The Blaauwberg Large-scale Sand Fynbos Restoration Project
Thursday, July 30, 2020
Posted by: Alexis Gibson
Text submitted by Patricia Holmes, Stellenbosch University
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"The restoration work therefore not only restores the threatened ecosystems, but also restores the sense of place and natural landscape of the original Cape lowlands. It is also quite humbling to realize the scale of the alien invasion problem and the amount of resources that will be required to restore fynbos to the reserve."
Immense Ecological, Historical, and Social Significance
Cape Flat Sand Fynbos are an endangered habitat type found only within the city of Cape Town, South Africa. The system is a Mediterranean-type, low-nutrient ecosystem
that requires summer fires to recycle nutrients and regenerate. The vegetation type is intrinsically rich in biodiversity (especially flora, with 16 endemic species; and invertebrates and smaller vertebrates such as herpetofauna). Pre-European colonization
the area would have been traversed by nomadic herders (Khoi-khoi) who could have grazed the area post-fire while at its most nutritious and potentially gathered other resources for consumption, such as geophytes and medicinal plants before moving
on to higher grazing potential areas.
|Uninvaded reference site (Photo: Stuart Hall).
The study site formed a part of one of the first colonist farms – Blaauwberg Farm (which still exists to the north of the nature reserve). This farm produced livestock for the Cape Town market and cattle were herded from there, across the current nature
reserve to Cape Town, 25kms to the south. In 1806 the Battle of Blaauwberg took place on the nature reserve with the battleground and associated field hospital declared a National Monument in 1996. This battle was important as it changed the colonial
history at the Cape, whereby the Batavians (Dutch) were defeated by the British who then took occupation of the area and controlled the sea-route to the East. The area therefore has immense ecological, historical, and social significance. Guided historical
walks are organized from Blaauwberg Farm, through the nature reserve, during the cooler months of the year. For more information please see the Friends of Blaauwberg Conservation Area website: www.bca.org.za.
Unrepresented and Disproportionately Affected
In the Fynbos Biome much attention has been paid to the mountain catchment areas over the past four decades, as these areas are considered very important for the delivery of ecosystem services, particularly water, for the cities and agriculture. By comparison,
the lowlands are considered of lesser importance. The lowlands support different biodiversity from the mountain catchments and this biodiversity is extremely threatened owing to the huge pressures from development, alien invasions, fragmentation,
and other factors impacting ecosystem functioning. Lowland ecosystems are under-represented in the reserve network and existing protected areas contain a high proportion of degraded land in need of ecological restoration. As resources for ecological
restoration are limited, it was considered important to seek funding to initiate research to improve restoration efficiency and effectiveness in collaboration with reserve management who advise on the practicalities of different approaches.
The project was initiated in 2012 by City of Cape Town and Stellenbosch University ecologists, but key partners throughout include Biodiversity Management of the City of Cape Town and external funders (Phase 1: Millennium Seed Bank Partnership, Royal
Botanic Gardens Kew; Phase 2: Hans Hoheisen Charitable Trust). The vision is for the restoration ecology research to provide practical management guidelines that will hasten the ecological restoration of 400ha of highly degraded Sand Fynbos in Blaauwberg
Nature Reserve over the next few decades. The aim is to restore representative ecosystem structure (i.e. to level 3 or 4 of the SER Restorative Continuum), then over time to improve plant community composition and re-introduce or bolster populations
of the most threatened species. Fire provides the window for species re-introductions and fire frequency is in the order of 10-15 years in this ecosystem type; hence the long-term nature of ecological restoration in these ecosystems.
Things Don’t Always Go as Expected
Predictions from previous fynbos restoration ecology studies indicated the importance of fire in stimulating residual buried fynbos seed banks at degraded sites and initiating recruitment. Fire also removes the alien biomass, kills shallow seed banks
of herbaceous alien species, and volatilizes some of the accumulated nutrients and was therefore considered an important treatment to include in ecological restoration. However, at Blaauwberg the burn resulted in very dense recruitment of the alien
Acacia saligna which made this treatment impractical owing to the high costs of alien follow-up control. We therefore had to go back to the drawing board and trial other more efficient ecological restoration methods.
Restoring a Sense of Place
| Felled wattle slash treatment (2012; left) and the site in 2019 (Photos: Stuart Hall).|
Having known the site since 2005 when it was a near monoculture woodland of alien Acacia saligna and today with 125ha cleared of the alien and indigenous species recolonizing is extremely uplifting. There is now a magnificent view of Table Mountain
whereas previously one could not even see it was there. The restoration work therefore not only restores the threatened ecosystems, but also restores the sense of place and natural landscape of the original Cape lowlands. It is also quite humbling
to realize the scale of the alien invasion problem and the amount of resources that will be required to restore fynbos to the reserve. The opportunity to work with other stakeholders, including our funders, the Millennium Seed Bank Partnership and
the City of Cape Town has been truly rewarding. The project would not have been possible without the ongoing support and investment by the Biodiversity Management Branch of the City of Cape Town that manages the nature reserve. These collaborations
have delivered benefits to both researchers and managers.
Since submitting the project last year, the Phase 2 funding was awarded by the Hans Hoheisen Charitable Trust to enable additional project implementation and research up until 2022. Our current PhD student has set up a second trial at an adjacent site
to look at a delayed burning treatment (i.e. alien slash burnt two years after clearing). The Blaauwberg Phase 1 study indicated that Acacia soil seed banks declined by 80% in two years post-clearing, therefore we are hopeful that delayed burning
may result in lower Acacia recruitment and follow up costs while promoting the benefits of fire for fynbos recruitment and establishment. There have been no other changes or new funding sources for the project identified as yet.
A Working Example of Collaboration
We submitted the project to the RRC because we consider the Blaauwberg Ecological Restoration Project to be a good working example of collaboration and co-learning between research and management spheres and wished to communicate our experiences
to the broader ecological restoration community. It is also good for our partners and funders to be acknowledged in this way and therefore to keep the door open for additional research funding, especially to improve establishment efficiency for seed-based
and rooted material re-introductions.
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