206
D. S. Gandhi and S. Sundarapandian
deciduous forests of Eastern Ghats, Andhra Pradesh. Plant diversity is directly influenced by many factors including climate, topography, soil and natural/anthropogenic
causes (Behera et al. 2016). All the 30 one-hectare study plots of Sathanur reserve
forest are located within the radius of 10 km and an altitude ranging from 192 to
250 m, hence, the climate cum topography of study plots largely remain the same.
The human disturbance varied considerably among the study plots due to closeness
to the settlement, agricultural field and rivulet, roads and path intrusions. The plots
located near to rivulet have more soil moisture and air humidity due to water flow.
The plots laid along roadsides and near human settlements are subjected to anthropogenic pressure which has resulted in an increase in cut stems. Seepage from the
agricultural land to forest area also increases soil moisture content in the study plots
which are close to them. These microclimatic variations among the plots 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. The low species richness
recorded in the present study compared to the Western Ghats and some regions of
Eastern Ghats could be ascribed to low and erratic rainfall pattern, anthropogenic
disturbances and extensive grazing.
Tree species richness is vital to tropical forest biodiversity because trees directly
or indirectly support almost all other life forms (Huston 1994). Tree (for individuals
≥10 cm DBH) species richness recorded in the current study plots ranged 7–28
species/ha, which is much lower than previous studies conducted in other parts of
Eastern Ghats, for example, Kadavul and Parthasarathy (1999a, b) reported 42 to 47
species/ha in Kalrayan hills and 33–50 species/ha in Shervarayan hills. Similarly,
Chittibabu and Parthasarathy (2000a) encountered 26–54 species/ha in Kolli hills
of Eastern Ghats. Reddy et al. (2008a) reported 60–69 species/ha in dry deciduous
forests of Eastern Ghats. Premavani et al. (2014) estimated 34–48 species/ha in
tropical dry forests of central Eastern Ghats. The relatively lower species richness
values obtained in the present study when compared to the other studies (Palomino
and Alvarez 2008; Powers et al. 2009; Rao et al. 2015; Naidu and Kumar 2016;
Sahoo et al. 2017) could be attributed to the greater extent of anthropogenic activities
prevailing in the study plots including stem cutting and stem removal in addition to
low rainfall.
The species richness of climbers registered in this study (3–23 species/0.125 ha)
is comparable to other areas of Eastern Ghats i.e., Kolli hills (2–17 species/ha;
Chittibabu and Parthasarathy 2001), tropical dry deciduous forest of Srilankamalla
wildlife sanctuary, Andhra Pradesh (6–27 species/ha; Mastan et al. 2015). However,
the value obtained in the present study is lower than in tropical dry deciduous forest
of Nallamalai–Seshachalam–Nigidi hills of Eastern Ghats (21–29 species/ha; Reddy
et al. 2008a), in the Vindhyan tropical dry deciduous forest (37 species/ha; Sharma
and Raghubanshi 2010) and in Mudumalai Wildlife Sanctuary, southern India (53
species/ha; Joseph et al. 2008). The species richness of climbers is comparable even
though this study site has low species richness (includes all life forms) in general
which could be attributed to anthropogenic perturbation as observed by Dewalt et al.
(2000), Laurance et al. (2001) and Schnitzer and Bongers (2002). According to Gerwing and Uhl (2002) and Schnitzer et al. (2004), human activities including logging
D. S. Gandhi and S. Sundarapandian
deciduous forests of Eastern Ghats, Andhra Pradesh. Plant diversity is directly influenced by many factors including climate, topography, soil and natural/anthropogenic
causes (Behera et al. 2016). All the 30 one-hectare study plots of Sathanur reserve
forest are located within the radius of 10 km and an altitude ranging from 192 to
250 m, hence, the climate cum topography of study plots largely remain the same.
The human disturbance varied considerably among the study plots due to closeness
to the settlement, agricultural field and rivulet, roads and path intrusions. The plots
located near to rivulet have more soil moisture and air humidity due to water flow.
The plots laid along roadsides and near human settlements are subjected to anthropogenic pressure which has resulted in an increase in cut stems. Seepage from the
agricultural land to forest area also increases soil moisture content in the study plots
which are close to them. These microclimatic variations among the plots 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. The low species richness
recorded in the present study compared to the Western Ghats and some regions of
Eastern Ghats could be ascribed to low and erratic rainfall pattern, anthropogenic
disturbances and extensive grazing.
Tree species richness is vital to tropical forest biodiversity because trees directly
or indirectly support almost all other life forms (Huston 1994). Tree (for individuals
≥10 cm DBH) species richness recorded in the current study plots ranged 7–28
species/ha, which is much lower than previous studies conducted in other parts of
Eastern Ghats, for example, Kadavul and Parthasarathy (1999a, b) reported 42 to 47
species/ha in Kalrayan hills and 33–50 species/ha in Shervarayan hills. Similarly,
Chittibabu and Parthasarathy (2000a) encountered 26–54 species/ha in Kolli hills
of Eastern Ghats. Reddy et al. (2008a) reported 60–69 species/ha in dry deciduous
forests of Eastern Ghats. Premavani et al. (2014) estimated 34–48 species/ha in
tropical dry forests of central Eastern Ghats. The relatively lower species richness
values obtained in the present study when compared to the other studies (Palomino
and Alvarez 2008; Powers et al. 2009; Rao et al. 2015; Naidu and Kumar 2016;
Sahoo et al. 2017) could be attributed to the greater extent of anthropogenic activities
prevailing in the study plots including stem cutting and stem removal in addition to
low rainfall.
The species richness of climbers registered in this study (3–23 species/0.125 ha)
is comparable to other areas of Eastern Ghats i.e., Kolli hills (2–17 species/ha;
Chittibabu and Parthasarathy 2001), tropical dry deciduous forest of Srilankamalla
wildlife sanctuary, Andhra Pradesh (6–27 species/ha; Mastan et al. 2015). However,
the value obtained in the present study is lower than in tropical dry deciduous forest
of Nallamalai–Seshachalam–Nigidi hills of Eastern Ghats (21–29 species/ha; Reddy
et al. 2008a), in the Vindhyan tropical dry deciduous forest (37 species/ha; Sharma
and Raghubanshi 2010) and in Mudumalai Wildlife Sanctuary, southern India (53
species/ha; Joseph et al. 2008). The species richness of climbers is comparable even
though this study site has low species richness (includes all life forms) in general
which could be attributed to anthropogenic perturbation as observed by Dewalt et al.
(2000), Laurance et al. (2001) and Schnitzer and Bongers (2002). According to Gerwing and Uhl (2002) and Schnitzer et al. (2004), human activities including logging