Decomposers in disguise: mycorrhizal fungi as regulators of soil C dynamics in ecosystems under global change

By J. M. Talbot, S. Allison, K. Treseder. 2008

528 citations recorded by the source corpus.

Author(s): Talbot, JM; Allison, SD; Treseder, KK | Abstract: 1. In the conventional view of soil carbon (C) cycling, mycorrhizal fungi are primarily considered vectors for plant C input to soils. However, there is accumulating evidence that mycorrhizal fungi may also contribute to the direct loss of soil C by acting as decomposers, that is by producing extracellular lytic enzymes and metabolizing soil C. 2. Most of the evidence that mycorrhizal fungi can act as decomposers comes from studies of ericoid and ectomycorrhizal fungi, although there is increasing experimental evidence for a role of arbuscular mycorrhizal fungi in soil C decomposition. Decomposition by mycorrhizal fungi implies that soil C balance is subjected to the ecological factors that affect both plant and fungal symbionts; this interaction has important consequences for how soil C stocks respond to global change. 3. In this synthesis, we propose a new model of soil C cycling, including decomposition of soil C by mycorrhizal fungi, and we evaluate how this new integrative model alters our predictions of soil C feedbacks to global change. We present three hypothetical mechanisms by which mycorrhizal fungi may metabolize significant quantities of soil C. The first hypothesis ('Plan B' hypothesis) is that mycorrhizal fungi metabolize soil C as an alternate C source when supplies of photosynthate from the host plant are low. Our second hypothesis ('Coincidental Decomposer' hypothesis) is that mycorrhizal fungi decompose soil C as a consequence of mining soil for organic nutrients. The third hypothesis ('Priming Effects' hypothesis) is that mycorrhizal fungi decompose soil C when allocation of plant photosynthate to mycorrhizal roots is high, such that plant C 'primes' the growth and activity of mycorrhizal fungi. 4. Further empirical tests of these hypotheses will clarify the role of mycorrhizal fungi in soil C balance and improve our understanding of soil C responses to global change. © 2008 The Authors.

Subfields: Nature and Landscape Conservation, Plant Science, Soil Science

View Paper: https://www.semanticscholar.org/paper/6557cf464d218c0584b8d713eb806ec001175799

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Citations in the corpus

Stoichiometry constrains microbial response to root exudation- insights from a model and a field experiment in a temperate forest (2012, background): “, lignin) through other mechanisms such as C allocation to mycorrhizal fungal associates, which decompose a wide range of SOM substrates and transfer large quantities of nutrients to plant hosts (Chalot and Brun, 1998; Hodge et al., 2001; Hobbie and Hobbie, 2006; Talbot et al., 2008; Kaiser et al., ”
Root carbon inputs to the rhizosphere stimulate extracellular enzyme activity and increase nitrogen availability in temperate forest soils (2011, background): “…hydrolytic enzymes (e.g., protease, chitinase, glucosidase) in addition to oxidative enzymes that attack recalcitrant forms of SOM (e.g., lignin, polyphenolic compounds) (Chalot and Brun 1998; Talbot et al. 2008), which also tend to occur in greater abundance in ECM soils (Finzi et al. 1998a).”
Arbuscular mycorrhizal hyphae promote priming of native soil organic matter mineralisation (2016, background): “ectomycorrhizal fungi (Talbot et al. 2008; Bodeker et al. 2014), there is no evidence that they have the saprotrophic capacity to mineralise polymeric organic”
Controls over mycorrhizal uptake of organic nitrogen (2010, background): “Plant C distribution to roots occurs when the plant exhibits high rates of photosynthesis, such as under high light availability or low cloud cover (Talbot et al., 2008), or when the plant experiences elevated levels of CO2 (Andrew and Lilleskov, 2009) or low levels of mineral nutrients in soils (Tr”
Rhizosphere priming: a nutrient perspective (2013, background): “These fungal decomposers act more like K-strategists, and may be saprotrophic or mycorrhizal (Talbot et al., 2008).”
Litter quality is in the eye of the beholder: initial decomposition rates as a function of inoculum characteristics (2009, background): “Certainly, the functional symbiosis of plants and mycorrhizal fungi, which may play a crucial role in decomposition (Talbot et al. 2008), was absent.”
Laccases: toward disentangling their diversity and functions in relation to soil organic matter cycling (2010, background): “…the SOM saprotrophically by producing extracellular enzymes, thus contributing to different parts of the soil carbon cycle, especially the influence of mycorrhizal fungi in both input and loss of soil carbon from the environment (Cullings and Courty 2009; Cullings et al. 2008; Talbot et al. 2008).”
Phenol oxidase, peroxidase and organic matter dynamics of soil (2010, background): “…metagenome shifts with canopy and litter composition and the shift from ectomycorrhizal to arbuscular mycorrhizal symbioses, but the implications of this for the regulation of soil oxidative activity in relation to global shifts in climate or N deposition are largely unknown (Talbot et al., 2008).”
Microbes as Engines of Ecosystem Function: When Does Community Structure Enhance Predictions of Ecosystem Processes? (2016, background): “While we acknowledge that factors such as unmeasured variables, macroinvertebrates (Ferris et al., 2004), fungi (Talbot et al., 2008), plant communities (Hanson et al., 2000), and non-linearity could reduce the explanatory power of our models, a number of ecological dynamics can disassociate…”