Now there are a lot of ways to measure NEE for terrestrial ecosystems, a lot of data on NEE from eddy covariance and transparent chambers. In turn, a lot of models use NPP for different calculations. Do you know how to calculate NPP from NEE? I need to do this separation for wetland. It is possible to estimate ecosystem respiration using night NEE data, but not the autotrophic respiration, which is necessary to estimate NPP.
If you need an "ad hoc" estimate of NPP, then you may simply assume that NPP is equal approximately to the half of GPP, and calculate NPP as a half of the difference between NEE and ecosystem respiration. But I would recommend to use a detailed carbon cycle model for assimilating all available observations. Then you can obtain more reliable estimates.
Присоединяюсь к мнению Георгия. В качестве достаточно простой ст. могу порекомендовать
Christensen T.R., Prentice I.C., Kaplan J., Haxeltine A., Sitch S. 1996. Methane flux from northern wetlands and tundra. An ecosystem source modelling approach. Tellus, 48B, 651-660.
In my opinion, you should first segregate different parts of you wetland, I mean, marsh, forest, etc. Each one has their own characteristics. For instance, in my own experience, a community dominated by cattail (Typha domingensis) has a NPP in a year about three times higher than maximum biomass. However, in trees, usually, biomass is higher than NPP in a year. Well, this is my experience working in tropical conditions, which can be different en temperate countries. In Europe, NPP in Typha stand is about 10% higher than maximum biomass, however, maximum biomass is higher than in tropical countries. So, I think it is necessary to determinate which kind of wetland and which vegetation is in it.
Using a constant ratio may be useful at yearly time scale. But at a daily time scale you have to estimate the heterotrophic respiration (NPP = NEP + Rh). Based on GPP we have to have the estimate of the autotrophic respiration perhaps easier to measure or simulate.
Regards
Serge
@ Serge Rambal how we can calculate Rh if we only know GPP, NEP but we want to estimate NPP? will you please guide us?
Regards
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