Euston-Brown, D., Rathogwa, N & Richardson ... - DWA Home Page

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9.2 Appendix 2: Results from field experiment near Tzaneen
9.2.1 Introduction
This experiment was done in August 2004 to try and test a range of control methods to determine
which method produced the best results for controlling chromolaena. This was needed to be able
to assess the impact that different clearing methods have on ecosystem recovery. The results of this
experiment were used as baseline information for developing the clearing protocols.
9.2.2 Methods
In this study we used Working for Water clearing teams to apply different clearing treatments to
permanently marked plots set up in two sites in the Tzaneen area. The Tzaneen region was chosen for
this study because C. odorata is a major alien invasive in the entire Tzaneen region, and appears to be
spreading rapidly here. We also found that the Tzaneen office were interested and keen to participate in
the project that relied on their assistance. The treatments were applied to two different study sites. The
sites were within 5 km of each other and both were chosen together with Brendon Mashabane, our
contact and manager for the Tzaneen WfW office (Ph 0828028796).
The Theuns Botha sites were on a game farm in Tzaneen Sour Bushveld with canopy trees up to 10 m
tall including Pseudolachnostylis maprouneifloia, Terminalia sericea, Euclea schimperi, Pilliostigma thonningii
and Bauhinia galpinii. A dense sward of Panicum maximum with numerous forbs and abundance of
younger trees were present. The site was on a gently sloping hill at 557 m asl with approximately 1 m
deep red clay soils with a 30 cm layer of brown loam on the surface. This site was densely covered with
C. odorata and had already been cleared once in 2003, one year before we applied our experimental
follow up treatments in 2004,2005 and 2006.
The Hilltop site was on the upper slopes of a steep hill with shallower stony soils at 774 m asl. The
plots were heavily infested with both C. odorata and L. camara that had never been cleared before. The
hilltop vegetation was also a mixed bushveld dominated by Trichilia emetica and Acacia spp.
The 4m radius circular plot locations were carefully chosen and they were spanned across several
hectares of natural bushveld. We chose plots that appeared to have a similar density and cover of C.
Appendix 2
The capped and numbered steel pegs that were used for marking the plots.
The soil was bored out at 10 cm intervals with a soil auger and placed in
piles that were given numbered labels in order from the top downwards. For
example, 2 is between 10 cm and 20 cm below the surface.