PARENT SESSION
Wednesday, August 9, 1:30-5:00 pm
COS 66 - Effects of herbivory II
Chickasaw, Mezzanine Level, Cook Convention Center
Presiders: S Louda
Nutrient amendment and herbivory interact differently for five arctic Alaska plant species.
Johnson, David*,1, Gough, Laura1, Ramsey, Elizabeth 1, 1 University of Texas at Arlington, Arlington, TX
ABSTRACT- Current and future atmospheric warming is expected to increase arctic tundra primary productivity by stimulating soil microbial activity thus increasing nutrients available for plants. Less well understood is how increased productivity may affect herbivore populations, with potential feedbacks to plants. We studied how adding nitrogen and phosphorus and excluding mammalian herbivores factorially for nine years affected growth of five plant species in dry heath (DH) and moist acidic tundra (MAT) communities at the Arctic Long Term Ecological Research site at Toolik Lake, Alaska. We predicted growth and sexual reproduction would be greatest inside fertilized herbivore exclosures, but the degree of response would differ among species depending on growth form and palatability. While all species increased growth following fertilization, species responded differently when herbivores were excluded depending on the amount of herbivory and growth form. For example, the tussock forming graminoid at DH increased growth and sexual reproduction regardless of the presence of herbivores, while the tussock forming graminoid at MAT grew better only when herbivores were excluded. Other fertilized plant growth forms were not affected by herbivore exclusion. Thus, herbivores can suppress growth of some species, while other species appear to grow well following herbivory, and yet others are not affected by herbivores because they are not being eaten. As the Arctic continues to warm and nutrients become more available to plants, the effect of herbivores on different plant communities may vary depending on initial species composition.
Key words: Arctic plant communities, herbivory, climate change