Woody flora of Karumpuliyuthu Hill, Tenkasi, Tamil Nadu, India: a checklist

: Qualitative field surveys were conducted to record the woody plant (tree, shrub, and liana) wealth in Karumpuliyuthu Hill, Tenkasi district, Tamil Nadu. All the recorded species were confirmed with regional floras. The qualitative field survey allowed us to record 42 species in 32 genera and 19 families. The family Fabaceae had a large number of species (13 species) in the study area. The present study adds valuable information about the occurrence of 42 woody plant species in a tropical thorn forest ecosystem. The woody plant community is dominated by native plants, and only three are introduced. Nearly half of the recorded species produce fleshy fruits, thus providing food to small mammals and birds.


INTRODUCTION
Information on plant diversity such as flora, checklist, and quantitative or qualitative ecological studies are useful for understanding the changes that take place in forest plant communities (Armonies et al. 2018).Besides, these data are vital to frame conservation measures (Francisco-Ortega et al. 2010) and forest restoration (Shetu et al. 2018).Invariably all types of forests and trees deliver an array of ecosystem services (Taye et al. 2021).There are about 61,000 tree species flourishing on this earth (Qian et al. 2019).Trees provide a range of non-timber forest products including honey, fuel wood and fiber (FAO 2014).In addition, they play important roles in combating global climate change through carbon storage and sequestration (Roebroek et al. 2023).In general, woody plants store relatively more amount of biomass than herbaceous communities in forest ecosystems (Borah et al. 2015).Tropical thorn forests support moderate woody plant diversity (Rahangdale et al. 2014;Evitex-Izayas & Udayakumar 2021;Muneeswaran & Udayakumar 2022).Data on plant diversity of tropical thorn forests in Tamil Nadu remain scarce.This study aims to explore the woody plant wealth (shrubs, trees, and woody liana) of a tropical thorn forest ecosystem existing within Karumpuliyuthu Hill located in Tenkasi district, Tamil Nadu.

Study area
Karumpuliyuthu Hill located in Tenkasi district, Tamil Nadu (Figure 1).The district was bifurcated from Tirunelveli district in 2019.The northern, eastern, western, and southern boundaries of the district are Virudhunagar, Thoothukudi, Tirunelveli, and Kerala, respectively.The mean annual precipitation of the district is 769.2 mm, while the mean maximum and minimum temperatures are 29 and 27°C, respectively (https:// mausam.imd.gov.in/chennai/).The total geographical area of the district is 2,882.43km 2 , whereas the forest cover is 439.99 km 2 (https://tenkasi.nic.in/).

Field survey
A sum of 32 field surveys have been conducted to record woody plant wealth (shrubs, trees, and liana) in the tropical thorn forest ecosystem existing within Karumpuliyuthu Hill, located in Tenkasi district, one of the southernmost districts of India.All the recorded species were identified with available regional floras and checklists (Gamble & Fischer 1921-1935;Muneeswaran & Udayakumar 2022).The nomenclature of families and the author citation of species followed Plants of the World Online (https://powo.science.kew.org/).The current status of all the recorded species was verified with the help of the IUCN Red List of Threatened Species (https://www.iucnredlist.org/).Further, the flowering and fruiting phenophases of woody plants were recorded monthly for one year.A plant with flower (bud & open) and fruit (immature & mature) considered as 'reproducing'.The length of reproductive phenophase was calculated and recorded in months.

RESULTS AND DISCUSSION
The qualitative field survey allowed us to record 42 species in 32 genera and 19 families.The family Fabaceae had the large number of species (13 species) followed by Apocynaceae and Rubiaceae (three species each).Capparaceae, Euphorbiaceae, Menispermaceae, Rhamnaceae, Malvaceae, Verbenaceae, and Vitaceae had two species each, while, nine families represented by just a single species each in the study area (Figure 2 & Table 1).Important species of study area featured in Image 1.
The anthropogenic activities (cutting of trees, fuel wood collection etc.) transformed close-canopied dry deciduous forest in to tropical thorn forest (Champion & Seth 1968).Murphy & Lugo (1986) found relationships among species richness and moisture gradients across tropical forests and shown least number of tree species in driest areas.Singh & Singh (1988) recognized tropical thorn forest as extremely poor in terms of species richness and inhabited by mostly deciduous species.Tropical thorn forests occurring in a drier habitat and experience 5-6 dry months in a year, hence act as a habitat for moderate number of woody plants.It has been investigated that range of factors including altitude, mean annual minimum and maximum temperatures, distribution and frequency of precipitation and soil moisture content influence tree density, species richness and diversity (e.g., Thakur et al. 2022).For instance, Dattaraja et al. ( 2018) investigated the relationship between diversity of woody plants and environmental factors in Indian tropical forests and found thorn forests support least number of woody species.Detailed studies of impact of environmental factors on thorn forest ecosystem are limited.
The members of Fabaceae dominating the woody plant community in tropical thorn forest ecosystem.It is well known that a considerable number of species belongs to the family Fabaceae (e.g., Acacia & Vachellia) are able to fix nitrogen with the help of soil bacteria (Brockwell et al. 2005

Mode of regeneration
All the recorded plants produce seeds and regenerate from them during wet season.Eight species viz., Coccinea grandis, Cissus quadrangularis, C. vitiginea, Commiphora berryi, Euphorbia antiquorum, Morinda coreia, Sarcostemma acidum, and Tinospora cordifolia regenerate through seeds and vegetative parts (stems and root sucker).In general, seed predation by insects and rodents affects seed germination and seedling establishment in tropical forests (e.g., Guariguata et al. 2000).Information on various functional traits of seeds and seedlings are limited, therefore, continuous field studies and monitoring are necessary for better understanding of regeneration of tropical thorn forests.

Life form and conservation status
Among three life forms (trees, shrubs, and lianas), the trees dominated the study area with 18 species, shrubs represented by 15, whereas the liana represented by nine species (Figure 3 & Table 1).Half of all the recorded species were categorized under Least Concern (LC), 20 species were identified as Not

25456
J TT Evaluated (NE) and only one was listed as Data Deficient (DD) (Table 1).All the listed species are native to India, except Prosopis juliflora, Senegalia mellifera, and Vachellia tortilis.Twenty-three species produced fleshy fruits (berry or drupe), remaining formed dry fruits (pod, lomentum, dehiscent and indehiscent capsules), thus the existing woody plant community in the study area partially fulfilled the food requirement of various birds (e.g., Bulbul, Myna) and small mammals (e.g., Squirrel, Civet, Forest rat).In addition, 21 species had mechanical protective structures either spine or thorn.It is well known that the presence of sharp protective structures (spine, thorn, prickle) is one of the common features for species growing in drier environments.

Reproductive phenophase of woody plants
The length of reproductive phenophase varied across species.Of 41 species, five species had four months of reproductive phenophase, 12 had five months, 11 had six months and six reproduced throughout the year (Table 1).The mean duration of reproductive phenophase of studied species was 5.214 ± 2.469 months.The reproductive phenophase peaked in April (39 species) followed by May (38), June (37), and July 25458 J TT (31).Whereas, 12 species each reproduced in January, October, November, and December.Most of the species tends to reproduce after north-east monsoon (October-December).Researchers found close relationships among reproduction of trees, relative humidity and moisture content of tropical forests (Bhat 1992; Sundarapandian

Wild edible plants
The thorn forest acts as a home for five wild edible plants.The palmyra palm Borassus flabelliber provides edible tender and mature fruits, seed haustoria, and J TT seedling.It has been well documented and known that many parts of the palmyra palm are economically important (Rahman et al. 2021).Carissa spinarum, Morinda coreia, and Ziziphus nummularia yield edible fruits.A large number of researchers made a detailed study on these fruits and recorded vitamin, mineral, antioxidant, and nutrient contents (C.spinarum: Liu et al. 2021;M. coreia: Chandra & Meel 2020;Z. nummularia: Uddin et al. 2022).Young and tender stems of Cissus quadrangularis is edible and medicinal.A considerable number of medicinally important bioactive chemical compounds have been isolated from C. quadrangularis (Bafna et al. 2021).

CONCLUSION
The present study adds valuable information about the occurrence of 42 woody plant species in the tropical thorn forest ecosystem located at Karumpuliyuthu Hill, Tenkasi district, Tamil Nadu.The forest ecosystem supports a moderate woody plant diversity and five wild-edible plants.Most of the recorded woody plants belong to India, except three species.Tropical thorn forests are least explored in terms of ecology and taxonomy, thus extensive quantitative field studies are to be carried out to record the plant wealth and realize the range of ecosystem services.Further, the thorn forests are endowed with substantial number of trees with nitrogen fixing ability, research on these lines are helpful to understand the evolution and survival of drought tolerant forest systems.

Figure 1 .
Figure 1.Map of study area in which field surveys conducted to record woody flora.

Table 1 . Botanical name, family and life form of woody plants found in Karumpuliyuthu hill, Tenkasi district, Tamil Nadu. (introduced species marked with '*' mark, wild edible plants with '@'). Botanical name Family Life form IUCN Red List status Fruit type Mode of regeneration Flowering and fruiting season
J TT