Plant Diversity and Distribution Pattern in Tropical Dry …
207
create canopy gaps, which lead to more light exposure that subsequently results in
the successful establishment of climbers and lianas.
The density of climbers enumerated in the present study was 569.6 individuals/ha
(range: 9–252 individuals/0.125 ha). This value is comparable with other reports from
tropical forest of Eastern Ghats such as Kolli hills (12.5–56 individuals/ha; Chittibabu
and Parthasarathy 2001) and Bobiri forest reserve, Ghana (152–280 individuals/ha;
Addo-Fordjour et al. 2009). The wide variations in the climber density among plots
could be due to different levels of anthropogenic pressures associated with canopy
opening and other microclimatic conditions. The low density of climbers in few
plots observed in the present study may be due to selective tree felling as stated by
Chittibabu and Parthasarathy (2000b).
Species richness of understory vegetation in 30 one-hectare plots in the tropical dry
deciduous forest of Sathanur reserve forest was 102 (fifty 25 m
2 quadrats for shrubs
and fifty 1 m
2 quadrats for herbs in each one-hectare plot). Comparatively, the value
obtained in the present study is moderately higher than the other parts of Eastern Ghats
and elsewhere (52 species/0.32 ha (eight hundred 4 m
2 quadrats) in tropical evergreen
forest in the Kolli hills, Chittibabu and Parthasarathy (2000b); 84 species/4 ha in
tropical dry deciduous forest in Odisha, Sahu et al. (2007); 32–93 species/0.05 ha
(twenty 25 m
2 quadrats) in riparian environments of Atlantic forests in Rernambuco,
Brazil, Gomes-Westphalen et al. (2012)). However, this is lower than several reports
of tropical forests in India (155 species/1.2 ha (three thousand 4 m
2 quadrats in 30 ha
plots) in tropical evergreen forest in Anamalais, Western Ghats, Annaselvam and
Parthasarathy 1999; 170 species/3 ha (shrubs + herbs) in tropical dry deciduous
forest in Nallamalai-Seshachalam-Nigidi hills of Eastern Ghats, Andhra Pradesh,
Reddy et al. 2008a; 107 species/2.04 ha (shrubs + herbs) in tropical dry deciduous
forest in Similipal biosphere reserve, Odisha, Reddy et al. 2008b; 269 species in
tropical forest tract of Sileur-Maredumilli hills of north Eastern Ghats, Reddy et al.
2011). The wide variations in understory species richness may be influenced by
various ecosystem processes like nutrient cycling, decomposition of organic matter,
hydrological cycle, soil formation, species composition of overstory, canopy cover,
light penetration, different levels of disturbances, etc., as suggested by Singh et al.
(2014). Comparison of understory diversity is very difficult because of the variations
in the area of sampling, size of quadrats, number of quadrats etc. as suggested by
Chittibabu and Parthasarathy (2000a, b). However, the value recorded in the present
study is well within the range (Annaselvam and Parthasarathy 1999). The population
density of understory species (shrubs and herbs) varied considerably among the
species as well as among the plots. In shrub community, the three dominant species
occupy 81% of populations. Lantana camara population contributed 32% of shrub
composition. In the herbaceous community, five dominant species were represented
by 62,318 individuals (57%) in all the study sites. In the herbaceous community,
annuals were more predominant than that of perennials. Similarly, annuals were
more predominant in the herbaceous community in tropical evergreen forests of
Anamalais, Western Ghats as observed by Annaselvam and Parthasarathy (1999). In
contrast, perennials dominated the understory community in Amazonian rainforest
(Poulsen and Balslev 1991). The prevalence of annuals in the herbaceous community
207
create canopy gaps, which lead to more light exposure that subsequently results in
the successful establishment of climbers and lianas.
The density of climbers enumerated in the present study was 569.6 individuals/ha
(range: 9–252 individuals/0.125 ha). This value is comparable with other reports from
tropical forest of Eastern Ghats such as Kolli hills (12.5–56 individuals/ha; Chittibabu
and Parthasarathy 2001) and Bobiri forest reserve, Ghana (152–280 individuals/ha;
Addo-Fordjour et al. 2009). The wide variations in the climber density among plots
could be due to different levels of anthropogenic pressures associated with canopy
opening and other microclimatic conditions. The low density of climbers in few
plots observed in the present study may be due to selective tree felling as stated by
Chittibabu and Parthasarathy (2000b).
Species richness of understory vegetation in 30 one-hectare plots in the tropical dry
deciduous forest of Sathanur reserve forest was 102 (fifty 25 m
2 quadrats for shrubs
and fifty 1 m
2 quadrats for herbs in each one-hectare plot). Comparatively, the value
obtained in the present study is moderately higher than the other parts of Eastern Ghats
and elsewhere (52 species/0.32 ha (eight hundred 4 m
2 quadrats) in tropical evergreen
forest in the Kolli hills, Chittibabu and Parthasarathy (2000b); 84 species/4 ha in
tropical dry deciduous forest in Odisha, Sahu et al. (2007); 32–93 species/0.05 ha
(twenty 25 m
2 quadrats) in riparian environments of Atlantic forests in Rernambuco,
Brazil, Gomes-Westphalen et al. (2012)). However, this is lower than several reports
of tropical forests in India (155 species/1.2 ha (three thousand 4 m
2 quadrats in 30 ha
plots) in tropical evergreen forest in Anamalais, Western Ghats, Annaselvam and
Parthasarathy 1999; 170 species/3 ha (shrubs + herbs) in tropical dry deciduous
forest in Nallamalai-Seshachalam-Nigidi hills of Eastern Ghats, Andhra Pradesh,
Reddy et al. 2008a; 107 species/2.04 ha (shrubs + herbs) in tropical dry deciduous
forest in Similipal biosphere reserve, Odisha, Reddy et al. 2008b; 269 species in
tropical forest tract of Sileur-Maredumilli hills of north Eastern Ghats, Reddy et al.
2011). The wide variations in understory species richness may be influenced by
various ecosystem processes like nutrient cycling, decomposition of organic matter,
hydrological cycle, soil formation, species composition of overstory, canopy cover,
light penetration, different levels of disturbances, etc., as suggested by Singh et al.
(2014). Comparison of understory diversity is very difficult because of the variations
in the area of sampling, size of quadrats, number of quadrats etc. as suggested by
Chittibabu and Parthasarathy (2000a, b). However, the value recorded in the present
study is well within the range (Annaselvam and Parthasarathy 1999). The population
density of understory species (shrubs and herbs) varied considerably among the
species as well as among the plots. In shrub community, the three dominant species
occupy 81% of populations. Lantana camara population contributed 32% of shrub
composition. In the herbaceous community, five dominant species were represented
by 62,318 individuals (57%) in all the study sites. In the herbaceous community,
annuals were more predominant than that of perennials. Similarly, annuals were
more predominant in the herbaceous community in tropical evergreen forests of
Anamalais, Western Ghats as observed by Annaselvam and Parthasarathy (1999). In
contrast, perennials dominated the understory community in Amazonian rainforest
(Poulsen and Balslev 1991). The prevalence of annuals in the herbaceous community