Restoration plantations accelerate recovery of fungal communities of coarse woody debris in southern Costa Rica

Fungi are essential to forests because of their role in the nutrient cycle as the primary decomposers of woody debris. Anthropogenic disturbances threaten forest ecosystems and reduce fungal diversity, changing the way carbon moves through the ecosystem. We experimentally investigated the effectiveness of two forest restoration treatments at recovering old-growth forest fungal communities and the relative importance of direct and indirect exposure of woody substrates to large insects for subsequent fungal colonization in a tropical premontane landscape. Restoration treatments consisted of 17–18-year-old, 50 × 50 m plantation and natural regeneration plots compared to nearby reference forest plots. We introduced three Inga edulis logs into each restoration and reference plot (nine logs/site; five sites) and applied the following treatments: 1) control logs open to the environment, 2) logs enclosed in cages to exclude arthropods >2 mm, 3) logs enclosed in cages and drilled with holes to mimic wood-boring arthropods. After one year, we extracted samples from the logs, describing their fungal communities using metabarcoding. Fungal community composition in logs from plantations resembled that of reference forests, while logs in natural regenerations did not. Limiting arthropod access diminished fungal richness in plantation treatments and reference forest by ∼19 %, suggesting that arthropods play a role in facilitating fungal colonization. Results suggest that the biotic and abiotic processes of tropical forests impacting fungal colonization and dispersal are effectively restored through restoration plantations in less than 20 years when remnant forest patches are present nearby, a shorter timeframe than that of natural regenerations.