Short-term intensive warming shifts predator communities (Parasitiformes: Mesostigmata) in boreal forest soils

Abstract

Increasing global mean surface temperatures from climate change will coincide with longer and more frequent short-term, extreme warming events. Because of this, habitats like boreal forests are predicted to have new temperature regimes. Boreal forest soils contain a diverse array of microarthropods and nematodes, which include the main soil predators, mesostigmatic mites (Acari: Parasitiformes: Mesostigmata). Although extensive research exists on how climate warming affects oribatid mite and collembolan communities, fewer studies have examined how warming effects Mesostigmata communities. We tested the effect of short-term (three months), intensive warming (+8 °C) on Mesostigmata communities from the boreal forest using experimental mesocosms containing forest-floor material. We collected moss mats and underlying forest floor organic material from a boreal forest and incubated them within individual mesocosms at 12 °C and 20 °C for three months, where 12 °C represented the long-term average growing season temperature and 20 °C corresponds to the potential extreme surface temperature from climate warming for the region. We enumerated all extracted microarthropods and nematodes, and identified all Mesostigmata adults to the species-level. In total, we counted 24,080 nematode individuals, and 19,582 total microarthropod individuals, of which 3349 individuals (1899 adults and 1450 juveniles) were mesostigmatic mites, consisting of 14 species. Mesostigmatic juvenile and adult abundances, along with adult community-level body mass were higher under warming, which lead to a shift in community composition. Changes to Mesostigmata communities were driven by the greater abundances of parthenogenetic species, primarily Veigaia mitis (Berlese), under warming—a response that has been shown in oribatid mite communities, but not mesostigmatic communities, before. Overall, we found that warming shifted mesostigmatic mite communities in the boreal forest, which has wide ranging implications for the soil food web.