Floristic enumeration of Torna Fort ( Western Ghats , India ) : a storehouse of endemic plants

The forts on hilltops of the Sahyadri (northern Western Ghats) have seen a turbulent historical past and are famous for their architectural style and cultural heritage. Besides this, these hilltops are home to an incredible plant diversity. One of the highest hilltop forts (ca. 1,403m) the Torna, has been explored since 2012 for floral assessment. The study documented ca. 399 plant species of which about 28% are endemic to the Western Ghats and 16 monotypic species were recorded. A brief account of the immense floristic diversity and new findings from Torna fort are summarized in the present article.


INTRODUCTION
India is one of the megabiodiverse countries of the world.It has diverse biogeography, and consists of about 18,000 plant species, which is almost 11% of total species in the world (Singh et al. 2015).One of the global biodiversity hotspots, the Western Ghats consist more than 7,400 plant species of which 1,270 are endemic (Nayar et al. 2014).Mountain ranges of the northern Western Ghats are commonly known as Sahyadri.These ranges are very diverse in the habitats, flora and fauna.
The northern Western Ghats spreads from Tapti (Gujarat) to Goa with an average elevation of 900m.Torna hilltop with an altitude 1,403m is one of the tallest peaks in Maharashtra and highest peak in Pune District.It is one of the renowned historical forts, which served as the capital of Maratha dynasty for 25 years and lies 50km southwest of Pune City in Velhe Tehsil.
Hilltop forts in Sahyadri are famous for their architectural style, cultural heritage and for being witness to the turbulent historical past.In addition, these forts and adjoining areas possess specific habitats like flat summits, rocky flanks, crevices, precipitous slopes, which shelter extremely rich plant diversity.Previous documentation of these centres of floristic diversity includes Sinhagad, Purandar and Khandala (Santapau 1951(Santapau , 1957(Santapau , 1967)), Torna Hills, Katraj Ghats and Rajgad Fort (Vartak 1953(Vartak , 1960(Vartak , 1965)), Harishchandragad (Billore & Hemadri 1969), and the enumeration of vegetation from hilltops near Pune and adjoining areas (Cooke 1901(Cooke -1908;;Razi 1952).Moreover, new species and new additions to the state flora have been published from these hilltops during the last century.Detailed study on the endemism from these hilltops has not been done so far and therefore, the present study on floristic assessment and endemism is the beginning of this endeavour.

Study area
The study was in and around Torna Fort which is situated between 18.29059722 0 N and 73.62444444 0 E, 18.26516389 0 N and 73.61055556 0 E, covering a study area of ca.10,000ha.It ranges from the foot of the mountain at village Velhe, Pune (750m) to the hilltop of Torna Fort situated at 1,403m and about 50km southwest of Pune, Maharashtra (Image 1).Foothill soil is mainly composed of 'moorum' (a soil type, comprising small pieces of disintegrated rock or shale) and red soil while slopes have loose red soil, the plateau top has very shallow soil cover on basalt.Average rainfall during the six months of monsoon is around 900mm (Maharashtra State Gazetteer 1992).Torna Fort is frequently visited by tourists, trekkers, and nature lovers during the monsoon.Hilltop and slopes are used by local inhabitants for grazing and collection of fuel wood.Widening of the tar road have opened a corridor for tourist vehicles up to the middle of the fort and it can be referred to as a possible threat to the habitat.

Data collection
Our study is an outcome of continuous expeditions to the Torna Fort during 2012-2017.Plant materials were collected during regular field visits at different seasons.Bridson & Forman (1999) have been followed for herbarium preparations.The identity of plants was confirmed with the help of floras (Cooke 1901(Cooke -1908;;Lakshminarasimhan 1996 (Tetali et al. 2000;Gaikwad et al. 2014;Nayar et al. 2014;Singh et al. 2015).The families have been arranged alphabetically.Binomials and nomenclature follows the International Plant Name Index (IPNI 2012).The monotypic taxa have been identified (Rana & Ranade 2009).Categorization for threat has followed the IUCN (2017).A glimpse of endemic plants is featured in the images (Images 3-7).The vegetation is also diversified in habits (Table 1) like annual, perennial, parasitic herbs, shrubs, scandent shrubs, trees, climbers, and lianas.

DISCUSSION
From the 399 plant species documented, 109 species (27.31%) are referred to as endemic to the Western Ghats and India.The Torna Fort is enriched with eight species of Ischaemum L. (4 endemic), seven species of Habenaria Willd.(5 endemic), seven species of Euphorbia L. (2 endemic), seven species of Smithia Aiton (5 endemic), four endemic species of Ceropegia L. (3 rare in occurrence) (Nayar & Sastry 1987, 1988, 1990).Sixteen species viz.Torna Fort is the only repository for the Critically Endangered Barleria sepalosa C.B. Clarke (Acanthaceae) which is rediscovered after a lapse of 128 years (Gosavi et al. 2013), and the recent study also extends the distribution of Flemingia rollae (Fabaceae), the species which was earlier known from its type locality at Kalsubai Hilltop, Ahmednagar, Maharashtra (Gavade et al. 2016).
In the context of anthropogenic activities and threat to the habitats, many hilltops like the table land of Panchgani (Satara District), Sinhagad Fort (Pune District), Panhala (Kolhapur District) are prone to disturbances viz., tourism, overgrazing, invasive species and grassland fires.Poor planning of tourism and lack of awareness regarding the unique habitat and vegetation are serious threats to these areas.Present efforts have been made to create awareness amongst the visitors, authorities and custodians as authors have witnessed the developmental activities like clearing of roadside vegetation for widening of roads and new road construction during the last four years at Torna Fort.The earlier enumeration by Vartak (1953) listed 241 species while the present study of Torna lists 399 angiosperms of which 109 (27.31%) are endemic to India.The detailed plant enumeration with its endemism, distribution, phenology, habitat and habit has been tabulated in Table 1.

CONCLUSION
Torna Fort in the northern Western Ghats exhibits habitat diversity with annual and perennial floristic components.The fort stands as a storehouse of endemic and unique floral diversity.The topography, elevation and distinct climatic conditions make the fort different from other lowland floristic habitats.Although, Torna Fort is in consideration for tourism development by the government as archaeological monument, we strongly believe that presence of endemic, threatened plant species and unique habitats can be adequate for 'Biodiversity Heritage Sites' to ensure further conservation measures.