Tonga Mangrove

Taxonomy
Scientific Name
Lumnitzera racemosa Willd. var. racemosa
Higher Classification
Dicotyledons
Family
COMBRETACEAE
Common Names
Tonga Mangrove (e)
National Status
Status and Criteria
Endangered* B1ab(ii,iii,v)+2ab(ii,iii,v)
Assessment Date
2017/01/18
Assessor(s)
A. Rajkaran, J. Adams & D. van der Colff
Justification
The species is assessed as Least Concern at the global scale, however it is experiencing population decline across its global distribution due to coastal development (Ellison et al. 2010). In South Africa at the regional level, this species is only known from a single location and it has a EOO and AOO <1 km ² with continuous decline as a result of harvesting. The intense pressure coming from harvesting has resulted in a decline in the population in the Kosi Bay area and the species is assessed as Critically Endangered, however because this is a regional assessment and the species is wide spread outside of the assessment area and also experiencing declines, based on IUCN regional assessment guideline, a regional assessment adjustment is required, and here we have adjusted the status to Endangered at the regional level.
Distribution
Endemism
Not endemic to South Africa
Provincial distribution
KwaZulu-Natal
Range
Occurs only in Kosi Bay. A globally widespread species also occurring from Kenya to South Africa, Madagascar, tropical Asia, Northern Australia and Polynesia.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Mangrove Forest
Description
Mangrove swamps, usually on the landward side.
Threats
The species occurs in the upper drier parts of the Kosi Bay estuary which makes the species more accessible to harvesters, branches are harvest most likely for firewood. These branches that are harvested result in a change in the growth form of the plant, this impacts on the reproductive output of the species by reducing resource allocation to reproduction (A. Rajkaran, pers. Comm. 2016). As a higher ratio of adults to seedlings have been recorded in a recent study by Rajkaran (2011).
Population

This species has a widespread global distribution, however its South African population is considered to be isolated from the neighbouring Maputo Bay population as few propagules are received, however this has not been quantified but based on propagule size and distance (±100 km) to travel to Kosi Bay; it is expected to be low (A. Rajkaran, pers. Comm. 2016). The potential recruitment in the Kosi Bay population from Maputo Bay is projected to be much lower than recruitment within the population.


Population trend
Decreasing
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Lumnitzera racemosa Willd. var. racemosa Least Concern Raimondo et al. (2009)
Lumnitzera racemosa Willd. var. racemosa Not Threatened Hilton-Taylor (1996)
Lumnitzera racemosa Willd.Vulnerable Hall et al. (1980)
Bibliography

Adams, J.B., Veldkornet, D. and Tabot, P. In press. Distribution of macrophyte species and habitats in South African estuaries. South African Journal of Botany.


Ellison, J., Koedam, N.E., Wang, Y., Primavera, J., Jin Eong, O., Wan-Hong Yong, J. and Ngoc Nam, V. 2010. Lumnitzera racemosa. The IUCN Red List of Threatened Species 2010:e.T178846A7625290. http://dx.doi.org/10.2305/IUCN.UK.2010-2.RLTS.T178846A7625290.en, Downloaded on 19 January 2017.


Exell, A.W. 1978. Combretaceae. In: E. Launert (ed). Flora Zambesiaca 4:100-183. Flora Zambesiaca Managing Committee, London.


Hall, A.V., De Winter, M., De Winter, B. and Van Oosterhout, S.A.M. 1980. Threatened plants of southern Africa. South African National Scienctific Programmes Report 45. CSIR, Pretoria.


Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical Institute, Pretoria.


Raimondo, D., von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. and Manyama, P.A. 2009. Red List of South African Plants. Strelitzia 25. South African National Biodiversity Institute, Pretoria.


Rajkaran, A. 2011. A status assessment of mangrove forests in South Africa and the utilization of mangroves at Mngazana Estuary. Unpublished Ph.D., Nelson Mandela Metropolitan University, Port Elizabeth.


Rajkaran, A. and Adams, J. 2015. Mangroves of South Africa. In: J.O. Bosire, M.M. Mangora, S. Bandeira, A. Rajkaran, R. Ratsimbazafy, C. Appadoo and J.G. Kairo (eds.), Mangroves of the Western Indian Ocean: Status and Management (pp. 51-73), WIOMSA, Zanzibar Town.


Citation
Rajkaran, A., Adams, J. & van der Colff, D. 2017. Lumnitzera racemosa Willd. var. racemosa. National Assessment: Red List of South African Plants version 2017.1. Accessed on 2019/08/17

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Distribution map


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