Browsing by Author "Peterson, Julie"

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    Diversity Paper (untitled)
    (2011-02-09) Peterson, Julie
    Species diversity, the number of species present in a community, is relatively easy to quantify but can be very difficult to explain. Mostly this is because through various sampling methods you can determine how many individuals of which species are present in an area. But to determine why those species are there in those proportions you need to know many details of the species and individual needs as well as how the factors interrelate. Three major factors thought to influence patterns of diversity are the physical structure of the habitat (vegetation, objects, soil), the climate and climatic stability of the habitat, and the productivity of the habitat as a whole and of individual resources (MacArthur, 1972). Our experiment examined the small mammal communities of various sites in both forest and prairie habitats. We wanted to determine which habitat type has greater species diversity and whether there are species present in both habitats.
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    Effects of Plains Pocket Gopher (Geomys bursarius) Mound Building on Plant Diversity
    (2011-02-09) Curry, Jessica; Avendano, Javier; Peterson, Julie
    The plains pocket gopher (Geomys bursarius) is a member of the order Rodentia and family Geomyidae. The effects of these subterranean herbivores on vegetation can arise from diet selection, foraging behavior, and burrow structure and dynamics. In the absence of pocket gophers there is higher soil fertility which lead to higher plant biomass, in turn reduces light availability at the surface. Our study was designed to examine the effect of gopher mounds on plant diversity. Of 256 unique patches of vegetation sampled we found that 195 (76%) were associated with a gopher mound and 61 (24%) were not associated with a mound. Of the total patches surveyed 28 (11%) were associated with new mounds, 81 (32%) with abandoned mounds, and 86 (33%) with old mounds. While the mounds may be detrimental to plant diversity while they are active, once they are abandoned by the gophers they become beneficial.
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    Northern Pike (Esox lucius) Home Range Area and Average Depth
    (2011-02-03) Peterson, Julie
    Northern pike (Esox lucius) are large ambush predators of other fish in northern temperate lakes. Cook and Bergersen (1998) found that in the summer these fish tend to occupy shallow water with large amounts of vegetation. They also reported that the pike in their study showed low levels of activity with most activity occurring at dawn or dusk. Some studies (Minns, 1995) have suggested a correlation between a fish’s size and the size of it’s home range. Others (Jepsen et al., 2001) suggest that individual fish within populations show different hunting behavior based on preference and prey availability. Some fish stay in one small area, some remain in a few favorite areas, and others move frequently and lack a distinct home range. Jepsen et al. suggest that in areas with higher prey density a small home range may be possible, while areas with low prey density may force the fish to move more frequently. Our study focused on the home range size and average depth of pike and whether these were correlated to the length of the fish. We also took data on the vegetation types, water temperature, and activity patterns but due to time constraints we were unable to analyze this data in depth. It is included in our raw data in Appendix B for future uses.