Student Number : 9904953T -
PhD thesis -
School of Animal, Plant and Environmental Science -
Faculty of ScienceThis study seeks to combine the knowledge of science and society to elicit the relationship
between the harvesting of woody plant species and the local availability of woody species in
South African savannas. Ten villages located in the former communal areas and homelands
within three broad vegetation types (i.e., Mixed lowveld bushveld, Eastern thorn bushveld,
and Natal lowveld bushveld) were studied. The study, conducted in the framework of the
coupled human-environment system poses challenges to both scientists and managers (e.g.,
setting common goals). Data were collected using modified Whittaker plots (MWP) and
focus group discussions (FGD), denoting ecology and society, respectively. There were nine
1000m² MWP plots sampled per village, each having nested 1m², 10m² and 100m² subplots.
The FGD involved six groups of local people based on gender and age. The study revealed
that the harvesting of woody plant species is a source of local disturbance to woody
vegetation. Generally, there were more woody species in locations farther from settlements,
having a mean of 41.97 ± 3.9, than for the intermediate (38.27 ± 5.6) and near locations (19.9
± 4.2) within the 1000m² plots, the result of the reduction in species closer to settlements
from higher harvesting levels. The larger sampling plot size of 1000m² of the MWP had the
highest diversity, decreasing sequentially to the smallest scale (1m²). The density of the
woody species was highest in the intermediate locations (517 ± 80 plants/ha), followed by the
far and near, relative to the settlements. The Natal lowveld bushveld broad vegetation type
had the highest mean density of trees (573 ± 71 trees/ha) compared to the Mixed lowveld
bushveld (366 ± 64 trees/ha) and the Eastern thorn bushveld (312 ± 40 trees/ha). The stem
diameters of trees were generally higher in the villages of the Mixed lowveld bushveld than
the other two vegetation types. The study reaffirmed that anthropogenic disturbances within
savannas impact vegetation and need to be studied concurrently with other disturbance
factors (e.g., biotic and abiotic or environmental). The mean total coppice shoots of stumps
within the 1000m² plots was relatively higher in the near locations (38.4%), than the far
(33.0%) and intermediate (28.7%). This difference in coppicing shows that although near
locations were less species rich, which is a result of disturbance, the growth of shoots may
nevertheless be greater. Harvesting disturbance will possibly favour the regeneration of some
species, as well as the maintenance of biodiversity. Whilst 135 woody species (from a total
191 from 42 plant families) sampled in the field were used by the local people, the
community knowledge yielded almost twice as many (267 species, from 69 plant families).
The ratio of mean useful woody species to total woody species remained relatively constant
at about 1.0:1.1 from the near to far locations around the villages and accompanied by increased woody species diversity with distance from village. The MWP sampling yielded
eight broad use categories (i.e., medicinal, wild edible fruits, fuelwood, housing and fencing
poles, craft (e.g., carving), cultural, local beverages (e.g., alcohol)), and nine for the FGD (the
eight for the MWP plus indigenous furniture). According to the local people, the highest
number of species was used for medicine (27.8% of species), followed by fuelwood (19.2%)
and wild edible fruits/seeds (19.1%). Over half of the species had multiple uses (i.e., three to
eight uses), raising questions of possible threats to their persistence. Useful woody species
were not restricted to any particular location or vegetation type. Large sized trees were
subjected to even more uses than smaller trees, another source of conservation concern.
Fifteen of the woody plant species are presently protected by law in South Africa (e.g.,
Adansonia digitata, Podocarpus latifolius, Mimusops caffra, Philenoptera violacea), while
others are facing various forms of regional threats (e.g., Alberta magna, Catha edulis, Ocotea
bullata). There is the need to popularise and make people (both local and outsiders) aware of
the state of NTFP species, using local and village level information as an additional criterion
for describing conservation threat (e.g., proposed “Locally Brown List” – Chapter 4). The
older generation of local people were highly knowledgeable in terms of the woody species
used for medicine, craft, fencing and housing poles, the middle aged in beverage making
species, and the younger generation in fuelwood species. Overall, older males were highly
knowledgeable of the useful species. The generally strong correlation (r = 0.99, p <0.0001)
between the cumulative woody species diversity from field and community knowledge
suggests the need to integrate data using multi-disciplinary approach and also to manage
NTFP species. Although threat reduction assessments (TRA) and monitoring have previously
been suggested, the participation of local people, harvesters and users will be crucial in
making TRAs effective. In conclusion, the harvesting of NTFPs, and the impacts of the
changes in the NTFP species on total diversity in savannas need to be understood in order to
move towards a more holistic approach to conserving the woody species that may be at risk
of extinction through harvesting. Disturbance criteria that describe harvesting levels should
be set to guide research and management protocols. Finally, when discussing NTFPs and the
species from which they are harvested, management should aim at incorporating all the
factors that affect sustainability, such as land and resource tenure and local participation, the
political economy, appropriate production and development cycles
