New natural products
with commercial potential
The potential of tropical forests as a
source of potential new medicines, other
natural products or wild relatives of
crop plants is a common reason given for
conservation. Bwindi Impenetrable forest
is no exception, and a least one
commercial company is interested in the
forest as a source of new antibiotics,
and there is no reason why this should
not proceed, provided certain conditions
are met.
Unfortunately, although forests are
seen as a source of new natural products
with commercial value, little thought is
given as to how equitable partnerships
could be developed, so that some of the
profits arising will return to the region
of origin of that product - whether this
be an oil, resin, an organic chemical
structure used as a basis for a new drug,
or genetic material for developing a
disease-resistant crop variety.
Consideration also needs to be given
to the impact that extractive harvesting
of forest products may have. Both issues
need to be taken seriously by both the
development and conservation partnership
surrounding Bwindi Impenetrable National
Park.
Allanblackia kimbiliensis seeds are a
source of a fat which may have potential
for use in cosmetics and cosmetic soaps.
In the Usambara mountains, Tanzania, the
seeds of the closely related A.
stuhlmannii, which contain 51% edible
fat, are harvested and sold by local
people to GAPEX (General Agricultural
Products Export Company) for the
extraction of "a firm, white and
somewhat brittle fat" (FAO, 1983a).
Carapa grandiflora (omuruguya) seeds,
which are used on a small scale by local
people for extraction of an oil used for
cosmetic purposes as a
"Vaseline" substitute, may also
have potential in the cosmetics industry.
Myrianthus holstii (omufe) (Photo 8,
page 17) may have value for genetic
enhancement as a new crop plant, just as
the closely related M. arboreus has been
proposed for planting and fruit
production (FAO, 1983a). Although M.
holstii fruits are sold commercially on a
small scale in local markets, development
of this plant as a new fruit crop is a
long-term project with less immediate
potential returns than from the two
species mentioned above.
Bwindi Forest contains representatives
of many plant families, and includes some
regionally endemic species of interest as
potential sources of new drugs. For
example, the families Rubiaceae and
Apocynaceae, both contain species which
are rich in alkaloids.
Edible fungi, for example Lentinus
prolifer (Photo 9, page17), may also have
potential for cultivation, perhaps grown
on crop surplus as practised in Asia
(FAO, 1983b).
A Pleistocene refugium with high
biological and topographic diversity,
Bwindi Impenetrable National Park is a
rich source of soil micro- organisms such
as Actinomycetes, which are a potential
source of new antibiotics.
Western Uganda, including Bwindi
Impenetrable Forest, is rich in plants
with horticultural potential as well,
including regional endemics in the genus
Impatiens.
Several wild relatives of crop plants,
for example the cowpea relative Vigna
luteolus, many members of the
Cucurbitaceae such as Coccinia
mildbraedii, and wild coffee (Coffea) may
be useful, in addition to plants in which
there is international interest for their
value in breeding programmes for forage
plants (e.g. Trifolium and Aeschynomene),
particularly as this is a high-altitude
refugium.
Farmers in the DTC area cultivate, and
have a rich knowledge of crops, either
developed in Africa (e.g. finger millet,
Eleusine coracana and Sorghum), or
introduced from elsewhere such as bananas
and sweet potatoes.
A probable reason for the greater
variety of land-races grown here compared
to many other areas is due to the great
altitudinal range of farmers’
fields. Local farmers have a greater
knowledge of these local land-races than
most formally trained plant breeders,
recognizing at least 20 bean varieties,
16 banana varieties, 9 sweet potato
varieties and a number of groundnut,
finger millet and cassava land-races.
Steps need to be taken in the DTC area to
avoid the genetic erosion of these
land-races that may take place if they
are replaced through the introduction of
new high-yielding varieties.
The future
In the foreseeable future, demand for
forest resources is going to increase.
Apart from meeting future wood
requirements, a major tree planting
effort is required even to make up the
existing backlog in wood requirements.
Howard (1991), Struhsaker (1987) and
others have all emphasized the need for
family planning if any conservation
programmes are to succeed in the
long-term.
If forest protection enables recovery
from the timber over-exploitation of the
past, then management recommendations
will have to be reviewed. Forests are
dynamic systems, and in the future, if
recovery of mature forest occurs
sufficiently, then selective controlled
removal of large trees, either by
pitsawyers or for beer boats, could again
be considered as a means of creating
canopy gaps, disturbance and diversity.
This may not take place for 40-50 years,
but needs to be borne in mind.
If urbanization patterns in Uganda
follow those experienced elsewhere in
Africa, then it is also likely that the
commercial trade in traditional medicines
will develop. This needs to be monitored,
so that pro-active management through
provision of cultivated supplies of
favoured, slow-growing species can be
implemented. Elephant numbers and forest
destruction by elephant need to be
monitored and, if necessary, steps taken
to avoid this threat to the forest
habitat.
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Recommendations for future
research and monitoring The
following suggestions are in
addition to those already made in
the text:
* An updated vegetation map is
needed for Bwindi Forest, based
on the relatively recent (1990)
aerial photographs, and
identifying high diversity sites.
Attention needs to be directed
towards the Ivi and Ihihizo River
valleys, which have been sparsely
collected in previous surveys
compared to the Ishasha Gorge,
yet on the basis of this short
study, are considered to be
equally important sites, with a
high diversity of plant species.
* Ecological work is required
on canopy gap densities in Bwindi
Forest, based on terrain
evaluation as well as on
vegetation type/age, since canopy
gap densities differ with slope.
* Work is needed on growth
rates, biomass production and
mapping of bamboo.
* Research should be focussed
on the biology of Parinari
excelsa var. holstii and Newtonia
buchananii, which, apart from
being useful plant species
harvested for timber, are key
species for supporting a high
diversity of epiphytes
(Orchidaceae, Cactaceae
(Rhipsalis baccifera), and
various pteridophytes). Why is
there such poor recruitment of
Parinari excelsa, and what
implications does this have for
epiphyte diversity?
* Assessment of elephant
damage to forest is needed, as a
result of their restricted range,
rather than wider seasonal
movements out of the forest. What
role do the elephants play in
creating and maintaining canopy
gaps? What is the carrying
capacity of the forest for
elephant, in terms of a balance
between disturbance, diversity
and mature forest?
* Ecological work is needed on
the biology of climbers and their
biomass production and spacing in
relation to canopy gap dynamics.
This work would have wide
applicability, as climbers are
important both to people and to
primates (e.g. Urera
hypselodendron as a food item for
gorillas).
* Disturbed sites of known
age, such as pitsawing sites and
old mining camps, need to be
relocated and studied in terms of
species composition and size
classes (growth rates) of trees.
This provides useful information
for forest ecology and
reforestation ("restoration
ecology"), as well as for
maintaining a certain level of
disturbance to create diversity
and habitat for canopy gap and
secondary forest specialists
(climbers, and trees such as
Maesopsis eminii).
* Encourage partnership
between Mbarara University
researchers, traditional healers
and Ugandan natural products
chemists such as Mr A. B. Kakooko
(Kampala), to evaluate herbal
remedies, whether for human use
or for livestock, and
micro-organisms that may have
value as sources of new
antibiotics.
* Additional work is required
that involves resource users and
traditional experts in resource
assessments and monitoring (see
Wild and Mutebi, 1996, Working
paper 5).
* Local experts, particularly
the Batwa, need to be more widely
involved as research partners.
They have a tremendous store of
knowledge that can add greatly to
an understanding of forest
functioning and ecology, whether
on specialist pollinators such as
Trigonid bees, canopy gap
formation and regeneration, seed
dispersal. Employment of local
people as
"parataxonomists",
after short training courses, is
also desirable.
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