UBC Theses and Dissertations
Influence of large-scale food supplementation on diversity of rodent communities Kohler, Chris Mark
Rodents were monitored bi-weekly to determine seasonal responses of rodent diversity to large scale supplemental feeding. Sunflower seeds were added by helicopter to thinned, fertilized, pole-sized lodgepole pine stands in the Montane Spruce (MS[sub dm]) - Engelmann Spruce-Subalpine Fir (ESSF[sub dc2]) biogeoclimatic zone (transition area) of southern interior British Columbia. My objectives were: 1) to determine the rate of seed consumption; 2) to determine the response of rodent communities to supplemental feeding; and 3) to evaluate methods for expressing species diversity. Forty-eight 1-m² seed plots were used to estimate seed consumption rate. Consumption rates did not differ among stands, or between inside (where trap bait was present) and outside small mammal trap grids. Seed consumption rate increased as summer progressed, and was faster during the second year than the first year of seeding. The Simpson index indicated that diversity decreased in seeded areas, as a result of declining evenness caused by increased deer mouse (Perornyscus inanicularus) population density. Species richness was maintained on seeded areas, and hence log series alpha expressed higher diversity on one of the two seeded areas, when compared to its respective control. I reviewed literature to assess the merits of using the Shannon-Wiener and Simpson indices, Shannon-Wiener and Simpson evenness, and log series alpha. For my purposes, the Simpson index was the most useful for expressing changing dominance, and log series alpha was most useful for reflecting richness. Both indices have low sensitivity to sample size and are highly discriminatory. The Shannon Wiener index and Simpson and Shannon-Wiener evenness were used for comparing results among other studies.
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