INTRODUCTION

The Western Ghats of the Indian peninsula constitute one of the 34 global biodiversity hotspots along with Sri Lanka, on account of exceptional levels of plant endemism and by serious levels of habitat loss (Conservation International 2005). The rugged range of hills stretching for about 1600 km along the west coast from south of Gujarat to the end of the peninsula (lat. 8° and 21° N and long. 73° and 78° E), is interrupted only by a 30 km break in Kerala, the Palghat Gap (Radhakrishna 2001). Covering a geographical area of about 160,000 km², the Western Ghats have an average height of 900 m, with several cliffs rising over 1000 m. The Nilgiri Plateau to the north and Anamalais to the south of the Palghat Gap exceed 2000 m in many places. Towards the eastern side the Ghats merge with the Deccan Plateau which gradually slopes towards the Bay of Bengal. The northern half of the Western Ghats is covered with basaltic rocks of volcanic origin whereas the southern half is of Pre-Cambrian rocks of different kinds like the crystalline rocks, the peninsular gneisses and the charnokites. Nearly a hundred rivers originate from these mountains and most run their westward courses towards the Arabian Sea that is close-by. Only three major rivers, joined by many of their tributaries flow eastward, longer distances, towards the Bay of Bengal (Dikshit 2001; Radhakrishna 2001). The Western Ghat rivers are very critical resources for peninsular India’s drinking water, irrigation and electricity.

The complex geography, wide variations in annual rainfall from 1000-6000 mm, and altitudinal decrease in temperature, coupled with anthropogenic factors, have produced a variety of vegetation types in the Western Ghats. Tropical evergreen forest is the natural climax vegetation of western slopes, which intercept the south-west monsoon winds. Towards the rain-shadow region eastwards vegetation changes rapidly from semi-evergreen to moist deciduous and dry deciduous kinds, the last one being characteristic of the semi-arid Deccan region as well. All these types of natural vegetation degrade rapidly in places of high human impact in the form of tree felling, fire and pastoralism, producing scrub, savanna and grassland. Lower temperature, especially in altitudes exceeding 1500 m, has produced a unique mosaic of montane ‘shola’ evergreen forests alternating with rolling grasslands, mainly in the Nilgiris and the Anamalais (Pascal 1988).

Peninsular India is a rich centre of flowering plant endemism, details of which are given by Ahmedullah and Nayar (1987) and Nayar (1996). There are 2015 endemic taxa in this region most of them confined to the Western Ghats, with only 76 taxa associated with the Eastern Ghats. Many of these endemics are threatened due to human impacts and figure in the Red List of International Union for Conservation of Nature and Natural Resources (IUCN, 2009). Our study being on Kathalekan relic forest in Central Western Ghats we have major focus on trees and details related to their endemic status highlighting also on the Red Listed tree species in the study area. The high degree of faunal endemism is illustrated through inventorisation of the amphibians.

‘Relics’ were described by Drude in 1890 as those taxa that occur in disjunct areas, the intermediate link being lost by environmental or geological changes. They have been termed variously as ‘palaeoendemics’ by Chevalier and Guenot in 1925 and as ‘relic’ or ‘ancient endemism’ by Herzog in 1926 (Nayar 1996). Most of the endemic plants of Peninsular India are palaeoendemics in ecological niches characterised by habitat temperature/rainfall gradients, and vegetational interphases. The ecological niches of Western Ghats resemble islands so far as the distribution of endemic species is considered (Subramanyam and Nayar 1974). Stebbins (1980) considers ‘relict’/palaeoendemics of restricted distribution as museums than active centres of speciation.

The ‘relic forests’ of Central Western Ghats, the subject of this paper, has to be understood better in a human historical context. Forest alterations began in these mountains with the introduction of agriculture just over three millennia ago (Chandran 1997). Under a community-based landscape management regime that prevailed during the pre-British period, the agricultural communities lived more in the lower altitudes causing alterations in the primeval forests leading to the creation of a mosaic landscape in which patches of unaltered or less altered forests were retained as sacred groves cum safety forests. Forests were not seen primarily as sources of timber but viewed more as the provider of fertile lands for agriculture (both of shifting and permanent kind), for pastoralism, as source of non-timber products for subsistence and sale, as hunting resources and also for hydrological security. The British domination of the region from early 19^th century marked the end of community-centered forest management. The sacred groves, especially larger ones, along with secondary forests and fallows became part of state reserved forests and in due course lost their special identity. Today many such primeval forest relics remain lost amidst the general category of state reserved forests. Being of evergreen nature with not much scope for harvest of commercial timbers these groves were simply preserved or alienated for alternative uses. A cultural change, emphasizing also temple-centered worship of gods, caused further neglect and decline of the system of isolated sacred groves associated with human settlements. Many ‘lost’ groves, nevertheless, along with their treasure trove of rare, endemic species can still be traced in parts of south Indian Western Ghats. Most forests, including sacred groves, shifting cultivation grounds and fallow growth on them got merged with state reserved forests. The society’s own changing worldview, associating gods with temples than groves, and rising need for biomass the harvest of which was restricted from the state reserved forests also caused degradation of sacred groves closer to habitations (Gadgil and Berkes 1991; Chandran and Gadgil 1993; Chandran 1998).

We refer here as ‘relic forests’ those ancient forest patches, which have no history of wholesale clearance or major alterations by humans so that the original composition persists to some degree. Many of the sacred groves obviously fit into this definition and are easier to find than any fragments of primeval forests that escaped destruction by humans due to their relative inaccessibility. Most sacred groves known today are from the densely populated west coast or in the vicinity of Western Ghat villages, often standing isolated amidst a humanized landscape. The relic forests of this type are indeed easily visible cultural or biological relics of any countryside in the western peninsular India. There are also lesser known relic forests along the thinly populated core forest belt of the Western Ghats. These could have been sacred groves of the pre-colonial past which lost, or almost so, their special identity as seats of gods due to forest reservation by the state. Such lost groves were often subjected to timber extraction pressures or sometimes even wholesale alterations getting converted into alternative land uses. Thus was forgotten the past of these ancient woods, which the early peasants had preserved through generations in the name of deities, to supplement their livelihoods and to serve vital ecological functions necessary for the stability of life in an otherwise fragile ecological region. Their earlier status lost, these relic forests often got engulfed with secondary forests of slash and burn fallows in the course of time. Their usual presence was more along the high rainfall region with sensitive soils prone to fast erosion and loss of fertility than along the low rainfall Deccan side of the mountains where soil resources are better though fire hazards to the deciduous forests are higher.

The forests which lost their earlier aura of sacredness under community-based management did not get any special consideration from the state and were subjected to routine forestry operations to meet state needs, harming their special biodiversity preserved through ages. Last few decades, however, have seen increased awareness on the need for conservation and sustainable use of the natural resources (Chandran 1998; Pathak 2009). The 1988 ban on timber extraction from natural forests has kindled hopes on biological revival of the Western Ghat forests. A renewed global interest in the institution of sacred groves saw numerous studies carried out in India on these relic forests. These studies mainly harp on linkages between culture and conservation in relation to mostly functional sacred groves. In this paper, on the contrary, we attempt to unravel for the first time, the biological richness of forgotten groves along with the carbon sequestration potential, hydrological and ecological linkages, through a special study of Kathalekan, highlighting also the need and urgency to recognize and salvage many more such relic forests. The main objectives of the study are to:

• characterize relic forests;
• establish norms for the identification of relic forests;
• devise a plan for systematic study of their vegetation;
• record habitat heterogeneity, tree diversity, endemism, basal area and biomass;
• document regeneration status of notable climax, endemic and relic tree species;
• relate hydrological conditions with plant diversity;
• understand faunal significance using amphibians as indicators;
• estimate carbon sequestration potential; and to
• formulate appropriate conservation strategy.

Tropical forests, harbouring rich biodiversity, high endemism and complex ecology, have been steadily impacted by humans, especially since the introduction of farming. Secondary forests throughout the world are increasing dramatically and in many tropical countries they now exceed the areas covered by primary forest (FAO 2005). Slash and burn cultivation which enables releasing nutrients accumulated in biomass in the form of ashes (Nye and Greenland 1960) is regarded as one of the major causes of deforestation in earlier times. Even the world’s largest blocks of rainforests, as of central Amazonia, Congo basin and Thailand considered ‘undisturbed’ had undergone clearances for habitation and cultivation. Such forests elsewhere too may actually be in the process of secondary succession (Froyd and Willis 2008).

‘Remnant’ primary forests were noticed to exist embedded in tropical agricultural landscapes (Power 1996). In the Pacific New Caledonia, a biodiversity hotspot (Myers et al. 2000), exists one of the world’s most endangered tropical dry forest, fragments of which from parts of a hectare to several hectares in area, rich in endemics and mostly situated in private lands, have been preserved due to fencing and fire protection (Gillespie and Jaffre 2003). In Ethiopia are many forest relics, considered as islands of diversity, having unique composition reflecting the original climax ecosystems of the Ethiopian highlands (Muys et al. 2006). “Enormous, well preserved, relic forests, probably the largest relic forests on the western slope of the Andes” are referred to by Llatas-Quiroz and Lopez-Mesones (2005), who argued for their preservation both for hydrological reasons and their plant wealth. Tropical swamps are often considered relics of the original rainforests. In the highland valleys (1500–2000 m) of New Guinea were many swamps dominated by Myrtaceae (mostly Syzygium)and Pandanus during the Early Holocene. During the Mid-Late Holocene, swamp forests were cleared using fire for wetland agriculture. However, there are relics still left, although the primeval Myrtaceae suffered a decline (Denham et al. 2004; Haberle 2007).

Many parts of the world had the tradition of preserving forest patches as sacred dedicated to deities or deified ancestors. This tradition got strengthened especially with the introduction of agriculture, which necessitated forest clearances in a big way. In shifting cultivation fallows, forests would re-grow, the burning of which after a lapse of several years would add a flush of nutrients to the soil in the form of ashes, facilitating growing the next round of crops. However, the shifting cultivators as well as those who settled with permanent cultivation in valleys kept alive the practice of protection of primeval forest patches as sacred groves. This practice dwindled in most of the world, except in some countries where it prevails among indigenous societies, especially in highlands (Chandran 1998; Hughes and Chandran 1998).

The indigenous people of Yunan, who had high dependence on forest resources for their livelihoods, had also engaged in worship of sacred forests (Pei et al. 2009). In the Republic of Togo the local communities protected sacred forests especially on riversides. Several of these forest fragments are considered “modern relics of old and disappearing plant communities”. Some of the plant species were stated to be available only within these relics and 56 species were recorded for first time from Togo in these relics (Kokou et al. 2006).

The Indian highlands, particularly in the North East India, the Himalayas, the Central India and the Western Ghats-west coast region are rich in sacred groves. The sacred groves are among the last representatives of climax vegetation in the Western Ghats and North East India. In the tribal tract of western Midnapur district even relics of sacred groves, present almost in every village, harbour good number of birds (Deb et al. 1997). The groves of north-eastern hill regions of India are considered relics of the original vegetation. In Meghalaya climax species like Quercus griffithi, Lithocarpus dealbatus and Schima khasiana were reported to be regenerating in the shade of undisturbed groves than in the disturbed forests (Tripathy 2005). Sacred groves of Tamil Nadu are considered as the remnants of the forests that once thrived there (Amrithalingam 1998).

Myriads of sacred groves which dot the landscape of the Western Ghats-west coast region are known by various local names like Devrai (Maharashtra), Kan, Devarakadu (Karnataka) and Kavu (Kerala). The areas under the groves were much larger once, ranging from few to several hundred hectares. As there is paucity of historical records to make such a claim, an effort was made to reconstruct the traditional land use system in a 25 sq. km area of a peasant dominated undulating terrain in eastern Siddapur of Uttara Kannada. The reconstruction was based on landscape names, folk history, forest settlement records, and vegetation. It was found that nearly 6% of the land was maintained under sacred groves, under community management. By 1990’s the area under groves had shrunk to mere 0.31%, although the number of groves are high (54) even today (Chandran and Gadgil, 1998). This appears to be a modest estimate for the Central Western Ghat region, as a forest working plan of 1966 for Sirsi and Siddapur mentions area under Kodkani village (close to Kathalekan) as having a Kan of 735 ha and Mulkund one of 1039 ha. Brandis and Grant (1868) reported 171 Kansof Sorab taluk (in the neighborhood of Siddapur) as covering over 13,000 ha. So there were two kinds of forests in Central Western Ghats. The kansacred groves and the ordinary forests or kadu. The Kanswere, obviously relic forests protected by local communities as sacred groves cum safety forests. While there was a taboo on timber harvesting from the Kansthe community collected black pepper, cinnamon bark, fruits and seeds, medicinal plants etc. and tapped palm juice from Caryota urens that grew plentifully in them (Chandran and Gadgil 1993; Chandran et al. 1998). The Kanswere hydrologically important being at the source of perennial streams and springs (Anonymous 1923). Some Kansof southern Uttara Kannada, harbour fragments of Myristica swamps, an endangered and ancient habitat of high watershed value (Chandran and Mesta 2001).

Myristica. magnifica was known only from southern Kerala (8-10° N) and at Malemane village of which Kathalekan is a hamlet (14.27° N) in the Siddapur taluk. Such swamps with M. magnifica were also found in the Mahime village of the adjoining Honavar taluk by Chandran et al. (1999). Each of the 51 swamps they recorded in southern Uttara Kannada had Gymnacranthera canarica, yetanother swamp species of the Myristica family and a new record for the district. Semecarpus kathalekanensis, a new tree species of Anacardiaceae was described from the swamps of Kathalekan (Dasappa and Swaminath 2000). Recent discovery of two Critically Endangered trees Madhuca bourdillonii and Syzygium travancoricum from some relic forests of Uttara Kannada, almost 700 km north of their recorded home range in southern Kerala, underscores the need for intensifying efforts for locating more such relics (Chandran et al. 2008). Both these species were feared to be extinct according to the Red Data Book of Indian Plants (Nayar and Sastry 1987, 1990), but rediscovered later in southern Kerala itself (Sasidharan and Sivarajan 1996; Sasidharan 1997). Nair et al. (2007) have provided a comprehensive account of the biodiversity of Myristica swamps of Kerala.

Most relic forest studies in India pertain to functional sacred groves in the vicinity of habitations which are in waning state due to anthropogenic pressures, and their ability to sustain rare and threatened species is obviously on the decline. On the other hand there is a whole class of sacred groves, as in the Western Ghats, which lost their special status as abodes of gods under local community management. This happened when the British reserved forests as state property. Consequently these patches of primeval forests got merged with a sea of secondary forests around, often re-growth on shifting cultivation fallows. During periods of intensified exploitation of evergreen forests for meeting industrial demands even these ancient groves were not spared. Kathalekan, the forest studied for the present work, was such a Kan sacred grove.