1) Over a 5-year study, a ridge-top forest is found to be accumulating carbon in
ID: 61623 • Letter: 1
Question
1)
Over a 5-year study, a ridge-top forest is found to be accumulating carbon in the biomass of the plants, detritus and soil organic matter at a total rate of 200 g/m2/ yr. Respiration of all consumers (primary consumers, secondary consumers, detritus consumers) has been estimated to be 600 g C/m2 per year. There is a stream flowing out of the forest exporting organic matter at an estimated rate of 25 g C/m2 per year. There have been no fires in the forest.
Calculate the rate of net primary productivity (NPP). State any assumptions you are making in your calculation. Include units in your answer. Show your work so that I can follow your reasoning or calculations.
2)
A plant in the Campus Forest grows a new leaf using carbon and energy acquired in the current year and carbon is initially stored in the leaf tissue. The leaf falls and gets blown into a small creek and then is washed out of the forest. Which of the following is true about the carbon in the leaf that has washed out of the forest? (You may pick more than one answer).
It counts as part of GPP (Gross Primary Production) for the current year in the Campus Forest.
It counts as part of NPP (Net Primary Production) for the current year in the Campus Forest.
It counts as part of NEP (Net Ecosystem Production) for the current year in the Campus Forest.
It counts as part of a positive change in stored carbon ( + corg) in the Campus Forest for the current year.
3)
Considering what you know about trophic efficiencies in ecosystems, which choice below would you consider to be the most likely path of a C atom ?
Plant to 1° consumer to 2 ° consumer to 3 ° consumer to detritus to detritivore to CO2
Plant to CO2 to Plant to detritus to detritivore to CO2 to Plant to CO2 to Plant
Plant to 1° consumer to 2 ° consumer to detritus to detritivore to CO2 to Plant
Plant to CO2 to Plant to 1° consumer to CO2 to Plant to 1° consumer
It counts as part of GPP (Gross Primary Production) for the current year in the Campus Forest.
It counts as part of NPP (Net Primary Production) for the current year in the Campus Forest.
It counts as part of NEP (Net Ecosystem Production) for the current year in the Campus Forest.
It counts as part of a positive change in stored carbon ( + corg) in the Campus Forest for the current year.
Explanation / Answer
1)
NPP = GPP - Ra
GPP = 200 + 25g C/m2 and Ra = 600 g C/m2 per year
NPP = 225 - 600 = -375g C/m2
2)
It counts as part of GPP (Gross Primary Production) for the current year in the Campus Forest and It counts as part of a positive change in stored carbon ( + corg) in the Campus Forest for the current year. Hence, statements 1 and 4 are true.
3)
The most likely path of a C atom Plant to CO2 to Plant to detritus to detritivore to CO2 to Plant to CO2 to Plant. Option b is correct.
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