Do biotic interactions control coastal forest resilience to extreme storm events? An exclusion experiment

Interactions between microbes, soil fauna, and root rhizospheres control the rates, pathways, and fates of plant litter decay through direct consumption and transformation of plant detritus, physical fragmentation and binding of organo-mineral aggregates, and microbial and plant root exudate accumulation and composition. Changes in the abundance and diversity of species affects the structure and functioning of ecosystems, as well as their ability to respond to and buffer the direct effects of abiotic drivers and disturbance events such as flooding. We describe a manipulative field experiment that assesses the regulatory role of belowground biotic interactions in coastal forest resilience to extreme storm events. Micrometer-scale mesh lining trenches in 0.75 m2 exclusion sub-plots were used to create four treatments: control (undisturbed forest floor); disturbance control (trenched and backfilled with no mesh to assess disturbance effect); microbes and fungi (roots excluded via 45 m mesh and 60 cm deep trench); and microbes only (1 m mesh, 60 cm trench). This work is part of the COMPASS project investigating the resistance and resilience of upland forests buffeted by extreme freshwater and seawater storm events, and we analyze (i) the separation of the four treatments CO2 and CH4 uptake and emission dynamics over 18 months and (ii) their differential response to a controlled freshwater flooding event. This experiment provides a robust and multifaceted estimate of heterotrophic and total soil respiration, and insight into how coastal forest soils respond to the rising intensity and frequency of disturbance events.