Taxonomic Diversity of Lianas in Tropical Forests of Northern Eastern Ghats of Andhra Pradesh, India

Lianas are important in forest ecosystem and strongly influence the forest dynamics and diversity. Lianas are common in the tropical moist deciduous and rain forests, which are competing with other forest trees. Little information is known on the habitat specialization in tropical lianas diversity and the root causes for variation among forests in liana species composition. A total of 170 liana species (≥ 1.5 cm girth at breast height) representing 109 genera and 43 families were reported in 5×5 m quadrate samples along with their climbing modes in the tropical forests of northern Eastern Ghats of Andhra Pradesh, India. A total of 210 grids were sampled in study area and reported that Convolvulaceae was the dominant family with 23 species followed by Papilionaceae, 22 species and Asclepiadaceae, 19 species and Ipomoea was the largest genera. Woody lianas were dominated by 128 species and these are classified into six climbing modes consisting in stem climbers (53.5%) that were the most predominant followed by stragglersunarmed (14.7%), stragglers armed and tendril climbers (13.5% each), root climbers (2.9%) and hook climbers (1.8%). The most dominant liana species in the northern Eastern Ghats were Acacia sinuata and Bauhinia vahlii. The results of this investigation suggests that better management and protection is an important for in situ conservation of liana diversity and involving local people is emphasized.


Introduction
Lianas are long-stemmed woody vines, which are fixed in the soil at ground level and depend on the physical support of other plants to reach the forest canopy (Araujo and Alves, 2010;Schnitzer and Bongers, 2002). These are prominent features of most tropical forests, where their leaves can constitute a large amount of the total area of the entire forest community (Putz and Mooney, 1991). Lianas make use of much greater ecological consequence than their size suggests and represent less than 5.0% of tropical forest biomass but up to 40% of leaf productivity (Hegarty and Caballe, 1991;Heidjen and Phillips, 2008). They struggle strongly with trees, very much reducing tree growth, tree reproduction and greatly increasing tree mortality (Wright et al., 2005;Schnitzer and Carson, 2010;Ingwell et al., 2010) and altering the course of regeneration in forests (Schnitzer et al., 2000). The density of lianas was greater than ever before and significantly increased their diversity during the last two decades of the twentieth century (Phillips et al., 2002).
The ecological importance of lianas is well documented, since they are of fundamental importance in the functioning of ecosystems as competing with trees either directly or indirectly. They act as key ecological components of whole forest in transpiration, carbon sequestration and forest regeneration (Schnitzer and Bongers, 2002). Lianas play a significant ecological role in different patterns of pollination, dispersal and phenological systems, provide several resources, and play vital roles in the protection of biological diversity (Reddy and Parthasarathy, 2006). The wealth and species diversity of lianas also depend upon a number of abiotic factors, including total occurrence of rainfall with seasonal variations, soil fertility and disturbances (Schnitzer, 2005). The main causes of the disturbance of lianas are the tree fallings not only important for sustaining the liana species but also maintain diversity that leads to increased development of lianas (Yuan et al., 2009;Reddy and Parthasarathy, 2003). The development of highest frequency of lianas is mainly because of declining the rainfall but several factors that are known to favour them are the increase anthropogenic impacts (Londre and Schnitzer, 2006). Lianas act as an indicator species response to increase CO2 concentrations and benefit from other anthropogenic disturbances (Zotz, 2006). A few studies on lianas have been carried out in the Eastern Ghats forests, India (Muthumperumal and Parthasarathy, 2009;Reddy and Parthasarathy, 2003;Parthasarathy et al., 2004). However, most of the studies were not exclusively on lianas as they involve general botanical surveys with reference to herbaceous, shrub and tree flora. Thus, main objective of present study was to inventory the lianas diversity and ecological findings in the northern Eastern Ghats forests of Andhra Pradesh, India.

Materials and methods
The Eastern Ghats are a long chain of broken hills and elevated plateaus and one of the nine floristic regions in India, running along the east coast of India in the states of Odisha, Andhra Pradesh, Tamil Nadu and Karnataka and lies between Mahanadhi and Vaigai rivers. The present study was carried out in northern Eastern Ghats of Andhra Pradesh, which lies between latitudes of 16º 15' and 19º 12' N and eastern longitudes of 80º 50' and 84º 47' E runs through five districts, namely Srikakulam, Vizianagaram, Visakhapatnam, East Godavari and West Godavari. The highest elevation measures about 1615 m above the msl in this region. Geological formation of the region consists chiefly in Charnokites and Kondalites and varied metamorphic rocks. Soils of northern Eastern Ghats is loamy, black, lateritic and alluvial. Lateritic soils are the common type along the deciduous forests of the area. The climate of the district is characterized by uncomfortably hot during summer and pleasantly cold during winter. There are three distinct seasons in a year; winter (November to February), summer (March to June) and rainy season (July to October). The maximum temperature ranges from 28°-46.2° C and minimum temperature ranges between 12.9°-27° C. The maximum rainfall is 1300 mm per annum in south-west monsoon period. At all the plots, a similar pattern of temperature and rainfall prevails throughout the year. The relative humidity varied between 70-88%. The forests in northern Eastern Ghats are broadly classified into Tropical Semi-evergreen, Tropical Moist Deciduous, Tropical Dry Deciduous, Tropical Thorny-Scrub vegetation and Tropical Dry Evergreen forest types (Champion and Seth, 1968).
The field work was carried out in a total 210 grids in the forests of northern Eastern Ghats of Andhra Pradesh for enumeration of lianas. The entire stretch of northern Eastern Ghats of Andhra Pradesh was divided into 6.25 × 6.25 km grids and within each grid a 0.5 ha transect (5m × 1km) was laid. Depending on the shape of the forest stand, these transects were divided into 5 x 200m sub transects. All lianas -1.5 cm gbh (5 gbh, girth at breast height) were enumerated in the whole transects, and those of herbaceous vines of < 1.5 cm gbh only in the beginning and end of the transects. The collected specimens were identified with the help of floras (Gamble andFischer, 1915-1935;Rao andKumari, 2002 -2008). The voucher specimens were deposited in the Botany Department Herbarium (BDH), Department of Botany, Andhra University, Visakhapatnam.

Results and discussion
The study area contained a total of 170 liana species representing 109 genera and 43 families, recorded from northern Eastern Ghats of forests in the total of 210 grids (Tab. 1). Muthumperumal and Parthasarathy (2009) enumerated 175 angiosperm climbing plants in 150 grids of southern Eastern Ghats; 60 liana species found in Maruthamalai hills of southern Western Ghats (Sarvalingam and Rajendran, 2012); 93 climbing plant species reported in land Atlantic forest, northern Brazil (Araujo and Alves, 2010); the total number of climbers that are found in Puerto Rico and the Virgin Islands amounts to 386 (Acevedo-Rodriguez, 2005). The present study identified a genus and species ratio of 1:1.55. Out of 170 species, only one species was Gymnosperm i.e. Gnetum ula and 169 species consist of 108 genera and 42 families were angiosperms. Among the angiosperms, there were 154 species representing 36 families of dicotyledons and 15 species belonging to 6 monocotyledon families.

Conclusion
Lianas play a key role in the ecology and dynamics of forests and may be helpful in conservation of forest resources. The present study has shown that the tropical forests of northern Eastern Ghats harbor has a high floristic diversity of lianas, which contribute to the overall biodiversity of the forests. These forests are deteriorating under constant anthropogenic activities. The present data of floristic diversity of lianas would be useful in species conservation and management. The importance of climbers can be useful to biologists in the establishment of a standardized methodology and to provide these data on the structural threats to tropical forests for a global audience.