J. Michael Kelly, Forestry, Principal Investigator
William R. Graves, Horticulture, Co-PI 

A Mechanistic Modelling Approach to Nutrient Uptake and Carbon Allocation in Selected Hardwoods
Use of mechanistic models in both research and management is experiencing greater acceptance as it becomes more and more difficult to deal with the increasing numbers of things that must be evaluated in order to develop complete understandings and formulate environmentally and economically sound management strategies. 

This research program is divided into three phases. The first involves refining our ability to describe and model nutrient uptake. The second combines a nutrient uptake model with a simple model of carbon allocation in a whole plant. The final phase uses the nutrient uptake model in a complex whole-plant carbon model and includes plant growth response to several environmental variables. During the next three to four years, emphasis will be placed on the accomplishment of the first two phases of the program.

Specific objects associated with the first two phases of the program are to: 

• Refine the methodology and approach used to acquire the soil supply, root morphology, and nutrient uptake kinetics data sets used to describe nutrient uptake; and 
• Couple, through the use of a mechanistic model, nutrient uptake, carbon allocation, and tree growth processes.

Significant strides have been made in recent years in the development and application of quantitative mechanistic models that allow complex chemical, physical, and biological processes to be evaluated in the context of changes in plant nutrient uptake and carbon allocation. Models developed by Stan Barber and Ruth Yanai, for example, provide a means to simulate nutrient uptake by various plant species once a basic set of parameters has been developed that describe: 

• the nutrient supplying capacity of the soil, 
• the root morphological characteristics of the plant, and 
• the kinetics of nutrient uptake.

Investigations of soil, root, and uptake kinetics will provide important insights into the nutrient requirements of hardwood species. Meshing a nutrient model and a carbon allocation model will ultimately provide insights into the most appropriate ways to manipulate nutrient availability to maximize growth and minimize negative impacts in managed settings.