Agriculture Reference
In-Depth Information
growing on the mounds may contribute to the substantial differences (up to 5.5 )
that may occur between the mounds and the adjacent C4-dominated surface soils
(Spain and Reddell, 1996).
5.4
Interactions between termites, higher vegetation and micro-organisms
Over long periods, termites may considerably influence the distribution and community
structure of higher plants. This influence is often indirect and may be mediated through
alteration of soil properties or through interactions with other environmental factors.
In the short time scales associated with agriculture and forestry, termites may directly
attack plants causing damage that may kill them or reduce their growth and productivity.
This is clearly of importance in agricultural and forestry enterprises but may also be
of relevance in disturbed but near-natural environments. Other, less direct biological
interactions also occur.
5.4.1
DIRECT EFFECTS
Termites are rarely sources of extensive plant mortality in undisturbed natural
ecosystems although in disturbed and man-made environments, a wide range of crop and
other plants may be severely affected.
Termites may be severe pests in cropping systems in contrast to the earthworms
that are almost always considered beneficial, sometimes unjustifiably. Wood (1996)
has noted that termites rarely fit into the common pest category of 'introduced species'.
While exotic termite species may cause problems in a few places, species that damage
crops (herbaceous or woody species) are nearly always present in the environment
at sub-economic population levels and their elevation to pest status normally results
from changes in the availability of food. However, to become pests they must also
