FUNCTIONING OF THE SOIL SYSTEM - Soil Ecology - page 529

5.4.2.4 High termitaria

High termitaria are a feature of many parts of the African continent. They may be up
to 10 m in height above the surrounding plain and as much as 30 m in diameter
(Pullan, 1979). These termitaria may have been originally built by species of the genus
Macrotermes but have undergone complex cycles of development and regression.
At various stages of their development they may be partly occupied by the original builders,
other species, or by none at all.
Since they are formed by different termite species from a variety of soil materials and exist
under a range of environmental conditions, they may develop in various ways. Pullan (1979)
describes how their development is influenced by the presence of fire, erosional influences
and the activities of man and large mammals (notably elephants).
These high termitaria may support a diverse (more than 336 species of higher plants) and
regionally-variable flora which may include cyanobacteria, grasses, forbs, shrubs, vines and
trees, including palms. This flora is characterised by a higher incidence of thorniness,
xeromorphy, succulence and eutrophy than occurs in that of the immediate surrounds. The
diaspores of many of the woody species of the high termitaria are dispersed by animals
(Malaisse, 1978).
The vegetative cover of these termitaria protects the surface from erosion and while it
remains intact, termitaria may exist for long periods. Based on the vegetation, complex food
webs may be associated with these termitaria. In addition, secondary termite species and a
range of other soil animals may also be present (Malaisse, 1978). When regularly fired, these
termitaria can degrade rapidly under the influence of raindrop erosion and surface water flows.

5.5 Interactions between termites and higher animals

The interactions between termites and higher animals may be direct - as in predation - or indi-
rect, as in the provision of habitat or other effects. However, apart from predation on termites
by the vertebrates mentioned in Chapter III, few direct relationships are known.
A number of indirect relationships have been recorded, most of which benefit
the vertebrates. Provision of habitat is an important way in which vertebrates interact indi-
rectly with termites and a widespread example of this is the use of both epigeal and arboreal
termite nests as nesting sites by a range of bird species (Hindwood, 1959)
and other vertebrates, particularly reptiles (see, for example, Araujo, 1970). The high
termitaria of Africa provide habitat for a wide range of vertebrate and invertebrate
animals, including secondary termites (Malaisse, 1978).
In a more general relationship, Braithwaite et al. (1988) demonstrated a positive
relationship between termite species richness and the species richness and abundance
of grasshoppers, but negative relationships with macropodid species richness and
abundance. These authors also reported a positive correlation between the species
richness of termites feeding on living trees and the abundance of the introduced water
buffalo ( Bubalus bubalis ) in parts of northern Australia. It was considered that soil
compaction caused by the buffaloes led to water stress in the trees and made them more
susceptible to termite attack.