PNNL

The Science                                 

Wildfires can influence both terrestrial and aquatic biogeochemical cycling through the alteration of organic matter during burning. This research compares different burning methods to simulate wildfire to examine alterations to the chemical composition of plants through the production of chars. The study found that the way a fire burns (in open air versus in an oven in a controlled lab setting) can greatly change the leftover materials (char or charcoal) and how they interact in the environment. Notably, open-air fires produce materials that can dissolve and move into water systems more easily. This suggests that our current lab methods might not fully capture the real-world impact of wildfires.

The Impact

This research helps us to better understand the environmental impact of wildfires. The open-air burns conducted in this study set the stage for more environmentally relevant studies on the aquatic biogeochemical impacts of wildfires. The study reveals that our current lab methods may not fully capture the chemical transformations of organic matter produced by wildfires, potentially leading to underestimations of their biogeochemical impacts. This is a significant finding as it could lead to more accurate predictions of biogeochemical cycling in post-fire landscapes.

Summary

Wildfires create leftover materials (chars) with unique properties that affect how they interact with the environment. Visual burn severity assessment is used to evaluate post-fire alterations to the landscape in field-based studies, yet muffle furnace methods are commonly used in laboratory studies to understand organic matter composition. In this study, we looked at the characteristics of chars from low-severity burns, created either in an open-air or lab setting. We found that the lab-produced materials had less easily dissolvable carbon and nitrogen and had more uniform organic matter chemistries than those from open-air burns. This shows that, even within the same severity of burns, there can be differences in the chars created, which could change how they behave in the environment, such as their movement and processing in watersheds. We recommend more open-air burn studies to better understand the behavior and fate of these materials in the environment.

Contacts

Allison Myers-Pigg, Pacific Northwest National Laboratory Marine and Coastal Research Laboratory, allison.myers-pigg@pnnl.gov  

Funding

This research was supported by the US Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research (BER), Environmental System Science (ESS) Program.