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Veld rehabilitation is work in progress, there is initial work undertaken and then depending on success rates of effectiveness, one or more follow up treatments may be necessary.
This is an interim progress report on the two rehabilitation (trial) projects approved by the Board in February 2017. Initial work was carried out in May and June 2017.
Veld Rehabilitation on Buffelsbed
A specialized 3-wheeler machine was deployed in the demarcated area shown below in Map 1.
Map 1. 55 ha Grewia spp. cleared on Buffelsbed
Pic 1: Original clearing in May/June 2017
Pic 2: Photographed in July 2017
As can see be seen from pictures 1 and 2 above, the cleared Grewia was spread out (brush packed) by the Conservation Team, while simultaneously applying herbicide to the cut stumps. Dye is added to the herbicide mix so herbicide applicators avoid duplicating cut stump treatment to the same plant.
Herbicide application is avoided when ambient conditions have either high moisture content or moderate to high winds. The former conditions dilute herbicide concentrations while the latter conditions cause rapid evaporation of herbicide, in both cases reducing the effectiveness of successful herbicide absorption by plants. To aid absorption, a wetting agent is also added to the herbicide mix.
Pic 3: Cut stump treatment with (blue) dye
Pic 4: (July 2017) dormancy phase
infused in the herbicide (May 2017)
This progress report falls during the winter season, where plants retreat into a “dormancy” phase. At the onset of Autumn, the plant growth season drops off entirely, and for survival plants invest their energy in root maintenance. They no longer expend any energy in stem and leaf growth, energy is directed to the roots, where nutrients are stored underground to sustain the plant through the dry and colder season.
Effectievely what this means is that there is no monitoring requirement on this trial site through the plant dormancy phase. Monitoring will recommence when the new growth season begins – usually coinciding with the first summer rains.
The Conservation Team has identified three monitoring sites within this 55 hectare trial site. Each monitoring site will measure 75mx75m. These sites are identified to represent the different plant communities found within the 55 ha block, namely Grewia Thicket, Mixed Grewia/Combretum and Mopane Veld.
Monitoring sites will be inspected for any sign of coppice and follow up treatment of folio spray will be applied to the coppice. Coppice throughout the 55ha block is treated.
The extent of coppice within the monitoring site will be calculated to express a percentage of success rate. For example, 20% of plants showed coppice, which concludes that this method of clearing Grewia has a success rate of 80%. Monitoring will continue in Year 2 and Year 3 to apply any further follow up treatment (folio spray) necessary.
Different plant communities can have varying success rates. These results will be compared with previous methodology used for Grewia clearing, where a tractor uses chains to uproot the plant. The three pillars of evaluating and comparing methodology effectiveness will be extent of coppice, catch per unit effort (area cleared vs time) and cost of effort.
Mopane Trial on Goedehoop
A second conservation trial was also approved at the February 2017 Board Meeting.
Map 2: Mopane trial area on Goedehoop
This trial site is on Goedehoop (see Map 2 above) and involves selective clearing of mopane trees and shrubs. Multi-stemmed mopane trees and shrubs of less than 300 mm in trunk diameter were selectively felled. The 50% removal rule was applied to multi-stemmed mopane trees. Single stemmed trees were not felled. From previous herbicide trials performed near Old Farmhouse we learned that for successful herbicide treatment mopane trees must be felled as close to the ground surface as possible.
Picture 5: Cut stump of mopane
close to ground level
Pic 6: Area selectively cleared
The next action required on this site is to “tidy up” the aesthetic appreciation, the visual impression. Once the leaf fall is complete, (September/October) the Conservation Team intends to deploy its two tractors and operators to drive over the area, mulching the thinner stems and branches to expose the thicker stems and stumps for manual retrieval. These larger pieces should be removed/collected to avoid negative impact to soil from future control burns or accidental fire.
These larger pieces can be used as natural biodegradable materials for important erosion control in gullies and drainage lines. It can also be used in retaining structures on the several sodic sites that occur on Goedehoop. Removal will also support improved light penetration necessary for grass germination.
by John Llewellyn