Using a process-based forest model to estimate the potential productivity of Eucalyptus plantations in southern China

Process-based models are increasingly being applied as a planning tool by forest managers. The 3-PG forest model offers significant benefits for application to Eucalyptus plantation management in southern China. In addition to providing a rational basis for decisions on stand establishment, tending and harvesting, a well-constructed model may act as a framework for storage and retrieval of tree performance data and an indicator of priority areas for research. Measurements of tree and stand growth, biomass relationships and water use from plantations on the Leizhou Peninsula of western Guangdong Province have been used to estimate model parameter values for major commercial eucalypt genotypes. The rapid early growth, high stand density and short rotations adopted by forest managers for woodchip production necessitate special forms of some parameters not included in other implementations of 3-PG. Climate data inputs for modelling may be satisfactorily estimated from routine daily meteorological observations including temperature, rainfall and sunshine duration. Physiological parameters which are not amenable to direct measurement may be estimated by fitting the modelled growth predictions to one or more sets of growth observations, ideally for multiple species on sites with a range of climate and soil conditions or stand densities. The accuracy and reliability of modelled predictions will improve over time as more data sets become available to incrementally improve the precision of estimated parameters.