||ECOLOGY OF THE CALICIALES
On the basis of our field knowledge, we have made a list of
ecological factors we find significant for the distribution of
the Caliciales species in Norway:
- Microclimatic humidity. This is perhaps the
most important ecological factor for explaining the
distribution of the Caliciales species. The microclimatic
humidity is primarily a product of topography and
vegetation, not of precipitation.
- Substrate. There are great differences
between the species in their ability to grow on various
substrates. Some species are very specific regarding
substrate, while species with a wider ecological
amplitude with regard to substrate, may grow on both
organic and inorganic substrates. The most common
substrates are lignum, bark, bryophytes and siliceous
- Light. Some species grow on lignum exposed
to high light intensity, some may grow in root caves with
a very low light intensity, and others may grow
intermediate. Several species seem to tolerate low light
intensity because of the correlation with high humidity.
- Degree of decomposition of lignum. Whether
the lignum is deciduous or coniferous seems to be of less
importance. More important is probably the degree of
decomposition of the substrate. Slightly decomposed
lignum is hard, acid and dry, while well decomposed
lignum is softer, more acid and has a higher water
capacity tBarkman 1969).
- Dispersal. Most of the species, especially
the endosubstratic ones, depend on spore dispersal. The
spores are not actively dispersed, but stay in the
mazaedium. Short distance dispersal may happen by means
of tiny animals like mites. Dispersal of thallus
fragments occurs in the sorediose/granular species e.g. Chaenotheca
furfuracea, G. stemonea and G. subroscida.
- Continuity of the environment. Perhaps a
combination of stable humidity and small temperature
amplitude is of importance in climax forests with a high
ecological continuity. It is probable that e.g. Chaenotheca
subroscida and Cyphelium karelicum demand old
spruce forests, while Chaenotheca chysocephala also
thrives in younger forests. National parks usually have a
high frequency of Caliciales species.
- Pollution or influence of urban areas.
Several species avoid urban areas. This may be due to air
pollution or other environmental factors produced by
towns. Many Caliciales species probably do not tolerate
the dryness and the short continuity of the environment
in the urban areas. However, according to Barkman (1969),
Chaenotheca ferruginea has extended in urban areas
in Europe. We have not found this species to be very
frequent in the surroundings of Oslo.
- Competition. Bryophytes and lichens
(especially Cladonia spp.) are competitors for the
Caliciales species. On the Norwegian west coast, with
oceanic conditions, bryophytes are abundant on stems and
stumps. In the central and eastern parts of Fennoscandia,
with more continental conditions, Cladonia spp.
overgrow stumps and leave little room for the Caliciales