Ectomycorrhizal decomposition responses to elevated atmospheric carbon dioxide enrichment of a mature temperate deciduous forest

Xianbang Feng1, Sami Ullah2, Liz Hamilton2, Rob Mackenzie2, Iain Hartley1

1Geography, Faculty of Environment, Science and Economy, University of Exeter, Exeter, UK

2School of Geography, Earth & Environmental Sciences, University of Birmingham, and Birmingham Institute of Forest Research, Birmingham, UK

Keywords: Ectomycorrhiza, Plant-soil feedbacks, Carbon cycling, Organic matter decomposition, Elevated atmospheric carbon dioxide.

Abstract

Introduction/Aim

Addressing climate change concerns, this study investigates the impacts of elevated atmospheric carbon dioxide (eCO₂) in a mature temperate forest on plant-soil feedbacks, focusing on the decomposition of organic matter in soil as influenced by ectomycorrhiza (ECM). While ECM aids nutrient absorption, concerns arise regarding potential resource competition and its implications for carbon and nutrient cycling in mature, nutrient-limited forests.

Materials and Methods

Decomposition studies in the absence and presence of ECM colonization trials were conducted at the University of Birmingham Free-Air Carbon Dioxide Enrichment Facility (BIFoR-FACE). We deployed two mesh sizes of ECM in-growth bags (1-μm and 41-μm) containing sand and 1mm-mesh inner litter bags with soil organic matter or oak leaf litter for decomposition measurements over time. Here we present initial results after 4-months incubation.

Results

We observed that the 1-μm mesh effectively reduced ECM colonization without significantly affecting moisture inside. Bags with ECM colonization exhibited higher microbial respiration rates (mean increases 31.2% in control arrays, p<0.05, and 40.1% in eCO₂ arrays, p<0.001).

Discussion

Our preliminary findings suggest that ECM influences organic matter decomposition and responds to eCO₂. Ongoing research will assess the broader implications on decomposition, analysing the relationship between ECM colonization and mass loss. Future investigations using gene sequencing and extended incubation periods are planned.

Conclusions

Overall, our ECM-exclusion experiments are expected to help understand the influence of ECM on organic matter decomposition and how it responses to eCO₂. This study could have significant implications for understanding the role of mycorrhizal associations in ecosystem functions and their responses to global changes.