Biodiversity is the variety of life in the particular habitat or ecosystem. For this week’s lab we examined the species diversity of plants in our backyards at home. We also compared the plant species diversity of both of our backyards. The Shannon-Wiener Index was then used to determine the more diverse ecosystem. The Shannon-Wiener Index is determined by both the number of species and the evenness of the distribution of individuals among those species. The number of species can also be referred to as species richness. Below is the data that was collected.
| Species (i) | ni | pi | Log2Pi | pilog2pi |
| Iris | 4 | 0.04 | -3.22 | -0.1288 |
| Wild Violet (weeds) | 100 | 1 | 0 | 0 |
| Quickweed | 20 | 0.2 | -1.61 | -0.322 |
| Creeping Charlie | 50 | 0.5 | -0.69 | -0.345 |
| Weedy Daisies | 6 | 0.06 | -2.81 | -0.169 |
| Bindii | 30 | 0.3 | -1.2 | -0.36 |
| Raspberry Weed | 40 | 0.4 | -0.91 | -0.364 |
| s=7 | sum=250 | -1.7 | ||
| Shannon Diversity Index (H)=1.7 | ||||
| Hmax= 1.95 | ||||
| Evennes= 0.87 |
| Species | i | ni | pi | log2pi | pilog2pi |
| Yellow Buckeye | 1 | 1 | 0.037 | -1.432 | -0.053 |
| Mockernut Hickory | 2 | 10 | 0.37 | -0.432 | -0.16 |
| Sweetgum | 3 | 7 | 0.259 | -0.587 | -0.152 |
| Slash pine | 4 | 6 | 0.222 | -0.654 | -0.145 |
| Northern Red Oak | 5 | 3 | 0.111 | -0.956 | -0.106 |
| -0.616 | |||||
| H: 0.616 | |||||
| Shannon Index | 0.616 | ||||
| Species Richness | 5 | ||||
| Evenness | 0.881 |
Identify the backyard that was most diverse.
The backyard that was most diverse was Jayla’s yard, which indicated a Shannon Wiener Index value of 1.7 in comparison to Nia’s which was 0.616. The species identified also differed with Jayla having a total of 7 species, and Nia having a total of 5 species.
Did any single species exhibit dominance in either community? Write a plausible explanation why you think this occurred.
In Jayla’s backyard, the wild violet weed was the most dominant species out of the other 6 species. This most likely occurred due to the plant’s ability to self-seed in optimum conditions, thus making them crowd many lawns. Additionally, the weed can be utilized for medical purposes and is an edible plant.In Nia’s backyard, the most dominant plant species was the Mockernut Hickory. This species was the most dominant because of its ability to grow in favorable conditions, which is usually humid environments. This specific species of trees also has a life span ranging up to 500 years, thus making it the most abundant of its kind. A special characteristic about the Mockernut Hickory is that its wood is often utilized for products that require strength, flexibility, and hardness.
What global locations and physical characteristics of an ecosystem could cause it to have a high value for the Shannon-Wiener Index? Explain.
The Shannon-Wiener Index, H, is a measure of diversity in an ecosystem, so it can be assumed that ecosystems with larger species richness would have a higher Shannon-Wiener Index. For example, tropical rainforests are ecosystems with high biodiversity and biomass which lead to a great species richness, R. When calculating the Shannon-Wiener Index, species evenness also needs to be accounted for. Global locations that have high species richness, but also face great episodes of extinction will have a lower H value—a common occurrence in tropical and dry forests. Temperate deciduous forests are another climate that would most likely have a high H value for the Shannon-Wiener Index. This climate has rich, fertile soils and seasonal climates which can be favorable for organisms. Climates like the tundra and deserts are least likely to have high Shannon-Wiener Index values. These climates are not ideal for organisms because they possess qualities, such as extreme variation in temperature and precipitation and hard, poor soils.
The importance of biodiversity has been positively correlated to ecosystem resilience and stability. According to your results, which backyard demonstrates the higher degree of ecological stability? Explain why this relationship exists.
An ecosystem that exhibits ecological resilience and stability is able to return to a state of equilibrium after an ecological disturbance. Mutualism between organisms, plants and animals, in an ecosystem are crucial to the organization of ecological communities. The plants from Jayla’s backyard could be found if the location was to go through secondary succession, a process where disturbances do not eliminate all life and nutrients from the environment. The plants in Nia’s backyard may be less likely to come back or they would take a longer period of time to regrow. Due to this, Jayla’s backyard demonstrates a higher degree of ecological stability. A greater amount of biodiversity allows for an ecosystem to bounce back from disturbances because biodiversity affects biomass production and nutrient cycling which affect ecosystem services.
Citation: Suweis, S., Simini, F., Banavar, J. & Maritan, A. (2013). Emergence of structural and dynamical properties of ecological mutualistic networks. Nature, 500, 449–452.
Author Contributions: The data collected and calculated was completed by Nia Alston and Jayla Watkins separately for their respective environments. The introduction and question 1 & 2 were answered by Watkins. Questions 3 & 4 were answered by Alston.
The Eco 411 