A bottom-up perspective on how fire changes ecosystem biogeochemistry via plant-soil interactions

The effect of fire on plants and soils cannot be viewed in isolation. Plant-soil interactions, and their role in determining the response of ecosystem to fire, has been a widely debated topic. Most studies describe patterns rather than the mechanisms that may lead to variable effects on soils across ecosystems.

In this mini-review, we compile the literature on fire effects on soil processes to propose that a bottom-up framework considering plant-soil interactions is needed to explain the myriad of effects that fire has on soil biogeochemistry.

We highlight a number of processes that may be at play: (i) soil carbon saturation and mineral stabilization dynamics; (ii) nutrient-acquisition strategies (e.g., plant-microbial symbioses) and the emergence of biogeochemical feedbacks; (iii) physical soil changes that constrain carbon and nutrient turnover. We then highlight papers in this Special Issue on fire and plant-soil interactions that address these three processes to unpack how fire changes biogeochemical cycling in an ecosystem.

We conclude that while shifts in plant biomass composition and inputs consistently influence soil properties across studies, increasing evidence shows the critical role of plant-soil interactions in determining belowground processes.