First-year effects of tundra fire on benthic macroinvertebrate communities in streams on the North Slope, Alaska

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Angela Allen
B.J. Peterson
A.D. Huryn
E.B. Schuett
S.M. Parker
G.W. Kling

Post-fire nutrient enrichment is known to affect benthic macroinvertebrate assemblages and stream food webs in forested regions, but little is known about the impact of tundra fires. The 2007 Anaktuvuk River fire (North Slope, Alaska), the largest recorded tundra fire (≈1,000 km2), provided an opportunity to study the first-year effects of a tundra fire on stream communities. We predicted that a tundra fire would increase inorganic nutrient inputs to streams, thereby increasing primary production and in turn, increasing abundance and biomass of benthic macroinvertebrates. To test these predictions, we examined water chemistry and benthic macroinvertebrate communities in streams draining burned and unburned catchments in the first post-fire summer. Preliminary results show higher NH4+ and SRP (p=0.003 and p=0.014, ANOVA, respectively) in burned streams compared to reference streams, but no differences in chl-a values. Contrary to our prediction, we observed significantly lower benthic macroinvertebrate abundances (p=0.049, ANOVA) in burned streams and no differences in biomass. These results suggest benthic macroinvertebrate abundance in tundra streams is sensitive to fire, but is compensated by higher growth rates or altered community composition. It is important to document macroinvertebrate community resilience as Arctic warming may increase the frequency and size of tundra fires in Alaska.

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