INTRODUCTION

Tropical forests are the store house of many economically important species and therefore liable to overexploitation. When the human population was small, forests were plentiful, and it provided enough for people’s basic needs. The increase in population and a shift from nomadic to settled livelihood resulted in forests being cleared for agriculture and habitation. Anthropogenic activities such as industrial exploitation, mining activities, release of forest land for developmental activities, urbanization, etc. have led to further large-scale deforestation. Burgeoning population has accentuated the pressure on the forests (Ravindranath et al., 2000). When the anthropic pressure is stronger, deciduous and hardy evergreen species become increasingly abundant. Degradation has caused complete substitution of the evergreen forest by secondary deciduous type (Bourgeon, 1998).

The immense potential of forest resources is slowly being realized with the discovery of two compounds hitherto unknown to science in common tropical plants found in Madagascar, Catharanthus roseus (Apocynaceae): Vinblastin and Vincristin. Using these two compounds to treat children’s leukaemia, it has been possible to reduce the mortality rates in certain forms of this disease from 90% to just 10% (Nauman, 2001). India with an area of 3,267,500 sq. km  situated in the Southern peninsula of the Asian continent, harbors a vegetation scattered over the entire country and exhibits diversification due to climatic, physiographic and biotic factors (Gamble, 1921, Ramaswamy et al, 2001). Indigenous people with a historical continuity of resource use practices often possess a broad knowledge of the complex ecological systems in their own localities and they do develop a stake in conserving, and in some cases enhancing biodiversity. In Western Ghats, forest conservation in pre-colonial days went hand in hand with utilization. Hunting was subjected to many community regulations. However, following the British occupation, there was large-scale forest exploitation and vegetation transformation into commercial plantations of coffee, tea, wattle and Eucalyptus (Chandran, 1997). Post independence, industrialization and commercialization has played further havoc while agriculture has cleared up a lot of pristine forestland. Deforestation, degradation and subsequent desertification have led to a process of no return for trees. Therefore sustainable management of biodiversity and prevention of its loss are of  paramount importance considering the severity of threats faced by the forests today. In this context, a study has been undertaken in 22 localities with varying degrees of human disturbance falling under evergreen-semievergreen to moist deciduous type. The aim of this paper is to bring out the following:

1. Floristic structure, composition and diversity of forests with varying degrees of human disturbance.
2. Need for conservation and different strategies for sustainable utilization of forest resources.