Multi-trophic resilience of boreal lake ecosystems to forest fires

Ecology
University of Alaska; US Fish and Wildlife Service (Yukon Flats NWR)
By: , and 

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Abstract

Fires are the major natural disturbance in the boreal forest, and their frequency and intensity will likely increase as the climate warms. Terrestrial nutrients released by fires may be transported to boreal lakes, stimulating increased primary productivity, which may radiate through multiple trophic levels. Using a before-after-control-impact (BACI) design, with pre- and postfire data from burned and unburned areas, we examined effects of a natural fire across several trophic levels of boreal lakes, from nutrient and chlorophyll levels, to macroinvertebrates, to waterbirds. Concentrations of total nitrogen and phosphorus were not affected by the fire. Chlorophyll levels were also unaffected, likely reflecting the stable nutrient concentrations. For aquatic invertebrates, we found that densities of three functional feeding groups did not respond to the fire (filterers, gatherers, scrapers), while two groups increased (shredders, predators). Amphipods accounted for 98% of shredder numbers, and we hypothesize that fire-mediated habitat changes may have favored their generalist feeding and habitat ecology. This increase in amphipods may, in turn, have driven increased predator densities, as amphipods were the most numerous invertebrate in our lakes and are commonly taken as prey. Finally, abundance of waterbird young, which feed primarily on aquatic invertebrates, was not affected by the fire. Overall, ecosystems of our study lakes were largely resilient to forest fires, likely due to their high initial nutrient concentrations and small catchment sizes. Moreover, this resilience spanned multiple trophic levels, a significant result for ecologically similar boreal regions, especially given the high potential for increased fires with future climate change.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Multi-trophic resilience of boreal lake ecosystems to forest fires
Series title Ecology
Volume 95
Issue 5
Year Published 2014
Language English
Publisher Brooklyn Botanical Garden
Publisher location Brooklyn, NY
Contributing office(s) Alaska Science Center Biology WTEB
Description 11 p.
First page 1253
Last page 1263
Online Only (Y/N) N
Additional Online Files (Y/N) N