Worksheet 8 – Ecosystem (100 pts)
This worksheet is designed to help you to:
Understand ecosystem processes through carbon cycling.
Understand the services that ecosystems provide.
Reminder: Follow the correct formatting for all worksheets and assignments (12 pt font, double-spaced, do not include original questions or instructions). Incorrect formatting and/or not including the .R file will result in a 5% penalty on this assignment. Plagiarism is unacceptable and will result in an automatic 0 on this assignment.
Answer/address all of the following questions. In all cases, we require that your work be typed and that you insert any tables, figures, and statistical outputs from R.
1. Measure one bush, one palm plant, and one leafy plant. (6 pts)
2. Define autochthonus and allochthonous. Give one example of an autochthonous AND one example of allochthonous input into an ecosystem of your choice (e.g., Florida Bay, Everglades, the city of Miami, etc.) (6 pts)
3. Define Liebig’s law of minimum. (6 pts)
4. A monitoring project was started in Biscayne Bay to detect nutrients in the water. In 2019, a large sewer main rupture occurred, releasing raw sewage into the bay. The researchers at the monitoring project recorded the levels of nutrients in the water for 1 week before and for 1 week after the sewage rupture. They also measured the amount of Sargassum (a seaweed) that washed up onto nearby Miami beaches during those weeks, as an indicator of its growth. (16 pts)
Nutrient Levels Carbon mg/L Nitrogen mg/L Phosphorus mg/L AMouNT (metric tons)
Before Rupture 630.2 38.3 3.1
AFTEr rupture 981.5 52.6 7.9 60
What is the limiting nutrient for the growth of seaweed before the sewage rupture? Show your work. (Hint: Redfield Ratio using nutrient measurements not cattail cover.) (4 pts)
What is the limiting nutrient for the growth of seaweed at after the sewage rupture? Show your work. (Hint: Redfield Ratio using nutrient measurements not cattail cover.) (4 pts)
Based on the limiting nutrient before and after the sewage rupture, explain what is happening to the nutrient balance in the Biscayne Bay aquatic ecosystem when the sewage rupture occurs in the area. Then, given the change in amount of seaweed, what may be happening to this species and to the plant community structure in Biscayne Bay? (8 pts)
5. Water flows from Lake Okeechobee south towards the Everglades, which is normally phosphorus-limited. Just south of Lake Okeechobee are large areas of agricultural land for growing sugar cane. Run-off from these fields often brings fertilizer (i.e., additional nitrogen and phosphorus) into the Everglades. Explain and discuss how agricultural run-off may affect Everglades’ aquatic communities and ecosystems. (10 pts)
Extra credit of 3 pts for ADDITIONALLY discussing the methods and results of one primary peer-reviewed article that has examined this phenomenon. Include the in-text citation in the paragraph and place the full citation immediately after this paragraph.
6. Do different plant types sequester the same amount of carbon? (27 pts)
Write a null and alternative statistical hypothesis about whether all plant types sequester the same amount of carbon. (Hint: You are comparing THREE groups, so be careful with your alternative hypotheses!) (5 pts)
Produce a summary table (do NOT include raw data) showing the mean carbon sequestration and standard deviations for all three plant types. Make sure you include a table caption above it and all necessary labels and units for clarification. (5 pts)
Produce a bar graph that shows the mean carbon sequestration and standard deviations for all three plant species. Remember to include axes titles, units, and error bars, as well as a figure caption below the graph. (5 pts)
Analyze your data using the appropriate statistical test (Hint: you are comparing THREE groups) and place the output below. Highlight the appropriate P-value. (5 pts)
Evaluate your P-value. Do you reject or fail to reject the null hypothesis? (2 pts)
Write out the appropriate conclusion (either the null or alternative hypothesis). Then, explain which plant(s) would be the most effective to plant with the goal of storing carbon. (5 pts)
7. Does carbon sequestration by leafy plants offset carbon emissions by your cars? (27 pts)
Write a null and alternative statistical hypothesis about carbon offset. (Hint: Carbon sequestration and carbon emission are comparable values.) (5 pts)
Produce a summary table (do NOT include raw data) showing the mean carbon sequestration of leafy plants, the mean carbon emission by vehicles, and the standard deviations. Make sure you include a table caption above it and all necessary labels and units for clarification. (5 pts)
Produce a bar graph that shows the mean carbon uptake by leafy plants and the mean carbon release by vehicles. Remember to include axes titles, units, and error bars, as well as a figure caption below the graph. (5 pts)
Analyze your data using the appropriate statistical test (Hint: you are comparing TWO groups) and place the output below. (5 pts)
Evaluate your P-value. Do you reject or fail to reject the null hypothesis? (2 pts)
Write out the appropriate conclusion (either the null or alternative hypothesis). Then, based on your results, explain whether afforestation (plant planting) is an effective strategy for reducing carbon emissions. (5 pts)
8. Your TA will use this space to assign you a grade and provide feedback on grammar and spelling. (2 pts)
0 pts: Frequent grammar/spelling errors. Writing style is rough and hard-to-read.
2 pts: Very few grammar/spelling errors. The writing style is mature and readable.
