Spatiotemporal controls on the delivery of dissolved organic matter to
streams following a wildfire
Abstract
Warmer and drier climate has contributed to increased occurrence of
large, high severity wildfires in the Pacific Northwest, drawing
concerns for water quality and ecosystem recovery. While nutrient fluxes
generally increase post-fire, the composition of organic matter (OM)
transported to streams immediately following a fire is poorly
constrained, yet can play an integral role in downstream water quality
and biogeochemistry. Here, we quantified spatiotemporal patterns of
dissolved OM (DOM) chemistry for five streams burned by wildfires in
Oregon, USA in 2020. We sampled over a 24-hour storm event one month
after the fire, revealing variable temporal behavior in DOM dynamics.
DOM chemistry was directly related with burn severity spatially.
Specifically, nitrogen and aromatic character of DOM increased in
streams burned at greater severity. Our results suggest a spatial
overprinting of DOM dynamics immediately following fire activity and
highlight a key gap in our knowledge of post-fire DOM transport to
streams.