Seasonal Variations in Numbers
93
corum. Analogous observations have been reported for the community of
myriapods in sclerophyllous formations of Southern France (Bertrand et al.
1987) and for the diplopods of the evergreen-sclerophyllous formations of
northern Greece (Iatrou and Stamou 1989a).
7.2
Seasonal Variations in Numbers
Seasonally varying numbers of Mediterranean arthropods have been documented in many cases (Paris 1963; Bigot and Bodot 1973; Maggioris 1985;
Trihas and Legakis 1991, among others). However, seasonality in numbers is
the outcome of a multifactor process, and direct relationships have scarcely
been established between varying numbers and individual micro climatic or
microhabitat components. For example, Warburg et al. (1984) were unable to
establish definite relationships between isopod abundance and cover provided by rocks, stones or vegetation or between abundance and temperature
or maximum, minimum or mean relative humidities. In general, such relationships are inferred indirectly. Again, Warburg et al. (1984) inferred a
relationship between the pattern of precipitation and isopod phenology
from the fact that, unlike the more xeric Egyptian habitats (Kheirallah 1980),
numbers increased 1 month after onset of precipitation in xeric habitats of
Israel.
Edmonds and Specht (1981) linked seasonality of numbers to seasonally
varying resources. More specifically, in an Australian Mediterranean-type
ecosystem two seasonal cycles were distinguished among plant consumers
(Specht 1985). The first cycle, associated with a major response to temperature, follows variations in shoot growth and flowering of the dominant bushes,
which occurs in late spring to summer. The second cycle, associated with a
minor temperature response, is imposed by plant growth and flowering of the
understory vegetation, which occurs in spring and is followed by summer
inactivity. Furthermore, Specht (1985) suggested that a third annual cycle
depending on temperature and moisture conditions in the litter and soil is
imposed on decomposers.
The phenologies of soil arthropods from a Greek Mediterranean pine
forest conform with the third type of cycle. These phenologies can be roughly divided into two groups. The first contains phenologies exhibited by more
or less hygrophilous groups (holometabolan larvae, some pseudoscorpions,
some diplopods, chilopods, and isopods) which are restricted during the
rainy season, while the second is associated with less hygrophilous groups
such as Araneae, Thysanoura, Dictyoptera, Hemiptera and Coleoptera (Karamaouna 1990). The temporal pattern of the latter is comparable to the patterns displayed by the macro arthropods of deciduous forests, while only the
more hygrophilous groups exhibit seasonality.
93
corum. Analogous observations have been reported for the community of
myriapods in sclerophyllous formations of Southern France (Bertrand et al.
1987) and for the diplopods of the evergreen-sclerophyllous formations of
northern Greece (Iatrou and Stamou 1989a).
7.2
Seasonal Variations in Numbers
Seasonally varying numbers of Mediterranean arthropods have been documented in many cases (Paris 1963; Bigot and Bodot 1973; Maggioris 1985;
Trihas and Legakis 1991, among others). However, seasonality in numbers is
the outcome of a multifactor process, and direct relationships have scarcely
been established between varying numbers and individual micro climatic or
microhabitat components. For example, Warburg et al. (1984) were unable to
establish definite relationships between isopod abundance and cover provided by rocks, stones or vegetation or between abundance and temperature
or maximum, minimum or mean relative humidities. In general, such relationships are inferred indirectly. Again, Warburg et al. (1984) inferred a
relationship between the pattern of precipitation and isopod phenology
from the fact that, unlike the more xeric Egyptian habitats (Kheirallah 1980),
numbers increased 1 month after onset of precipitation in xeric habitats of
Israel.
Edmonds and Specht (1981) linked seasonality of numbers to seasonally
varying resources. More specifically, in an Australian Mediterranean-type
ecosystem two seasonal cycles were distinguished among plant consumers
(Specht 1985). The first cycle, associated with a major response to temperature, follows variations in shoot growth and flowering of the dominant bushes,
which occurs in late spring to summer. The second cycle, associated with a
minor temperature response, is imposed by plant growth and flowering of the
understory vegetation, which occurs in spring and is followed by summer
inactivity. Furthermore, Specht (1985) suggested that a third annual cycle
depending on temperature and moisture conditions in the litter and soil is
imposed on decomposers.
The phenologies of soil arthropods from a Greek Mediterranean pine
forest conform with the third type of cycle. These phenologies can be roughly divided into two groups. The first contains phenologies exhibited by more
or less hygrophilous groups (holometabolan larvae, some pseudoscorpions,
some diplopods, chilopods, and isopods) which are restricted during the
rainy season, while the second is associated with less hygrophilous groups
such as Araneae, Thysanoura, Dictyoptera, Hemiptera and Coleoptera (Karamaouna 1990). The temporal pattern of the latter is comparable to the patterns displayed by the macro arthropods of deciduous forests, while only the
more hygrophilous groups exhibit seasonality.