The forests are valuable resources on innumerable counts viz. as sources of various useful products to humans, for their environmental and ecosystem services (soil and water conservation, regulation of water flow, carbon sequestration, nutrient cycling, etc.) and as centres of biodiversity. Out of the total 329 million ha land area of India, 43% is under cropping and 23% classified as forests. The total area of forest cover in India, as per the latest assessment is about 692,027 km2 or 21.05% of the total geographical area.
The Western Ghats range of hills, running close and parallel to the Arabian Sea along the western Peninsular India for about 1600 km from the south of Gujarat to Kanyakumari, covers an area of about 1,60,000 sq.km. This region harbours very rich flora and fauna and there are records of over 4,000 species of flowering plants (38% endemics). Western Ghats is among the 34 global biodiversity hotspots on account of exceptional plant endemism and serious levels of habitat degradation. 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. While tropical evergreen forest is the natural climax vegetation of the more humid western slopes, along the rain-shadow region eastwards vegetation changes rapidly from semi-evergreen to moist and dry deciduous forests, the last one being characteristic of the semi-arid Deccan region as well. 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. All these types of natural vegetation are prone to or have already undergone degradations due to human impacts.
Uttara Kannada district with 76% of its 10,291 sq.km area covered with forests has the distinction of having highest forest area. This is the northernmost coastal district of Karnataka State (13.9220o N to 15.5252o N and 74.0852o E to 75.0999o E) has a geographical area of 10, 291 km2. Topographically the district can be divided into three zones – the narrow and relatively flat to low hilly coastal along the west of Karwar, Ankola, Kumta, Honavar and Bhatkal taluks; the precipitously rising main range of Western Ghats towards the eastern interior of these taluks, the crestline zone composed of Sirsi, Siddpur Supa and Yellapur taluks and Haliyal and Mudgod taluks towards the north-east flattening and merging with the Deccan Plateau. The district can be divided broadly into five vegetation zones namely: Coastal, Northern evergreen, Southern evergreen, Moist deciduous and Dry deciduous. The evergreen to semi-evergreen forests form major portion of the district especially towards the more rainy western parts. Towards the eastern rain-shadow portion, the forests change rapidly into moist and dry deciduous types.
Whereas substantial areas of natural forests, through forestry practices over a period of more than one century, have been converted into monoculture tree plantations of teak, eucalypts (in the past) and into Acacia plantations in recent decades, there also remained in many places blocks of ancient patches of evergreens, known as kans, which were or still are sacred to the local people being the seats of village deities. These are relatively less impacted areas of climax evergreen forests, being sacred groves protected by the people through generations. Being preserved forests from ancient times these kans or their remains still might harbor rare species of plants, with high degree of Western Ghats endemism, and also endemic faunal elements. Eg. Asollikan (Ankola), Kathalekan (Siddapur), Karikan (Honavar) etc.
Slash and burn cultivation that prevailed almost till close of 19th century, especially in the heavy rainfall zone created considerable areas of secondary forests that replaced primary evergreen. Wherever clear felling has taken place in the past in the heavy rainfall belt, for shifting cultivation or under forestry operations, very sensitive evergreens and those without coppicing character tend to vanish. Old growth forests in stages of late secondary almost resemble the primary forests. But conspicuously absent in them are climax evergreen forest trees like Dipterocarpus indicus, Vateria indica, Palaquium ellipticum, and species confined to Myristica swamps like Myristica fatua (M. magnifica), etc. The forests bearing centuries of history is a grant mosaic of evergreen and semi-evergreen to secondary moist deciduous (in the high rainfall areas) to deciduous types. These are intermingled in many places with degraded stages like savannah, and scrub or entirely changed into grassy blanks used for cattle grazing, which within forest zone also have crucial role of supporting wild herbivores.
Karnataka has five National Parks and 21 Wildlife Sanctuaries. Uttara Kannada has mainly two important protected areas namely Anshi National Park and Dandeli Wildlife Sanctuary. These two PA’s are brought together under Dandeli-Anshi Tiger Reserve with focus on tiger conservation. The DATR presently covers an area of 1365 sq.km. in the taluks Joida, Karwar and Haliyal. We could not carry out forest studies within the DATR due to want of permission from the Wildlife wing of Forest Department. However, prior to the imposition of restrictions on studies within Tiger Reserves we had carried out a study on the grassland resources within the Reserve. Recently (in 2011) Attivery Bird Sanctuary was declared in Mundgod taluk covering 2.23 sq.km area, mainly composed of a reservoir and its peripheral areas.
Conservation Reserves are a new concept within the framework of PAs under the Wildlife (Protection) Amendment Act of 2002. They seek to protect habitats that are under private ownership also, through active stakeholder participation. They are typically buffer zones or connectors and migration corridors between established national parks, wildlife sanctuaries and other RFs. They are designated as conservation reserves if they are uninhabited and completely owned by the government but used for subsistence by communities, and community reserves if part of the lands are privately owned. Administration of such reserves would be through joint participation of forest officials and local bodies like gram sabhas and gram panchayats. They do not involve any displacement and protect user rights of communities. In Uttara Kannada, four such Conservation Reserves were set up by the Government of Karnataka:
- Aghanashini LTM Conservation Reserve (299.52 sq.km), to protect Lion tailed macaque and Myristica Swamps.
- Bedthi Conservation Reserve (59.07 sq.km) as Hornbill habitats and for medicinal plant species like Coscinium fenestratum.
- Shalmala Riparian Eco-system Conservation Reserve (4.89 sq.km) for conservation flora and fauna of a riverine ecosystem and
- Hornbill Conservation Reserve (52.5 sq.km) covering part of Kali River basin for specifically hornbill conservation.
The current study investigates floristic diversity associated with different forests and computes basal area, biomass and carbon sequestration in forests. Apart from this inventorying and mapping of endemic tree species has been done to find out areas of high endemism and congregations of threatened species. A set of criteria for holistic conservation of forest ecosystems, particularly of high endemism of Western Ghats has been prepared based on field investigation, interaction with stakeholders (researchers working in this region, forest officials, local people, subject experts)
Forests of all major kinds were studied using transect cum quadrat methods (altogether 116 transects, each transect with five quadrats of 400 sq.m each for tree vegetation, 10 sub-quadrats each of 25 sq.m for shrubs and tree saplings and 20 subquadrats of one sq.m for herb layer diversity. Out of 116 transects 8 were studied using point-centre quarter method). Altogether for tree vegetation 540 quadrats, each of 400 sq.m were studied. Necessary permission was, however, not granted for forest studies within the Dandeli-Anshi Tiger Reserve areas.
Altogether 1068 species of flowering plants were inventorised during the study period, through sample surveys and opportunistic surveys outside the transect zones. These species represented 138 families. Of these 278 were trees species (from 59 families), 285 shrubs species (73 families) and 505 herb species (55 families). Moraceae, the family of figs (Ficus spp.), keystone resources for animals, had maximum tree sp (18), followed by Euphorbiaceae (16 sp.), Leguminosae (15 sp.), Lauraceae (14 sp.), Anacardiaceae (13 sp.) and Rubiaceae (13 sp.). Shrub species richness was pronounced in Leguminosae (32 sp.), Rubiaceae (24 sp.) and Euphorbiaceae (24 sp.). Among herbs grasses (Poaceae) were most specious (77 sp.), followed by sedges (Cyperaceae) with 67 sp. Orchids (Orchidaceae) were in good number.
Tropical forests are major reservoirs of carbon in the terrestrial areas of the planet which is confronted with the prospects of imminent climatic change. World over all countries need to be alert to this major catastrophe. Apart from regulating pollution levels from various sources carbon sequestration in biomass has to be increased considerably. Our estimates on carbon sequestration based on tree biomass estimates from 116 forest samples show that the average carbon sequestration per hectare of forest (barren areas, scrub and grasslands excluded from sampling) was 154.251 ha.
It is a significant find that the sacred kan forests of pre-colonial era, despite their merger with state reserved forests, and subjection of most to timber extraction pressures in the post-independence era, continue to lead the chart of sites having some of the highest carbon sequestration per unit area. Thus the kan forest adjoining the Karikanamman temple in Honavar taluk had the highest carbon sequestration at 363.07 t/ha in the tree biomass alone. This is followed by Tarkunde-Birgadde in Yellapur (357.67 t/ha), and some of the swamp-stream forest samples in Kathalekan (299.66 t/ha, 275.18 t/ha, 259.21 t/ha etc.). Likewise Kanmaski-Vanalli in Sirsi had 242.43 t/ha of carbon.
The lowest carbon sequestered was found to be in the savannized forests, for obvious reasons of low to very low number of trees in them. These savannas whether they be in high evergreen forest belt (in Siddapur or Joida for instance) or be in drier zone of Haliyal or Mundgod have carbon storage of <50 t/ha in the tree biomass. Savannization was a necessity in the past for agricultural occupation of humans in the Western Ghats, for cattle grazing and slash and burn cultivation. Today the process is repeating to some extent still as forest encroachments have happened rampantly in all taluks increasing the porosity of otherwise in tact forests. Most bettalands allotted to arecanut orchard owners for exercising the privilege of leaf manure collection are in poor state of biomass and carbon sequestration (Eg. 14.19 t/ha in Gondsur-Sampekattu betta in Sirsi, Talekere betta in Siddapur 41.47 t/ha).
The study highlights the importance of conservation of riparian forests occurring along streams and swamps, not only from high species endemism but also for higher carbon sequestration. A very detailed study in Kathalekan involving nine samples of such forests versus nine samples away from such water courses reveal that the average carbon sequestration in the former was 225.506 t/ha against 165.541 t/ha in the latter. This is despite the fact both types occur within what is traditionally designated as a kan forest. We therefore recommend that forests adjoining or covering streams, swamps and riverbanks of the Western Ghats be considered sacrosanct and as critical areas for hydrology not only of the coast but of the entire Indian peninsula.
As regards trees are concerned, in principle, there are close associations between areas of rich tree endemism and occurrence of RET tree species. Forests with high tree endemism also tend to shelter endemic/RET non-tree species and fauna- especially fishes and amphibians- which are indicators of other such organisms as well. Tree species in danger of local or total extinction mainly exist in and closer to the Myristica swamps. These include Syzygium travancoricum (Critically Endangered), Myristica fatua (M. magnifica) (Endangered), Gymnacranthera canarica (Vulnerable), Semecarpus kathalekanensis (newly discovered), Mastixia arborea (rare endemic) etc. Madhuca bourdillnoni, a Critically Endangered tree, was not in our samples, but occurred very sparingly close to some Myristica swamps. The Kathalekan swamp forest sheltered at least 35 species of amphibians, most of them within a range of few hundred meters. While 26 species (74%) of them were Western Ghat endemics, one species Philautus ponmudi is Critically Endangered and five species each were Endangered and Vulnerable. Scores of Myristica dominated forest swamps would have perished in the Western Ghats in past centuries having given way to human impacts, notably due to reclamation of primeval forest clad valleys for making rice fields and arecanut-spice orchards. The last remains are also under threat, mainly being looked upon for areca orchards by encroachers. Swamps being excellent sources of perennial streams we recommend tracing out all such swamps and potential swamps (of degraded vegetation or waters diverted for agriculture) for hydrological needs. The swamps along with their catchments, even if they have secondary forests, need to be safeguarded as prime areas of hydrological significance and as the last refugia of rain forests in the central Western Ghats.
Floristic diversity, biodiversity, Western Ghats.
Citation : Ramachandra T.V., Subash Chandran M.D., Rao G R, Vishnu D. Mukri and Joshi N.V., 2015. Floristic diversity in Uttara Kannada district, Karnataka, Chapter 1, In Biodiversity in India-Vol. 8, Pullaiah and Sandhya Rani (Eds), Regency publications, New Delhi, Pp 1-87
||Dr. T.V. Ramachandra
Energy & Wetlands Research Group, CES TE 15
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