ReStory narrator: Karen Esler
This ecological restoration project began in 2012 as a collaboration among City of Cape Town, Stellenbosch University and the Millenium Seed Bank programme. The project has both research and operational management components, fostering a co-learning approach that is designed to improve the outcomes of ecological restoration interventions. The project also explores ways to scale-up restoration and improve efficiency. This is important as restored ecosystems will improve the conservation of biodiversity, delivery of ecosystem services, adaptation to climate change and potentially contribute to climate change mitigation and the social value of nature reserves.
The current phase of the ecological restoration project continues the City of Cape Town and Stellenbosch University collaboration and is funded by the Hans Hoheisen Trust for three years from 2019-2021. There are two components: The first is an operational component, administered through the Wilderness Foundation, to clear 24 ha of Acacia saligna from highly degraded Cape Flats Sand Fynbos, and collect, sort and pre-treat Fynbos seeds for sowing across the alien-cleared landscape. The second component comprises two research projects and is administered through Stellenbosch University. The PhD study will examine restoration techniques that avoid the immediate use of fire (which results in expensive acacia follow-up) and the MSc study will explore applied nucleation as a method to scale-up restoration.
Photo 1A & B. Uninvaded reference sites – Cape Flats Sand Fynbos has high biodiversity and high endemism and these lowland sites are highly transformed (invasion) and fragmented.
Photos 5 A & B. Fell & Burn, Active Restoration (Seeded) – 2013 (Photo: Stuart Hall) and 2019 (Photo: Pat Holmes). In this treatment, massive recruitment response from acacia post-fire swamps indigenous recruitment; aliens dominate seed banks; fire beneficial where remnant patches survived (higher restoration potential areas). Follow-up manual acacia clearing is most effective but too expensive to be viable large-scale. Herbicide foliar spray kills some indigenous species, but is less costly for dense acacia recruitment. Herbicide must be applied to cut stems to prevent coppicing in A. saligna but must be done carefully to minimize collateral damage. Sowing back of serotinous Proteaceae post-fire greatly improves vegetation structure in cases where some fynbos soil-stored seed banks persist. In dense acacia-invaded fynbos, post-fire sowing of a comprehensive fynbos mix is required to improve fynbos recruitment yet guild structure & community composition do not approach reference site conditions after a single sowing (Hall et al. 2017; Hall 2018).
Photos 6 A & B. Fell & Stack, Passive Restoration in low restoration potential area – 2014 (Photo: Stuart Hall) and 2019 (Photo: Pat Holmes). Fell & stack treatment sufficient if >10% cover structurally intact fynbos is present, but very low recruitment following alien removal in closed stands with <10% fynbos cover. Legacy effects of Acacia results in medium-term altered soil chemistry and potential to promote secondary invasions by herbaceous species (Krupek et al. 2016; Hall 2018; Nsikani et al. 2019)
Hall, S., Newton, R., Rebelo, P., Gaertner, M., Esler, K.J. (2017) Heat and smoke pre‐treatment of seeds to improve restoration of an endangered Mediterranean climate vegetation type. Austral Ecology, 42(3): 354-366.
Hall, S. (2018) Restoration potential of alien-invaded Lowland Fynbos. PhD Dissertation, Stellenbosch University. Supervisor: Prof. K.J. Esler; Co-supervisors: Prof Patricia M. Holmes; Dr M. Gaertner. 143p.
Holmes PM, Esler KJ, Gaertner M, Geerts S, Hall SA, Nsikani MM, Richardson DM, Ruwanza S (2019) Biological invasions and ecological restoration in South Africa In: van Wilgen BW, Measey GJ, Richardson DM, Wilson JR, Zengeya, T (eds) Biological invasions in South Africa. Springer, Berlin [Book In Press].
Krupek, A., Gaertner, M., Holmes, P.M., Esler, K.J. (2016) Assessment of post-burn removal methods for Acacia saligna in Cape Flats Sand Fynbos, with consideration of indigenous plant recovery. South African Journal of Botany 105:211-217.
Nsikani, M.M., Gaertner, M., Kritzinger-Klopper, S., Ngubane, N.P., Esler, K.J. (2019) Secondary invasion after clearing invasive Acacia saligna in the South African Fynbos. South African Journal of Botany 125: 280-289.
The City of Cape Town, Key contact: Dr Charmaine Oxtoby; Biodiversity Management Branch I Environmental Management Department I Spatial Planning and Environment Directorate; email@example.com
Stellenbosch University, Centre for Invasion Biology and Dept. Conservation Ecology & Entomology. Key Contacts: Professor Karen J Esler (ConsEnt; firstname.lastname@example.org), Professor Pat Holmes (ConsEnt & C.I.B, email@example.com).
Centre for Invasion Biology (2012 – Ongoing)
City of Cape Town (Operational and in-kind, 2012 – ongoing)
Millenium Seed Bank programme (2012 – 2015)
Hans Hoheisen Trust (2019-2021)