The accumulation, decomposition and ecological effects of above-ground litter in terrestrial ecosystem

Abstract

Understanding of the accumulation and decomposition processes of above-ground litter is of importance for us to study its ecological function and service in terrestrial ecosystems. The current paper first reviews the accumulation and decomposition processes of above-ground litter in terrestrial ecosystem and factors that affect these two ecological processes, then summarizes the ecological effects of above-ground litter in terrestrial ecosystem as a result of its accumulation and decomposition. Finally, under the view of global climate change, based on previous research progress, we review the perspectives of research on above-ground litter in terrestrial ecosystem. On the temporal scale, the accumulation of above-ground litter commonly follows the plant life cycle, and it is also regulated by environment factors, such as climatic conditions, soil temperature and moisture. On the large spatial scale, the accumulation of above-ground litter is primarily controlled by hydrothermal factors, resulting in the change in vegetation type, which show a decreased trend with the elevated latitude. However, on the local scale, apart from the constraints of hydrothermal factors, the accumulation of above-ground litter are also impacted by community structure, soil conditions, activities of herbivores, which shows more variability. Human disturbance is also an important factor that induces change of terrestrial vegetation cover and litter accumulation, and in many cases the changes are even irreversible. The decomposition processes of above-ground litter in terrestrial ecosystem include leaching, photo-degradation, soil animal and microbial decomposition. These decomposition processes occur simultaneously and interactively. Although still it is not well known now, distinguishing these decomposition process and fate of decomposition products with them are of importance for understanding the nutrient recycle in terrestrial ecosystem. Litter decomposition firstly is determined by its type, chemical composition, species diversity, but also affected by decomposer community and abiotic environment factors. Among these factors, the relationships between decomposition and litter chemical traits, species diversity and soil nutrient status are the key focus of this study. Through its accumulation and decomposition, above-ground litter has significant effects on terrestrial ecosystem physically, chemically and biologically. Currently, there are ample studies on the physical and chemical properties of above-ground litters, but there are very few studies on the biological property of above-ground litter, especially for the effects above-ground litters on vegetation that are still controversial as they are limited by complicated factors, including litter quantity, environment condition, the traits from impacted plants, even some unknown factors by now. Global climate change may change the accumulation and decomposition of above-ground litter and their ecological effects on the distribution, growth and traits of terrestrial plants in terrestrial ecosystem, through changes of climate and soil conditions. Under the global climate change, it is necessary to study the litter production and trait change on the spatial scales, expound the compartment model of litter decomposition on the temporal and spatial scales, deeply analyze the relationships between above-ground litter traits and decomposition, and further reveal the ecological effects of above-ground litter when relative limited factors are integrated into analysis, understand and predict the impact of above-ground litter on terrestrial ecosystem function and service under the scenario of the future environment change.