SOIL ORGANISMS - Soil Ecology - page 311

Damp wood-feeding termites have larger colonies, mostly in the range of 3000 to
8000 individuals. Medium-sized colonies include those of the Australian termopsid
species Porotermes adamsoni which nests in living trees and is a notable pest of timber
in the areas where it occurs. Nkunika (1990) reported small colonies (to ca. 5500) while
elsewhere the larger trees present permitted colony expansion up to ca. 62,000 individuals
(Lenz, 1985).
Colonies of the soil-feeding termite Cubitermes fungifaber had populations ranging
from 7000 to 69,000 (Maldague, 1964) although Noirot (1990) states that worker popu-
lations rarely exceed 30,000 individuals. Easey and Holt (1989) reported estimates for
four Australian grass- and litter-feeding species of the family Termitidae that ranged
from 14,100 to 257,000 individuals. It should be noted that the colonies of some of these
species were distributed throughout more than one mound (Holt and Easey, 1985).
Large termite colonies occur mainly in the species belonging to Abe's (1987)
intermediate and separate categories and examples have been reported from the
Afrotropical, Neotropical and Australian biogeographic regions. Mastotermes
darwiniensis normally forms only small colonies but when substantial food resources
become available, the species can rapidly expand its populations due to its ability to
produce large numbers of neotenic (secondary) reproductives (Watson and Gay, 1991). In
a plantation of the exotic conifer Pinus caribaea in northern Australia, Spragg and Paton
(1980) estimated the population of a large diffuse colony of Mastotermes darwiniensis at
seven million individuals including several nests and spread over one hectare. However,
because of the methodological problems considered above, this may be an overestimate.
Other examples of species with estimated colony populations of more than one million
individuals include the Australian wood-feeding species Coptotermes acinaciformis
(Greaves, 1967), Coptotermes lacteus (Gay and Greaves, 1940) and Nasutitermes exi-
tiosus (Gay and Weatherly, 1970), some African fungus-cultivating termites of the genus
Macrotermes (one of which, M. michaelseni, had a total population in excess of five
million (Darlington and Dransfield, 1987) and the neotropical species Nasutitermes
macrocephalus (Martius, 1994).
Despite the substantial estimates in the large colony category, most colonies are much
smaller than this. Most termite colony population estimates are likely to fall within the
low to medium end of the size range considered above but will also depend on the eco-
logical strategies of the species under consideration.
Estimates on an areal basis
On the basis of surface area, estimated termite populations and biomasses range up to
exceptional maxima of more than 10,400 individuals and live weight
(Eggleton et al., 1996). However, most population and biomass estimates are consider-
ably lower than the above values and the medians presented by Wood and Sands (1978)
and Collins (1983) for a total of 24 sites are, respectively, 1429 ind. (inter-quartile
range 400 to 2939) and 3.0 (inter-quartile range 1.5 to 8.7). However, as stated
above, termite abundances are often grossly underestimated, due to their aggregated dis-
tributions, small sizes, high mobilities and the specificities of their behaviours (Eggleton
and Bignell, 1995; Eggleton et al., 1996).
As a group, termites tend to survive such disturbances as land clearing and cultivation