Konza Prairie Data Analysis
It requires you to create a few graphs in Excel (or a similar program) and interpret the data.
If you are not familiar with making charts in Excel, there are many tutorials online that you may find helpful. Google ‘how to make a scatterplot in Excel’ or ‘how to make a trendline in Excel’. A brief written description is also provided below.
Step 1: Download the excel file form cite that contains the Konza Prairie Data. The worksheet contains data for individual years. Below the data are important notes that describe the data found in each column. For instance, in class we looked at a graph of columns D and E (productivity of annual &amp;amp;amp;amp; 20-year burn treatments) versus column B (total precipitation). The notes tell us that columns D and E contained data averaged across vegetation type and topography. This means that this data does not distinguish between grasses and forbs or upland and lowland sites.
Step 2: Create scatterplots that allow you to answer the following questions.
? How does topography (upland versus lowland) affect the relationship between precipitation and productivity? (Make one plot of column B versus column F and a second plot of column B versus column G, in both cases column B should be on the x-axis.)
? Does the relationship between precipitation and productivity hold for all vegetation types? (Make one plot of column B versus column H and a second plot of column B versus column I, in both cases column B should be on the x-axis.)
Instructions for Excel 2010: Use the mouse to select/highlight column B cells, including the header cell ‘total precipitation’. Next, while holding the Control key, select/highlight columns F or G including the header cells. Once you have selected the data you want to plot you can release the mouse button and the control key but DO NOT CLICK in another cell. At the top of the page click on the tab Insert ? Charts ? Scatter ? Scatter with only markers. A chart will appear in your open worksheet. You can move this chart by dragging and dropping if it covers your data. The next step is to add axis labels. With the chart selected, you should see new tabs for Chart Tools. Select the ‘layout’ tab. There will be a button for adding axis titles. After you have labeled the x- and y-axes you are ready to create a trendline. Select your data by clicking on one of the data points on the chart. In the Chart Tools, Layout tab there is a button called Trendline. Select ‘More trendline options’ at the bottom. A new window should open. You want a linear trend. Also check the box “display R-squared value on chart”.
Follow the same procedure for all plots to investigate the relationship, if any, between productivity and precipitation.
The following page contains questions related to the scatterplots you have created. Please copy and paste your excel charts into this document and answer the questions. When submitting your assignment, please delete this page of instructions.
Step 3: Report
Paste copies of your topography scatterplots here.
1) In which topographic position is plant productivity most responsive to precipitation? How do you know?
2) Does the slope of the line differ by position?
3) Which position is more productive? Why do you think this is?
Paste copies of your vegetation type scatterplots here.
4) How do the vegetation types differ in their response to precipitation on upland sites?
5) What does this difference signify with respect to reliance on water?
6) What fraction of total productivity do forbs contribute? Why is it so low? (Think back to the data from the in-class exercise)
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