other species) becomes established, with highly efficient roots and whose seedlings and
saplings thrive in conditions of extreme shade. (I say ‘may be reached’ because this
successional process does not occur everywhere, e.g. in many of the forests of South
America where the successional process is absent.)
Brasnett, Philip and Eggeling all shared the view that in Budongo Forest there were
three successional stages: Colonizing, Intermediate and Climax. If that is right, then the
part of Budongo that has today reached the Climax phase would be the part that was first
colonized and therefore the oldest part, while the youngest forest would be the part that
still shows the Colonizing species such as Maesopsis eminii. As shown by Plumptre
(1996), when looked at as a whole, Budongo Forest shows a gradual change of tree species
composition from the southwest to the northeast. The southwest has more species associ-
ated with Colonizing and Mixed Forest, while only in the northeast do we find heavy con-
centrations of CynometraForest. From this we can deduce that the initial colonization of
grassland or bush during the present phase of growth of Budongo Forest occurred in what
is now the northeast part, and from there the forest spread southwards and westwards.
We can now return to the issue raised by Brasnett in stating that the Budongo Forest
is a young forest, only 300–500 years old. Because the forest has all three forest types
he made the assumption that it had only reached Climax conditions in the areas where
Cynometrawas dominant, and elsewhere had not yet reached the Climax phase. In his
view, it would take some 300–500 years for the present tree distribution to come about,
from an original state of grassland or bush.
A major study of the ecology of the Budongo Forest was published after those of
Harris (1934) and Brasnett (1946). This was a lengthy and detailed study by Eggeling
(1947). His descriptions of the three major forest types in Budongo were based on
extensive tree enumerations and surveys in and around Budongo. His classification was
as follows: the forest is surrounded by grassland. Closest to the grassland is Colonizing
Forest. This has two types, each of which is maintained for one generation and then
develops into Mixed Forest. The two types are as follows:MaesopsisForest, which
develops on better soils, and Woodland Forest which develops on poorer soils.
Colonizing Forest is succeeded by Mixed Forest. This is rich in species, with almost
50 species reaching the canopy. It contains the mahoganies (Khaya anthothecaand three
species of Entandrophragma). As the forest ages, more shade-tolerant species are found
in Mixed Forest, including Cynometra(Ironwood) in the upper understorey. Finally we
have Ironwood Forest, with Cynometraoccurring at all sizes and a general paucity of
species as those found in the earlier stage of Mixed Forest die out. A fourth forest type
was also distinguished by Eggeling, namely Swamp Forest, occurring along rivers that
are seasonally waterlogged. It contains the spiky Calamusor rattan climber (studied in
Budongo Forest by Okia 2001) as well as wild palms (Raphia farinifera) and riverine
tree species such as Pseudospondias microcarpaandMitragyna stipulosa. The species
distribution of Budongo Forest and the development of its climax vegetation have been
further studied by Walaga (1993).
Eggeling’s views on the succession of Budongo Forest have not gone unchallenged. It
has been pointed out that they do not take account of the possibility of human disturbance
Dynamics of Budongo Forest 13