Disturbance is a fundamental process in ecosystems, regulating the storage and turnover of carbon and nutrients in soils and the composition and diversity of plants and microbes. The potential for interactions among plants, microbes, and soils creates a complex landscape of possible biogeochemical responses to the changes in disturbance regimes brought on by climate change. Here, we attempt to unravel these interactions by focusing on one disturbance in particular, fire, and quantifying the effect of repeated burning on soil carbon and nutrients, and the composition and function of the plant and microbial communities. We use these measurements to evaluate how fire-driven changes in soil carbon and nutrient storage and cycling are coupled with changes in vegetation and microbial communities.
We intensively sampled five sites that have experienced altered fire frequencies for >30 years. We measured carbon and nutrients in soils using a stratified sampling approach to sample soils underneath focal plant species. Measurements of plant traits were combined with sequencing of microbial communities to gain insight into both the effect of fire on plants and microbes and the coupling among soil, plant, and microbial responses.
Results/Conclusions
We found that while frequent burning reduces plant biomass across all sites, its impact on soils are much more variable and differ considerably both among and within sites. Fire also altered the composition of plant species and their associated functional traits, which in some cases were associated with changes in soil nutrients. The response of microbial communities provided further insight into the complex response of the ecosystem to fire. Our results shed light on both the overall effects of fire on the biogeochemistry of ecosystems, as well as the complex indirect effects that emerge through the interaction between plants, microbes, and soils.