Geoscience Reference
In-Depth Information
These approaches are returned to in future chapters, but in considering the ar-
chitecture of the soil world it is convenient to start on its roof - at the soil surface -
for this is the part that is easiest to observe, and hence is most familiar. A variety of
creatures are found simply by turning over stones and logs, and while some of these
may not strictly be called soil animals, yet they are often very dependent upon the
nature of the underlying material at some stage of their life. Many are nocturnal, and
merely shelter here during the day to avoid desiccation or predation by birds. These
include predatory ground beetles and spiders, and vegetarians such as woodlice and
slugs. Stones that are smaller than about 10cm are of little value for providing special
microclimates unless they are scattered quite thickly over the ground as in shingle, in
a quarry or on a mountainside;
Figure 1
shows the temperature and moisture regimes
at different depths within a heap of stones inhabited by various arthropods. Large
boulders, on the other hand, are usually well bedded into the ground, and if turned
over will reveal true subterranean animals such as worms, or the underground galler-
ies of ants.
F
IG. 1
Microclimate: temperature and humidity gradients in a stony habitat in strong sunlight, and the effects on
