Wildfires are increasing in severity and frequency, with well-documented, long-term effects on terrestrial ecosystem productivity and recovery, but the effects of wildfire on streams and rivers are less well understood. Most studies that include monitoring of streams post-fire are short-term and, by necessity, are designed to examine changes immediately following a fire event, not quantifying long-term or lagged responses to fire. In arid regions, changing fire regimes are coupled with changing precipitation regimes, potentially compounding disturbance signals and endangering downstream water supplies. We propose a conceptual framework describing how linked accumulation, transformation, transport, and propagation processes influence responses to fire in aridland catchments. We tested components of this framework using pre- and post-fire observations of stream chemistry from watersheds in southern California and northern New Mexico which are two areas with differing precipitation regimes. Using a multivariate autoregressive state-space approach, we demonstrate that changes in stream chemistry (e.g., nutrients and conductivity) due to wildfire can be lagged by up to 3-5 years due to intermittent precipitation. Such effects vary between the two hydroclimatic regimes (i.e., Mediterranean vs. snowmelt/monsoonal). Quantifying effects of feedbacks among fire and precipitation regimes will reduce uncertainty in predicting watershed processes and water quality following arid land wildfire in the Anthropocene. 

Primary Presenter: Alex Webster, University of New Mexico (awebster2@unm.edu)

Authors:

Heili Lowman, University of Nevada, Reno, Department of Natural Resources & Environmental Science  ()

Betsy Summers,   ()

Stevan Earl,   ()

Xiaoli Dong, University of California Davis, Department of Environmental Science and Policy  ()

Ann Marie Reinhold,   ()

Joanna Blaszczak,   ()

Marina Lauck,   ()

Leah Gaines-Sewell,   ()

Nancy Grimm,   ()

Tamara Harms, University of Alaska-Fairbanks, Institute of Arctic Biology  ()