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Molecular Soil Biology
21
fertility (Doweling et al., 1986). Doran and Parkin
(1994) claimed that organic carbon in soil is one of
chemical parameters, which facilitates food access as
well it is an effective environment element in soil
quality. There is a converse relation between
earthworm abundance and carbon (Kooch et al., 2008;
Jalilvand, and Kooch, 2012). In the paper the greatest
amount of soil carbon was seen in Cypress with a
significant difference which is correspondent with
Chiti et.al 2007 (Table 4). Regonald and Palmer (1995)
used nitrogen as a chemical feature in soil to evaluate
its quality disturbances in different under control
systems. Soil carbon and nitrogen is much related to
its biological and physic-chemical features and
generally they can be considered as quality indices
(Pashani et al., 1991; Warren and Zou, 2002; Yan et
al., 2012).
Moreover there is a significant link between
earthworm number, sub-mass and C/N (Table 4). It
means more this ratio is, less their abundances. In
several studies soil carbon and nitrogen contents
considered as important variables in forest soil fertility
(Loffler, 2007). C/N is a great index to assign humus
breakdown which through it we can calculate weight
and volume drop-offs in humus (Sinha et al., 2003).
Antunes et al. (2008) confirmed that C/N is a
non-biological factor affects on macro-fauna plenty,
their existence or lack of them. Neiryck et al. (2000)
found that the small soil C/N ratio in Maple
sub-canopy cover resulted in an increase in the
number of soil habitant invertebrates.
Soil
macro-fauna abundance and biomass relates to this
ratio conversely (Rahmani and Saleh Rastin, 2000).
However, Mboukou-Kimbatsa (2007) noticed how
nitrogen affects positively earthworm abundance and
biomass. Leaves of broad-leave trees are better than
needle- leave ones.
Therefore, they decompose faster and form sweet
humus (alkaline) which, in turn, in decomposed by
microorganisms’ activity. But needle- leave trees
produce sour humus (acidic) and this reduces the
number of soil habitant invertebrates. However
needle-leaved produce acidic (sour) humus which it
decreases soil invertebrate population. Soil acidity is
an effective factor that affects directly or indirectly
macro-fauna as well food access (Armour et al., 2004).
But it can be different in accordance with the age of a
tree and area conditions (Agusto et al., 2002). The
earthworms are sensitive to acidity in such a way their
population and biomass will reduce in acid soils. The
soil under cypress is more acidic in contrast to the
other types; it means its reaction rate is slower, since
most of soil creatures are sensitive to acid
environment which it causes fewer in number and
biomass (Rahmani and Saleh Rastin, 2000; Klimenk
et al., 2011). Noticing the studies presented, most of
tiny microphages prefer almost neutral reaction (Bird
et al., 2004).
Based on available figures it is specified that most
macrofauna are present in 0~10 cm depth and their
number and biomass declines in deeper sites. Proper
ventilation, enough space and abundant nutrients are
main factors increasing the number and biomass of
earthworm in 0~10 cm depth. The 10~20 cm layers
are not proper in terms of mentioned factors and,
hence, the number and biomass of macrofauna is
smaller in them. On the other hand, deeper layers
downward would be more compressed, that is the bulk
density increases (Jafari haghighi, 2003), it is obvious
in deeper layers (10~20 cm). in upper layers while soil
is furrowed also the plants roots as well worm
activities are more than the deeper ones then soil
privileges more pores which it reduces bulk density.
All these results are correspondent with ones gained
by Kooch (2008). Going down in depth, the bulk
density increases which brings consequently heavier
texture. Some of soil features such as moisture and
food elements relate to soil texture. This characteristic
for sure affects detritivores population (Rahmani and
Saleh Rastin, 2000; Groffman et al., 2004). In the
research whereas the bulk density in 0~10 was less
than 10~20 layers then macro-fauna abundance and
biomass in the former layer is greater. In addition to
aforementioned factors, the picked species for
forestation can affect these creatures population.
3 Materials and Methods
3.1 Research site
The research was conducted in four plantations and an
Molecular Sil Biology