84
Phenological Patterns
leptokyrtic (oribatids), right-skewed platykyrtic (Mediterranean Gamasidae)
and right-skewed leptokyrtic (Mediterranean Collembola and Gamasidae
from India). In both Mediterranean and monsoon ecosystems, adversity
engenders asymmetric phenologies. However, the phenological responses
reflecting avoidance-tolerance strategies are taxon-specific as well as regionspecific. Oribatids respond to adversity in the same way in both the Mediterranean and monsoon ecosystems. Numbers are relatively low at the beginning of an adverse period, while immature instars develop rapidly during
and/or immediately after the adverse period. Gamasidae display rightskewed phenograms in both regions, although differences in kurtosis are
revealed. In Mediterranean ecosystems, Gamasidae seem to tolerate adversity and their relevant phenograms are platykyrtic, whereas in India they are
leptokyrtic. Collembolans also display region-specific phenograms. As mentioned above, Mediterranean Collembola display left-skewed phenologies,
while the corresponding phenologies in India are right-skewed.
Skewed phenologies apparently characterise arthropods encountering
adverse periods. For example, unlike their Mediterranean and monsoon
counterparts, Collembola from a temperate forest (Fontainebleau, France;
Sgardelis et al. 1993) respond to unfavourable seasons by migrating through
both the organic and mineral layers of the soil. In winter, they are abundant
in the mineral layers and migrate upwards in spring.
6.3
Numerical Responses of Macroarthropods
The phenologies of long-lived arthropods must be synchronised with both
seasonally varying climatic variables and interannual cycles. As shown above,
in long-lived diplopods such as G. balcanica from Greece, A. t. /udaicus from
Israel and O. moreletii from Australia, synchronisation with interannual
cycles is ensured by the timing of oviposition. In contrast, the mass development of short-lived immature stadia is related to seasonality and confined to
more or less short periods of time. Finally, long-lived adults display seasonal
activity patterns. Figures 6.7,6.8 and 6.9 show phenograms of the immature
stadia I, II, III and IV and of the pseudomature stage and adults of G. balcanica. Immature stages appear to be susceptible both to the seasonality of the
Mediterranean climate and to the 3- to 4-year interannual climatic cycle.
Mass development of immature individuals into subsequent stadia occurs
over short periods. Although constantly present in samples, they are recorded
in low numbers due to unsuccessful recruitment to the population, while
peaks in their density follow the 3-year interannual cycle. Adult numbers displaya clear-cut left-skewed seasonal pattern, and dense ecological time coincides with the moulting period in summer. Adults thus respond rapidly to
Phenological Patterns
leptokyrtic (oribatids), right-skewed platykyrtic (Mediterranean Gamasidae)
and right-skewed leptokyrtic (Mediterranean Collembola and Gamasidae
from India). In both Mediterranean and monsoon ecosystems, adversity
engenders asymmetric phenologies. However, the phenological responses
reflecting avoidance-tolerance strategies are taxon-specific as well as regionspecific. Oribatids respond to adversity in the same way in both the Mediterranean and monsoon ecosystems. Numbers are relatively low at the beginning of an adverse period, while immature instars develop rapidly during
and/or immediately after the adverse period. Gamasidae display rightskewed phenograms in both regions, although differences in kurtosis are
revealed. In Mediterranean ecosystems, Gamasidae seem to tolerate adversity and their relevant phenograms are platykyrtic, whereas in India they are
leptokyrtic. Collembolans also display region-specific phenograms. As mentioned above, Mediterranean Collembola display left-skewed phenologies,
while the corresponding phenologies in India are right-skewed.
Skewed phenologies apparently characterise arthropods encountering
adverse periods. For example, unlike their Mediterranean and monsoon
counterparts, Collembola from a temperate forest (Fontainebleau, France;
Sgardelis et al. 1993) respond to unfavourable seasons by migrating through
both the organic and mineral layers of the soil. In winter, they are abundant
in the mineral layers and migrate upwards in spring.
6.3
Numerical Responses of Macroarthropods
The phenologies of long-lived arthropods must be synchronised with both
seasonally varying climatic variables and interannual cycles. As shown above,
in long-lived diplopods such as G. balcanica from Greece, A. t. /udaicus from
Israel and O. moreletii from Australia, synchronisation with interannual
cycles is ensured by the timing of oviposition. In contrast, the mass development of short-lived immature stadia is related to seasonality and confined to
more or less short periods of time. Finally, long-lived adults display seasonal
activity patterns. Figures 6.7,6.8 and 6.9 show phenograms of the immature
stadia I, II, III and IV and of the pseudomature stage and adults of G. balcanica. Immature stages appear to be susceptible both to the seasonality of the
Mediterranean climate and to the 3- to 4-year interannual climatic cycle.
Mass development of immature individuals into subsequent stadia occurs
over short periods. Although constantly present in samples, they are recorded
in low numbers due to unsuccessful recruitment to the population, while
peaks in their density follow the 3-year interannual cycle. Adult numbers displaya clear-cut left-skewed seasonal pattern, and dense ecological time coincides with the moulting period in summer. Adults thus respond rapidly to