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D. S. Gandhi and S. Sundarapandian
Campbell et al. 1992; Swamy et al. 2000; Sundarapandian and Karoor 2013). This
type of distribution indicates that this forest has a good potential for regeneration.
Species richness also decreased with increase in diameter class. A similar trend was
exhibited by the dominant species. Greater proportion (81.9%) of stems belonged to
lower diameter class (≥3.2 cm −<10 cm). This is so because of growth of coppices
from illegal cutting of adult stems for firewood and domestic purposes. This is the
same case with many other dry forests where lower diameter class individuals are
more in number. The greater density of low diameter class individuals is primarily
due to open canopy (Manokaran and La Frankie 1990).
A/F ratios indicate species distribution patterns in a community. According to
Odum (1971), generally, contagious distribution is the most common pattern in
nature; while random distribution is restricted to very homogeneous microclimates
and regular distribution prevails where competition among the population exists.
Species distribution patterns vary due to differences in microclimate, habitat heterogeneity, dispersal ability and allelopathy (Kandari et al. 2011). Understanding
the distribution patterns would be useful to develop management strategies in these
forests that are under pressure.
Human activities and cattle grazing in forest ecosystems have changed the diversity, structure and functions of ecosystems (Sundarapandian and Swamy 2000;
Swamy et al. 2000; Sundarapandian and Karoor 2013; Sundarapandian et al. 2015).
The effect of anthropogenic disturbances on forest features would be plot-specific
(Htun et al. 2011). Some plots (plot nos. 1–10) in the present study are near roads,
human settlements or the agricultural fields which are easily accessible to human
exploitation. The tree species richness was found to be low in these plots (plot nos.
1–10 except for 1, 7 and 10) compared to other study plots while shrub and herb
species richness are observed to be more in these plots. The lower number of tree
species may be due to several kinds of anthropogenic perturbations. Although the
study area is a reserve forest, localites frequently cut trees and collect firewood, lop
branches and graze their cattle. Illegal selective cutting of Chloroxylon swietenia
for fencing, agricultural tools and other domestic purposes and Albizia amara for
firewood are quite frequent in this forest. This kind of selective cutting may result in
coppicing of those species which could affect forest species composition and stand
structure. This has resulted in more density of both species in the plots near to the
road, agriculture field and settlements which enhance the tree density in these plots.
Due to greater tree density in these plots, the density of the herbaceous community
is comparatively low here. Study plots (plot no. 21–30) are located on both sides of
the rivulet. In general, the plots near the rivulet also have lower species richness; this
could also be attributed to human disturbance and edaphic factors. The study area
has a rocky terrain that would alter the structure of the forests. People regularly use
the rivulet for day to day activities. In addition to that, this is a source of drinking
water for cattle and hence, these plots were also under high anthropogenic pressures.
The present study reveals that the edaphic variations and anthropogenic disturbance
alter the microclimate among the plots which could be the reason for the significant
spatial variation in species richness and density among the plots even though they
are located within 10 km radius.
D. S. Gandhi and S. Sundarapandian
Campbell et al. 1992; Swamy et al. 2000; Sundarapandian and Karoor 2013). This
type of distribution indicates that this forest has a good potential for regeneration.
Species richness also decreased with increase in diameter class. A similar trend was
exhibited by the dominant species. Greater proportion (81.9%) of stems belonged to
lower diameter class (≥3.2 cm −<10 cm). This is so because of growth of coppices
from illegal cutting of adult stems for firewood and domestic purposes. This is the
same case with many other dry forests where lower diameter class individuals are
more in number. The greater density of low diameter class individuals is primarily
due to open canopy (Manokaran and La Frankie 1990).
A/F ratios indicate species distribution patterns in a community. According to
Odum (1971), generally, contagious distribution is the most common pattern in
nature; while random distribution is restricted to very homogeneous microclimates
and regular distribution prevails where competition among the population exists.
Species distribution patterns vary due to differences in microclimate, habitat heterogeneity, dispersal ability and allelopathy (Kandari et al. 2011). Understanding
the distribution patterns would be useful to develop management strategies in these
forests that are under pressure.
Human activities and cattle grazing in forest ecosystems have changed the diversity, structure and functions of ecosystems (Sundarapandian and Swamy 2000;
Swamy et al. 2000; Sundarapandian and Karoor 2013; Sundarapandian et al. 2015).
The effect of anthropogenic disturbances on forest features would be plot-specific
(Htun et al. 2011). Some plots (plot nos. 1–10) in the present study are near roads,
human settlements or the agricultural fields which are easily accessible to human
exploitation. The tree species richness was found to be low in these plots (plot nos.
1–10 except for 1, 7 and 10) compared to other study plots while shrub and herb
species richness are observed to be more in these plots. The lower number of tree
species may be due to several kinds of anthropogenic perturbations. Although the
study area is a reserve forest, localites frequently cut trees and collect firewood, lop
branches and graze their cattle. Illegal selective cutting of Chloroxylon swietenia
for fencing, agricultural tools and other domestic purposes and Albizia amara for
firewood are quite frequent in this forest. This kind of selective cutting may result in
coppicing of those species which could affect forest species composition and stand
structure. This has resulted in more density of both species in the plots near to the
road, agriculture field and settlements which enhance the tree density in these plots.
Due to greater tree density in these plots, the density of the herbaceous community
is comparatively low here. Study plots (plot no. 21–30) are located on both sides of
the rivulet. In general, the plots near the rivulet also have lower species richness; this
could also be attributed to human disturbance and edaphic factors. The study area
has a rocky terrain that would alter the structure of the forests. People regularly use
the rivulet for day to day activities. In addition to that, this is a source of drinking
water for cattle and hence, these plots were also under high anthropogenic pressures.
The present study reveals that the edaphic variations and anthropogenic disturbance
alter the microclimate among the plots which could be the reason for the significant
spatial variation in species richness and density among the plots even though they
are located within 10 km radius.