Revisiting the ‘Gadgil effect’: do interguild fungal interactions control carbon cycling in forest soils?

Abstract

1382I.1382II.1383III.1383IV.1384V.1386VI.1387VII.1389VIII.13911391References1391 Summary 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.

Maintaining connectivity: understanding the role of root order and mycelial networks in fine root decomposition of woody plants

“…the 'Gadgil Effect. ' (Gadgil andGadgil 1971, 1975;Koide and Wu 2003;Fernandez et al 2015). The magnitude of the Gadgil effect is thought to be greatest in organic soil layers which are sensitive to changes in soil moisture and where competition for N is likely high (Bending 2003;Koide and Wu 2003).…”

“…SAP fungi tend to colonize more recently shed litter at the forest floor surface and mycorrhizal fungi are more abundant in the underlying layers which contain older, more decomposed litter (Lindahl et al 2007;Clemmensen et al 2013;Bödeker et al 2016). Whether this vertical separation is the result of competitive exclusion of saprotrophic fungi by ECM or niche differentiation needs to be addressed (Fernandez and Kennedy 2015). Bödeker et al 2016 tried to address this question by investigating the vertical positions of saprotrophic and ECM fungi in the soil profile and the potential for different fungal guilds to colonize substrates of varying quality.…”

Trait‐dependent distributional shifts in fruiting of common British fungi

“…Meanwhile, there is evidence that some ECM species can associate with novel hosts, facilitating range expansion and invasion into new habitats (Wolfe and Pringle 2012). Furthermore, interactions between saprotrophic and ECM fungi can contribute to the structuring of fungal communities (Leake et al 2002), with important ecosystem-level consequences (Fernandez and Kennedy 2016). Furthermore, interactions between saprotrophic and ECM fungi can contribute to the structuring of fungal communities (Leake et al 2002), with important ecosystem-level consequences (Fernandez and Kennedy 2016).…”

Ian A. Dickie

“…Mycorrhizal carbon cycling is incredibly complex, requiring an understanding of fungal community ecology, stoichiometry, evolution, genomics, and ecosystem ecology (Chagnon et al, 2016). New Phytologist has published a number of key papers in this area recently, including some pretty strong divergence in viewpoints (Lindahl & Tunlid, 2015;Fernandez & Kennedy, 2016;Baskaran et al, 2017;Pellitier & Zak, 2017). This is both a biologically fascinating and environmentally critically important area to watch over the next few years, and I expect that New Phytologist will be playing a key role in publishing the most innovative advances.…”