Adenium swazicum - South African National Parks

The ecology and population biology of the
critically endangered succulent – Adenium
swazicum
K. van der Walt¹, E.Witkowski²
¹Threatened plants project – Lowveld National Botanical Garden – SANBI
²Wits University – School of animals plants and environmental sciences.
The ecology and population biology of the
critically endangered succulent – Adenium
swazicum
INDEX:
• Species description.
• Threatened status and reasons.
• Study area.
• Objectives and results to date.
• Conclusion.
Adenium swazicum - Stapf
• Apocynacea family.
• Described in 1963 by Codd.
• Homotypic synonym: A.boehmianum Schinz
var swazicum (Stapf).
Species description:
Branches:
• Sparingly branched, erect and
simple.
• Branch size: 15-30cm high
and 1.5cm in diameter.
Adenium swazicum - Stapf
Species description continue:
Leaves:
Clustered at end of branches, subsessile and folded
Size: 6-13cm long and 1-3cm broad.
Flowers:
• Showy, pink or mauve to deep
reddish purple.
• Usually darker in the throat, vary
in size.
Fruit:
Paired, cylindrical follicles covered
in hair – splitting to release seed.
Adenium swazicum - Stapf
Species comparison: A.multiflorum:
Threat status of A.swazicum
IUCN threat status:
• 1980 – Indeterminate status (Hall)
• 1996 – Indeterminate status (Hilton-Taylor)
• 2002 – Endangered for Swaziland, not accessed in
SA.
• 2008 – Critically endangered in SA based on
following:
1. There is actual or potential levels of
exploitations which is not halted or understood.
2. 50% of its past habitat has been transformed by
sugar cane agriculture over 3 generations.
3. Past and future declines is estimated as an overall
decline of 80% over 3 generations.
KNP is indicated as a “safe habitat” where an
estimated 10-20% of the population occur.
EXPLOITATION:
Medicinal purposes:
• One of the top 10 medicinally used plants in the Thambokhulu and
Mbuzini areas (Lotter et al. )
• Harvesting method is destructive – tuber removed.
• Tuber is boiled and extract is sold to cure stomach ailments.
April 2007
November 2008
EXPLOITATION:
Horticultural:
• Adenium horticulture is a multi-million dollar industry in Taiwan,
India and USA.
• Species most favoured for hybridization is A.obesum and
A.swazicum.
Adenium hybrids are sold for U$1000.00
as gifts and good luck charms.
STUDY AREA:
• Komatipoort, Marloth
Park and Mananga.
• Kruger National Park –
south and central.
• Swaziland.
• Northern KzN??
AIM:
To determine the population biology and ecology
of Adenium swazicum and to develop a
management plan for in situ and ex situ
conservation.
OBJECTIVES
• To determine the population size and structure of
all A.swazicum subpopulations.
• Determine the biotic and abiotic characteristics of all
sub-populations (soil, geology, altitude, climatic data).
• Determine the regeneration capacity of A.swazicum.
• Determine disturbance regimes .
• Establish propagation protocols to ensure
successful propagation of ex situ collections.
OBJECTIVES
To determine the population size and structure of all
A.swazicum subpopulations.
1.
A complete count of all the individuals.
• Komatipoort area – 2 localities = 115
• KNP = 4 separate localities around 300
2. Known localities still to be counted:
• 3 Localities in KNP
• 1 Locality at Malelane.
• Swaziland.
OBJECTIVES
To determine the population size and structure of all
A.swazicum subpopulations.
2. Plant size and growth.
Measurements:
• Plant height (soil level to canopy top).
• Maximum canopy diameter.
• Diameter at right angles to maximum canopy diameter.
• Number of stems per plant.
Measurements = Canopy area and Canopy volume per plant.
OBJECTIVES
Determine the regeneration capacity of A.swazicum.
1. Flowering and seed production.
• Number of flowers per plant per season.
• Number of follicles produced per plant per season.
• Ratio between flowers and follicles.
• Number of seed per follicle.
2. Pollination:
• The pollinator for the genus Adenium is still unknown.
• Flowers have no smell, attraction is visual.
• Very limited pollinator activity observed during
daytime.
• Possibilities of nocturnal pollinator now needs to
be investigated.
OBJECTIVES
Determine the regeneration capacity of A.swazicum.
3. Seedling survival – in situ.
• Three quadrats containing 100 seed each.
• Quadrat no. 1 at Matjulu bridge, no exclusion
methods used – seed planted directly into ground.
OBJECTIVES
Determine the regeneration capacity of A.swazicum.
3. Seedling survival – in situ.
• Quadrat no. 2: Covered with poultry mesh to exclude any
mammals, but insects can get access to seedlings.
• Quadrat no. 3: Covered with poultry mesh and mosquito net
to exclude all possible mammals and insects.
OBJECTIVES
Determine the regeneration capacity of A.swazicum.
3. Seedling survival – in situ - Results.
Quadrat 2 (mesh) = 13 Seedlings –
Jan and Feb 2010
Quadrat 3 (complete) = 58 seedlings
Jan and Feb 2010)
Open quadrat at Matjulu bridge =
6 seedlings – Jan and Feb 2010
OBJECTIVES
Determine disturbance regimes .
• Grazer and browser impacts:
Porcupine
Chrysolina (Naluhia)
Dacus
frontalis
Black
Rhino??
OBJECTIVES
Determine disturbance regimes - Lowveld NBG.
• Damage recovery:
OBJECTIVES
Establish propagation protocols to ensure successful
propagation of ex situ collections.
Propagation experiments that include:
• Soil medium – Compost, sand and clay at different ratios.
• Depth of seed sowing – on surface, 5mm below and 10mm
below surface.
• Watering frequency – Daily, once a week, once every second week
only natural rainfall.
• Seed viability at different ages – germination success of fresh seed, 3
month old seed and 6 month old seed.
CONCLUSION: GOALS FOR 2010/2011
Continue monitoring of 4 sub-populations ( 2 inside KNP; 2
outside KNP).
Swaziland plants need to be counted and habitat preference
compared to known populations.
Count the remaining KNP plants.
Establish the pollinator of A.swazicum.
Determine the relationship between sodic sites and Adenium
swazicum.
Determine TPC for KNP population.
Seed behaviour research at Kew Millennium Seed bank,
England.
If you see this plant in natural habitat, please contact me at:
K.vanderwalt@sanbi.org.za
ACKNOWLEDGEMENTS:
SANBI
SANParks
Michele Hofmeyr and nursery staff, Thembi Khoza,
section rangers and game guards.
UNIVERSITY OF WITWATERSRAND:
Prof Ed Witkowski (Supervisor).
NORAD:
Norwegian Agency for Development Cooperation for
research funding.