Farm Forestry New ZealandPreliminary juvenile height yield models for three durable Eucalyptus species by integrating site-specific factors
By Serajis Salekin, Jack H. Burgess, Euan G. Mason, Justin Morgenroth, February 2020.
Download SWP-T094 (pdf)
Executive summary
Juvenile height growth models are useful to get an indication and understanding of site-species matching and initial decision making. Furthermore, juvenile height yield models are rare especially from sparsely available datasets. However, such models could still be useful to get generate initial information. The aim of this study was to develop preliminary juvenile height yield models from very limited data sources by including site-specific variables for three durable Eucalyptus species, namely E. argophloia, E. quadrangulata, and E. tricarpa. The models were plausible and precise with minimal errors as Root Mean Square Error (RMSE) ranges from 0.454 to 1.175 metres. All the models showed a slight negative bias, which implies a minimal underprediction. Topographic wetness index (TWI) negatively influenced height growth of all three of these species, while maximum monthly temperature (MXT) positively influenced height growth of all three of these species. In addition, E. argophloia preferred to have more shelter from wind, higher rooting depth and precipitation to grow taller. All variables together indicated E. agrophloia’s sensitivity to soil moisture availability. This study will provide a first-hand indication of how to handle the management and silviculture of these species, specifically with regard to planting them on appropriate sites.
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