You can take a look to the file in this link

http://www.caryinstitute.org/sites/default/files/public/reprints/Lovett_et_al_2006_Ecosystems.pdf

Thanks Heba.

this chapter may help you to clarify your doubt.

Pretzsch, H. (2010). From Primary Production to Growth and Harvestable Yield and Vice Versa: Specific Definitions and the Link Between Two Branches of Forest Science. In Forest Dynamics, Growth and Yield: From Measurement to Model. Berlin, Heidelberg: Springer Berlin Heidelberg. doi:10.1007/978-3-540-88307-4

Thank you very much José.

For my studies, I define NEP as primary production above and beyond metabolic needs of the primary producers (or all primary carbon that can be consumed or lost in the system). NEP can then be utilized by primary consumers or enter the detrital part of the system. I then breakdown the detrital pathway as detrital consumption or export out of the system. After all of these terms have been taken into account the residual carbon (NEP) should enter the remaining path....burial. This is the pool that can be considered sequestered given a defined timeframe. Very over simplified, but this sheds some light on my hierarchy.

Also look into the blue carbon grey lit for some policy definitions.

I tackled this question in a chapter for a book in press the effects of climate change and aquaculture on subaquatic ecosystems blue carbon sequestration and storage

Its in aquaculture ecosystems wiley blackwell ed Mustafa S. And I'm currently writing a paper about the intrinsic assumptions in blue carbon research that is relevant to definitions it will first be in ICOMSA 2014 proceedings as one of the keynote addresses. It has to be in by the end of June , so watch that space.

Yes the literature at times is confusing here is my take.

First, when you see NEP net ecosystem production substitute NCP net community production which is the excess production from the ecosystem at its landscape scale. Even in the papers headed by the major researchers in blue carbon (Duarte et al 2005) these twi terms have been interchangeable betWeen the figures and the txt just to confuse you. NECP is another term used it is the net ecosystem community production. This is not like the NCP and NEP. The NECP removes the production exported from the ecosystems landscape, the NCP and NEP is inclusive of the material exported from the ecosystems landscape.

I think things can be made clearer by the following equations

NCP = GPP - cR i.e. Gross primary production of plant and the community respiration, the plant s and animals, microflora

NPP = GPP - pR i.e. The plant respiration

NECP = (GPP - cR - E ) = S. Where E is the amount exported S the amount stored in the ecosystems landscape unit.

Often to measure one or the other production values it is necessary to substitute one form each equation, depending on the method of measurement.

In the last equation is is assumed that all the exported carbon is respired so the NECP is very much smaller than the NCP the excess production of the ecosystem stored in biomass and sediments and the detrital material exported, which may may not be mineralised back to the surface waters. The latter is something I discuss in the chapter and paper

Hope this clears things up for you