New checklist by Keralam research team records 3,261 flowering plant species in Agasthyamalai Biosphere Reserve
A research team compiled a new checklist of flowering plants (angiosperms) of the Agasthyamalai Biosphere Reserve, recording 3,261 species along with 26 subspecies and 28 varieties, spread across 1,139 genera and 190 families.
The compilation was carried out by a team from the Jawaharlal Nehru Tropical Botanic Garden and Research Institute (JNTBGRI), Thiruvananthapuram, and published in the journal Plant Science Today.
Fabaceae emerged as the most species-rich family (349 taxa), followed by Rubiaceae (194 taxa), Poaceae (193 taxa), and Orchidaceae (168 taxa).
The checklist recorded 1,018 endemic taxa (31.2% of the total), including 245 steno-endemic taxa (species restricted to an extremely narrow range within the reserve), alongside 347 taxa shared with Sri Lanka and notable floristic affinities with tropical America.
The findings were presented as reaffirming the global significance of the Western Ghats as a biodiversity hotspot and underscoring the need for region-specific conservation strategies within the reserve.
Biodiversity Hotspot: Criteria and the Western Ghats
A biodiversity hotspot is a biogeographic region identified using criteria devised by ecologist Norman Myers (1988): it must hold at least 1,500 endemic vascular plant species (over 0.5% of the world's total) and must have already lost at least 70% of its original natural habitat. The Western Ghats, one of the world's 8 "hottest hotspots," qualifies decisively on both counts and is one of only 4 biodiversity hotspots recognised in India (the others being the Himalaya, Indo-Burma, and Sundaland extending into the Nicobar Islands).
Key Details
- The Western Ghats support over 5,000 flowering plant species, of which roughly 1,700 are endemic; endemism is similarly high among trees (about 54%), amphibians (about 65%), reptiles (about 62%), and freshwater fishes (about 53%).
- UNESCO inscribed 39 serial component sites across the Western Ghats as a World Heritage Site in 2012, citing its exceptional concentration of endemic flora and fauna, including several protected areas within the Agasthyamalai landscape.
- The hotspot concept (distinct from a Biosphere Reserve, National Park, or Wildlife Sanctuary) is a global conservation-prioritisation tool, not a legal protection category under Indian law.
The new checklist's high endemism figure (31.2% of recorded taxa) offers fresh, region-specific data reinforcing why the Agasthyamalai segment of the Western Ghats meets Myers' hotspot threshold and merits continued global conservation attention.
Biosphere Reserve: Category, Zonation, and Agasthyamalai's Status
A Biosphere Reserve is an internationally recognised conservation category under UNESCO's Man and Biosphere (MAB) Programme (launched 1971), distinct from a National Park or Wildlife Sanctuary in that it is managed through a three-zone model — a strictly protected core zone, a buffer zone permitting regulated activity, and a transition zone allowing sustainable human use — rather than being governed primarily as an inviolate protected area. In India, Biosphere Reserves are designated by the Ministry of Environment, Forest and Climate Change (MoEFCC) and may additionally seek UNESCO's international "Biosphere Reserve" tag under the World Network of Biosphere Reserves.
Key Details
- The Agasthyamalai Biosphere Reserve was notified in 2001 and added to UNESCO's World Network of Biosphere Reserves in 2016.
- It spans about 3,500 sq. km at the southernmost tip of the Western Ghats, straddling Thiruvananthapuram, Kollam, and Pathanamthitta districts in Kerala and Tirunelveli and Kanyakumari districts in Tamil Nadu.
- It encompasses multiple existing protected areas, including the Kalakkad-Mundanthurai Tiger Reserve and the Neyyar, Peppara, and Shendurney Wildlife Sanctuaries, illustrating how a Biosphere Reserve can nest several protected-area categories within a single landscape-level unit.
The checklist was compiled specifically at the scale of the Biosphere Reserve (not a single protected area), which is why the researchers frame it as supporting "focused, region-specific" conservation strategy for the whole landscape rather than any one sanctuary.
Endemism and Species Documentation as a Conservation Tool
Endemism refers to species naturally restricted to a defined geographic area and found nowhere else; "steno-endemic" species are endemic to an even narrower range, often a single hill range or valley, making them especially vulnerable to localised threats such as habitat fragmentation or land-use change. Systematic checklists and floristic inventories are foundational to conservation planning because they establish the baseline against which habitat loss, invasive species spread, and climate impacts are measured, and they inform IUCN Red List assessments and Wildlife (Protection) Act scheduling for individual species.
Key Details
- Species documented as endemic or steno-endemic are priority candidates for site-specific conservation and are more likely to require targeted, in-situ protection since translocation or captive propagation is less viable for narrowly distributed plants.
- Updated checklists also help detect newly naturalised invasive alien species and track shifts in native flora over time when compared against older inventories of the same landscape.
The 245 steno-endemic taxa flagged in the new checklist are the clearest evidence cited for why conservation planning in Agasthyamalai needs to be calibrated to specific micro-habitats within the reserve, rather than applying uniform, landscape-wide measures.
- Total flowering plant species recorded: 3,261 (plus 26 subspecies and 28 varieties), across 1,139 genera and 190 families.
- Most species-rich families: Fabaceae (349 taxa), Rubiaceae (194), Poaceae (193), Orchidaceae (168).
- Endemic taxa: 1,018 (31.2% of the checklist); steno-endemic taxa: 245; taxa shared with Sri Lanka: 347.
- Agasthyamalai Biosphere Reserve: notified 2001; ~3,500 sq. km across Kerala and Tamil Nadu; added to UNESCO's World Network of Biosphere Reserves in 2016.
- Western Ghats: one of India's 4 biodiversity hotspots; inscribed as a UNESCO World Heritage Site (39 serial sites) in 2012.
- Hotspot qualifying criteria (Norman Myers, 1988): ≥1,500 endemic vascular plant species and ≥70% original habitat loss.