Agriculture Reference
In-Depth Information
2.4.3
INVERTEBRATES
The large variety of microhabitats and food resources present in slowly-decomposing
litter favours the establishment of highly-diverse communities (see
e.g.,
Anderson, 1977).
This fauna includes a large proportion of saprophages which feed on decomposing litter
and sometimes the colonising microflora and the products of its external digestion.
A significant part of this fauna is predatory and regulates the population dynamics of
the saprovores.
These invertebrates are 'litter transformers' (see Chapter III.4.4.1.6) and are generally
unable to egrade phenol-protein complexes. Although certain groups may ingest some
mineral components from the soil and mix them with organic matter (
e.g.,
Collembola,
Touchot
et al.,
1983; Isopoda, Mocquard
et al.,
1987; Enchytraeidae, Albrecht, 1984,
Wolters, 1991), most litter transformers produce purely organic faecal structures and do
not participate in the transfer of decomposing litter into the sub-soil or to other systems
of decomposition, such as the drilosphere or termitosphere. Consequently, their direct
contribution to decomposition through respiration is limited to a small percentage of
overall mineralisation. For example, in a Swedish coniferous forest, Persson
et al.
(1980)
calculated that a faunal community with a biomass of 1.7 g dry weight contributed only
4 % of heterotroph respiration; however, through the grazing of 30-60 % of microbial
production in the litter and humus layers, they directly contributed between 10 and 49 %
