Decreased Soil Microbial Biomass and Changed Microbial Community Composition following a Defoliation Event by the Forest Tent Caterpillar

With climate change projected to increase the frequency and severity of episodic insect outbreak events, assessing potential consequences for soil microbial communities nutrient dynamics is importance understanding forest resilience. The tent caterpillar (Malacosoma disstria) an important defoliator deciduous tree species in temperate mixed forests eastern North America with invasion cycle every 10–12 years events that can last 3–6 years. Following a defoliation episode on trembling aspen (Populus tremuloides) from 2015 2017 Abitibi-Témiscamingue, QC, Canada, we sought test if resulted changes bacterial fungal communities. We hypothesized biomass due increased frass inputs community structure following event. Soils were sampled August 2018, May 2019 July sites had been subjected during where no recorded. assessed total activity ratio all sampling dates, Community Level Physiological Profiles (CLPPs) 2018 only using substrate-induced respiration method. Contrary our hypothesis, observed significant 50% decrease (μg biomass-C g−1 hour−1) defoliated stands, suggesting carbon normally allocated towards root exudates was reallocated foliage regeneration. noted differentiated carbon-based substrate usage defoliation, but ratio. two event suggest episodes above-ground could trigger chemistry below-ground effects may, turn, feedback influence plant dynamics.