title: Revisiting the 'Gadgil effect': do interguild fungal interactions control carbon cycling in forest soils?
abstract: In forest ecosystems, ectomycorrhizal and saprotrophic fungi play a central role in the breakdown of soil organic matter (SOM). Competition between these two fungal guilds has long been hypothesized to lead to suppression of decomposition rates, a phenomenon known as the 'Gadgil effect'. In this review, we examine the documentation, generality, and potential mechanisms involved in the 'Gadgil effect'. We find that the influence of ectomycorrhizal fungi on litter and SOM decomposition is much more variable than previously recognized. To explain the inconsistency in size and direction of the 'Gadgil effect', we argue that a better understanding of underlying mechanisms is required. We discuss the strengths and weaknesses of each of the primary mechanisms proposed to date and how using different experimental methods (trenching, girdling, microcosms), as well as considering different temporal and spatial scales, could influence the conclusions drawn about this phenomenon. Finally, we suggest that combining new research tools such as high-throughput sequencing with experiments utilizing natural environmental gradients will significantly deepen our understanding of the 'Gadgil effect' and its consequences on forest soil carbon and nutrient cycling.
authors.affiliation: Departments of Plant Biology and Ecology, Evolution, and Behavior, University of Minnesota, St Paul, MN, 55108, USA.
authors.forename: Christopher W
authors.identifier: http://orcid.org/0000-0002-6310-6027
authors.initials: CW
authors.lastname: Fernandez
authors.affiliation: Departments of Plant Biology and Ecology, Evolution, and Behavior, University of Minnesota, St Paul, MN, 55108, USA.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Kennedy
mesh_terms: D057486:Carbon Cycle; D065928:Forests; D005658:Fungi / Q000502:physiology*; D008954:Models, Biological; D012106:Research; D012988:Soil Microbiology
keywords: carbon sequestration; competition; decomposition; ectomycorrhizal fungi Gadgil effect; litter; nitrogen cycle; saprotrophic fungi; soil organic matter (SOM)