Angiosperms , Climbing plants in tropical forests of southern Eastern Ghats , Tamil Nadu , India

We provide a check list of angiosperm climbing plant species, along with their climbing modes, enumerated from a total of one hundred and fifty grids in tropical forests of southern Eastern Ghats, peninsular India. The Eastern Ghats constitute an important biodiversity area in India and have been studied earlier mainly for the floristics, and that too confined to a few prioritized sites. Lianas, the woody vines contribute substantially to the diversity and structure of most tropical forests. Yet, little is known about the importance of habitat specialization in maintaining tropical liana diversity. A total of 175 climbing plant species that belong to 100 genera and 40 families are included in this enumeration. Introduction Lianas, the woody vines are an important, but understudied growth-form, common to most forests throughout the world, particularly in the tropics (Schnitzer and Bongers 2002). The past few decades have brought increasing awareness of the importance of lianas to species diversity (Gentry and Dodson 1987; Schnitzer and Carson 2001; Burnham 2002). Lianas constitute ~ 25 % of the woody stem density and species diversity in tropical forests (Gentry 1991). They are often a large component of the canopy in tropical forests, often one-third or more of the entire leaf area, though only a small component of the basal area and biomass (Schnitzer and Bongers 2002). Recent studies on lianas have focused on the significant contribution of this life-form to the overall density and species diversity of tropical forests (Mascaro et al. 2004; Rice et al. 2004), mechanisms by which lianas alter the tropical forest diversity and regeneration (Schnitzer and Carson 2001), harming some shade tolerant species, while promoting some pioneer species (Schnitzer et al. 2000; Toledo-Acewes and Swaine 2007), and their significant contribution to carbon sequestration (Restom and Nepstad 2001; Schnitzer and Bongers 2002). The mean abundance, diversity and taxonomic composition of lianas in lowland tropical moist and wet forests are similar among tropical regions, although liana abundance is higher in Africa (Schnitzer and Bongers 2002). Liana density (≥ 1.6 cm diameter) decreased with increasing altitude, whereas richness was highest at intermediate elevations (Parthasarathy et al. 2004). Reports suggest that lianas are now increasing in tropical forests as a result of the recent climatological trend (Malhi and Wright 2004). The higher frequency of lianas is not only caused by declining rainfall (Swaine and Grace 2007) but also several other factors are known to favour them such as an increase in disturbance (Laurance et al. 2001; Ibarra-Manriquez and Martinez-Ramos 2002; Londre and Schnitzer 2006), or an especially high responsiveness to elevated CO2 (Grandos and Korner 2002; Zotz et al. 2006). More recently (Schnitzer 2005) examined floristic data from 69 tropical forests worldwide and found a negative correlation between mean annual precipitation and liana abundance. Materials and methods The Eastern Ghats constitute an important biogeographic region, as one of the nine floristic zones in India and form a broken chain of mountains spreading along the states of Orissa, Karnataka, Andhra Pradesh and Tamil Nadu and lie between Mahanadhi and Vaigai rivers. The present study was carried out in southern-most Eastern Ghats which falls in Tamil Nadu (10° 93'12° 18' N) (Figure 1) in six major hill complexes viz., Chitteris, Kolli hills, Pachaimalais, Check List 5(1): 092–111, 2009. ISSN: 1809-127X


Introduction
Lianas, the woody vines are an important, but understudied growth-form, common to most forests throughout the world, particularly in the tropics (Schnitzer and Bongers 2002).The past few decades have brought increasing awareness of the importance of lianas to species diversity (Gentry and Dodson 1987;Schnitzer and Carson 2001;Burnham 2002).Lianas constitute ~ 25 % of the woody stem density and species diversity in tropical forests (Gentry 1991).They are often a large component of the canopy in tropical forests, often one-third or more of the entire leaf area, though only a small component of the basal area and biomass (Schnitzer and Bongers 2002).Recent studies on lianas have focused on the significant contribution of this life-form to the overall density and species diversity of tropical forests (Mascaro et al. 2004;Rice et al. 2004), mechanisms by which lianas alter the tropical forest diversity and regeneration (Schnitzer and Carson 2001), harming some shade tolerant species, while promoting some pioneer species (Schnitzer et al. 2000;Toledo-Acewes and Swaine 2007), and their significant contribution to carbon sequestration (Restom and Nepstad 2001;Schnitzer and Bongers 2002).
The mean abundance, diversity and taxonomic composition of lianas in lowland tropical moist and wet forests are similar among tropical regions, although liana abundance is higher in Africa (Schnitzer and Bongers 2002).Liana density (≥ 1.6 cm diameter) decreased with increasing altitude, whereas richness was highest at intermediate elevations (Parthasarathy et al. 2004).Reports suggest that lianas are now increasing in tropical forests as a result of the recent climatological trend (Malhi and Wright 2004).The higher frequency of lianas is not only caused by declining rainfall (Swaine and Grace 2007) but also several other factors are known to favour them such as an increase in disturbance (Laurance et al. 2001;Ibarra-Manriquez and Martinez-Ramos 2002;Londre and Schnitzer 2006), or an especially high responsiveness to elevated CO 2 (Grandos and Korner 2002;Zotz et al. 2006).
More recently (Schnitzer 2005) examined floristic data from 69 tropical forests worldwide and found a negative correlation between mean annual precipitation and liana abundance.

Materials and methods
The Eastern Ghats constitute an important biogeographic region, as one of the nine floristic zones in India and form a broken chain of mountains spreading along the states of Orissa, Karnataka, Andhra Pradesh and Tamil Nadu and lie between Mahanadhi and Vaigai rivers.The present study was carried out in southern-most Eastern Ghats which falls in Tamil Nadu (10° 93'-12° 18' N) (Figure 1) in six major hill complexes viz., Chitteris, Kolli hills, Pachaimalais, Shervarayans, Kalrayans and Sathyamangalam forests (Figures 2 and 3).These sites harbor five distinct forest types -tropical evergreen, semievergreen, mixed deciduous, dry deciduous and thorn forests.
The overall climate in the Eastern Ghats is dry and salubrious.The climatic conditions favour both the south-west and the north-east monsoons.The months of April to June are hottest, while November to February is relatively cooler.The average summer temperature in the plains can reach up to 40 °C particularly in some of the semiarid areas in interior Tamil Nadu, while the average minimum temperature normally stays around 18-20 °C and the relative humidity is quite high throughout the year 70-75 %.Much of the region's rainfall occurs between October and December and ranges from 635-1,905 mm a year (Areendran and Rao 2006).----------------Enumeration of angiosperm climbing plants was carried in a total of 150 grids in forests of southern Eastern Ghats.The entire stretch of southern Eastern Ghats (10°93'-12°18' N) was divided into 6.25 km × 6.25km grids and within each grid a 0.5 ha transect (5m ×1km) was established.Each transect was subdivided into fifty 5m × 20m units.All lianas -1.5 cm dbh (5gbh, girth at breast height) were enumerated in the whole transect, and those of herbaceous vines of <1.5 cm dbh only in the beginning and end of the transect.Voucher specimens were collected and identified using regional floras (Hooker 1872(Hooker -1885;;Gamble andFischer 1921-1935;Matthew 1991), confirmed with the collections lodged in Department of Ecology and Environmental Sciences (DEES), Pondicherry University and Botanical Survey of India, Coimbatore (MH) and deposited in the herbarium of DEES.

Results and Discussion
A total of 175 angiosperm climbing plants in 100 genera and 40 families were recorded from the total of 150 grids of southern Eastern Ghats forests.Jongkind and Hawthorne (2005) 1.The enumerated climbing plants were classified into woody vines, the lianas (145 species) and herbaceous vines (30 species).Six climbing modes of lianas were recognized: stem twiners (46 %) followed by stragglers-armed (22 %), stragglersunarmed (17 %), tendril climbers (13 %), root climbers (1 %) and hook climber (0.5 %).Only one climbing mode, the grapnel-like climber (rattans) which was reported from Indian Western Ghats sites (Muthuramkumar and Parthasarathy 2000;Padaki and Parthasarathy 2000), did not occur in our study transects.Presently, many forest sites of southern Eastern Ghats are subjected to various anthropogenic pressures and the data of plant diversity, such as this on lianas will be useful in highlighting the importance of these forests in species conservation and forest management.

Figure 2 .
Figure 2. a) Overview of Chitteri hills; b) Inner stand view of Chitteri hills; c) Overview of Kolli hills; d) Inner stand view of Kolli hills; e) Overview of Pachaimalais; f) Overview of Shervarayans g) Inner stand view of Shervarayans; h) Overview of Kalrayans.