor and litter chemistry, N deposition indirectly changes litter decomposition rates. The direct effects of N deposition on forest litter decomposition range from positive to negative, and the mechanisms are reviewed in this paper. Finally, present and future research about the effects of N deposition on forest litter decomposition are also discussed.