Anthropogenic Nitrogen Deposition and Decomposer Fungi: Altered Composition and Function Fosters Greater Soil Carbon Storage

atmospheric N deposition;fungi;fungal communities;Ecology and Evolutionary Biology;Natural Resources and Environment;Science;Natural Resources and Environment

Entwistle, ElizabethJames, Timothy Y ;

University of Michigan

关键词: atmospheric N deposition;    fungi;    fungal communities;    Ecology and Evolutionary Biology;    Natural Resources and Environment;    Science;    Natural Resources and Environment;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/135783/eentwis_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The anthropogenic deposition of reactive nitrogen (N) onto terrestrial ecosystems has accelerated dramatically in the last 160 years as the result of human activity, with future rates of deposition projected to increase further.In some temperate forests, experimental increases in N deposition have reduced decomposition and concomitantly increased soil carbon (C) storage.One mechanism proposed to explain this response is that experimental N deposition negatively affects fungal decomposers of lignin, a recalcitrant constituent of plant cells which limits the overall rate of plant litter decay. More specifically, anthropogenic N deposition is hypothesized to reduce fungal lignolysis, and, as a result, reduce the representation of lignolytic fungi while favoring fungal taxa which are less efficient lignin decomposers.I tested this mechanism by examining the composition and diversity of fungi and the lignolytic genes that they express in a long-term field experiment in a series of northern hardwood forests, which have received experimental N deposition (3 g N m-2 y-1) for nearly 20 years.First, I found that experimental N deposition altered the composition of the active fungal community in the forest floor, whereas it had miminal effect on fungal richness and diversity.In my second experiment, experimental N deposition reduced the abundance of lignolytic fungi occurring on high-lignin and wood substrates; this appeared to be part of an overall change in fungal community composition in response to experimental N deposition, wherein lignolytic taxa declined and cellulolytic fungi increased in relative abundance.In Chapter 3, I found that experimental N deposition altered the composition, but not the richness or diversity, of expressed class II fungal peroxidases in the forest floor.Together, my results revealed that experimental N deposition reduces decomposition of plant litter and increases soil C storage by altering the composition and activity of fungal decomposers.This research improves our understanding of the biological mechanism through which an agent of global change alters biogeochemical cycling in temperate forest ecosystems.