User:Shauna McManus/Notebook/Biology 210 at AU

Observing a Transect 01/22/2015

Purpose Life on Earth is incredibly diverse. While no one knows for certain how many different species exist, scientists predict that there are anywhere from 10 to 100 million different species (Freeman, Allison, Quillin, 2008). This incredible diversity can be represented on a small scale, in a contained ecosystem. An ecosystem, or transect, is a community that contains both biotic and abiotic components (Bentley, Walters-Conte, Zeller, 2015). One small 20 by 20 transect on the American University campus can be observed, and experimented on, in order to demonstrate the incredible diversity of life. If this is done, then it will be possible to observe the interrelation and complexity of species in several different niches within the same transect.

Materials and Methods A triangular piece of land with 20-meter long sides was marked off. This land establishes the experimental transect (transect #5). The general characteristics of the transect were carefully observed and marked down in order to form a topographical map. Both biotic and abiotic components of the transect were carefully recorded. After thoroughly observing the transect, a sample of the soil and vegetation that was representative of the transect was collected in a 50 mL conical tube. This sample was then used to make a Hay Infusion Culture. This was done by removing 12 grams of the soil sample and adding it to a plastic jar. 500 mLs of deerpark water was then added to the jar, followed by 0.1 gm dried milk. With the lid placed on the jar, the solution was gently mixed. The top was then removed, and the jar was left to sit for one week.

Data and Observations Transect #5 is situated in the “manicured grass” of the American University Eric Friedheim Quadrangle. The grass which dominates most of the transect is cut short, and clearly maintained. There are small patches of dirt and snow visible throughout the transect, and fallen leaves and acorns are scattered across the grass. There is also 2 pieces of visible trash on the grass, a straw and a fork. Along one side of the transect there is a slightly elevated, and clearly landscaped, mulch area. This mulch, which also has patches of dirt and snow, contains both deliberately planted (landscaped) and wild-growing plants. The landscaped plants include bushes with sharp thorns, which possibly resemble beach roses. There is also a different unidentified landscaped plant. There are several varieties of wild-growing plants, or weeds, as well, including dandelions, crabgrass/wild grass, and clover.

As the transect is an ecosystem, both biotic (living) and abiotic (nonliving) components present.

Biotic: Bushes with thorns (beach rose bushes?) Grass Berries Weeds (clover, dandelion, crabgrass) Worm Other landscaped plants

Abitoic: Snow Dirt Mulch Rocks Trash (straw, plastic fork)

After making detailed observations, an aerial-view topographical map of the transect was drawn. The red line represents the border of the transect.

Conclusions and Future Directions A quick overview of the transect would probably lead to the conclusion that it is mainly grass, with some landscaped plants. However, by more closely observing the transect, it was possible to see a bit more of the diversity. It revealed that there were actually two separate kinds of landscaped plants, as well as some naturally growing weeds that were almost hidden by the beach rose bushes. It also revealed that there was mulch and partially melted snow mixed in with the dirt and grass. There were also pieces of trash hidden among the grass. This demonstrated how an ecosystem does in fact have both biotic and abiotic components. The complexity of the kinds of organisms within the transect was revealed through the closer observation. However, not all species of organisms were visible to the naked eye. In fact, about 1 teaspoon of soil can contain billions of microbes including unicellular eukaryotes and bacteria (Freeman, Allison, Quillin, 2008). By setting up the Hay Infusion Culture and letting it sit it will be possible to observe microscopic protists, algae, bacteria, and more, in the coming weeks.

References Freeman, S., Allison, L., & Quillin, K. 2014. Biological science (5th ed.). Pearson: Glenview, IL. 531, 1174-1175. Bentley, M., Walters-Conte, K., Zeller, N. 2015. A Laboratory Manual to Accompany General Biology II. American University Department of Biology: Washington, DC. 16.

-SM

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