SAEON Arid Lands Node takes on monitoring of de-proclaimed Vaalbos Park

The Vaal River meandering through the northern, eastern and western side of the park adds to the scenic splendour of the area The de-proclaimed Vaalbos National Park was named after the dominant Camphor bush (regional Afrikaans name “Vaalbos”) in the area

Named after the dominant Camphor bush (Tarchonanthus camphoratus) or regional Afrikaans name “Vaalbos” in the area, the de-proclaimed Vaalbos National Park (VNP) is situated 70 km south west of Kimberley.

The Vaal River meandering through the northern, eastern and western side of the park adds to the scenic splendour of the area, which encompasses about 18 000 ha and varies in altitude from 1011-1175 m above sea level. The intermingling of Savanna and Nama Karoo biomes at the Gras-Holpan section makes this park unique.

Only a few years back large herds of buffalo and a number of rare and endangered animals such as black rhino and roan antelope roamed the area. The park was once a tourist attraction that featured a wide range of activities including game viewing, a bird hide and a picnic area.

Land claim

Vaalbos National Park was proclaimed in 1986. In 1998 documents were received of a land claim lodged against the park by the adjacent claimant community. In 2002 the land claim was officially gazetted and SANParks accepted the validity of the claim. The VNP was subsequently de-proclaimed in 2006. In March 2006 the first animals were translocated to Mokala National Park, which was proclaimed in 2007.

Long-term observation

A vegetation map of VNP was generated in 1991 as part of a monitoring programme aimed at improving management’s understanding of vegetation dynamics in reaction to abiotic (i.e. rainfall) and biotic (i.e. herbivores) impacts, ultimately ensuring the successful management of fauna and flora in the park. The monitoring programme was initiated by Dr Hugo Bezuidenhout from SANParks, who conducted annual surveys at the end of April or beginning of May between 1993 and 2003.

In 2011, the decision was made by SAEON’s Arid Lands Node to continue monitoring the vegetation of all the plots, using the original methods proposed by Bezuidenhout. The wheel point method was used to determine herbaceous layer to estimate the canopy cover and plant species composition, while the belt transect method was used for the shrub and tree layers - to estimate the plant species composition and density of the woody plant species.

Understanding land use change

In the early 1920s the alluvial diamond mines along the Vaal River were in operation, but all mining activities ceased when a cattle farm was established in the area in the 1960s. The claimant community is expected to change the land use into a mixture of conservation, livestock ranching and crop farming, while small companies are once again mining the floodplain of the Vaal River.

Long-term monitoring is vital to understand the interaction between vegetation change and land use.

Preliminary results: Climate

Figure 1. Long-term rainfall trends show an increase in total annual rainfall, with a clear wetter cycle during the last ten years

Plot 131 forms part of 30 permanently marked transects in the de-proclaimed VNP where changes in vegetation have been monitored over a period of 19 years. This plot forms part of Chloris virgata grassland, which is restricted to the floodplains (adjacent to the Vaal River) along the north-westerly part of the VNP. Vegetation changes (plant cover and composition) in this plot were monitored using wheel point and fixed point photographs.

Photo: Hugo Bezuidenhout (1993) Photo: SAEON Arid Lands Node (2012) Figure 2. Fixed point photography reveals a marked change in species cover. In 1993 (photo left), the plot was covered by dense Chloris virgata and Aristida adscensionis grass species. Nineteen years later the same plot (photo right) is dominated by the Cynodon dactylon grass species.

Figure 3. Change in species canopy cover (%) over sampling periods (year) of plot number 131 (Chl vir – Chloris virgata, Cyn dac – Cynodon dactylon, Ari ads – Aristida adscensionis, Era ech – Eragrostis echinochloidea, Fel mur – Felicia muricata and Pen inc – Pentzia incana)

Plot 131 evolved from a Chloris virgata dominated grassland to a Cynodon dactylon grazing lawn. Current trends in rainfall might be favouring the dominance in cover of Cynodon dactylon. Although there has been a shift in species dominance over the years, the plot did not undergo drastic changes in species composition.

Figure 4. Stocking rate over years in Vaalbos National Park

The uncertainty surrounding the land claim led to a high stocking rate between 2001 and 2005, which might have put pressure on the Chloris virgata grassland. The specific grass species is known to be sensitive to heavy grazing and the high concentration of game on the floodplain could have influenced the decline of this grass species. The results show that the change in the species dominance and cover of Plot 131 is a combination of increased rainfall and grazing pressure.

Monitoring is a long-term process and this study will continue in order to determine trends with expected land-use and changes in climate. Vegetation dynamics in all plant communities of VNP will be analysed (herbaceous and woody components).

The SAEON Arid Lands Node is grateful to the Vaalbos claimant community for permission to access the property.