100
Community Structure
occur in environmental variables. Consequently, the working hypothesis of
relevant studies relates to the extent to which anthropogenic impacts lead to
broader climatic and/or habitat selection on a major scale.
7.4.1
Fire-Induced Structures
Fire results in less heterogeneous and less detached habitats within burned
sites. Consequently, reduced seasonal climatic variation as well as variation
between microsites are expected. However, burned areas lose their capacity
to buffer climatic fluctuations due to the loss of vegetation and litter which is
expected to be stronger in burned sites (e.g. Lopes and da Gama 1994). Therefore, apart from the direct effect of fire, fire-induced changes in the availability of resources and in the structural and micro climatic correlates of habitats
considerably affect both the numbers and composition of arthropod communities.
Referring to the direct effects of fire, Majer (1984), Saulnier and AthiasBinche (1986),as well as Lopes and da Gama (1994) reported a markedreduction in the numbers and biomass of epidaphic consumer and predator, while
a minor reduction in the numbers of euedaphic ones was also recorded. The
occurrence of fire during the active season has a considerable and immediate effect on fauna, whereas only a minor effect of fire is recorded at the end of
the active period (Bornenissza 1969 in Sgardelis and Margaris 1993; Majer
1984). Furthermore, the immediate effect of fire also depends on its intensity. Natural fires of high intensity have a destructive effect on numbers, whereas the effect of controlled burning is quite moderate. Finally, the effect of fire
depends on the type of ecosystem. In general, fire is much less destructive in
more xeric environments than in forests (De Izzara 1977). In the former,
increased populations have even been recorded shortly after fires (Pomeroy
and Rwakaikara 1975). According to Majer (1984), soil and litter invertebrates
exhibit a broad array of responses to fire, including immediate reduction in
numbers, delayed reduction in population densities, and temporary absence
of some taxa while others remain unaffected by fire or may increase their
numbers.
7.4.1.1
The Effect of Fire on Microarthropods
Short- and long-term effects of fire on Mediterranean micro- and macroarthropods have been studied by Sgardelis (1988), Sgardelis and Margaris
(1993), and Sgardelis et al. (1995). Results concerning the numerical response
of some soil micro arthropods are summarised in Table 7.3. The first finding
is that the immediate effect of fire is most pronounced on litter dwellers,
while animals that live under stones remain almost unaffected (Figs. 7.3, 7.4).
Community Structure
occur in environmental variables. Consequently, the working hypothesis of
relevant studies relates to the extent to which anthropogenic impacts lead to
broader climatic and/or habitat selection on a major scale.
7.4.1
Fire-Induced Structures
Fire results in less heterogeneous and less detached habitats within burned
sites. Consequently, reduced seasonal climatic variation as well as variation
between microsites are expected. However, burned areas lose their capacity
to buffer climatic fluctuations due to the loss of vegetation and litter which is
expected to be stronger in burned sites (e.g. Lopes and da Gama 1994). Therefore, apart from the direct effect of fire, fire-induced changes in the availability of resources and in the structural and micro climatic correlates of habitats
considerably affect both the numbers and composition of arthropod communities.
Referring to the direct effects of fire, Majer (1984), Saulnier and AthiasBinche (1986),as well as Lopes and da Gama (1994) reported a markedreduction in the numbers and biomass of epidaphic consumer and predator, while
a minor reduction in the numbers of euedaphic ones was also recorded. The
occurrence of fire during the active season has a considerable and immediate effect on fauna, whereas only a minor effect of fire is recorded at the end of
the active period (Bornenissza 1969 in Sgardelis and Margaris 1993; Majer
1984). Furthermore, the immediate effect of fire also depends on its intensity. Natural fires of high intensity have a destructive effect on numbers, whereas the effect of controlled burning is quite moderate. Finally, the effect of fire
depends on the type of ecosystem. In general, fire is much less destructive in
more xeric environments than in forests (De Izzara 1977). In the former,
increased populations have even been recorded shortly after fires (Pomeroy
and Rwakaikara 1975). According to Majer (1984), soil and litter invertebrates
exhibit a broad array of responses to fire, including immediate reduction in
numbers, delayed reduction in population densities, and temporary absence
of some taxa while others remain unaffected by fire or may increase their
numbers.
7.4.1.1
The Effect of Fire on Microarthropods
Short- and long-term effects of fire on Mediterranean micro- and macroarthropods have been studied by Sgardelis (1988), Sgardelis and Margaris
(1993), and Sgardelis et al. (1995). Results concerning the numerical response
of some soil micro arthropods are summarised in Table 7.3. The first finding
is that the immediate effect of fire is most pronounced on litter dwellers,
while animals that live under stones remain almost unaffected (Figs. 7.3, 7.4).