Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 March 2020 | 12(4): 15468–15474
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
doi: https://doi.org/10.11609/jott.5148.12.4.15468-15474
#5148 | Received 03 June 2019 | Final
received 04 March 2020 | Finally accepted 12 March 2020
An assessment of the conservation
status of a presumed extinct tree species Wendlandia
angustifolia Wight ex. Hook.f. in southern
Western Ghats, India
Chellam Muthumperumal
1, Paramasivam Balasubramanian 2 & Ladan Rasingam 3
1,2 Sálim Ali
Centre For Ornithology and Natural History, Anaikatty
Post, Coimbatore, Tamil Nadu 641108, India.
3 Botanical
Survey of India, Deccan Regional Centre, 2nd Floor, Kendriya Sadan, GPOA, Sultan
Bazar, Koti, Hyderabad,
Telangana 500095, India.
1 perumal.ecology@gmail.com
(corresponding author), 2 balumayura@gmail.com, 3 rasingam@gmail.com
Editor: Navendu Page, Wildlife
Institute of India, Dehradun, India. Date
of publication: 26 March 2020 (online & print)
Citation: Muthumperumal, C., P. Balasubramanian & L. Rasingam (2020). An assessment of the conservation status of a presumed
extinct tree species Wendlandia
angustifolia Wight ex. Hook.f. in southern
Western Ghats, India. Journal
of Threatened Taxa 12(4): 15468–15474. https://doi.org/10.11609/jott.5148.12.4.15468-15474
Copyright: © Muthumperumal et al. 2020. Creative
Commons Attribution 4.0 International License.
JoTT allows unrestricted use, reproduction,
and distribution of this article in any medium by providing adequate credit to
the author(s) and the source of publication.
Funding: Science and Engineering Research Board (SERB),New Delhi provided fund through Young Scientist Research Project.
Competing interests: The authors declare no competing interests.
Author details: Chellam Muthumperumal is working as a Program Officer of an ENVIS Centre,
Amrita Vishwa Vidyapeetham, Coimbatore. His area of specialization is
Biodiversity studies, which include plant inventory, plant functional traits,
ecosystem services, restoration ecology and conservation. He has published
seven peer-reviewed research articles in International and national journals.
He has co-authored a book and several peer-reviewed book chapters. Paramasivam
Balasubramanian is a Senior Principal Scientist in the Sálim Ali Centre for Ornithology and Natural History,
Coimbatore. His specialization includes plant taxonomy, ecology and
plant-animal interactions. He has published nearly 100 research articles in
peer-reviewed national and international journals and authored three books and several
technical reports. He has also guided several PhD scholars in the field of
forest botany. Ladan Rasingam is working as
Scientist-D in Botanical Survey of India, Hyderabad and is interested in the
systematics of flowering plants with special reference to Andaman & Nicobar
Islands, Western & Eastern Ghats floras. He has published around 70
research articles in peer-reviewed International and national journals and
co-author of three books.
Author contribution: CM conducted field works, data collection, data
analysis, interpretation and prepared the manuscript. PB provided technical
inputs and guidance for data collection, LR provided the primary location of
the species, herbarium details, and helped in confirming the identity of the
species.
Acknowledgements: The authors acknowledge the Science and Engineering
Research Board, New Delhi for financial support through a Young
Scientist Research Project (YSS/2015/001844). The authors express their sincere thanks
to the Director, Sálim Ali Centre for Ornithology and
Natural History, Coimbatore for providing facilities and encouragement. We are
thankful to the Tamil Nadu Forest Department for giving permission to conduct
field surveys. L. Rasingam is grateful to the
Director, Botanical Survey of India, Kolkata and Scientist In-charge, Deccan
Regional Centre, Hyderabad for facilities and encouragement.
Abstract: In this study, we carried out an assessment of IUCN
conservation status of Wendlandia
angustifolia Wight ex. Hook.f. (Rubiaceae), based on field data on populations and
distribution status of this species that is narrowly endemic to southern
Western Ghats. This species was earlier
presumed to be extinct, however, our data suggests that it should be assigned
to the Endangered (EN) category based on the IUCN Red List criteria.
Keywords: Conservation assessment, endemic plant, endangered
category, Rubiaceae, Wendlandia
angustifolia.
introduction
A species unique to a defined geographic unit such as
an island/nation or habitat type and not found elsewhere is known as an endemic
species. Physical, climatic, and
biological factors influence endemism (Chitale et al.
2014). According to Lavergne et al. (2004) some common traits have been
observed among the endemic species such as inhabiting microhabitats, producing
fewer flowers and seeds, and having lower fecundity than their widespread
congeners. Endemic species are poor
competitors, and least tolerant to environmental stress (Lavergne et al. 2004).
Species with a narrow distribution range and/or fewer individuals are
considered to be the most prone to extinction due to changing climatic
conditions and competition from alien species (Chitale
et al. 2014). Endemic species have long
been targets for conservation efforts, because they are not found anywhere else
in the world and if lost from their native habitat they are lost forever (Chitale et al. 2014).
Myers et al. (2000) opined that conservation of endemic species could
result in conservation of species rich landscapes. Assessing present and future distribution of
endemic species would form crucial contribution for their conservation planning
and management.
India is one of the mega diversity countries with a
wide range of topography, climate and habitat.
India has a total of 18,532 flowering plant species of which 23.2% are
endemic (Singh & Dash 2017). The
Western Ghats (along with Sri Lanka) is one of the four designated biodiversity
hotspots in India on account of its high degree of endemism and loss of primary
forest cover. Of the 2,116 endemic
flowering plants recorded in the Western Ghats, 410 are distributed in the
state of Tamil Nadu (Singh et al. 2015).
Many of these species are rapidly disappearing due to increases in human
population, urbanization, habitat fragmentation and the increased dependency of
the world’s population on limited natural resources (Woodruff 2001). Accordingly global, regional, national and
local lists of threatened species have proliferated over the past four decades
(Burton 2003). The first step to
initiate conservation action for endangered organisms is to identify the
populations of species that are in decline or are facing the risk of extinction
(Caughley 1994; Brook et al. 2006). The present study was carried out to assess
the population status of Wendlandia
angustifolia, a narrow endemic and extinct category (IUCN 2012; version
3.1) tree species distributed in the southern Western Ghats, India.
MATERIALS
AND METHODS
Study area
The study was conducted in Kalakad-Mundanthurai Tiger Reserve (KMTR), in the southern
Western Ghats which is part of the Agasthiamalai
Biosphere Reserve. KMTR represents a
wide variation in the topographical, geo-morphological, edaphic and climatic
features, and thus supports a wide range of forest types. The vegetation type varies from thorny shrub
jungle to lush evergreen forests and montane grass-lands. Eleven major forest types are present here,
out of which the Tirunelveli semi-evergreen forests are unique in the
area. KMTR partly comprises a large
contiguous tract of around 400km2 of wet evergreen forest.
Sampling and assessment
The population status and
distribution of Wendlandia angustifolia in
the stream habitat of Tamirabarani River basin was
ascertained along Karaiyar, Servalar
and Manimuthar rivers. Field surveys were carried out in Mundanthurai range that lies between 8.566–8.716 0N
and 77.266–77.433 0E. Quadrats measuring 0.1ha area (31.7×31.7m)
were established along the river banks to assess the population of this
species. Contiguous plots (each includes
five number of quadrats) were established along 1.5km stretch for each
stream. The number of individuals in
each quadrat was enumerated along with their location, height, girth, phenological
status and associated species. Geographical coordinates were recorded using
Global Positioning System (Garmin eTrex 30x). Height and girth were measured by a measuring
tape. Phenological status such as
presence of flowers and fruits were observed by periodic field visits. Various growth categories were fixed based on
the height and girth classes. A majority
of the individuals are less than minimum measurable threshold of 1.3m height
from the rooting point. Hence height
classes have been incorporated to include those plant individuals which are
less than 1.3m height. Individuals which
have grown less than 1m height are capable of producing flowers and fruits and
hence considered as adults. Girth class
was categorised as saplings (<10cm gbh), recruits
(10–20 cm gbh) and established (>20cm gbh) individuals. In
the height categories, the above mentioned saplings were further classified
into seedlings (<1m) and saplings (1–2 m), the corresponding girth classes
are mentioned as height class ranges between 1.2–3.5 m as recruits and 1.3–6.5
m as established individuals.
The species was further
evaluated as per IUCN Red List criteria, version 3.1 (IUCN 2012). We used the minimum convex polygon method to
calculate the range size as an estimate of its extent of occurrence (EOO). Area of occupancy (AOO) of the species within
the grid is studied taking into account of the terrain features with respect to
altitude. The EOO and AOO values were
calculated by using the GEOCAT software developed by Kew with the standard cell
width of 2km (Bachman et al. 2011).
Formal thresholds based on population size and geographic range were
used for categorization.
RESULTS
AND DISCUSSION
History and characteristic
features of endemic tree species
Wendlandia angustifolia is a small tree belonging to
the family Rubiaceae.
This plant species usually grows on rock crevices at low to medium
altitude in riparian forests. It was
first collected from the Courtalam Hills, Western
Ghats by Robert Wight and described by Hooker (1882) in his Flora of British
India. The species was re-collected from
Kannikatti area in 1917 by Rangachari
and after that no collection was made for about 81 years. Viswanathan et al. (2000) re-collected the
species from Inchikuzhi area of KMTR in 1988. Gamble (1921) stated that this species was
found in the Deccan forests of Kadapa and Western Ghats of Tinnevelly. The distribution in Kadapa forest, however,
was reported by Gamble based on the Beddome
collections (Coll. No. RHB 1880) available at Madras Herbarium (MH). The distribution of this species in Kadapa
forest seems doubtful, as there is no re-collection from the Kadapa forests
since Beddome’s collection. Beddome has
extensively explored the Western Ghats during the period 1880. We presume that
the location details could be wrongly labeled as
Kadapa forests with collection number 1880 and it could have been collected
from Western Ghats in the year 1880.
This species is assessed as Extinct (Ex) in the Red List Assessment by
the World Conservation Monitoring Centre (1998). Deb & Maiti in Nayar & Sastry (1987) analyzed
the species and suggested that this species is presumed extinct. They also suggested that efforts should be
made to relocate the species from the river beds at low altitudes and introduce
in botanic gardens for its conservation.
Nomenclature
Wendlandia angustifolia Wight ex. Hook.f.,
Fl. Brit. India. 3: 40. 1880. Gamble, Fl. Madras 588. 1921 (repr.
ed. 2. 415. 1957); Deb & Maiti in Nayar & Sastry, Red Data Book Indian Pl. 1: 348. 1987.
Specimens examined: Tamil Nadu:
Tirunelveli District: Courtallum, R. Wight, s.n., (Barcode No. K000030922); Courtallum,
R. Wight 1334 (Barcode No. K000030921) both are at Kew Herbarium (K); Mundanthurai, 16.iii.1917, Rangachari
14623; Kannikatti, 19.iii.1917, Rangachari
14663 (MH); Inchikuzhi, 1000 m, 16.ii.1998, M.B.
Viswanathan, E. Harrison Premkumar & N. Ramesh
1641; Inchikuzhi, 1,000m, 24.v.1998, M.B.
Viswanathan, E. Harrison Premkumar & N. Ramesh
2010 (SPKCESH); Ambalam, Aruvipuram
River bank, 29.iv.1990, R. Gopalan 93319 (MH); Papanasam,
Near Sorimuthu Ayyanar
Temple, 04.iii.2011, L. Rasingam, 3101 (BSID).Karaiyar 224m, 05.xii.2016, C. Muthumperumal
3201; Servalar, 218m, 07.xii.2016, C. Muthumperumal 3202;Inchikuzhi, 625m, 19.i.2017, C. Muthumperumal 3203; Kandamparai,
283m, 22.ii.2017, C. Muthumperumal 3204; Inchikuzhi, 617m 01.iii.2017, C. Muthumperumal
3205 (SACONH-Herbarium of Sálim Ali Centre for
Ornithology and Natural History).
Species description
Wendlandia angustifolia is a small tree with slender
branches, growing up to 5m height.
Leaves are ternately whorled; linear-lanceolate, attenuate at base,
entire at margin, acute at apex, 4–11 x 0.5–1.8 cm, coriaceous; lateral nerves
6–8 pairs; petioles up to 1cm long; stipules triangular-ovate, subulate or
cuspidate at apex. Inflorescence at
terminal branches in panicles; panicles slender, pyramidal, leafy below;
flowers densely crowded; bracts ligulate, hastate at base, acuminate at apex. Calyx tube turbinate, glabrous,
about 1.5mm long, lobes cuspidate, about 1mm long, subulate. Corolla tube slender, about 5mm long; lobes
almost orbicular, small. Stamens exserted, filaments short; anthers dorsifixed,
linear, about 1mm long. Style about 6mm
long, exserted; stigma bifid. Fruits globose, 2mm across, rugose and many
seeded; seeds brown, irregular, oblong-trigonous.
This species is distinct from
other known species by its glabrous stem,
ternately-whorled, linear-lanceolate leaves and glabrous
calyx tube with subulate lobes. Further,
the habitat of the species is very distinct, as it grows only on rocky
riverbeds, whereas be congeners grows along the stream banks as well as other
forest types.
Species distribution
A total of 1,091 individuals
were enumerated in 9.3ha area (93 quadrats of 0.1ha) sampled. This species was present in seven out of 11
streams surveyed (Figure 1). Among the
seven streams explored, Inchikuli had a higher number
of individuals (398), followed by Moolakasam (190), Baana tirtam (178), Kandampaarai (139), Pambar (105) and
less number of individuals were recorded in Varattar
(47) and Servalar (34) (Table 1; Figure 3). The major associating taxa are Syzygium zeylanicum var.
lineare, Syzygium
cumini, Garcinia gummi-gutta, Pongamia pinnata,
and Phyllanthus singampattianus.
Growth category
Growth categories of tree
individuals were classified into both girth and height classes. Among the 1,091 individuals recorded in the
study site, the girth categories show the occurrence of 862 saplings (<10cm gbh), 175 recruits (10-20cm gbh)
and 54 established >20cm gbh) individuals (Figure
4a). In the height class categories,
saplings were further classified into seedlings 648 (<1m) and saplings 214
(1m-2m). About 175 recruits fall in the
ranges of 1.2–3.5 m height class whereas 54 established individuals fall
between the ranges of of 1.3–6.5 m height (Figure
4b). Almost all individuals growing
along the water course area are impacted by water flow. Hence, even the matured individuals were
recognized in stunted growth form.
Individuals recorded on river banks attained a reasonable girth. Individuals that attained height ≥1.3m and
girth ≥5cm gbh were considered as adults. They are matured enough to produce flowers
and fruits even in the dwarf condition.
This species produced new leaves in December, flower buds in January,
full blooming in February–March and seeds developed during April–May (Image 1).
Assessment of conservation
status
This is the first attempt to
assess the population of W. angustifolia, a narrow endemic tree species
which has been presumed Extinct from the original distribution range in
southern Western Ghats, India as per the recent IUCN category (Ver. 3.1; 2012).
This species is distributed in the eastern slopes of southern most Western
Ghats and grow in gentle rocky beds in rivers and river banks. Moreover this
species is found in semi-shade condition and distributed between the elevation
ranges of 250m to 720m. As this species occurs in river course area, we
observed the flood force impacting the growth of the individuals leaving only a
stunted growth.
The geographic range of W.
angustifolia was quantified using two metrics, extent of occurrence (EOO)
and area of occupancy (AOO), both of which can be used for assessments under
criterion B (restricted range species) as recommended by IUCN. EOO which is
calculated by constructing the minimum convex polygon (convex hull) around
known occurrences using the GEOCAT software developed by Kew with the standard
cell width of 2km (Bachman et al. 2011). AOO is also calculated with the same
tools by overlaying a grid and interpreting known occurrences as occupied grid
cells. The sum of occupied grid cells equates to the AOO value. The EOO of W.
angustifolia was estimated to be 143 km2 and distributed in five
major streams indicated in Figure 1 and 2. As per IUCN Sub-criteria “B1-a” the
species qualifies to Endangered category, as this species is distributed in ≤ 5
locations. Among the 7 localities assessed the number of individuals had
extreme fluctuation which is clearly indicated in table 1. Hence the
Sub-criteria“B1-c” also supporting that this plant under endangered category.
The AOO of W. angustifolia was 60 km2 (Figure 2) and since
this estimate is less than 500 km2 and hence this species qualifies
for Endangered category (B2). Among the
1,091 individuals recorded during the present study, 293 were adults.
Individuals which have grown ≥1.3m height and girth ≥ 5cm gbh
were considered as adults. These individuals are capable of producing flowers
and fruits in appropriate season of the year. Hence the number of adult
individuals is less than 2500, the species quantifies for Endangered category.
Moreover number of mature individuals in majority of subpopulations were ≤ 250
individuals [C2 (ai)] and percentage of mature
individuals in one subpopulation is 95–100 % [C2 (aii)]
also fit for Endangered category.
Final assessment: Based on field observations and
population assessment of W. angustifolia it is stated that this species
is Endangered [EN B1ac(i–iv)+2ac(i–iv);
C2a(i,ii)] and not Extinct.
CONCLUSION
W. angustifolia is a habitat and altitude specific species which is
reported from seven tributaries of the river Tamirabarani,
Kalakad-Mundanthurai Tiger Reserve, southern Western
Ghats, India. The current assessment
shows that this narrow endemic tree species qualifies for the Endangered (EN)
category. It is recommended that this
species should be regularly monitored in all the tributaries of river Tamirabarani and further explorations in the neighborhood habitats are suggested. There is an immense need to implement a
restoration program to conserve this narrow endemic tree species.
Table 1. Population
assessment of Wendlandia angustifolia
in different stream habitats in Tamirabarani River
basin, Kalakad-Mundanthurai Tiger Reserve, southern
Western Ghats.
Name of the reservoir |
Name of the stream |
Elevation range (m) |
Number of quadrats sampled |
Area sampled (ha) |
Number of individuals recorded |
Karaiyar dam |
Inchikuliar |
617–717 |
15 |
1.5 |
398 |
Baanatirtam |
354–439 |
18 |
1.8 |
178 |
|
Pambar |
286–424 |
15 |
1.5 |
105 |
|
Varattar |
436–452 |
03 |
0.3 |
47 |
|
Servalar dam |
Vaalaiyar |
268–309 |
05 |
0.5 |
34 |
Manimuthar dam |
Kandampaaraiar |
250–390 |
17 |
1.7 |
139 |
Moolakasamar |
380–453 |
20 |
2.0 |
190 |
|
Total |
93 |
9.3 |
1091 |
For figures & image - - click here
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