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Abiotic and Biotic Features of Microhabitat Selection L-403 Joshua Lee November 26, 2003 Introduction Most niche of an organism is comprised of both biotic and abiotic factors. Biotic factors are the living elements, such as food resources, predatory animals, or a mutual relationship with other organisms. Abiotic factors are the non-living elements of the environment, such as temperature, moisture, and refuge. All of these living and non-living factors comprise the niche requirements of every organism on earth. These organisms are capable of choosing the microhabitat that best meets their niche requirements. Plethodon cinereus is the organism studied in this project, nick named the red-backed salamander, and along with the four-toed salamander. Plethodon cinereus is perhaps the most abundant and widespread salamander in North America. It mainly lives in forested habitats. On a micro scale, the red-backed salamander burrow under logs, rocks, leaf litter, and choose to live in underground burrows made by other organisms, or in naturally occurring crevices. Its entire life cycle takes place on land as an amphibian, no stage in its life it enters an aquatic environment. Plethodon cinereus is a predaceous creature feeding on a variety of small invertebrate arthropods in the forest soils. As an amphibian a certain amount of moisture is needed within its niche for the prevention of dehydration and decreased performance, which could ultimately result in its death, therefore moisture is considered as one aspect of important niche to salamander. In this lab, three particular aspects of the red-backed salamander’s niche have been examined in relation to microhabitat selection. The three aspects are moisture, refuge, and abundance of food resources. These aspects were interpreted to find any preference in their niche; under logs or in leaf litter for soil moisture and in resource abundance. Following is the discussions of the method used to test the three aspects of niche, and the statistical analysis used to test the findings and validate the results. Methods The study took place at the Dune Acres area of the Indiana Dunes National Lakeshore. Sampling sites featured two main microhabitats, under logs or in forest litter, beside a hiking trail. In forest litter a 1 x 1 meter plot was measured with a meter stick, and then boundaries were marked with flags. Leaf litter within the boundary was carefully removed from the plot, and any salamanders found in the plot were captured, and carefully handled.
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