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Latebreaking Poster

Session: Plant-Insect Interactions (Latebreaking)

LB 33-273 - The circle of life in the arctic tundra: Does burning affect the relationship between tussock cottongrass, grass flies, and parasitoid wasps?

Thursday, August 10, 2023
5:00 PM – 6:30 PM PDT
Location: ESA Exhibit Hall
Polar amplification is causing climate change to proceed faster in the Arctic regions than anywhere else, threatening the health and stability of unique ecosystems like the tundra. Eriophorum vaginatum, (tussock cottongrass) is considered a foundation species in the peat bogs, and rolling hills of the circumpolar region. The optimum climate for Alaskan cottongrass has already shifted 140 kilometers northward because of warming temperatures associated with climate change. In order to better understand the impacts polar amplification could have on the tussock tundra, we need to first understand the roles cottongrass serves as a foundation species. E. vaginatum is known to be well-adapted to disturbed habitat, so by comparing undisturbed habitat to a burned site, we aimed to determine if this system is regulated by the habitat and nutrients present or herbivore/predator relationships. In early June of 2007, exclusion bags were fastened to the inflorescences of Eriophorum vaginatum at three sites in the northeast Brooks Range: Toolik Lake (68°38'N 149°35'W), Sagwon (69°27'N, 148°39'W) and the Anaktuvuk Burn (68°58'N, 150°16'W). The mesh of the bags was large enough to allow pollen to pass through, but too small to allow parasitoid wasps in or phytophagous flies out. After collecting bagged and unbagged infructescences from each site, the fruits were dissected and the number of seeds, flies, and wasps per sample was recorded. After log transforming these data, results of two-way ANOVA and Tukey’s HSD test reveal higher seed counts in control samples from the burned site, indicating an influence of nutrients on production, consistent with prior findings. Bagged samples from the burn site were not significantly different from other sites, showing a significant effect of the herbivorous fly on the number of viable seeds, and indicating the importance of the parasitoid wasp in regulating the community. Our study suggests this unknown, rare wasp plays a significant role in preventing the fly from consuming too many seeds, and its removal from the ecosystem could result in devastating trophic cascades.