Investigating the Effects of Future Climate on Arbuscular Mycorrhizal Fungal Spore Dynamics in a Belgian Pear Orchard Ecosystem

Chloë Vercauteren , Vera Claessens, Nadia Soudzilovskaia

Climate change affects soil microbial communities, including arbuscular mycorrhizal fungi (AMF), crucial for plant nutrient uptake and resistance to pathogens. This study examines the impact of future climate on the abundance, functional group composition and temporal dynamics of AMF spores in Belgian pear orchards using an advanced Ecotron climate simulation facility. By simulating present (2013-2018) and future (2042-2046) climates based on the “worst-case” scenario (RCP 8.5), the sporulation responses of the two main AMF functional groups (Glomeraceae and Gigasporacea) to climate change were assessed. Gigasporaceae prioritize biomass allocation to slow-growing extraradical hyphae, favoring survival in low-stress, low-disturbance environments. In contrast, Glomeraceae fungi adopt a ruderal strategy, prioritizing rapid colonization of roots rather than soil. The results show that overall AMF spore abundance was not affected by climate treatment, suggesting that AMF sporulation is resistant to climate alterations. However, Glomeraceae consistently exhibited higher spore abundance than Gigasporaceae across all phenological time points. Despite this, the abundances of the functional groups—i.e., functional group composition— remained unaffected by climate treatment. Notably, phenological shifts in spore production were observed, with a mid-summer peak in Glomeraceae spore counts in 2013-2018 that diminished towards 2042-2046, leading to a more stable phenological distribution. This outcome suggests that climate change influences AMF phenology rather than overall abundance or functional group composition. Our research advances the understanding of climate-driven dynamics of AMF in agricultural systems, providing insights into sustainable crop production and soil fertility under future climate conditions.