#06 2020

Mariepskop Catchment: A new platform for studying the impacts of restoration on freshwater supply and biodiversity

By Dr Tony Swemmer, Manager, SAEON Ndlovu Node

On the slopes of Mariepskop Mountain in Mpumalanga Province, a new SAEON project is investigating the role of land management and vegetation change on the provision of freshwater in north-eastern South Africa. 

The slopes of the South African Escarpment mountains were extensively afforested with exotic pine and gum trees over the past century, and while many of these remain as active and productive plantations, others have been abandoned or reclaimed for other uses.

A large area of former plantations on the eastern slopes of the escarpment near the Mpumalanga-Limpopo boundary has recently been restituted to a number of communal property owners who have chosen to incorporate the land into the neighbouring Blyde River Canyon Nature Reserve.

This will ultimately bring a range of societal benefits, from income generated through ecotourism, to restoration of the exceptionally high biodiversity of the area, to increased water flows of the rivers that rise on the mountain slopes and support agriculture and ecotourism industries downstream. However, these benefits will only be realised if the abandoned forestry plantations can be restored to the montane grasslands and savannas that once covered the mountain slopes.

On the slopes of Mariepskop Mountain, a new SAEON project is investigating the role of land management and vegetation change on the provision of fresh water in north-eastern South Africa. (Picture: Malachite Media)

River flow in the Klaserie River, which rises on the eastern slopes of Mariepskop, declined drastically in the 1930s and 40s, when planting of gum and pine plantations began.

The restoration of forestry plantations is a relatively new field of study in South Africa, and little is known regarding the most effective methods to remove alien vegetation, promote recolonisation by grassland species and prevent soil erosion. While fire is a well-understood and widely-used management tool for maintaining montane grasslands and fynbos in the southern parts of the country, research is needed to understand the impacts of both controlled and wildfires on areas of abandoned plantations in the Mariepskop area.

In collaboration with universities, the Kruger-to-Canyons Biosphere NPO, the Department of Environment, Forestry and Fisheries (DEFF) and Mpumalanga Tourism and Parks Agency (MTPA), SAEON has initiated long-term studies to detect and understand ecological and hydrological changes that occur as restoration proceeds. These studies include continuous measurements of weather, soil water and the flow of mountain streams for data needed for hydrological models, as well as regular vegetation surveys.

Fire would have been a regular occurrence along the escarpment throughout South Africa, but natural fire regimes were disrupted due to fire suppression by foresters tasked with protecting plantations. Restoring the natural fire regime is critical for restoring biodiversity, ecosystem structure and river flows. (Photo: Tony Swemmer)

Local community members have been trained to assist with data collection, in this case the regular measurement of soil water in patches of grassland and plantations. Project partners have also employed locally sourced teams to clear alien trees in abandoned plantations, which is critical for creating natural experimental treatments needed to study and model the hydrology of the area. (Photo: Tony Swemmer)

The project is expected to have high research impact through providing data for numerous postgraduate research projects, with the first MSc project – a study on the use of remote sensing to map alien plants – already underway. The novelty of the research questions and the understudied ecosystems involved are also expected to attract international researchers, and a pilot study with American ecologists has already begun.

However, the societal impact of the research is perhaps even more important. Both the incoming management authority for the area (MTPA) and the new owners (the land claimants) have limited financial and scientific resources available for managing the area as a nature reserve and prime ecotourism destination.

Cost- and time-effective ways to restore and maintain grasslands and savannas are therefore crucial, as are cheap and reliable monitoring methods (which require the use of open-source remote sensing products). Hard evidence of positive impacts of restoration on biodiversity and freshwater supplies is also key for securing future funding that will be needed to clear massive areas infested by alien plants.

Results will be important beyond the Mariepskop site, as many former plantations on the escarpment are in need of similar restoration. The platform has been designed around these needs, with a focus on the efficacy of cutting versus fire for clearing alien plants and restoring indigenous species, acquiring data for hydrological modelling and developing remote sensing tools for vegetation monitoring.

Collaborators from Kansas State University (USA) collecting soil samples from one of the few remaining grassland patches at the Mariepskop site, an important benchmark site for informing restoration goals and progress. (Photo: Tony Swemmer)

A land cover map of the major vegetation types of the study area, produced by SAEON MSc student Keletso Moilwe and SAEON scientist Dr Glenn Moncrieff. Maps such as these are critical for identifying areas for restoration, as well as tracking changes in vegetation cover to evaluate the progress of restoration initiatives.