ARS | Publication request: Forecasting annual aboveground net primary production in the intermountain west

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 15, 2010
Publication Date: February 6, 2011
Citation: Finzel, J., Weltz, M.A., Seyfried, M.S., Kiniry, J.R., Launchbaugh, K. 2011. Forecasting annual aboveground net primary production in the intermountain west [abstract]. Society for Range Management. p. 258.

Technical Abstract: For many land manager’s annual aboveground net primary production, or plant growth, is a key factor affecting business success, profitability and each land manager's ability to successfully meet land management objectives. The strategy often utilized for forecasting plant growth is to assume every year is an average year and make changes and adjustments to management as needed. This strategy leaves little time or opportunity for land managers to plan ahead and prepare for below average years, or take advantage of above average years. This study tested the accuracy of plant growth forecasts from two computer models: Agricultural Land Management Alternatives with Numerical Assessment Criteria (ALMANAC) and the Soil Ecohydrology Model (SEM). ALMANAC is a physiologically based crop production model designed to quantify key plant-environment interactions that influence productivity. SEM is a capacitance parameter model that uses a water-balance approach to simulate soil moisture and the DeWitt equation to forecast yield. Model forecasts of plant growth were compared to field collected yield data. Preliminary results indicate that ALMANAC forecasts provide reasonably accurate yield numbers when input criteria are properly calibrated for each site while SEM forecasts are not consistently accurate. A special emphasis was placed on soil moisture expressed as volumetric water content as a model calibration tool. Both ALMANAC and SEM forecast soil moisture as a part of the plant growth forecasting process. Soil moisture was chosen over other variables that affect plant growth because it is a direct way to measure plant available water, a common plant growth limiting factor.