South Africa offers a large amount of grasslands and pasture lands to study and monitor.
During our workshop organized in Pretoria (June 2016), two pilot sites have been more formally proposed to join the RAPP initiative: The Kruger Site (1) and the Cathedral Peak Site (2).
SITE 1: The Kruger Site
The Kruger National Park (KNP) and surrounding areas are located in a semi-arid Lowveld of South Africa and support high wildlife diversity in the park and livestock production in adjacent communal lands. Ecotourism represents the main income generating activity in the park and contribute substantially to the South African economy. Livestock production is the mainstay of the rural economy in the communal lands – including food and energy security. KNP is representative of South African savanna ecosystem and is a unique laboratory for research on savanna dynamics and ecosystem services. Savanna ecosystems are open canopy forests (about 50% or less tree cover) made of heterogeneous layers of grass and woody plants. As the largest biome in sub-Saharan Africa (approximately half of the land surface), these ecosystem hosts a large proportion of the African population – human densities are proportionally higher than in denser forests, generally the poorest communities who rely extensively on ecosystem services, e.g. fuel wood, timber, grazing resources and edible fruits.
Research activities on remote sensing based rangeland assessment (including grass quantity and quality as well as tree cover) are underway. The research on rangelands has been geared towards the development of remote sensing tools to estimate leaf nitrogen (N) and biomass as an indicator of grass quality and quantity (Ramoelo et al. 2011, 2015). The latter indicators are important for understanding the feeding patterns of livestock and wildlife. Again, leaf N and biomass are important for deriving rangeland management tools such as carrying capacity of grazers and browsers, stocking rates and spatial zoning (grazing camps).
There are key threats to provisioning capacity of the rangelands, i.e. bush encroachment and overgrazing. Bush encroachment is affecting the availability and quality of forage for wildlife and livestock. Bush encroachment is a national problem which affects 10M ha in South Africa (O’Connor 2014). Overgrazing in the communal lands has resulted into highly levels of depletion of grazing resources in terms of quantity (as measured by biomass) and quality (leaf nitrogen concentrations). The latter factors influence the occurrence and population dynamics of animals at a particular point in time. We now further investigate remote sensing techniques for understanding how bush encroachment manifests itself through time, using vegetation indices and Synthetic Aperture RADAR (SAR).
All above research activities are linked to several research projects including; ECOPOTENTIAL: Improving future Ecosystem Benefits through Earth Observation funded by H2020 EU framework, SASSCAL (involved in Biodiversity, Agriculture and Forestry themes), Council for Scientific and Industrial Research (CSIR) funded projects: Towards operational earth observation based rangeland assessments, Common Multi-Domain Development Platform (CMDP) to Realise National Value of the Sentinel Sensors for various land, fresh water and marine societal benefit areas and National Woody Vegetation Monitoring System for Ecosystem and Value-Added Services.
Collaboration & Stakeholder involvements
For the H2020, we are collaborating with several institutions in Europe and other countries. For the SASSCAL projects, we are collaborating with South African institutions e.g. Agricultural Research Council (ARC), University of KwaZulu Natal etc.
Our key stakeholders are:
- South African Departments:
- Department of Agriculture, Forestry and Fisheries (DAFF),
- Department of Science and Technology (DST),
- Department of Environmental Affairs (DEA),
- Department of Rural Development and Land Reform (DRDLR),
- South African National Parks (SANPARKS)
Main contact point details
Dr. Abel Ramoelo – Senior Researcher
Earth Observation Research Group
The projects explore the use of in situ and remote sensing data to assess and monitor tree cover, bush encroachment, rangeland quality and quantity – using suite of tools – including empirical (parametric and non-parametric) and physically-based models.
Kruger National Park (KNP) is a fenced National Park located in the north-eastern part of South Africa. KNP is located in the dry savanna biome, and was established in 1898 to protect wildlife. Savanna means is characterized by the co-dominance of grasses and trees. The surrounding areas of KNP have various land use activities including grazing for livestock production, crop cultivation (commercial and subsistence), forestry and human settlements (rural communities).
The major drivers of vegetation distribution in this system are geology, fire, topography and soils (Venter et al. 2003). Two main geological types exist in KNP which influence the density of trees and grass biomass. Basalt geological type is characterized by high fertility soils dominated by grasses and Acacia tree species. On the other hand, granite geological types are characterized by low fertile soils dominated by high tree cover- especially the Combretum species. The abiotic and climatic factors make this dry savanna a complex ecosystem. Several studies has been conducted in this National Park and its surroundings ranging from mapping grazing and browse resources to understanding the feeding patterns and population dynamics of wild and domestic animals.
In situ data with GPS coordinates
- Leaf N (2009, 2010, 2009, 2014)
- Leaf Area Index (2009, 2012, 2014)
- Herbaceous Biomass (2009, 2010, 2013, 2014)
- Grass composition or cover (2009, 2010, 2012, 2014)
- Tree cover (2011)
- Animal data
- Climate data
- Fires (several years)
EO Data requirements
Existing remote sensing data
- Hyperspectral data (2008, 2010)
- Airborne LiDAR data (2008, 2010)
- RADAR-SAT (C-band) (multi-season) (2009 and 2010)
- ALOS PALSAR (2008 and 2010)
- WorldView 2 (Dry and Wet Season)
- RapidEye (Dry and Wet Season)
- Landsat data (current and historical)
- SPOT 5 (current and historical)
- MODIS (current and historical)
Additional data requirements
- Time series data or data cubes for
- Landsat 1 – 8
- Sentinel-1 and 2
- ALOS PALSAR
See Google Earth: Kruger National park (KNP) – pilot site.kmz
Project reports and some selected scientific publications
Kaszta Z, Marino J, Ramoelo A, Wolff E. 2016. Bulk feeder or selective grazer: African buffalo space use patterns based on fine-scaled remotely sensed data on forage quality and quantity, Ecological Modelling, 323, pp. 115-122
Naidoo et al. 2014. Savannah woody structure modelling and mapping using multi-frequency (X-, C- and L-band) Synthetic Aperture Radar data, ISPRS Phot and Remote Sens, 105
Mathieu et al. 2013. Toward structural assessment of semi-arid African savannas and woodlands: The potential if multitemporal polarimetric RADARSAT-2 fine beam images, Remote Sensing of Environment, 138, 215 – 231
O’Connor T.G. et al. 2015. Bush encroachment in southern Africa: changes and causes, African Journal of Range and Pasture Science, 31(2), pp: 67-88.
Ramoelo A. Cho M.A. Mathieu R, Madonsela S., van de Kerchove R., Kaszta Z., Wolff E. 2015. Monitoring grass nutrients and biomass as indicators of rangeland quality and quantity using random forest modelling and WorldView-2 data, International Journal of Applied Earth Observation and Geo-information, 43, 43-54.
Ramoelo A., Cho MA. Mathieu R., Skidmore A.K. 2015. Potential of Sentinel-2 spectral configuration to assess rangeland quality, Journal of Applied Remote Sensing, 9(1), 094096
Ramoelo A, Skidmore A.K. Cho M.A. Schlerf M. Mathieu R, Heitkonig I.M.A.2012. Regional estimation of savanna grass nitrogen using the red-edge band of the spaceborne RapidEye sensor, International Journal of Applied Earth Observation and Geoinformation,19: Pages 151-162
Venter, F. J., Scholes, R. J. & Eckhardt, H. C. (eds.) 2003. Abiotic template and its associated vegetation pattern, London: The Island Press.
SITE 2: The Northern Khahlamba Drakensberg Site – Cathedral Peak
The South African temperate grassland biome covers approximately one third of the land area of South Africa. It is arguably the most important biome for the country’s economy. This is because of its size in combination with essential services we get from healthy grasslands. Water is one of the most potentially limiting factors for economic growth in South Africa. Grasslands are the major vegetation cover of the primary water-producing mountain catchment areas in summer rainfall regions and are thus valuable “ecological infrastructure assets” in the landscape. There is a significant degree of overlap in South Africa’s strategic water production areas and the grasslands. The grassland biome also provides natural forage, contributing significantly to dairy, beef and wool industries, as well as subsistence livestock production and game ranching activities. It is diverse, productive and rich in natural resources traditionally used sustainably for subsistence. Our healthy mesic grasslands also hold a significant proportion of the country’s carbon stocks, due to relatively high percentages of carbon within the soils in combination with the extent of the system.
There are also extractive and transformative activities within the biome, including commercial forestry, a significant proportion of the country’s commercial and subsistence crop production as well as close to half the mining activities in the country. These activities as well as urbanization have resulted in over 30% of the Grassland biome being permanently transformed, over 7% badly degraded and increasing fragmentation within this system. Only 2% of the grassland biome is formally protected. The expansion of mining, forestry, cultivation and urbanisation are considered immediate threats to grasslands and consequently the ecosystem services they provide to society. In addition, the direct and indirect impacts of climate change on this biome are predicted to be significant.
The use of grasslands as rangelands is a potentially compatible landuse to ensure continued ecosystem services from this system. However, poor rangeland management, particularly in mountainous areas, is also causing degradation through reduced plant cover and cattle paths, leading to soil lose and gully formations. The net effect is likely to be reduced productivity of these systems which may be further exacerbated climate change impacts.
SAEON’s mandate is to detect change resulting from anthropogenic forcing. The approach adopted is to measure responses to a specific set of drivers linked to human activity. Within this context, science activities at the Grasslands-Forest-Wetlands Node aim to be policy relevant, and need to address how global change is impacting on key services provided by these ecosystems, such as rangeland productivity.
Research activities are designed around four interlinked themes representing key services of ecological and economic value;
- Productivity and carbon dynamics
- Water delivery
- Land use-biological feedback with earth system processes.
We are working on these themes arose landuse and altitudinal gradients including “pristine” reference sites, degraded areas, sites undergoing restoration and alterNative land use sites (forestry). We have active research assessing in situ biodiversity and productivity across landuse gradients. Partnering with SANSA and RAPP, the aim is to use a combination of remote sensing and in situ measurements to understand rangeland productivity over a land use gradient in a changing climate.
Collaboration and Stakeholders
SAEON sites are intended as national platforms to enable and stimulate global change research. Collaboration is this central to our ethos. Currently we have active collaborations with academic instruction, provincial and national government as well as international scientists. Active participation include
- The University of Pretoria
- Witwatersrand University
- University of KwaZulu Natal
- University of Free State, Qwa Qwa Campus
- Department of Agriculture and Rural development (DARD)
- Department of Science and Technology
- Department of Environmental Affairs: Natural Resource Management Programmes
Host institution and collaborator: Ezemvelo KZN Wildlife
Main contact point details
Susan Janse van Rensburg: Node Coordinator: Grasslands
South African Environment Observation Network
This project will form a part of an integrated program centred on understand carbon water energy and biodiversity patterns and process and how these are changing.
The spatial extent of the project covers a diverse range of natural and anthropogenic landscapes. The area falls within the grassland biome of southern Africa, one of the most species rich habitats in southern Africa. A portion of the study area is protected as a World Heritage Site and managed by the provincial conservation authority, Ezemvelo KwaZulu-Natal Wildlife. The relatively high rainfall in the area also supports various commercial agriculture practices such as cropping, livestock production and afforestation. Importantly, the broader area is known as the “water tower” of southern Africa due to the productive catchments and large rivers that have their source here.
A number of historic research projects have been performed in the area. Significantly, the hydrological research at Cathedral Peak (see map above) was instrumental in the South African Forest and Mountain Catchment Area Act that was developed to secure water production in the country. There is a wealth of historic data in the region making it an attractive research site.
The benchmark core site is within the protected area enabling researchers to look at rangeland productivity and change detection specifically with respect to climate. Treatments (pristine grassland, degraded and fire protected catchments) within the site as well as a rangeland use gradient (including sites undergoing restoration) in the surrounding landscape provide opportunities for assessing multiple landuse impacts and on rangeland condition and productivity.
Altitudinal range: 1400 – 3000 m.a.s.l.
Mean annual temperature (Mikes Pass Weather station): 13.8°C
Summer rainfall: MAP ̴ 1 400 mm
In Situ Observations
- SteamFlow and weather monitoring
- Carbon flux (Eddy covariance as well as soil respiration)
- Soil carbon
- Biomass (root and above ground)
- Soil Moisture
- Water quality
- Fire history
- Land use gradients impacts on botanical diversity
- Energy balance
- We will be initiating plant N and C analysis
- South African environmental observations network data systems
To be specified soon
29° 00’ S; 29° 15’ E
There is an extensive reference collection available from SAEON linked to all historical and current work relating to the full program. Useful synthesis reports are listed below.
Toucher, ML; A Clulow, A; Janse van Rensburg, S, Morris, F; Gray, B; Majozi, S; Everson, C; Jewitt, GPW; Taylor, MA; Mfeka, S and Lawrence K (2016) Establishment of and demonstration of the potential of the Cathedral Peak research catchments as a living laboratory (WRC Report No. 2236/1/16).
(2016) Exploring the potential of Cathedral Peak as a living lab. Technical brief linked to WRC Report No. 2236/1/16