DISCUSSION

Most of the transects in the coastal sectors were harbouring mainly moist deciduous forests, despite annual rainfall of over 3000 mm.  Navagadde of Sector-1, a sacred grove with a shrine, was semi-evergreen, obviously due to the taboo on tree felling on account of its sacredness (Fig. 5). The Sector-7 (Arlihonda near Idugundi) in the mid altitude portion of Western Ghats proper also had a sacred grove, in much better state of preservation being in an interior thinly populated zone. This sector along with Sector-6 had a mosaic of evergreen to semi-evergreen forest. The Sector-1 having the Navagadde en-route the transect possessed high 40 tree species due to the combination of the semi-evergreen sacred grove with other deciduous zone forests. The eastern plains (Sectors 9 and 10) had relatively low number of species because of the teak dominated deciduous forests in the rain-shadow region.

Shannon diversity index for Sectors 6 and 7 had the highest plant species diversity (Figure 6), mainly due to the semi-evergreen to evergreen forests and relatively lesser human disturbances as compared to the other more approachable sectors. Among the evergreen trees were many Western Ghat endemics like Knema attenuata, Myristica malabarica, M. dactyloides. There were as well older individuals of deciduous species such as Terminalia alata, T. paniculata, Xylia xylocarpa, Lagerstroemia microcarpa, etc., species which practically had no regeneration under the canopy of the evergreens. These deciduous species might have appeared here during the times of shifting cultivation cycles in the past, over a century ago. Whereas the sectors 9 and 10 were found to be having the least Shannon diversity values because of the over-exploitation of natural resources and domination of teak. Sector 1 also showed a high Shannon diversity (3.3) due to the combined presence of evergreen and deciduous forests. The overall trend of the diversity analysis showed that the diversity was high in the first sector and decreased thereafter until the Ghat section where again the diversity was high and furthermore in the plains, it again reduced.

Evergreenness and Endemism: The percentage of endemism among trees was highest in forests with more percentage of evergreen trees (Fig. 7) particularly in mid altitude Sector 6 (45%).  These sectors cover the vegetation of Vajralli – Birgadde villages of Yellapur taluk characterized by the presence of rugged chain of steep hills and narrow valleys with higher evergreen to semi-evergreen forests with lower anthropogenic pressures. More evergreen forests also accounted for relatively higher basal areas and therefore higher carbon sequestration in the biomass. Of the notable endemic species in these evergreen-semi-evergreen zones were Cinnamomum macrocarpum, Diospyros candolleana, Knema attenuata, Myristica malabarica, Holigarna spp. etc. As one moves towards the coast or the plains both the evergreeness and endemism drops with lowest in plain area sectors (sectors 9 and 10) which are highly degraded due to high accessibility and anthropogenic pressures coupled with lower rainfall.

Basal Area: Mid altitude forests such as sector 6 with higher evergreeness and endemism also had higher basal area/ha and tree density/ha. They were characterized by lofty evergreen and semi-evergreen species with magnificent individuals of Lophopetalum wightianum, Persea macrantha, Ficus nervosa, etc. some with girths of over 400 cm. Sector 10 characterized by degraded teak plantations mixed with highly impacted bamboo mixed scrub with distantly placed deciduous trees had the least basal area (2.24 m²/ha) and lowest tree density (33 trees/ha) (Figs. 7, and 8).  Human impacts such as fire, grazing, logging, encroachment etc., from neighbouring villages (such as etc.,) had contributed to the impoverishment of these forests.

Clustering of Sites: Cluster analysis reveals three different clusters. The first cluster comprised of mainly low altitude sectors 2, 3, 4 and 5 belonged to the coastal taluk of Ankola. They were similar in having highly human impacted secondary deciduous forests. The second cluster included low altitude sectors 1 from the coast (which included the Navagadde sacred grove) and mid-altitude 6, 7 and 8, all of them being mosaic of semi-evergreen to evergreen forests. Sector 1, shows that climax vegetation along the coast could have been more of evergreen to semi-evergreen but for widespread human impacts through centuries. The third cluster included mid altitude sectors 9 and 10 and comprised of highly fragmented dry deciduous forests dominated by teak.

The shrub layer studies highlighted that in all the sectors, except sector 6, Eupatorium sp., either dominated or were present in large numbers indicating excessive canopy opening and disturbances. However, the presence of the saplings of species such as Olea dioica, Aporosa lindleyana and Lea indica in 7 out of 10 sectors indicates the likely return of evergreens in moist deciduous forests, may be due to reduced fire risk. The deciduous tree Terminalia paniculata was seen in 9 of 10 sectors and numerically highest in sectors 8 and 9 of deciduous forest zone prone to dry season fires. sectors 3 and 4 had high presence of Strobilanthes sp., which in some places formed large thickets affecting human movements. In the coastal to slightly inland sectors and the lower slopes of the Ghats, Xylia xylocarpa showed major presence in the deciduous forests. In the sectors 9 and 10, Tectona grandis and Terminalia paniculata formed the major part of shrub layer (being juveniles in the ground layer) and the regeneration of other species was poor.