Conservation of Bivinia jalbertii: A special tree of the Nyuni Hills.

Abstract

Assessment of Bivinia jalbertii resorces in Nyuni Hills.

Full text

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ForMatForMatForMat
Newsleer of the Research & Training Division, Zimbabwe Forestry Commission
P.O. Box HG 595, Highlands, Harare. Tel: +263-4-496878/9. Fax: +263-4-497070
October 2014
Vol. 14 No. 1
Conservaon of Bivinia jalberi: A special tree of the Nyuni Hills
Background
As one drives southwards from Masvingo town
towards Beitbridge, at the T-juncon about 15 km
before Ngundu Halt on the le side of the road the
signpost to Tokwe-Mukorsi Dam would appear. the dirt
road towards the construcon site of Tokwe-Mukorsi
dam wall would lead to a beauful view of the riverine
vegetaon of Nyuni Hills. These hills are home to Bivin-
ia jalberi, the cobweb seed tree which the locals call
Mutuputupu, a special tree that grows only in the
Ngundu area in Zimbabwe. Scaered pockets of the
tree are found in thickets along the hill slopes. About 8
km from Nyuni Hills are a few other small hills also
providing a habitat for B. jalberi. However, only close
to 20 mature trees sll remain at Dumbuguru and
Bende gap, southwest of Nyuni Hills. This is a clear sign
that B. jalberi, once a common tree in Ngundu area,
is fast becoming exnct. Also growing on hilly slopes
in close associaon with B. jalberi is Androstachys
johnsonii, the iron wood tree. This tree is equally rare
and occurs at low altudes only in the south and east
of the country (Coates-Palgrave, 2002). Both these
trees are in danger from the excessive exploitaon by
villagers in the surrounding neighborhood in
Ngundu. With the construcon of Tokwe-Mukorsi dam
almost reaching compleon, one prays that the hills
will become islands in the dam to become germplasm
hotspots for B. jalberi.
Taxonomy and Distribuon
Bivinia jalberi Tul belongs to the Salicaceae family.
According to Coates-Palgrave (2002), it grows in
evergreen forests, forested ravines and on rocky hill
outcrops in areas of high rainfall and some winter mist
or drizzle. It reaches a height of 20 to 30 m when
mature. B. jalberi is nave to four African countries
namely Kenya, Madagascar, Mozambique and
Zimbabwe. In Zimbabwe, the Internaonal Union on
Conservaon (IUCN) lists the species as near
threatened (IUCN 2013).
In-situ Conservaon
Apart from roune surveys to assess the conserva-
on status of B. jalberi very lile work has been
done in the past to protect the species from over-
exploitaon by local communies. Early conserva-
on eorts for B. jalberi started between 1986 and
1989 driven by communies led by the Forestry
Commission's Conservaon and Extension Division.
The objecve was to plant more trees in and around
the Ngundu area to enrich the natural populaon.
Jephias Mhike (born 1952) , a headman (sadunhu)
under Chief Gororo and Naphet Chihamure (born
1971, son of Chief Madzivire) are the surviving vil-
lage pioneers of tree planng and conservaon of B
jalberi tree conservaon at Ngundu. According to
Naphet, the tree planng project at Banga Irrigaon
Scheme in Chivi started in 1987 with assistance
from the Forestry Commission. They raised both
exoc and indigenous tree seedlings at the nursery.
The Forestry Ocer then, was in charge of the tree
planng project then. Following the 1992 drought
Banga dam dried up and the severe water shortage
forced terminaon of the tree planng project. The
nurseryman was transferred to Chivi, a develop-
ment that impacted negavely on the tree conser-
vaon work. As a result of these early eorts, the
Research and Training Division of the Forestry Com-
mission became more interested in research on the
conservaon of Bivinia jalberi. The tree always has
a straight bole, comparing very well with the fa-
mous gum tree, Eucalyptus species. It also has good
coppicing ability (also very comparable to the gum
tree) and the wood is not suscepble to pest infes-
taon or damage, maybe superior to the gum tree.
Meanwhile researchers from the Forestry Commis-
sion had inuenced the villagers to bar trespassers
from entering the tree’s natural habitat to avoid
unlawful access to germplasm by unauthorized per-
sons and warned the villagers against unauthorized
cung down of these trees. Below is an image
showing a mature B. jalberi tree in the Nyuni Hills

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Fig. 1. Mature B. jalberi tree. Most Mature trees are
characterised by straight stems and can grow to a height of
up to 30 meters.
Fig. 2 Image showing sampling points (numbered) for B. jalberi trees in Ngundu.
Ex-situ: Threats and opportunies for sustainable
conservaon of B. jalberi
B. jalberi is mostly exploited for fencing and roong
poles and general construcon mber by villagers.
However, exploitaon of B. jalberi seems to have
gone unchecked for a long me to the extent that only
a few mature trees are now le in the area. This
requires urgent acon to save the few remaining pop-
ulaons.
Fires caused by human acvies on the hill slopes
contribute a fair share to destrucon of tender saplings
which are regenerang naturally from seed dispersal.
This causes further tree loss. The construcon of Tokwe
Mukorsi dam poses a further threat to the nearby tree
populaons, especially those at Nyuni Hills which are in
the dam (see Fig 2 below). Under unmanaged
condions the species has a very limited geographic
range that favours its growth.
Despite these challenges, the species is quite promising
from a conservaon point of view. It is relavely easy
to propagate through seed and is relavely fast grow-
ing, making it a candidate for ex-situ conservaon. Cut
stumps show good coppicing abilies (see Fig 3). This
means that the tree can also be managed through cop-
ping from stumps of cut trees
Below is a google earth image showing sites where the
remaining B. jalberi populaons sll exist.

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Fig. 3 A Bivinia jalberi stump with coppices
Fig. 4 Nursery stock for establishment of eld gene banks
So what has been done so far?
In 2013, a domescaon and conservaon iniave
was launched to rescue the fast-declining populaon of
B. jalberi. The Zimbabwe Forestry Commission, in
partnership with the World Agroforestry Centre
(ICRAF—Internaonal Centre for Research in Agro-
forestry), embarked on a conservaon programme,
targeng the remaining populaons of B. jalberi in
the Nyuni range in Ngundu. The project is being
conducted under the theme “Methods for
conservaon and sustainable management of genec
resources of important tree species”. Fig. 4 shows
seedlings raised at the Forest Research Centre nursery
in Harare for planng as ex-situ conservaon plots. An
acve ex-situ conservaon programme was launched
to conserve B. jalberi in secure habitats where it is
likely to thrive. A suitable site was idened on the
rocky outcrops in the Nyamukwarara area in the East-
ern Higlands at John Meikle Forest Research Staon, in
Stapleford Estate where environmental condions are
similar to its natural habitat. Here eld gene banks will
be established at John Meikle for ex-situ management
of B. jalberi.
How important is this conservaon eort?
Through collaborave research work between FC and
ICRAF, conservaon of this threatened forest genec
resource can be improved.
This work will have a signicant impact on forest ge-
nec resources and forest biodiversity conservaon
eorts as it will restore the availability of rare and
threatened species therby achieving an ecosystem bal-
ance. Demand for poles for construcon had put more
pressure on the remaining populaons of B jalberi ,
and hopefully this research work will ensure that this
indigenous tree species is conserved for use by future
generaons.
Acknowledgements
Hearelt acknowledgements go to ICRAF’s Gene bank
Fund for nancial support and Forestry Commission for
providing research personnel. Mr. Matarirano (ICRAF
Country Liaison Ocer) and Belinda Machingauta (FEO
for Chivi District) are acknowledged for facilitang lo-
giscal and local project management support and mo-
bilizing communies respecvely.
References
1. Coates Palgrave, M. 2002. Keith Coates-Palgrave
Trees of Southern Africa, 3rd Ed., 2nd Imp. Struik
Publishers, Cape Town
2. IUCN 2013. IUCN Red List of Threatened Spe-
cies. Version 2013.2. <www.iucnredlist.org>.
Downloaded on 26 February 2014.
M.C TEMBANI , L MATARIRANO AND P. MUTETE

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PEST ALERT:
Glycaspis brimblecombei
Red Gum Lerp Psyllid in Zimbabwe.
Glycaspis brimblecombei (Psyllidae, Hemiptera),
commonly referred to as the red gum lerp psyllid, is
a major sap-sucking insect that feeds on eucalypts
leaves. This pest is nave to Australia, but has been
accidentally introduced into the USA (1998), Mexico
(2000), Chile (2002), Brazil (2003), Argenna (2005),
Ecuador (2006), Venezuela (2007), Uruguay (2008)
and Peru (2008). It has also been recently introduced
in Europe in the following countries; Portugal (2007),
Spain (2007), Italy (2010) and France (2011). Zimba-
bwe is now the fourth African country to record red
gum lerp aer it was recorded in Maurius (2001),
Madagascar (2004) and in South Africa (2012).
Red gum lerp psyllid females lay between 45 and
700 eggs in batches or randomly. The eggs are spin-
dle shaped cream or yellow coloured and hatch in 10
to 20 days. They hatch into yellowish orange nymphs
which pierce the plant ssues with their stylets
(mouth parts), feeding on the xylem cells. As the
nymphs feed they secrete honeydew with which
they construct a waxy cover (called a lerp) around
themselves. This waxy cover is whish and conical in
shape and shelters the insects unl the adult stage.
Lerps are the rst visible sign of the presence of the
red gum lerp psyllid infestaon. In Australia there
are two to four generaons per year.
The red gum lerp psyllid is known as an aggressive
insect that spreads rapidly once it is introduced in an
area. Symptoms of its feeding include dropping of
leaves and drying of leading shoots (twig dieback).
Infested leaves are covered with waxy secreons
and honeydew, on which sooty mould grows. Heavy
infestaons can totally defoliate and kill trees. Euca-
lyptus species dier in their suscepbility to aack
by the red gum lerp psyllid, with E. camaldulensis
and E. terecornis being highly suscepble while E.
grandis is reported to be more tolerant.
Both chemical and biological control measures have
been used especially in America in an aempt to con-
trol infestaons of the red gum lerp psyllid. Contact
inseccides are known to be ineecve as the
nymphs are protected by their covers. Systemic insec-
cides have been used with some limited success,
and their use is of limited value in plantaon forestry
due to the high cost. In the USA, natural enemies of
the red gum lerp psyllid were imported from Austral-
ia. One of these, the parasic wasp Psyllaephagus
bliteus (Hymenoptera, Encyrdae) has become estab-
lished in the USA as a biological control agent for the
red gum lerp psyllid.
For the rst me now the red gum lerp psyllid has
been detected in Zimbabwe around Bulawayo. This
could be aributed to increased movement of goods
and people between our countries and across the
globe in the last few decades hence we need to anc-
ipate the arrival of new invasive pest species. New
pests in South Africa oen appear in Zimbabwe soon
aerwards and good examples are the eucalyptus
snout beetle (Gonipterus scutellatus), the bronze bug
(Thaumastocoris peregrinus) and the blue gum Chal-
cid (Leptocybe invasa). Since the rst report of red
gum lerp psyllid in South Africa in 2012 we have been
on alert for the introducon into Zimbabwe and this
rst report in Bulawayo is very recent and currently
we know that it is restricted in Hillside, Matopos and
Chesa reserve.
The red gum lerp psyllid is a serious Eucalyptus pest
hence we need to take stock of all our eucalyptus
planngs to map out the extent of dispersal and chart
a way forward. The sooner new insect pests are de-
tected, the sooner control measures can be imple-
mented. If you see these symptoms on Eucalyptus
(shown in the picture above), or any unusual symp-
toms on your trees, please report it to:
Mr Member Mushongahande
Forestry Research Centre
Box HG 595, Highlands, Harare.
Phone: 04-496878/9; Cell: 0772372660
e-mail: membermushongahande@gmail.com or
member@frchigh.co.zw
The dierent stages of the Red gum lerp psyllid (eggs,
orange nyph, green adult and the waxy lerp
Red Gum lerp psyllid on eucalypts