Enhancing predictive precision of dominant height projection equations for eucalypts by incorporating rainfall and temperature terms

Abstract

Short-rotation forest stands are sensitive to extreme climate conditions during their growth period, which presents a challenge to managing forests and modelling forest growth in a constantly changing climate. We developed climate-sensitive dominant height models for the Eucalyptus grandis × Eucalyptus urophylla hybrid (GU) in South Africa. In addition, dominant height growth under three future climate scenarios was investigated. The Chapman– Richards and Gompertz models, modified by within-rotation and long-term climate data, were used to model dominant height. Model testing using independent permanent sample plot data showed that the Gompertz model modified by within-rotation bioclimatic data performed better than the other models. The climate-modified Gompertz model was used to project height growth for eucalypt stands under three future climate scenarios; ‘No change’, ‘RCP4.5’ and ‘RCP8.5’, for two periods: 2050 (years 2040 to 2060); and 2070 (years 2061 to 2080). Climate change might decelerate dominant height growth in the study area, therefore forest management plans need to be adapted accordingly.