Agriculture Reference
In-Depth Information
concentrations has been demonstrated. Parker
et al.
(1982) found increased concentra-
tions of organic matter in a desert soil following experimental eradication of the
subterranean termites present. Similarly, the absence of fire and an effective termite
fauna from the vertisol studied by Moore
el al.
(1967) in sub-tropical Australia, were
considered to be the causes of the large standing crop biomass of above-ground dead
organic materials. These authors estimated that there were 75 Mg of litter together
with 58 Mg of standing dead organic materials on the site, in addition to the
relatively-elevated levels of soil organic matter and nitrogen characteristic of these
soils, when undisturbed.
Sequestration of organic matter in termite constructs
Carbon concentrations in most epigeal termite structures are higher than those of
the soils from which they are formed. This is due to the incorporation during mound
construction of salivary or - more importantly - faecal materials that are frequently
used as adhesives, or as linings to chamber and gallery walls. Waste materials may
also be used as void infill ings in mounds, subterranean galleries and other structures.
A salivary adhesive from the mound wall of the wood-feeding species
Coptotermes
acinaciformis
has been identified as a glycoprotein (Gillman
et al.,
1972). In structures
formed mainly from soil materials, the degree of organic matter enrichment depends
primarily on whether faeces are included. The Macrotermitinae do not incorporate their
faeces into the mound fabric which consequently has a lower C concentration than that
of the soil-feeding species.
The C:N ratios of the constructs built by termites are often higher than those of the
surrounding surface soils (Tables IV.22, IV.23), although the differences change between
trophic groups. As discussed above, the macrotermitine fungus-feeding termites do not
build faeces into their mound structures and their C:N ratios may be similar to or lower
than those of the surrounding soils (Garnier-Sillam, 1989).
