Short-term effects of wildfire on high elevation stream-riparian food webs

Understanding how wildfires affect food web structure and function remains an important challenge, especially at high elevations that historically have burned infrequently. In particular, fires may alter the magnitude of reciprocal cross-ecosystem subsidies, leading to indirect effects on aquatic and terrestrial consumers. We quantified characteristics of high-elevation (2500 to 3000 m) stream-riparian food webs at 10 locations in the southern Rocky Mountains less than one year following high-intensity, stand-replacing wildfires. Using a paired 'burned-unburned' stream survey design, we assessed benthic periphyton, aquatic macroinvertebrate community structure, trout population characteristics, trout stomach contents, inputs and emergence of insects to and from streams, and abundance of predatory riparian spiders that consume aquatic insects. Benthic macroinvertebrate density, flux of emerging aquatic insects, and riparian spider abundances were lower at burned sites. Fluxes of insect i..., Stream surveys – We surveyed five pairs of streams in late July and August of 2021 in the northern Colorado Rockies within the Arapaho and Roosevelt National Forests.  Three of the burned sites were within the perimeter of the Cameron Peak Fire, one was within the East Troublesome Fire, and one was within the Williams Fork Fire. Each burned site was paired with an adjacent unburned site outside of the fire perimeter. At each site, we calculated the percentage of upstream watershed area that had been burned. We also visually estimated local tree mortality along the riparian corridor (% of trees killed by fire). To characterize the stream environment, we measured stream widths, depths, discharge, chlorophyll a from periphyton, canopy cover, adjacent burn severity, water chemistry (dissolved oxygen, pH, water temperature, conductivity), and turbidity at each site at the time of the survey. We attempted to select sites that were similar in elevation, aspect, stream size, and valley classifi...,