earthworm distribution as compared to the type of soil. Wever et al. (2001) studied
the growth response of earthworm, Aporrectodea tuberculata, at different moisture
levels, i.e. 10%, 15%, 20% and 25%. They observed that with an increase in
moisture content, the growth rate of earthworm was increased and the maximum
growth rate was observed in 25% moisture level. They assessed the growth rate on
the basis of biomass and maturity of earthworm in different moisture conditions.
Andriuzzi et al. (2015) reported that earthworm tries to avoid high moisture conditions during intense rainfall by producing more burrows and vice versa. Thus,
change in the pattern of rainfall influences the burrowing behaviour of earthworms
in the soil. Singh et al. (2016b) also studied that the earthworm diversity and
abundance changed with change in soil moisture level. Thus, soil moisture can
directly influence the numbers and biomass of earthworms at any location.
19.4.2 pH
The earthworms’ population is very sensitive to the hydrogen ion concentration
which is an important factor that affects the species, numbers and distribution of
earthworms within the soil. Several researchers have indicated that maximum
earthworm species prefer to live in a soil having a neutral pH and also can resist
pH from 5.0 to 8.0 (Edwards and Bohlen 1996). According to Bouche (1972),
earthworms can also survive in pH less than 4 but their burrowing activity is
decreased and the same has been increased beyond pH 5.4. Various studies reported
that the pH of any particular site varies according to organic carbon (OC) and
organic matter (OM) content. Gillman (1985) reported that with a 1% increase in
OC content in the soil, pH declined by 1 unit and vice versa. Thus, long-term
accumulation of OC and OM in the soil might result in the acidification and addition
of inorganic and organic fertilizers further decreases the pH to an acidic level which
ultimately disturbs the earthworm species within the soil (Solomou et al. 2013).
19.4.3 Temperature
The average worldwide surface temperature has increased by 0.8
C since 1880 and
is expected to rise by 1.5
C during the following century (IPCC 2014). This increase
in the average surface temperature of the earth day by day, impacts all living
organisms (Brose et al. 2012). This increase in temperature has no effect on species
which favours high temperature but has a negative effect on those species which
prefer cold or normal temperature for their activities (Hering et al. 2009; Somero
2010). The earthworm is also depending on the optimal temperature which is
required for its growth, metabolism, respiration and reproduction. The fecundity
rate in earthworm is greatly affected by different temperature conditions. The
optimum temperature requirement by Lumbricus terrestris for production of the
19 Earthworm Communities and Soil Structural Properties
341
the growth response of earthworm, Aporrectodea tuberculata, at different moisture
levels, i.e. 10%, 15%, 20% and 25%. They observed that with an increase in
moisture content, the growth rate of earthworm was increased and the maximum
growth rate was observed in 25% moisture level. They assessed the growth rate on
the basis of biomass and maturity of earthworm in different moisture conditions.
Andriuzzi et al. (2015) reported that earthworm tries to avoid high moisture conditions during intense rainfall by producing more burrows and vice versa. Thus,
change in the pattern of rainfall influences the burrowing behaviour of earthworms
in the soil. Singh et al. (2016b) also studied that the earthworm diversity and
abundance changed with change in soil moisture level. Thus, soil moisture can
directly influence the numbers and biomass of earthworms at any location.
19.4.2 pH
The earthworms’ population is very sensitive to the hydrogen ion concentration
which is an important factor that affects the species, numbers and distribution of
earthworms within the soil. Several researchers have indicated that maximum
earthworm species prefer to live in a soil having a neutral pH and also can resist
pH from 5.0 to 8.0 (Edwards and Bohlen 1996). According to Bouche (1972),
earthworms can also survive in pH less than 4 but their burrowing activity is
decreased and the same has been increased beyond pH 5.4. Various studies reported
that the pH of any particular site varies according to organic carbon (OC) and
organic matter (OM) content. Gillman (1985) reported that with a 1% increase in
OC content in the soil, pH declined by 1 unit and vice versa. Thus, long-term
accumulation of OC and OM in the soil might result in the acidification and addition
of inorganic and organic fertilizers further decreases the pH to an acidic level which
ultimately disturbs the earthworm species within the soil (Solomou et al. 2013).
19.4.3 Temperature
The average worldwide surface temperature has increased by 0.8
C since 1880 and
is expected to rise by 1.5
C during the following century (IPCC 2014). This increase
in the average surface temperature of the earth day by day, impacts all living
organisms (Brose et al. 2012). This increase in temperature has no effect on species
which favours high temperature but has a negative effect on those species which
prefer cold or normal temperature for their activities (Hering et al. 2009; Somero
2010). The earthworm is also depending on the optimal temperature which is
required for its growth, metabolism, respiration and reproduction. The fecundity
rate in earthworm is greatly affected by different temperature conditions. The
optimum temperature requirement by Lumbricus terrestris for production of the
19 Earthworm Communities and Soil Structural Properties
341