intro download

Current and former projects related to PnET at the Complex Systems Research Center.

Site level modeling in New England: Harvard Forest and Hubbard Brook The earliest applications of the PnET model were to the Harvard Forest (MA) and the Hubbard Brook (NH) experimental research forests. Many of the parameters and imperical relationships used in PnET were derived from research at these sites. The model output also shows a good degree of corellation with validation data from these two New England sites.

1. Modeling Nitrogen Saturation In Forest Ecosystems In Response To Land Use And Atmospheric Deposition.

2. Effects of Land Use, Climate Variation and N Deposition on N Cycling and C Storage in Northern Hardwood Forests.

Modeling multiple stress effects on forests: O3, CO2, N deopsition and land use history Recent functional enhancements to PnET include development of new algorithms for estimating the effects of changing CO2 concentrations on leaf-level physiology. Integration of these algorithms into PnET-CN, along with existing equations for estimating O3 effects on photosynthesis, have allowed us to perform multiple-factor analyses on temperate forest C and N dynamics.

1. Interactive effects of nitrogen deposition, tropospheric ozone, elevated CO2 and land use history on the carbon dynamics of northern hardwood forests.

2. Simulating ozone effects on forest productivity: Interactions among leaf-, canopy- and stand-level processes.

3. Inorganic N Losses from a Forested Ecosystem in Response to Physical, Chemical, Biotic and Climatic Perturbations (In Review).

Regional analysis : PnET and regional GIS In the northeastern U.S., a regional forest ecosystem study has been conducted using the PnET models in conjunction with a 1 km regional GIS database. The GIS-model link allows equations representing important ecosystem processes to interact with spatial variability in the environmental variables that drive them. This is useful not only for making spatially-explicit predictions, but also for examining environmental controls on ecosystem productivity, carbon storage and nutrient fluxes. To date, PnET has been used to predict regional net primary production (NPP) and water balances (Ollinger et al. 1997), net ecosystem production and climate change effects (Aber et al. 1995), nitrogen cycling rates (Aber et al. 1997) and tropospheric ozone effects on forest productivity (Ollinger et al. 1997). These studies have also examined the relative importance of water, energy and nutrient limitations on forest ecosystems and their potential response to global change.

1. Estimating regional forest productivity and water yield using an ecosystem model linked to a GIS.

3. Bibliography and references.

Model comparisons: PnET and TEM An effort has been made to compare results derived from the PnET-II forest canopy model to those from the popular Terrestrial Ecosystem Model (TEM 4.0) at Harvard Forest and Hubbard Brook.

1. Predicting the regional impacts of increased CO2 and climate change on forest productivity: A model comparison using PnET-II and TEM 4.0.

2. Bibliography and references.

© 2012 Earth Systems Research Center