The evaluation of bush thickening in two management systems in three districts of the North West Province in South Africa : a LandCare initiative
Van Vuuren, Anja Jansen
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The problem of land degradation is something that can not be ignored in this day and age. A food shortage as a result of desertification is a reality in especially, the African continent. One of the factors contributing to the problem of land degradation, is bush thickening. Bush thickening leads to the reduction of the grazing potential of natural rangelands. This has a direct effect on the cattle production and thus on the human livelihoods itself. Bush thickening usually occurs in areas that were exposed to over grazing in the past. The North West Province is the sixth largest province of South Africa. Nine (9) of the 28 magisterial districts of this province are considered to have a severe bush thickening problem. Several programmes have been initiated in South Africa to address the land degradation problem in order to make the land users more aware of the problem and to get involved in more sustainable natural resource management practises. Such an initiative is the LandCare program in South Africa, introduced by the National Department of Agriculture. LandCare has five themes, of which VeldCare is mainly based in the North West Province. This involves, amongst others, bush thinning, clearing or the total eradication of undesirable woody andlor alien plants to improve the grazing potential of rangelands. The clearing of the hush can be achieved by direct or indirect practices. Direct practices are when bush is eradicated by chemical or mechanical methods, whereas indirect practice focus more on the stocking rate and management of livestock, to prevent bush thickening. The indirect rangeland management practices were introduced together with awareness creation programmes in this study. Through this project, communities are given the opportunity to participate and take charge of the degradation problems in their region. LandCare therefore also focuses on education, training and capacity building of the land users in the rural areas. Three magisterial districts in the Western Region of the North West Province namely Ganyesa, Kudumane and Taung were identified by the Provincial Department of Agriculture to be monitored on account of their project development at the time. All three magisterial districts are subdivided into three Agricultural Development Centres (ADC's). These ADC's are again divided into a number of Field Service Units or FSU's. Benchmark sites were selected in certian FSU's for this study. The study sites were chosen to represent both the Morafe Ranches and Communal managed systems. The Morafe Ranch and communal management systems in the Ganyesa magisterial district were Water-Fouch6 and Austrey respectively. In the Kudumane magisterial district, the Morafe Ranch systems were studied at the Heuningvlei study site. No communal managed rangeland system was monitored in this district, as there were no woody species in the vicinity of the exclosure plots used in this study. The Morafe Ranch system in the Taung magisterial district was at the Orange Grove study site and the communal managed rangeland was at the Ipelegeng study site. The data of the Ipelegeng study site however is unpresentable. The reasons are fully discussed in Chapter 4. In the study areas, several benchmark plots were selected that would represent the vegetation and management systems of the region. At the benchmark, an exclosure was erected. The fenced-in area would serve as a control to demonstrate the effect resting would have on a rangeland, while the outside of the exclosure normal grazing practise occurred. The aim was to determine the extent of bush thickening at the selected benchmark study sites, and how it will change both under the current grazing regime (outside the exclosure) and during resting (inside the exclosure) in the two management systems (Morafe Ranch and communal managed system). Quantitative surveys were carried out over a two year period to determine the structure and composition of the woody species. The average percentage of the woody species was calculated for the past three sampling periods (April 2001, December 2001 and May 2002). Although a two year period (three seasons) is much too short to detect any changes in the structure and composition of the woody component, the data and results will serve as good baseline data for long term monitoring and management projects. The benchmark sites are also used as demonstration plots that contribute to the awareness and training of the land users as part of the Landcare initiative. The vegetation sampling methods included the belt transect method, 2 x (4 x 100 m) or 5 x (4 x 40 m), depending on the size and shape of the exclosure. Each woody species rooted in the 4m belt was noted as well as the structure class it occurred in. Five height classes were noted, namely: less than 0.5 m, 0.5 - 1 m, 1 - 2 m, 2 - 3 m, 3 - 4 m and higher than 4 meters. The environmental factor, rainfall, had the most influence on the slight changes that occurred in the species composition and structure of the woody vegetation. The rainfall data of the past five years could be considered as above average. It had a significant impact on the germination of seedlings of woody species, and thus influenced the less than 0.5 m height class the most A major drawback to the data collection was the sampling practises, as different people participated in each sampling event Some of the species such as Grewiaflava, which has a multi stemmed growth form, was noted as one individual during one survey and in other cases as several individual plants. This caused much distortion in especially the density data and contributed to the fact that the results between sampling events and seasons could not be clearly correlated with each other. The data collected is represented as a percentage of the woody species for each benchmark site, inside and outside the exclosure. The species that were present in a more than 5 % abundance, as well as the structure classes, were represented in bar graphs. To give more perspective on the woody species data, the tree equivalents per hectare (TEha) per structure class, as well as the total tree equivalents, were calculated for each study site and survey period. The dominant height class was the less than 0.5 m. The tree equivalent per hectare data show the 1 - 2 meter height class to have more influence on the herbaceous data at the study area. A species that was found in most of the benchmarks was Grewiaflava. The reduction in the grazing area might be significant, due to the growth form and large canopy cover of G. flava. Although Acacia mellifera was present in all the benchmark sites with more deep sandy soils, such as the Water-Fouch6 -, Austrey -, Heuningvlei - and Ipelegeng study sites, the presence of A. hebeclada seems to be greater problem leading to bush thickening. Acacia hebeclada was more abundant than Acacia mellifera in most cases. The attitude towards the LandCare projects in each of the communities improved as the data was analysed and results presented to the land users, agricultural officers and the communities, a task which is often neglected in feedback sessions by scientists. Feedback to the communities therefore forms an integral part of such a long term study. As mentioned, the study period was too short to determine any significant differences in woody species composition, but it has contributed considerably to the awareness and capacity building of all stakeholders. If future data collection is done, it is essential that the surveyors should be thoroughly trained beforehand in the identification of woody species, especially the seedlings of the different Acacia species, as well as the sampling procedures, to avoid problems in the data analysis and results. Woody species should be noted as multi- or single stemmed to eliminate the problem of perception differences of different surveyors. Sampling methods can also be improved on in future. All in all, this LandCare project can be viewed as a success story. Despite some drawbacks, a lot was learned about the different natural resource management systems.