PREDICTING <em>EUCALYPTUS</em> PRODUCTION IN SOUTHERN CHINA USING THE 3-PG MODEL

Abstract

HUA, L. Z., MORRIS, J., HE, X. B. & JIANG, X. D. 2007. Predicting Eucalyptus production in southern
China using the 3-PG model. The 3-PG model was applied to predict plantation growth and yield in
reference to climate, soil conditions, management and species. Tree growth in three Eucalyptus genotypes, E. urophylla, E. urophylla Clone U6 and Eucalyptus ABL12 (E. tereticornis) Clone W5, was monitored between 1999 and 2002 at Jijia on the Leizhou Peninsula, Guangdong. Parameter values for 3-PG were determined by calibration on the basis of monitoring data. The model was tested using additional growth data of the three genotypes from two sites on the Leizhou Peninsula. The calibration results for various stand variables were satisfactory (overall mean r² > 0.93 and mean accuracy > 88% for stand growth, accuracy > 82% for stand biomass and leaf area index). Root biomass was less accurately predicted because root systems actually extended to greater depth than we were able to assess. Independent testing of the calibrated model showed simulation accuracy for most variables was > 91%. Stand volume (SV) responded positively to fertility but negatively to salinity for each species. SV was not closely correlated with rainfall, but under dry condition, it significantly declined with rainfall decrease. It implied that soil water was not a main limiting factor on stand growth in the rainy area.