Effects of Prescribed-Fire and the Las Conchas Wildfire on the Resistance and Resilience of a Montane Grassland Stream on the Valles Caldera National Preserve

Prescribed fire is a management tool used to reduce fuel loads.  In contrast, wildfire severity may be so great as to result in recovery taking decades. On 26 June 2011, the Las Conchas wildfire burned a total of 63,420 ha making it the largest recorded fire in New Mexico. The fire burned over 30% of the Valle Caldera National Preserve including an open meadow stream treated in 2005 to a prescribed burn. Six years later, the Las Conchas fire provided an opportunity to compare the effects of the prescribed burn with a severe wildfire on fish density and sediment carbon:nitrogen (C:N) as an indirect measure of ash contribution. In 2005, density of adult brown trout decreased from 80 to 56 fish/100 m² after the prescribed burn.  Three years post-wildfire, populations of brown trout remain suppressed.  Adult brown trout has varied from 1.0 to 5.5 fish/100 m².  Average C:N varied slightly between pre-burn (11.5 ± 0.42, mean ± standard error) and post-burn (13.4 ± 0.39) indicating very little contribution of ash to the stream from the prescribed burn.  As a result of the Las Conchas fire, however, C:N has remained elevated for three years post-burn (spring 2014; 22.6 ± 4.50).