Publication Date:
2018-07-06
Description:
Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 15 (2005): 1772–1782, doi: 10.1890/04-0643
Description:
To facilitate the simulation of isotope dynamics in ecosystems, we developed software to model changes in the isotopic signatures of the stocks of an element using the output from any parent model that specifies the stocks and flux rates of that element based on a mass balance approach. The software alleviates the need to recode the parent model to incorporate isotopes. This parent model can be a simple mass balance spreadsheet of the system. The isotopic simulations use a linear, donor-controlled approximation of the fluxes in the parent model, which are updated for each time step. These approximations are based on the output of the parent model, so no modifications to the parent model are required. However, all fluxes provided to the simulator must be gross fluxes, and the user must provide the initial isotopic signature for all stocks, the fractionation associated with each flux, and the isotopic signature of any flux originating from outside the system.
We illustrate the use of the simulator with two examples. The first is based on a model of the carbon and nitrogen mass balance in an eight-species food web. We examine the consequences of using the steady-state assumption implicit in multi-source mixing models often used to map food webs based on 13C and 15N. We also use the simulator to analyze a pulse chase 15N-labeling experiment based on a spreadsheet model of the nitrogen cycle at the Harvard Forest Long Term Ecological Research site. We examine the constraints on net vs. gross N mineralization that are necessary to match the observed changes in the isotopic signatures of the forest N stocks.
Description:
The information in this document has been funded in part by the U.S. Environmental Protection Agency (QT-RT-00-001667). This work was also supported in part by grants from the National Science Foundation (DEB-0108960, OPP-9911681).
Keywords:
C-13
;
Food web model
;
Harvard Forest, Massachusetts, USA
;
Isotope dynamics
;
Isotope simulation
;
Mass balance model
;
N-15
;
Nitrogen cycle
;
Stable isotopes
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
102912 bytes
Format:
233472 bytes
Format:
application/msword
Format:
application/msword
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