A comparison of planting and coppice regeneration of Eucalyptus grandis × Eucalyptus urophylla clones in South Africa

Abstract

Results from two coppice compared to replant trials are presented that originated from clone by site interaction (CSI) trials established on high- and low-productivity sites in subtropical coastal KwaZulu-Natal, South Africa. After the 84-month CSI trial measurements were completed the trees were harvested. Selected plots were allowed to coppice with the remainder replanted to the same four Eucalyptus grandis × Eucalyptus urophylla hybrid clones. Growth was higher at Kwambo Timbers (average mean annual increment [MAI] 34 wet white tonnes [wwt] ha⁻¹ y⁻¹), characterised by a higher mean annual precipitation, than at Palm Ridge (average MAI 11 wwt ha⁻¹ y⁻¹). In these trials coppicing of sufficient stumps per hectare (>1 000 stumps ha⁻¹ ) resulted in similar volume production on the higher-productivity site and slightly improved (additional 3.4 wwt ha⁻¹ y⁻¹) yield on the lower-productivity site compared with the planted crop. The benefit of coppicing was mainly related to a reduction in the temporary unplanted period and reduced establishment cost. This study showed that coppicing can be a viable, cost-effective alternative to planting in commercial forestry if a number of criteria are met. However, it is recommended that the decision to coppice or to replant should be evaluated on a case-by-case basis.

Keywords: coppice, Eucalyptus grandis × Eucalyptus urophylla hybrid clones, re-establishment methods, rainfall, replant, sprouting, stocking, volume production