the economic valuation of the proposed ... - Nature Uganda

which include schist’s, phyllites, quartzites and
amphibolites. The gneisses and granites are generally
fairly uniform and give rise to little variation in resistance
to soil erosion other than along joints and fracture
planes. Under humid conditions, granitic rocks are very
liable to chemical decomposition and, in most parts of
the area, the rocks are now weathered to a considerable
depth. The overlying metasediments, by contrast, are
heterogeneous and include hard resistant bands of
quartzite and, to a lesser extent, amphibolite, alternating
with soft, easily eroded schist’s.
Soils
The soils in the forest reserve are strongly influenced
by the local topography. The forest lies on the Buganda
catena which comprises of red soils with incipient
laterisation? on the slopes and black clay soils in the
valley bottoms. There are four principal members of
this catena which are described as follows, starting with
those at the highest altitude:
a. Shallow Lithosols of the highest ridge crests
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consisting of grey and grey brown sandy loams
overlying brashy, yellowish or reddish brown
loam with laterite or quartzite fragments and
boulders.
b. Red Earths (Red Latosols) which cover most
of the land surface and are strikingly apparent
in the large conical termitaria dotting a rather
monotonously green landscape. The soil profile
consists of up to 30 cm of brown sandy or clay
loam overlying uniform orange-red clay to a
depth of 3 m or more.
c. Grey Sandy Soils appearing at the base of the
slopes of the catena these may be derived from
hill-wash or river alluvium. Underlying the sandy
topsoils are fine sandy clays of a very pale grey
colour mottled to orange brown.
d. Grey clay usually water logged and occupied by
papyrus stand at the base of the catena. Below
this are sandy and even pebbly clays. Despite
the waterlogged condition for most of the year,
surface peat accumulation is rarely more than a
few inches thick. The last two members of the
catena are very acid in reaction (pH 3.8 – 4.8) and
are deficient in all plant nutrients except sulphur
and magnesium.
Due to the weathering, the soils are not so fertile and
the fertility that is there is because of the forest litter
that decomposes and releases nutrients. However, the
cutting away of the forest will result into further soil
degradation because of the removal of the forest cover
and subsequent loss of litter. It will also lead to quicker
leaching of nutrients and higher soil erosion levels.
2.3. PLANTS
Three hunded sixty five plant species are known to occur
in Mabira forest as recorded by Howard & Davenport
(1996) and Ssegawa (2006). Of the species recorded in this
reserve, nine are uncommon and have been recorded
from not more than five of the 65 main forest reserves in
Uganda (Howard & Davenport, 1996). Trees and shrubs
recorded in Mabira but not previously known in the
floral region include Acacia hecatophylla, Aeglopsis
eggelingii, Alangium chinense, Albizia glaberrima,
Aningeria adolfi-friederici, Bequaertiodendron
oblanceolatum, Cassipourea congensis, Celtis adolfi-
fridericii, Chrysophyllum gorungosanum, Dombeya
goetzenii, Drypetes bipindensis, Elaeis guineensis,
Elaeophorbia drupfera, Ficus dicranostyla, Khaya
anthotheca, Lannea barteri, Manilkara multinervis,
Musanga cecropioides,Myrianthus holstii, Neoboutonia
macrocalyx, Rawsonia lucida, Rhus ruspolii, Rinorea
beniensis, Schrebera alata, Tapura fischeri and Warburgia
ugandensis. Restricted-range trees and shrubs recorded
from Mabira include Caesalpinia volkensii, Antrocaryon
micraster, Chrysophyllum delevoyi, Elaeis guineensis,
Lecaniodiscus fraxinfolius, Tricalysia bagshawei,
Chrysophyllum perpulchrum, Ficus lingua and Picralima
nitida. The Mahogany species namely, Entandrophrama
cylindricum, Entandrophragma angolense and Khaya
anthotheca are listed as globally threatened species
(IUCN, 2000). Others include Hallea stipulosa, Lovoa
The Economic Valuation of the Proposed Degazettement of Mabira CFR | 2011