Hybrid ecophysiological growth model for deciduous Populus tomentosa plantation in northern China

Abstract

Short rotation plantation forestry (SRF) is being widely adopted to increase wood production, in order to meet global demand for wood products. However, to ensure maximum gains from SRF, optimised management regimes need to be established by integrating robust predictions and an understanding of mechanisms underlying tree growth. Hybrid ecophysiological models, such as potentially useable light sum equation (PULSE) models, are useful tools requiring minimal input data that meet the requirements of SRF. PULSE models have been tested and calibrated for different evergreen conifers and broadleaves at both juvenile and mature stages of tree growth with coarse soil and climate data. Therefore, it is prudent to question: can adding detailed soil and climatic data reduce errors in this type of model? In addition, PULSE techniques have not been used to model deciduous species, which are a challenge for ecophysiological models due to their phenology. This study developed a PULSE model for a clonal Populus tomentosa plantation in northern China using detailed edaphic and climatic data. The results showed high precision and low bias in height (m) and basal area (m²·ha⁻¹) predictions. While detailed edaphoclimatic data produce highly precise predictions and a good mechanistic understanding, the study suggested that local climatic data could also be employed. The study showed that PULSE modelling in combination with coarse level of edaphic and local climate data resulted in reasonably precise tree growth prediction and minimal bias.