title: Differences in fungal and bacterial physiology alter soil carbon and nitrogen cycling: insights from meta-analysis and theoretical models.
abstract: Since fungi and bacteria are the dominant decomposers in soil, their distinct physiologies are likely to differentially influence rates of ecosystem carbon (C) and nitrogen (N) cycling. We used meta-analysis and an enzyme-driven biogeochemical model to explore the drivers and biogeochemical consequences of changes in the fungal-to-bacterial ratio (F : B). In our meta-analysis data set, F : B increased with soil C : N ratio (R(2) = 0.224, P < 0.001), a relationship predicted by our model. We found that differences in biomass turnover rates influenced F : B under conditions of C limitation, while differences in biomass stoichiometry set the upper bounds on F : B once a nutrient limitation threshold was reached. Ecological interactions between the two groups shifted along a gradient of resource stoichiometry. At intermediate substrate C : N, fungal N mineralisation fuelled bacterial growth, increasing total microbial biomass and decreasing net N mineralisation. Therefore, we conclude that differences in bacterial and fungal physiology may have large consequences for ecosystem-scale C and N cycling.
authors.affiliation: Section of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA. bonnie.waring@gmail.com
authors.forename: Bonnie G
authors.initials: BG
authors.lastname: Waring
authors.forename: Colin
authors.initials: C
authors.lastname: Averill
authors.forename: Christine V
authors.initials: CV
authors.lastname: Hawkes
mesh_terms: D018407:Bacterial Physiological Phenomena; D002244:Carbon / Q000032:analysis*; D005658:Fungi / Q000502:physiology*; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis*; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen