In natural systems ecology we learned (also it goes by commonsense) that Net primary production = gross primary production - respiration loss of carbon.
so, gross primary production = respiration + net primary production.
However, in the recent literature it had become very common to state that
Gross Primary production = respiration - net primary production.
Some literature states this change is due to sign convention.
Does anybody think a sign convention can change fundamental relationships like this in nature?
I would value your opinion on this issue.
Hello Dr. Anapalli,
Gross Primary Productivity meant and should always mean the surplus production after the expenditure through respiration has been incurred hence cumulative respiration and net primary productivity data are needed and recorded. Net primary productivity is the amount of carbon sequestration that remains after the respiration has been subtracted from the GPP. These simple equations cannot and should not be modified nor changed due to sign conventions. As you have mentioned in the descriptive part of your query, GPP can never be calculated or yielded by subtracting the NPP data from respiration as it yields a value that would almost always be negative in any healthy oxic ecosystem and that most certainly is not the GROSS PRIMARY PRODUCTIVITY. The negation would be however a natural state of affairs in a healthy near anoxic or anaerobic environment as productivity in those regions follow a path devoid of oxygen as the terminal electron acceptor.
Thanking you,
Dr. Abhishek Mukherjee
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