User:Nadia Khan/Notebook/Biology 210 at AU

Examining Biological Life at AU: Hay Infusion of Amphitheater Stream, June 30th, 2015

Introduction: The goal of this experiment was to understand how different organisms in an ecosystem are categorized and to familiarize oneself with observing niches in great detail, seeing natural selection play out as evidenced by the evolution of said organisms. The study of a transect, which is a land sample used to assess the vegetation patterns and animal population of a specific area, is effective in analyzing biodiversity and phylogeny. This in turn helped reach the goal of the experiment. The transect chosen was the stream next to the amphitheater on American University’s campus because of its important role on AU’s campus as a certified wildlife habitat. If there are several different biotic elements present in the transect, then all of these organisms bear traits that were selected for and prove the organisms’ fitness for this particular environment.

Methods: Upon arrival to the stream, we used a meter stick to chalk out a 20 m by 20 m space as the transect for our observations and sample collection. We observed the stream and its surrounding wooded area, taking note of the evident biotic and abiotic elements and photographing the ecosystem. Then we collected a sample of soil next to the stream that was reflective of the majority of soil in our transect and sealed it in a plastic bag. After returning to the classroom, 500 mL of Deerpark water was obtained and kept in a jar. Using a balance, 10 to 12 grams of the soil sample was measured and added to the jar. Again, using the balance, 0.1 gram of dried milk was measured and added to the water and soil mixture that was then shaken up in a now closed jar for 10 seconds. The jar was opened and after having been labeled, kept aside in the lab.

Results: Abiotic factors included water, sand, gravel, pebbles, stones and dirt in the stream. Surrounding the stream there was a sidewalk. Biotic factors included plants, grass, trees, and roots that bordered the stream. There was also a robin, house sparrows, and a gray catbird that flew over the transect. There was low traffic in the area with rarely anyone in the transect itself as it was a fairly isolated space among due to the heavy vegetation.

Discussion: The lack of human invasiveness likely proves beneficial to the ecosystem. After observing the site, there was evidence of a variety of organisms. This transect was an environment that could provide nutrients for several different organisms as they could flourish. They proved to coexist well. This could change due to availability of resources and thus competition due to overpopulation.