Colorado mountains
From Long-Term Data to Understanding: Toward a Predictive Ecology
2015 LTER ASM Estes Park, CO - August 30 - September 2, 2015

Ant (Hymenoptera: Formicidae) assemblages in aspen-dominated versus black spruce-dominated post-fire successional trajectories in boreal black spruce forest of interior Alaska

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Alexandria Wenninger
Diane Wagner

Research suggests that climate warming will cause an increase in fire frequency and severity in Alaskan boreal forests, increasing the proportion of younger successional forests over time, and shifting forests previously dominated by black spruce to forests dominated by deciduous species. These changes in post-fire succession have the potential to cause widespread changes in arthropod communities throughout boreal interior Alaska. I predict that heterogeneity in understory vegetation and microclimate associated with young forests will foster a diverse prey base, promoting a rich community of predatory Hymenoptera, specifically ants (Formicidae). Additionally, I hypothesize that an increase in deciduous trembling aspen (Populus tremuloides) will increase the diversity of ants; aspen is highly palatable in comparison to black spruce, which may increase the diversity and abundance of available prey, and also produces extrafloral nectar, which mediates an indirect defense by attracting and nourishing ants. The objectives of this project are 1) to characterize changes in the boreal Hymenoptera community during post-fire succession and 2) to test the hypothesis that aspen fosters higher abundance and diversity of ants than black spruce. Ants will be sampled across successional time (young and intermediate-aged post-fire regenerating forests) and between two successional trajectories (shift to aspen and return as black spruce). Field collection of ants includes pitfall trapping and sweep netting. The data will be used to characterize and compare the Hymenoptera communities among successional ages and trajectories. Preliminary results suggest that ants are more abundant and speciose in young successional forests compared to intermediate aged forests, regardless of successional trajectory. The ant communities of young successional forests are also compositionally dissimilar to the intermediate aged forests. This work will contribute to understanding how climate change will impact boreal insect communities. 

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