Collaborative research: Restricted plasticity of canopy stomatal conductance: Conceptual basis for simplified models of canopy transpiration. National Science Foundation, Directorate for Geosciences, Hydrological Sciences Division, April 1, 2004 to April 1, 2007, $388,000 (UB portion is $178,278). Principal Investigator, with Brent E. Ewers (co-PI, U. Wyoming) and Eric L. Kruger (co-PI U. Wisconsin).

This project seeks a conceptual model of forest transpiration that embraces the spatial variability of stomatal control while retaining a tractable measure of generality that is the hallmark of empirical models of stomatal conductance. The conceptual model is based on the idea that canopy stomatal conductance is regulated primarily by water potential when water fluxes are high and of significant hydrologic import. It is hypothesized here that species plasticity in canopy stomatal conductance, which determines its spatial variability and challenge for quantifying, follows a linear relationship keyed to an easily quantifiable reference conductance. The knowledge gained from this research has broad implications for land surface modeling efforts directed at global change effects on water cycling. It will provide a relatively simple, but transportable and scientifically defensible, canopy model. Such models are essential foundations for the creation and implementation of credible policies aimed at mitigating or adjusting to the consequences of anticipated global change.

Measuring and modeling the source, transport and bioavailability of phosphorus in agricultural watersheds. Environmental Protection Agency (in collaboration with the United States Department of Agriculture), STAR Grant, Nutrient Science for Improved Watershed Management Program, $749,307, November 1, 2002 to October 31, 2005. co-PI.

We will measure and model the sources, transport, and fate of bioavailable phosphorus (BAP) in the mostly agricultural 604-km2 watershed of Lake Mendota near Madison, Wisconsin. This well-known eutrophic lake is impacted by phosphorus (P) loading from agricultural sources, including row crops, dairy operations, and land applications of manure and commercial fertilizers. The research will compliment an on-going nonpollution abatement program targeted at reducing P inputs to the lake through improved management of these agricultural sources. Our multidisciplinary team provides the expertise in social science, outreach, environmental modeling, environmental chemistry, hydrology and sediment transport, environmental engineering, and limnology – all of which are needed to accomplish our “systems” goals. Our focus is on the scale-dependent processes that link agricultural P sources to watershed export of BAP. Our plan involves six major objectives: 1) Quantification of the effects of manure management on runoff BAP; 2) Measurement of the amounts, spatial patterns, and transport of sediment and BAP in channels and streams acting as routes for transport through the watershed; 3) Quantification of the in-stream processes governing the fate and transport of sediment P; 4) Evaluation and improvement of modeling tools (APEX, SWAT) for assessing P transport over a wide range of spatial scales; 5) Determination of the relation of BAP losses to the scale of animal operations; and 6) Integrated outreach with stakeholders, agency partners and other researchers through farmer-feedback procedures, agency assessments and model refinement. Knowledge gained will be crucial for effective state and national TMDL development and implementation.

Chequamegon Ecosystem-Atmosphere Study (ChEAS)

ChEAS is a NSF-funded interdisciplinary research collaboration network project aimed at understanding land-atmosphere exchange of cabon, water, and energy at one of the tallest AmeriFlux towers, located near Park Falls, Wisconsin. The lead institution for the project is Penn. State University; Dr. Mackay is one of 6 members of the ChEAS steering committee.

Terrestrial Regional Ecosystem Exchange Simulator (TREES)

We are developing this object-oriented land surface process model, which provides the flexibility to examine model complexity requirements, for application to flux towers, watersheds, and remote sensing regional scale projects. Data handling is through a data dictionary, which supports rapid definition of frames for the input of data, maintenance of state and flux variables, and output of model results. The flexibility afforded by objects is exploited for rapidly developing simulation models that are tailored to specific analytical requirements. Early TREES development began with a version of RHESSys developed as part of Mackay's PhD dissertation. Subsequently, TREES has departed from the RHESSys approach in that it relies on a pure object-oriented approach.

Adaptive Parameter Restriction and Selection (APReS)

We are developing a general framework for the analysis of uncertainty in simulation models. Our approach is motivated by methods such as GLUE and Parato Optimality. The premise of APReS is that parameter uncertainty and even model structure uncertainty are interpretable in terms of fuzzy sets. A nonmonotonic reasoning approach is supported to allow for the evaluation of simulations based on multiple criteria in different combinations and priorities. APReS has been applied to simulation of streamflow in forested watersheds, transpiration at hillslope to watershed scales, and to transpiration at individual tree and whole-stand scales. It is currently being used as one of numerous analytical tools for projects funded by NSF and EPA.

Past Projects

Long-term water flux changes from converting old-growth pine forests to hardwood forests in northern Wisconsin. NASA, Land Surface Hydrology Program, NAG5-8554, $359K (1999-2002), Mackay (PI).

Highlights and milestones of the Land Surface Hydrology Project were:

1. A comprehensive database of vegetation, water fluxes, micrometeorology, remote sensing, soil moisture, tower flux, and process-based models were used in the first successful scaling-up exercise at the WLEF tower (Mackay et al., 2002; Ahl et al., 2004b).

2. An essential bridge was developed between leaf and tower flux measurements with measurements of leaf water potential and transpiration among seven key species in the WLEF tower footprint (Ewers et al., 2002; Ewers et al., 2004).

3. Accurate simulations of transpiration models and parameterization for the heterogeneous forests around WLEF (Mackay et al., 2003a,b; Samanta and Mackay, 2003).

4. We developed a parameterization scheme to use MODIS land surface temperature to estimates canopy stomatal conductance for simulation transpiration and photosynthesis (Mackay et al., 2003c; Mackay et al., 2004).

• Distributed parameter non-point source pollution modeling in nested watersheds: Guide to implementing legislated surface water quality restrictions in Wisconsin. Hatch/McIntire-Stennis, $90K, October 2000 to September 2004, Mackay (PI).
• Context elicitation to support the semantic integration of environmental models. University of Wisconsin Graduate School Fall Competition, $15K, July 2000-June 2001, Mackay (PI).
• Long-term water flux changes from converting old-growth pine forests to hardwood forests in northern Wisconsin. University of Wisconsin Graduate School Fall Competition. Awarded $20K for 1999-2000, but not used.
• Effects of parameter spatial aggregation on agricultural non-point source pollutions models. US EPA (Pass-through from Wisconsin Department of Natural Resources), $15K (1999-2000), Mackay (PI).
• Remote sensing teaching and research in support of creating a vision for the environment as a whole. NASA, Centers of Excellence in Remote Sensing, NAG5-6535, $424K (1997-1999), Mackay (PI). (Equipment Grant).
• Coupling forest ecosystem process-based models to groundwater models: tools to guide natural resource management in northern Wisconsin. Funded by McIntire-Stennis. $200K (1997-2001), Mackay (co-PI) with Gower (PI).
• Affiliated Research Center (ARC). NASA., Mackay (one of several co-investigators) with Lillesand (PI), 1996-2001.
• ARCII. NASA, Mackay (one of several co-investigators) with Lillesand (PI), 2001-2006.
• Scaling spatial simulation of forest disturbance on watershed processes, University of Wisconsin Graduate School Fall Competition. $21K (1997-1998), Mackay (PI).
• Characterization of evapotranspiration and forest water relations in northern Wisconsin. University of Wisconsin Graduate School Fall Competition. Awarded $15,792, July 2001-June 2002.
• Chequamegon Ecosystem-Atmosphere Study. National Science Foundation, Division of Biological Sciences, Research Collaboration Network Program. Mackay one of several co-investigators with Ken Davis, Penn. State (PI), January 1, 2002 to December 31, 2006.
• Development and Evaluation of TMDL Planning and Assessment Tools and Processes. USDA CSREES Regional Project DC 00-02, Theo Dillaha, U. Virginia (PI). Mackay, one of two UW-Madison representative, October 1, 2001 to September 30, 2006.
• Quantifying non-point source phosphorus losses from field to watershed scales. University of Wisconsin Graduate School Fall Competition, $23,353, Interdisciplinary, July 2002-June 2003; co-investigator with K.G. Karthikeyan as PI.
• WebGrant Award. University of Wisconsin Division of Technology instruction web page improvement award, $750; Web page development for Regional Hydrology.