Basic HTML Version
Molecular Soil Biology (online), 2013, Vol. 4 No.2, 7-15
ISSN 1925-2005
http://msb.sophiapublisher.com
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Table 3 Statistical parameters resulted in PCA for soil
characters
Axes Eigenvalue Percentage
of
variance
Cummulative
variance
1
5.44
90.69
90.69
2
0.52
8.71
99.41
3
0.03
0.55
99.97
4
0.00
0.03
100.00
Table 4 Eigenvectors of soil characters for the PCA axes
Row
Soil characters
Axis 1
Axis 2
1
pH
-0.07
-0.00
2
Organic matter
0.42
-0.05
3
Organic carbon
0.42
-0.04
4
Total nitrogen
0.59
-0.02
5
C/N ratio
-0.15
-0.01
6
Water content
1.22
0.11
Figure 1 PCA bibplots of microsites, soil characters and
earthworm species
than to temperature extremes (Kooch et al., 2008).
The soil moisture availability and diversified
landscape patterns are probably responsible for the
earthworm colonization in this region.
High assemblage of earthworm biomass within pit is
related to earthworm's higrophillous. Some of
earthworms are semi-aquatic and prefer positions with
high water content (Schwert, 1990; Kooch et al.,
2008). Nachtergale et al (2002) pointed that the
increase of epigeics biomass in pits is a reaction to
more assemblage of trees litters within this microsite.
Pits creation in forest ecosystem produce an especial
condition as is due to increase of litter thickness and
water content, thus the epigeics biomass will increase.
Many researchers claimed that less abundance of
earthworms in acid condition is related to lack of
calcium ion in soil ecosystem (Sanjabi, 2004). The
most earthworms especially anecic, prefer rich
environments of nutrient source with lower carbon to
nitrogen ration. Endogeic and anecic species are more
resistance to soil inpropre textures and are able to
withstand dry conditions (Kooch and Jalilvand, 2008).
Thus, these species are able to migration in soil deeper
depths for avoiding of dryness (Hale and Host, 2005).
Whereas epigeic species are more asseblaged on soil
surface and upper layers of mineral soil (Hale and
Host, 2005). These subjects are visible in this study
also. According to obtained results the epigeic, anecic
and endogeic species were more gathered in 0~15 cm,
15~30 cm and 30~45 cm depths, respectively.
Soil C/N ratio is the other effective factor that
can be considered in relation to earthworms'
groups' assemblage of different positions.
Wood (1995) found that earthworm population
and biomass will increase in soil with low C/N
ratio. Rahmani (1999) also pointed that
earthworm densities are affected by C/N ratio,
as earthworms assemblages are reduced with
increasing of this ratio. Neyrinck et al (2000)
reported that the low C/N ratio in soil
ecosystem is due to gathering of different
earthworms. Antunes et al (2008) demonstrated
soil C/N ratio as an abiotic factor and the most
important effective factor on earthworm's
populations in forest sites. Kooch et al (2009)
introduced the soil C/N ratio factor as the most
important of effective factor on earthworm
populations in plant ecological groups of
Chalous lowland forests located in north of
Iran. In our study, the least amounts of soil C/N
ratio found in pit position, thus more
earthworms' densities were detected in this
microsite. Principal component analysis
confirmed the accuracy of above phrase. Also,
earthworms abundance were correlated to theirs
biomass (r = 0.99
**
) that is according to
obtained results in Haynes et al (2003)
research. The analysis of factor analysis in this
research showed that the earthworm's
assemblage in quarter 4 of principal
components is indicating more proper condition