Introduction

• Land cover analysis
• Land use classification and evaluation of land resources
• Monitoring and management of natural resources

The terms land use and land cover are often used in natural resources management, meaning types or classes of geographical determinable areas. Land cover analysis is done to discern vegetation, hydrological or anthropogenic features on the land surface. Land cover provides the ground cover information for baseline thematic maps. The land cover features can be classified using the data of different spatial, spectral and temporal resolutions. Broadly speaking, land cover describes the physical state of the Earth's surface and immediate surface in terms of the natural environment (such as vegetation, soils, groundwater, etc.) and the man-made structures (e.g. buildings). In contrast, land use refers to the various applications and the context of its use. This involves both the manner in which the biophysical attributes of the land are manipulated and the intent underlying that manipulation (the purpose for which the land has been used). Land use and Land-cover information play an important role at local and regional as well as at macro level planning. The land-cover changes occur naturally in a progressive and gradual way, however sometimes it may be rapid and abrupt due to anthropogenic activities. The planning and management task is often hampered due to insufficient information on the rates of land-cover and land-use change. Identifying, delineating and mapping land cover on temporal scale provides an opportunity to monitor the changes, required for sustainable management of natural resources. Thus, GIS and Remote Sensing allow spatial analysis approach to address the issues related to conservation and sustainable management of ecosystems

Remote sensing in the field of conservation and management of natural resources has varied applications. Aerial photography has been used for census of wildlife especially marine mammals, and carnivores in savannas. It is also used in monitoring the movement of wildlife. But the increasing applications of remote sensing have been primarily in the area of plant sciences. Practically most of the work done in remote sensing revolves around vegetation classification, crop monitoring and harvesting, mapping patterns in different forests, range lands, agricultural lands and diseases detection in crops (James, 1996). GIS along with remote sensing data help in inventorying, monitoring and assessing the natural resources on both spatial and temporal scale.

Increasing interest is being expressed worldwide in conservation largely as a result of a serious concern that has dawned due to the present state of local and global environmental conditions. This awareness is based on the recent realization that the state of the biological systems is of fundamental importance for the survival of human community. A key part of the global conservation effort is the mapping of biodiversity to pinpoint the hotspots, the most threatened and also the most species rich ecosystems of the world. With the increasing availability of global remote sensing data sets of high resolution it is important to combine field surveys to provide more accurate resource assessments. It being impractical and impossible to determine all the species or sample at all the places in a particular ecosystem, knowledge of presence and absence of certain indicator species has been favored in assessing the degree of stress and disturbance on the ecosystem. The most often used indicator species as trees, birds, butterflies and higher mammals are easy to sample and monitor and also represent diverse groups of biological significance. But not all exhibit interrelations with diversity of other taxa nor show response to changes in the ecosystem (Oliver and Beattie 1996).

Ants due to their high diversity (about 9600 species worldwide), high abundance, intricate relations and mutualistic behavior with both flora and fauna qualify as excellent ecological indicators (Agosti et al 2000). Ants belonging to the family Formicidae, super family Vespoidea, order Hymenoptera, are relatively less known in the Indian scenario wherein 600 species of ants have been identified (Bingham, 1975; Veeresh and Ali, 1987). Ants constitute 15% of the total animal biomass in a Central Amazonian rainforest (Fittkau and Klinge, 1973). Studies carried out by Erwin (1989) at Peru showed that 69% of the total insect specimens collected by fogging the forest canopy were ants. Wilson (1987) has reported that a single tree in Peruvian tropical lowland forest yielded 26 genera and 43 species of ants. Sampling in 33 one-hectare plots from 12 habitats at the Western Ghats, Gadagkar et al (1990) have reported 120 species from 31 genera in Uttara Kannada district. Ants tend to be very aggressive and have great ability to dominate themselves because of which direct interactions between them and plants and also with other arthropods and insects are distinctly seen. Ants exhibit high degree of variability in food preference. Some cultivate fungus gardens to meet their food requirements, some are accomplished scavengers and necrophagous while a majority of species serve as general predators on other insect groups exerting enormous pressure on other invertebrate populations in their habitats. Members belonging to the primitive genera of Amblyopone sustain mainly on centipedes (Dumpert, 1978), Leptogenys processionalis and L.chinensis on termites (Shivshankar, 1985) while Strumigenys, Cerapachys, Proceratium are specialized predators that feed on restricted set of arthropods (Kaspari, 2000). Eciton burcelli consumes more than 10000 captured animals per day, a majority of which are insects (Dumpert, 1978). Some ants survive on plant exudates (Tennant and Porter 1991). The diversity seen in ant fauna globally suggests that their ability to survive in various biotopes, is due to their specialized nesting structures to suit different environmental conditions. Ant nests vary from small crevices in buildings to anthills over 1m in height and 9m in circumference. Ants also nest under stones, in plants (myrmecophytes) and makes carton nests on trees. Together with Homo sapiens, ants are one of the few animal groups that commonly manipulate and modify their surroundings to suit their needs and it’s a truism that they occupy a position among terrestrial invertebrates equivalent to that occupied by our species in/among the vertebrates (Bolton 1995). They offer insight to ecosystem functioning to those who are interested in long-term monitoring, inventory and ecology.

Most of the ants have either a direct or an indirect relationship with vegetation. Some of these are highly specific to the habitat in which they occur, depending on the maximum benefits they attain for nesting, mating and food availability. Their preferences of microhabitat due to the above mentioned criteria were investigated by sampling ant fauna in various habitats along with mapping the vegetation using remote sensing and GIS (macro level analyses) to provide a detailed idea of the distribution of ant fauna, endemism and changes in patterns with habitat. By further determination of spatial distribution of certain indicator ant species the degree of stress and disturbance for prioritizing conservation strategies for this section of the Western Ghats was analyzed.