The Jonkershoek Nature Reserve includes the smaller Assegaaibosch Nature Reserve and forms part of the Boland Mountain Complex, about 70 km east of Cape Town. The reserve (14 635ha management area) lies within the larger Hottentots Holland Mountain Catchment Area which is approximately 84 936 ha in extent. The entrance to the reserve is about 10 km from Stellenbosch.
Similar to the rest of the Cape Fold Belt, Jonkershoek is characterized by dramatic sandstone cliffs, steep topography and valley bottoms associated with soils less resistant to weathering. A number of kloofs (ravines) occur in the Jonkershoek mountains, draining the valley through the Jonkershoek River, a major tributary of the Eersterivier.
The area has a Mediterranean climate with rainfall occurring as a result of frontal systems from the south Atlantic during the winter months of May to August. This period is also associated with strong north westerly winds. The highest peak at the head of the valley (Dwarsberg) holds the distinction of having the highest recorded annual rainfall in South Africa (3874 mm). A steep rainfall gradient exists from here to the valley bottom which receives only 1180 mm. The town of Stellenbosch receives 780 mm per annum. The hot summers are associated with south easterly winds that blow moist air from the warmer Indian Ocean into the higher elevations where it precipitates as mist. A small amount of rainfall also occurs in summer, mostly as the result of advection related storms. The Eersterivier flows through the urban and rural developments of Stellenbosch and passes through mostly agricultural land (viticulture and deciduous fruit) before its mouth in False Bay.
The Jonkershoek valley has for a long time been a centre of research activity within the Cape Floristic Region because of its location and proximity to universities in the Western Cape. An intensive weather - and stream flow monitoring programme has been operational at Jonkershoek for more than 70 years. There are currently six operational stream flow measurement weirs and a network of weather stations and rain gauges throughout the valley. The historic network of equipment was refurbished by SAEON between 2009 and 2012. Long-term data are already available from the Jonkershoek valley and the site thus offers tremendous opportunities for the monitoring of long-term change.
Part of the Jonkershoek Nature Reserve has been under pine plantation at various stages of its history and plantations are currently managed by MTO. The predominant vegetation types at Jonkershoek according to the latest vegetation map for South Africa are Kogelberg Sandstone fynbos, Cape Winelands Shale Fynbos, and Boland Granite Fynbos. A distinctive attribute of Jonkershoek is a high diversity of habitats on a local scale, fuelled by variable climatic and topographic conditions within a small valley.
The Jonkershoek valley has a rich publication history. Most notable among these are (i) the work carried out when the area was the Mountain Fynbos intensive study site for the multi-year Fynbos Biome Programme as summarised in the book by Van Wilgen et al. (1992) which concentrated on the fire ecology of the fynbos and covered the interactions between climate and fynbos vegetation and (ii) the Water Research Commission report (810/1/00) published on the catchment afforestation experimental data collected from the valley.
Detailed information on the background and management strategy for Jonkershoek is outlined in the management plan for the reserve.
Existing monitoring programmes
1) Six V- notch weirs measuring water level and water temperature hourly.
2) A set of ten rain gauges at lower elevations and four at high elevations have been monitoring weekly and monthly rain over several decades. The lower elevation sites were refurbished in 2011 when modern tipping bucket rain gauges were installed. Higher elevation rain gauges were automated in early 2015.
3) One automated weather station maintained by the Agricultural Research Council, with data available to SAEON.
4) One high elevation weather station with fog/cloud precipitation and soil moisture sensors (since March 2013).
5) A transect of weather stations across an elevation gradient investigating fog/cloud precipitation within one of the small sub-catchments (since May 2014).
Van Wilgen, B.W., Richardson, D.M. Kruger, F.J, and van Hensbergen, H.J. (Eds) 1992. Fire in South African Mountain Fynbos: ecosystem, community and species responses at Swartboskloof. Ecological Studies vol 93. Springer-Verlag, Berlin.
Scott, D.F., Prinsloo, F.W., Moses, M., Mehlomakulu, M. and Simmers, A.D.A. (2000). A Re-analysis of the South African catchment afforestation experimental data. Water Research Commission Report No. 810/1/00, Pretoria, South Africa.
Data available from Jonkershoek archives
Table Mountain National Park (TMNP) comprises all public land within the Cape Peninsula Protected Natural Environment (CPPNE), as well as private land that has been donated, contracted-in, or purchased within the CPPNE, with the exception of Kirstenbosch National Botanical Gardens. The TMNP covers a land area of 340 square km with a marine component of 980 square km and 130 km of coast line. Geographically it stretches from Signal Hill to Cape Point and is surrounded by intensive agriculture and urban development in the City of Cape Town.
TMNP forms part of the Cape Fold Belt which is characterized by sandstone ridges that are highly resistant to weathering, surrounded by softer sediments such as shale. A steep topographical gradient also exists where mountains rise dramatically from sea level to about 1085 m.a.s.l on Table Mountain.
The park and adjacent city have a Mediterranean climate with rainfall (400-2270 mm per annum) mostly brought on by frontal systems from the south Atlantic during the winter months of May to August. Strong north westerly winds are a feature of this time of year. Summer is associated with strong south easterly winds that blow moist air from the warmer Indian Ocean into the higher elevations where it forms clouds. About 25% of rainfall also occurs in summer, mostly as the result of advection related storms. Very steep rainfall gradients exist as a result of topography, aspect, slope and mist deposition. The oceans adjacent to this narrow landmass have an ameliorating effect on temperature with mean annual temperature being 18-20 degrees Celsius and a relatively small difference between mean minimum and maximums (6-10 degrees Celsius).
TMNP forms part of the Cape Floristic World Heritage Site and includes Mountain Fynbos, Lowland Fynbos, Renosterveld, Western Cape Afrotemperate forests, Milkwood forest, Strandveld, Rivers, Lowland wetlands, High altitude wetlands and Exotic plantations, sandy beaches, rocky shores and inshore kelp beds.
Due to its proximity to the city of Cape Town, parts of the TMNP have a long history of research and have been intensely studied by institutions such as the University of Cape Town, University of the Western Cape, South African National Biodiversity Institute and various museums.
Existing monitoring programmes
1) Hugh Taylor plots – 100 vegetation plots (5x20m) at Cape Point established in 1966 with subsequent re-surveys in 1996, 2006, 2008 and 2009.
Table Mountain: a Natural History by Anton Pauw
Between Two Shores by Liz and Mike Fraser
Mountains in the Sea – An interpretative guide to the Table Mountain National Park
Living Shores of Southern Africa’ by Margo and George Branch
TMNP Management - 2000 Management Policy
2000-2004 Strategic Management Plan (Reviewed in 2005)
Cape Point - Table Mountain National Park
The Cederberg study area is located approximately 200 km north of Cape Town in the section of the Cape Fold Belt known as the Cederberg mountains. It forms part of the Greater Cederberg Biodiversity Corridor (GCBC), a planning domain of 1.8 million ha that extends from Niewoudtville in the north to the Grootwinterhoek in the south, Elandsbaai in the west and the Tanqua Karoo National Park in the east. The GCBC includes land under various degrees of legislative protection with the Cederberg Wilderness Area being among the most protected.
Geologically this part of the Cape Fold Belt consists mostly of Table Mountain Sandstone (TMS), rising from low elevation (150 m.a.s.l.) valley floors to 2027 m.a.s.l. at the highest peak, Sneeuberg. The TMS outcrops are surrounded by finer grained, more nutrient rich soils at low elevations.
Climate has been described as Mediterranean, with most rain falling as a result of frontal systems from the South Atlantic during the winter months between June and August. Snow regularly occurs at high elevations during this time. Summers are typically dry and hot with south westerly winds predominating. A rainfall gradient of 200-900 mm per annum occurs around the study area with Algeria recording 500-900mm/a and Krakadouw 200-300 mm per annum. During the dry months very little rain is recorded (5mm mean for Wupperthal).
The GCBC includes a transition between the Fynbos Biome and the Succulent Karoo and represents the most north western part of the Cape Floral Region. The Cederberg mountains are dominated by mountain fynbos with afromontane forest patches found in the wetter ravines. A “cedar zone” occurs above 1000 m.a.s.l. mostly along cliffs and overhangs where the endemic Widdringtonia cedarbergensis has been studied extensively. Lower slopes and valley bottoms surrounding the mountainous areas support renosterveld and transitions to succulent karoo.
Cape Nature is currently the custodian core Cederberg Wilderness Area and manages its catchments as a water source. The Olifants River, which receives a lot of its water from these catchments, is of major importance for people on the low lying surroundings. Land use activities in the broader area are mostly agricultural. The upper Olifants River valley is a major producer of citrus, wine and deciduous fruit. Rooibos tea and potatoes are also becoming increasingly important in the wider area.
In addition to baseline data collected by CapeNature, this protected area has also been the subject of study for a variety of disciplines associated with South Africa National Biodiversity Institute, the South African Museum as well as the Universities of Stellenbosch, Leicester (United Kingdom), Kwazulu Natal and Cape Town. Research topics have covered diverse biophysical and other aspects of the Cederberg area including vegetation change, faunal communities, and geological aspects. Further ongoing research by initiatives such as the Bird-, Bat-, Frog- and Protea Atlas Programmes contribute to baseline data held by CapeNature.
In December 2015 SAEON installed an automated weather station and two rain gauges at strategic points in the Cederberg Wilderness Area. We plan to collaborate with Cape Nature towards future expansion of this monitoring network.
February & Stock’s 1999 “Declining trend in the 13C/12C ratio of atmospheric carbon dioxide from tree rings of South African Widdringtonia cedarbergensis” was the second southern hemisphere, and first African, example of a decline in δ13C in trees (Widdringtonia cedarbergensis) which can be related to anthropogenic impacts on atmospheric CO2.
February, E.C. & Stock, W.D. 1998. The relationship between ring width measures and precipitation for Widdringtonia cedarbergensis. South African Journal of Botany 64 (3), 213-216.
February, E.C. & Stock, W.D. 1999. Declining trend in the 13C/12C ratio of atmospheric carbon dioxide from tree rings of South African Widdringtonia cedarbergensis. Quaternary Research 52, 229-236.
February, E.C., West, A.G. & Newton, R.J. 2007. The relationship between rainfall, water source and growth for an endangered tree. Austral Ecology 32, 397-402.
Low, A.B., Mustart, P. and Van der Merwe, H. 2004. Greater Cederberg Biodiversity Corridor: Provision of Biodiversity Profiles for Management. Coastec, Rondebosch.
The Baviaanskloof River drains a 1,234 km2 catchment area located approximately 120 km west of Port Elizabeth in the Eastern Cape Province. The central valley runs roughly west to east along a major geologic fault in the Cape Fold Belt, with the Baviaans Mountains to the north and the Kouga Mountains to the south. The area is characterized by steep, quartzitic sandstone mountains flanking the long narrow floodplain in the central valley with a 20-30 m thick deposit of coarse alluvium. Due to multiple continental uplift events there is a high plateau of 600-900 m.a.s.l, while the central floodplain lies at 550-320 m.a.s.l. Mountain peaks above the plateau rise to highs of 1757 m.a.s.l (Smutsberg and Cockscomb peaks).
The majority of the catchment area (759 km2, 62%) is part of the Baviaanskloof Nature Reserve (BNR) managed by Eastern Cape Parks and Tourism Agency (ECPTA). The remainder is privately and communally owned farm and conservation land. The Baviaanskloof Nature Reserve extends into the Kouga and Groot River catchment areas and covers 2,110 km2. Much of mountainous area of the BNR had been managed by the Department of Forestry since the 1920s. The reserve area expanded under a government policy of catchment protection in the late 1960’s with the construction of the Kouga Dam which is fed by the Baviaanskloof and Kouga Rivers. The BNR forms part of the Baviaanskloof Mega Reserve (BMR) (5,000 km2), a World Heritage Site encompassing both public and privately held land.
The Baviaanskloof lies in the climatic transition zone between the winter rainfall area of the South Western Cape and the summer rainfall area to the east and north-east. Rainfall thus occurs throughout the year in a bimodal pattern, peaking in March and November, with high interannual variability in quantity and timing. Averages of 425-1021 mm per annum occur in the BMR area, depending on aspect as rainfall is driven by orographic as well as cyclonic processes. Frequent thunderstorms occur in summer. Temperatures are mostly between 15-32 degrees Celsius in summer and 5-18 degrees Celsius in winter. Snow can occur at higher elevations, but this is not an annual occurrence.
Due to its location on the eastern edge of the Cape Floristic Region, seven of South Africa's biomes are represented in the BMR. These are: fynbos, subtropical thicket, grassland, savanna, forest, nama-karoo and succulent karoo. In the formerly and currently farmed areas, high stocking rates of livestock significantly degraded areas of once closed canopy subtropical thicket. Various fire regimes were used to promote grazing or control fires in fynbos areas on both privately and public land. There is no active fire management or prescribed burning at present. Croplands and river modification have affected wetlands and floodplain function in the central valley.
Monitoring of hydrologic processes in the catchment area is being used to inform and calibrate hydrologic models of the catchment area to explore the impacts of land and water management options, ecological restoration, and climate change. Monitoring is been done in partnership with the NGO LivingLands who initiated a monitoring programme in 2011.
In addition repeated vegetation plot surveys and plant physiological surveys in the fynbos zones have been completed in partnership with the University of Connecticut to look at vegetation change over time and possible drivers.
Existing monitoring programmes
1) Four instream pressure transducers used to estimate streamflow since 2012
2) Two weather stations (operational since 2011) and six rainfall and temperature gauges (operational since 2014) managed by SAEON and LivingLands. Three additional weather stations are operating in the catchment, two from ECPTA and one from SAWS.
3) Seven manually read staff gauges in floodplain groundwater pits, monitored bimonthly since 2011
4) Eighteen piezometers in the floodplain, four of which are instrumented with pressure transducers and the remainder are read manually bimonthly, are used to monitor groundwater level changes around a Working for Wetlands gabian weir.