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Presented at the NABS Annual meeting, Vancouver, British Columbia, 2004
in Communities 2
“Trait succession”: species traits of stream insects explain community succession after post-fire flash floods
N.K.M. Vieira. Department of Biology, Colorado State University, Fort Collins, CO 80523
Species traits (i.e. life–history, morphological and behavioral adaptations) interact with environmental conditions to shape how stream insect populations respond to disturbance. Therefore, changes in trait frequencies in a community should explain species–based patterns of community recovery. Using a BACI approach, I compared changes in insect communities and trait frequencies between burned and reference streams (north–central NM) for two years before, and six years after post–fire flash floods. A priori hypotheses regarding the resistance/resilience strength of traits to hydrologic disturbance were developed from the literature and were tested by exploring trait responses to flood magnitude, recovery time and season. As predicted, resistant traits (mediating displacement through swimming, attachment or burrowing) characterized species in early post–fire years with moderate floods. Resilient traits also characterized early successional species (strong larval dispersers, multivoltine, collector feeders), as well as species that recolonized once floods abated (strong adult dispersers, sediment/silt tolerant). Over the same eight–year period, trait frequencies in reference communities only fluctuated seasonally and trait diversity remained high. “Trait succession”, in context of environmental conditions and geographic barriers to colonization, explained mechanisms behind community recovery after post–fire flooding. In general, trait–based analyses provide an ecologically relevant tool for comparing communities along spatiotemporal gradients of disturbance.
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