Community Structures Induced by Human Practices
103
with capabilities for rapid recolonisation of destroyed areas are essential
components of the adaptive strategies of microarthropods. The adaptations
of litter-dwelling animals can be illustrated by collembolans and oribatids.
Collembolans are strongly reduced in numbers after fire. They can, however,
recover rapidly thanks to species able to colonise a wide range of habitats that
survive in sheltered sites under stones. Similarly, most oribatids resist the
immediate effect of fire, while species occupying a wide range of habitats
such as S. latipes, can exploit intact resources under stones lying on the surface of the soil. Fire apparently engenders the selection of broad habitats,
increased reproductive effort, and rapid development. In general, burned
areas are dominated by species such as the uropodid mite Olodiscus minimus
(Athias-Binche 1987) that select a wide range of habitats and climatic conditions.
From supplementary data collected annually, Sgardelis and Margaris
(1993) estimated that the recovery of microarthropods in the Greek phryganic ecosystem lasts roughly 3-4 years. Analogous durations were also reported Majer (1984) for a Western Australian Mediterranean-type forest,
while Lopes and da Gama (1994) recorded even higher densities of Collembola accompanied by a slight decrease in the number of species. Apparently,
the recovery of microarthropods follows the rapid recovery of Mediterranean vegetation. According to Athias-Binche (1987),recolonisation is due either
to the migration of animals that take refuge in the deeper soil layers or to
facultative phoretics such as O. minimus which are the most resistant and
dynamic colonisers.
7.4.1.2
The Effect of Fire on Macroarthropods
7.4.1.2.1
Numerical Response
The intensity of either natural or deliberate fires is usually moderate in Mediterranean ecosystems. Data provided by Abbott (1984), Majer (1984), and
Saulnier and Athias-Binche (1986) show that, due to the decline in food
resources, saprophagous litter species are most susceptible to this kind of
fire. Thus, the main constraint on the recovery of long-lived arthropods such
as julids is the shortage of resources.
The effects of a fire that took place in August 1980 in a Greek phryganic
ecosystem were studied by Sgardelis et al. (1995). The fire was of moderate
intensity and its immediate effect on macroarthropods was negligible, since
most of them were absent from the topmost organic layers at the time of fire.
Thus, unlike the case for the majority of micro arthropods, the long-term
effect of fire on macroarthropods is more salient than the short-term one, as
might be expected.
103
with capabilities for rapid recolonisation of destroyed areas are essential
components of the adaptive strategies of microarthropods. The adaptations
of litter-dwelling animals can be illustrated by collembolans and oribatids.
Collembolans are strongly reduced in numbers after fire. They can, however,
recover rapidly thanks to species able to colonise a wide range of habitats that
survive in sheltered sites under stones. Similarly, most oribatids resist the
immediate effect of fire, while species occupying a wide range of habitats
such as S. latipes, can exploit intact resources under stones lying on the surface of the soil. Fire apparently engenders the selection of broad habitats,
increased reproductive effort, and rapid development. In general, burned
areas are dominated by species such as the uropodid mite Olodiscus minimus
(Athias-Binche 1987) that select a wide range of habitats and climatic conditions.
From supplementary data collected annually, Sgardelis and Margaris
(1993) estimated that the recovery of microarthropods in the Greek phryganic ecosystem lasts roughly 3-4 years. Analogous durations were also reported Majer (1984) for a Western Australian Mediterranean-type forest,
while Lopes and da Gama (1994) recorded even higher densities of Collembola accompanied by a slight decrease in the number of species. Apparently,
the recovery of microarthropods follows the rapid recovery of Mediterranean vegetation. According to Athias-Binche (1987),recolonisation is due either
to the migration of animals that take refuge in the deeper soil layers or to
facultative phoretics such as O. minimus which are the most resistant and
dynamic colonisers.
7.4.1.2
The Effect of Fire on Macroarthropods
7.4.1.2.1
Numerical Response
The intensity of either natural or deliberate fires is usually moderate in Mediterranean ecosystems. Data provided by Abbott (1984), Majer (1984), and
Saulnier and Athias-Binche (1986) show that, due to the decline in food
resources, saprophagous litter species are most susceptible to this kind of
fire. Thus, the main constraint on the recovery of long-lived arthropods such
as julids is the shortage of resources.
The effects of a fire that took place in August 1980 in a Greek phryganic
ecosystem were studied by Sgardelis et al. (1995). The fire was of moderate
intensity and its immediate effect on macroarthropods was negligible, since
most of them were absent from the topmost organic layers at the time of fire.
Thus, unlike the case for the majority of micro arthropods, the long-term
effect of fire on macroarthropods is more salient than the short-term one, as
might be expected.