ECOSYSTEM MODEL EVALUATION Physiological Principles for Predicting Growth

ECOSYSTEM MODEL EVALUATION • Physiological Principles for Predicting Growth (3 -PG) – Landsberg and Waring, 1997 – Managed in several forms: Peter Sands, CSIRO Australia, Excel format; Nicholas Coops, UBC, Command prompt – http: //3 pg. forestry. ubc. ca/ • Domain/Objective – Dynamic, process-based tree growth model for even-aged stands that is distance-independent and bridges gap between mensuration-based growth & yield models and process-based, C-balance models • Key Assumptions -Species and individual plants not defined Temporal/Spatial Scale -Monthly time step/ spatially undefined but output is based upon (1 -multiple) forest stands up to landscapes

Input Drivers • Climate – • Site and Soil – • Monthly mean temperature, radiation, precipitation, VPD, Latitude, soil texture, water capacity, fertility rating Stand Characteristics – Foliage, Stem and Root biomass, stocking, available soil water Key Outputs • Biomass pools, stocking, available soil water, NPP & ET, DBH and standard stand attributes

Testing/Validation • Forest productivity • Environmental limitations on growth • Measure NPP • Predict soil properties • Estimating Mean Monthly Incident Solar Radiation • Estimating maximum mean canopy stomatal conductance

Testing/Validation

Testing/Validation Investigating Eucalyptus growth using 3 -PG Vol, DBH, Height, GPP (Mg dry mass/ha/month) 50, 0 45, 0 300 Volume, m 3/ha • Determine whethere is a relationship between height and DBH as well as volume and GPP 350 40, 0 250 35, 0 200 30, 0 25, 0 150 20, 0 100 15, 0 10, 0 50 5, 0 0 0, 0 0 2 Maximum Avail. Soil Water effect on GPP with LAI = 1. 0 8 10 25 14, 0 13, 0 20 12, 0 50 mm 11, 0 75 mm 10, 0 100 mm 9, 0 150 mm 8, 0 200 mm 1990 1995 Year 2000 2005 Tree height, m GPP, Mg (DM)/ha/yr 4 6 Stand age, years Predicted (blue) vs. Mesured (red) mean tree height 15, 0 7, 0 1985 Height, m • Comparison of observed and projected volume and stem height 15 10 5 0 0 20 40 60 Stand Age, months 80 100