You placed 18 lilterbags into 3 plots in a tropical forest and collected one bag

Question

You placed 18 lilterbags into 3 plots in a tropical forest and collected one bag from each plot at the following time points. Each bag initially contained 5 g litter (dry weight). At each of 6 time points, you retrieve 3 litterbags, dry them, and weigh the litter inside. You record the following data. What is the decay constant for the litter in units of day^-1 ? Step 1: Convert litter masses into the fraction of mass remaining at each time point. Step 2: Using Excel (or similar program) calculate the average fraction of mass remaining at each time point. Also calculate the standard deviation at each time point. Write your results in the table. Step 3: Use Excel to make a "scatterplot" of the average fraction remaining versus time (in days). Plot the standard deviations as error bars on each point (use "custom'' error bars on the y-data series and select the standard deviations you calculated; see http://office.microsoft.com/en-us/excel-help/add-change-or-remove-error-bars-in-a-charl-HP010007462.aspx). Attach your plot. Step 4: Take the natural log of the average fraction of mass remaining. Step 5: Use Excel to make a scatterplot of the natural log of the average fraction remaining versus time (in days). Step 6: Fit a linear trendline to the data points and attach the plot. Do not force the intercept through zero. Have Excel display the trendline equation: the slope is your decay constant.

Explanation / Answer

Lets first compete the table as follows :

The above have been calculated in MS Excel and all the formulas are ready available for average and natural log in fx button.

The first scatter plot is with avg fraction decay and its standard deviation as bars

Time Avg Fract rem Std dev mass rem In ( Avg fract mass rem) 0 5.00 0.00 1.61 25 4.17 0.35 1.43 70 2.97 0.32 1.09 150 2.10 0.36 0.74 220 1.40 0.36 0.34 360 0.67 0.42 -0.41

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.