The reserves lie on the Free State/North-west Province border, surrounding the Bloemhof Dam, an impoundment on the Vaal river. Sandveld Nature Reserve protects a remnant patch of the eastern form of Kalahari Thornveld, which projects into the grassland biome. The Kalahari Thornveld in this region previously covered a much greater area. The central portion of the reserve supports some excellent dense stands of Acacia savanna with Brachiaria as a co-dominant. The remainder of the reserve is dominated by open short grassveld, with clumps of Tarchonanthus and small thickets of Ziziphus, Rhus and Acacia scattered throughout.There are also extensive areas which, in the past, were cleared for grazing or cultivation; these open areas persist in the reserve either as open grassland or regenerating woodland. There is also an area of previously intensely overgrazed grassland, where karroid vegetation has invaded. Most of the reserve is very flat; there are a few low koppies and ridges, covered mainly with hillside bush of Olea and Rhus. Although the level of Bloemhof Dam can show large fluctuations, there are also times when it remains low for extended periods because the Vaal Dam, upstream, captures the major part of the catchment waters. Pans form under these conditions, and the exposed dam basin is colonized by grasses and extensive stands of annuals.
See Box for key species. The dam regularly supports more than 5,000 waterbirds and it has once supported more than 10,000 individuals. At times, when the water-level is low, islands and aquatic vegetation become exposed, making the system highly productive and suitable for many species of waterbird. Several mixed heronries are found around the dam, supporting a variety of breeding egrets, herons and cormorants. One heronry, c.1 km north-east of the bridge over the Vaal river, regularly supports over 3,500 breeding pairs. Another, on the southern shore (c.30 km from the first colony), regularly supports 2,200 breeding pairs. The dam regularly holds notable numbers of Phoenicopterus minor, Sterna caspia, Mycteria ibis and a few pairs of Circus ranivorus. The Kalahari thornveld surrounding the dam supports several large raptors and terrestrial birds, including breeding Aquila rapax, Gyps africanus and Ardeotis kori, as well as visiting Circus macrourus and Polemaetus bellicosus.
Non-bird biodiversity: Several large mammals have been reintroduced, including Ceratotherium simum (LR/nt).
Pressure/threats to key biodiversity
The area consists of two provincial reserves surrounding Bloemhof Dam: the Bloemhof Dam Nature Reserve (22,072 ha) was declared in 1975, and Sandveld Nature Reserve (14,700 ha) in 1980. The Department of Water Affairs and Forestry (DWAF) manages the dam water-level. The government controls the land along the Free State shoreline of the dam, but the narrow buffer strip that extends from 27°36’S 25°50’E to 27°32’S 26°12’E, about 100 km upstream, is leased to farmers. The surrounding land is commercial farmland.Threats to some aquatic birds include poor dam management—water is released into and out of the dam without consulting the reserve manager. Threats to scavenging raptors include foraging from carcasses that have been poisoned by farmers to eradicate vermin. Certain invasive plants have caused minor problems in the reserves. Two species of prickly pear Opuntia are controlled with herbicides, introduced Cactoblastus cactorum and cochineal insects. Prosopis scrub has also invaded and there are plans to remove it.
BirdLife International (2021) Important Bird Areas factsheet: Sandveld and Bloemhof Dam Nature Reserves. Downloaded from
http://www.birdlife.org on 24/01/2021.