The structure of SIPNET

SIPNET was designed to estimate fluxes that could also be measured using an Eddy Flux
tower. The major pools of Carbon and Water in the SIPNET model are shown below in
boxes; the arrows represent fluxes into, out of or between pools.

The SIPNET model has vegetation carbon pools in wood, leaves and roots and soil carbon pools with three different substrate pools depending on quality of decomposition in soil organic matter. Photosynthesis is dependent on PPFD, soil water and atmospheric humidity, whereas respiration is dependent on both substrate quality and temperature. Evapotranspiration is partitioned according to stomatal control over transpiration. Evaporation is driven by climate and soil transport properties. The structure of the SIPNET model is shown in the figure below:

The SIPNET project

The SIPNET project
Collaborators: Russell K. Monson, Laura Scott-Denton, Diego A. Riveros-Iregui (University of Colorado), David Schimel, (National Ecological Observatory Network), Bill Sacks & Ankur Desai, (University of Wisconsin) and John Zobitz (Augburg College Minnesota)

The SIPNET model is a simple ecosystem model which has been used to interpret carbon and water exchange between vegetated ecosystems and the atmosphere. The SIPNET model has been developed from the PnET family of models (Aber & Federer 1992) to include a data-assimilation capability. Initial work by Rob Braswell and Bill Sacks has allowed this model to be implimented at Harvard Forest (Braswell et al 2005) and Niwot Ridge (Sacks et al. 2006, 2007). The SIPNET group is now expanding to other forests and ecosystems, using different data streams (Moore et al 2008, Zobitz et al 2008) to parameterize the model and also using the model at larger spatial scales (ACME project) and at longer temporal scales (Niwot Ridge climate change projections).

We do not currently have support to maintain regular code updates for the SIPNET model. However the code is held at the University of Wisconsin and maintained collectively by the collaborators. We are exploring ways to make the code more widely available.

If you have used the SIPNET model for your field site please let us know and contribute to this blog.


References:
Aber JD, & Federer CA (1992). A generalized, lumped-parameter model of photosynthesis, evapotranspiration and net primary production in temperate and boreal forest ecosystems. Oecologia 92(4): 463-474.

Braswell BH, Sacks WJ, Linder E, Schimel DS (2005) Estimating diurnal to annual ecosystem parameters by synthesis of a carbon flux model with eddy covariance net ecosystem exchange observations. Global Change Biol. 11: 335-355.

Moore DJP, Hu J, Sacks WJ, Schimel, DS & Monson, RK (2008) Estimating transpiration and the sensitivity of carbon uptake to water availability in a subalpine forest using a simple ecosystem process model informed by measured net CO2 and H2O fluxes. Agricultural and Forest Meteorology 148, 10(3), 1467-1477

Sacks WJ, Schimel DS, Monson RK, Braswell BH (2006) Model-data synthesis of diurnal and seasonal CO2 fluxes at Niwot Ridge, Colorado. Global Change Biology 12(2): 240-259.

Sacks WJ, Schimel DS, Monson RK (2007) Coupling between carbon cycling and climate in a high-elevation, subalpine forest: a model-data fusion analysis. Oecologia 151(1): 54-68.

Zobitz JMZ, Moore DJP, Sacks WJ, Monson,RK, Bowling, DR & Schimel DS (2007) Integration of Process-based Soil Respiration Models with Whole-Ecosystem CO2 Measurements. Ecosystems DOI: 10.1007/s10021-007-9120-1