Assessing forest yield and site suitability for...

This project considered the potential impact of climate change on both yield and production risk of eucalypts. The aim of this study was to project future mean annual temperature (MAT), mean annual precipitation (MAP), species site suitability, forest yield and the risk of the Leptocybe invasa pest for Eucalyptus grandis x Eucalyptus urophylla (EGU) in coastal Zululand of South Africa. The study utilised projected future climate variables from Global Circulation Models (GCMs). The climate data was also combined with recorded presence of the L. invasa pest to develop an ecological niche model using the Maximum Entropy (Maxent) model and project the possible risk of the pests’ infestation in the study site. Generally, projected future climates revealed increasing MATs amid reducing MAP over most of the study points in both RCP 4.5 and 8.5, as well as shifts in species site suitability for EGU. After validating and testing the r3PG model for use in coastal Zululand using field data, the r3PG runs across the future scenarios projected a pattern of reducing volume yield for EGU. A second species that was tested, Pinus elliottii, exhibited a relatively more severe trend of reducing yields from the current scenario through the future scenarios. These projected changes were observed amidst a reducing risk of L. invasa over the study grid points in both pathways by the end of the century. This study showed how integrating projected climate information, processed-based growth models and pest risk models can improve the information available to South Africa’s Forest industry. The integration of these data and models could contribute to the preparedness of the forest industry and inform policymaking towards mitigating uncertain climate futures.