Belowground communities in lowlands are less stable to heat extremes across seasons

Gerard Martínez De León , Ludovico Formenti, Jörg-Alfred Salamon, Madhav P. Thakur

Ecological responses to climate extremes vary drastically in different spatiotemporal contexts. Here, we investigate how soil communities at high- and low-elevation sites respond to extreme heat events in different seasons (spring, summer and autumn). We simulated 1-week heat events based on site-specific climatic history in laboratory experiments using 360 field-collected soil cores and measured the resistance and recovery of two major groups of soil biota: Collembola and fungi. We found that Collembola communities from low elevations exhibited the lowest resistance to extreme heat in spring and summer, with full recovery occurring primarily in spring soils. Fungal communities remained generally stable, though pathogens increased their relative abundances following summer heat events. Network analysis revealed increased connectance of negative associations between Collembola and fungi in response to extreme heat. We provide experimental evidence for how heat events can restructure and destabilise ecological communities depending on spatiotemporal contexts like elevation and seasonality.