The impact of climate on the dominant height and climate thresholds for P. elliottii, P. taeda, P. patula , and P. patula x P. tecunumanii plantation forests

Plantation forests were introduced into South Africa to satisfy the regional demand for wood-based products, which are largely found in the Mpumalanga province. To better understand the impacts of climate on the dominant height growth of commercially important plantation species, enumeration data collected from 2012 to 2023 was scrutinised, representing 34740 plots in 2082 plantation compartments. Statistically significant multiple linear regression models were developed to predict dominant heights for Pinus elliottii, Pinus taeda, Pinus patula, and Pinus patula x Pinus tecunumanii hybrids using climate variables as independent factors. Mean annual maximum temperature was statistically significant when modelling dominant height for P. elliottii, while winter maximum temperature was significant for P . taeda, P. patula, and P. patula x P. tecunumanii. Rainfall was found to be significant for P. elliottii and P. taeda, while spring rainfall was found to be more important when modelling dominant height for P. patula. Interestingly, autumn rainfall was found to have a negative impact on dominant height growth of P. taeda and P. patula, while rainfall was not significant in P. patula x P. tecunumanii. The findings imply that the southern pines have water thresholds, while Mexican pines are more temperature limited than water limited.