Prevalence of stochastic processes in the fire-mediated reassemblage of the soil arthropod community of a pine forest

Abstract

Wildfires are significant disruptors of established communities, but natural fire regimens are essential to sustaining biodiversity in fire-prone ecosystems. Besides plants, soil arthropods are highly affected by wildfires, but their communities are also highly resilient to such catastrophic events. It is known that both stochastic (local extinction, dispersion, and colonization probabilities) and deterministic (environmental and biotic filters) processes take part in the reassembly of biotic communities after wildfires. However, the contribution of stochastic and deterministic processes in reassembling soil arthropod communities after wildfires remains unclear, and it is largely unknown how this is affected by fire severity. This study reports on the trophic guilds, taxa composition, and alpha and beta diversity partitioning of a soil arthropod community over one year, considering unburnt forest and two levels of fire severity in a pine forest in the eastern mountainous region of Mexico. The wildfire had a positive effect on the abundance of saprophagous species, especially in moderate-fire severity sites. Overall, the diversity of the community of soil arthropods has increased over time since the fire. Taxa turnover contributed beyond random expectations to the observed beta diversity, suggesting that stochastic processes predominated in the reassemblage of the soil arthropod community. We conclude that the changes in the alpha and beta diversity of the postfire soil arthropod community were affected by the severity of the wildfire and by the time that had passed since the fire event, showing a capacity for recovery to this type of disturbance.