Site preparation and vegetation management impacts on Pinus patula growth and rotation end productivity in South Africa

ABSTRACT

Intensive silviculture is carried out within commercial timber plantations within South Africa during the re-establishment phase, however, there is limited information as to the rotation end benefits of this input. A trial investigating the rotation end (17.1 years) impact of slash management (Burn vs. No Burn), preparation of a planting position (Pit, Rip, Chopper roll+Pit and Chopper roll+Rip) and vegetation management (Weedy vs. Weedfree), and their interactions, was implemented on Pinus patula grown on a pulpwood regime in Mpumalanga, South Africa. Preparation of a planting position had a notable influence on vegetation biomass, where biomass was lowest within the Rip treatments. At 17.1 years, slash management did not significantly (P ≤ 0.05) influence growth, whereas the preparation of a planting position had a significant influence on basal area (BA) and volume (Vol), and vegetation management a significant influence on all the measured growth variates (diameter at breast height, BA and Vol). In addition, there was a significant interaction between the preparation of a planting position and vegetation management for BA and Vol. The greatest reduction in Vol was recorded for the mean of the treatments where only pitting was carried out (211.1 m³ ha⁻¹) compared to the ripping treatments (27.1 m³ ha⁻¹). These outcomes highlight the importance of vegetation management during re-establishment on rotation end P. patula productivity. In addition, these results support previous studies which found an interaction between the preparation of a planting position and vegetation management.

KEYWORDS:

• burning
• chopper-rolling
• ripping
• slash management
• weed control

Acknowledgements

Komatiland Forests (KLF) are thanked for providing the land and labourers used for this trial. Nico Olivier and Karel Pauw (KLF) were instrumental in terms of making this trial happen. Numerous ICFR staff were involved with this trial, Jurgens Kritzinger designed and implemented this trial with Gavin Higgs (deceased), with subsequent maintenance and measurements carried out by Ryan Connolly. NCT is thanked for providing MSc scholarship funding for Noxolo Ndlovu for the writing up of this trial.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the South African forestry industry through the Institute for Commercial Forestry Research.