Growth and fibre yield ofPinus patulaandPinus elliottiipulpwood plantations at high altitude in Mpumalanga

Abstract

SYNOPSIS The demand for pine pulpwood in the Mpumalanga province approaches two million tonnes per annum. To meet processor demand for low cost wood, it is important to maximise timber productivity per planted hectare. Selection of species for a site can significantly influence plantation productivity. The aim of this study was to measure and compare the relative performance of 13- to 14-year old adjacent stands of Pinus patula and P. elliottii pulpwood, to determine which species is the more productive on high altitude sites (in the region of 1600 m a.m.s.1.) The results from the study show that P. patula is consistently and significantly taller than P. elliottii and has consistently thinner bark than P. elliottii across all eleven sites. No significant difference in diameter was measured between the two species. Underbark volumes of P. elliottii are therefore significantly lower than P. patula. The superiority of P. patula is consistent across sites previously considered as unsuitable for the species, including sites with low mean annual rainfall and sites with very shallow soil depth. The higher volume production of P. patula, together with the superior pulp yield of 2–3% over P. elliottii measured in previous studies, make P. patula a more productive species than P. elliottii, in terms of fibre production per hectare.