Underground Lag: Fungal Community and Edaphic Legacies After Disturbance

ABSTRACT Páramos are neotropical mountain ecosystems that regulate water and store large amounts of carbon, but are increasingly degraded by agriculture and grazing. Although native vegetation often recolonizes after abandonment, belowground recovery remains poorly understood. We tested whether natural regeneration over contrasting recovery times yields parallel recovery of soil properties, arbuscular mycorrhizal fungi (AMF) abundance, and root‐associated fungal community composition. We compared two naturally regenerating sites in the Cumbal páramo (Nariño, Colombia) representing 12 and 45 years since disturbance. We measured soil properties, quantified AMF root colonization and spore density, and profiled root‐associated fungi using ITS metabarcoding. Soil organic matter and organic carbon showed no significant differences between sites, reaching comparable levels after 12 years of recovery. In contrast, soil fertility indicators increased with recovery time, with cation exchange capacity rising by ~8% and available phosphorus by ~21% at the long‐recovery site. AMF colonization decreased with recovery time (51.2%–44.6%), whereas spore density did not differ between sites and was highly variable. Alpha diversity of the root‐associated fungal community did not differ between sites. However, PERMANOVA showed that community composition varied with host plant species, recovery site, and their interaction, and redundancy analysis identified cation exchange capacity as the main edaphic correlate of community structure. Overall, results reveal a temporal decoupling between rapid vegetation/carbon recovery and slower, sometimes incomplete, recovery of soil fertility, highlighting root‐associated fungi and AMF functional metrics as sensitive indicators of belowground recovery and supports their application in nature‐based restoration and monitoring of high‐mountain páramo ecosystems.