Abstract
Predicting the influence of biotic and abiotic factors on species interactions and ecosystem processes is among the primary aims of community ecologists. The composition of saprotrophic fungal communities is a consequence of competitive mycelial interactions, and a major determinant of woodland decomposition and nutrient cycling rates. Elevation of atmospheric temperature is predicted to drive changes in fungal community development. Top-down regulation of mycelial growth is an important determinant of, and moderator of temperature-driven changes to, two-species interaction outcomes. This study explores the interactive effects of a 4 °C temperature increase and soil invertebrate (collembola or woodlice) grazing on multispecies interactions between cord-forming basidiomycete fungi emerging from colonised beech (Fagus sylvatica) wood blocks. The fungal dominance hierarchy at ambient temperature (16 °C; Phanerochaete velutina > Resinicium bicolor > Hypholoma fasciculare) was altered by elevated temperature (20 °C; R. bicolor > P. velutina > H. fasciculare) in ungrazed systems. Warming promoted the competitive ability of the fungal species (R. bicolor) that was preferentially grazed by all invertebrate species. As a consequence, grazing prevented the effect of temperature on fungal community development and maintained a multispecies assemblage. Decomposition of fungal-colonised wood was stimulated by warming, with implications for increased CO2 efflux from woodland soil. Analogous to aboveground plant communities, increasing complexity of biotic and abiotic interactions appears to be important in buffering climate change effects on soil decomposers.
Highlights
The influence of environmental change on species interactions is a major determinant of community structure and function [1]
This study explored the interactive effects of soil invertebrate grazing and warming on the outcomes of three-species interspecific mycelial interactions and fungal-mediated wood decomposition
A clear hierarchy of competitive dominance was evident at ambient temperature (16 uC) from three-species interactions between wood decomposer fungi
Summary
The influence of environmental change on species interactions is a major determinant of community structure and function [1]. Predicting how biotic and abiotic context affects the responses of species interactions and ecosystem processes to climate change remains one of the greatest challenges in community ecology [2]. Competitive mycelial interactions determine fungal dominance and community composition [13]. These fungi largely compete, for space first and foremost, by antagonistic mechanisms commonly referred to as combat [13]. Factors affecting competitive fungal interaction outcomes will influence nutrient cycling and CO2 efflux from soil, as a consequence of species-specific extracellular enzyme production and resource decomposition rates [14,15]
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