Journal of
Threatened Taxa | www.threatenedtaxa.org | 26 May 2018 | 10(6):
11753–11759
Distribution of Rhododendron
falconeri Hook. F. (Ericales: Ericaceae) in Yuksam-Dzongri trekking corridor of Khangchendzonga National Park, Sikkim, India
Aseesh Pandey 1
& Hemant K. Badola 2
1,2 G.B. Pant National Institute of Himalayan
Environment and Sustainable Development, Sikkim Regional Center,
Pangthang, Gangtok, East
Sikkim, Sikkim 737101, India
2 Present address: D-408, Aditya Doonshire Apartments, Sailok Phase II, GMS Road, Dehradun, Uttarakhand
248001, India
1 draseeshpandey@gmail.com (corresponding author), 2 hkbadola@gmail.com
Abstract: Rhododendron falconeri
Hook.f. [= Azalea falconeri
(Hook.f.) Kuntze] is a
potential candidate for conservation in Sikkim State due to its threatened
status and startling features especially during the flowering period. We studied the status and habitats for R.
falconeri across the Yuksam-Dzongri
trekking corridor in Khangchendzonga
National Park, Sikkim eastern Himalaya.
These findings will help to develop conservation strategies for R. falconeri and landscape beautification sustainability
in the long run.
Keywords: Eastern Himalaya, Khangchendzonga National Park, protected area, Rhododendrons.
doi: http://doi.org/10.11609/jott.3911.10.6.11753-11759
Editor: P. Lakshminarasimhan, Botanical Survey of India, Pune, India. Date
of publication: 26 May 2018 (online & print)
Manuscript details: Ms # 3911 |
Received 22 November 2017 | Final received 04 April 2018 | Finally accepted 08
May 2018
Citation: Pandey, A. & H.K. Badola (2018). Distribution of Rhododendron
falconeri Hook. f. (Ericales: Ericaceae) in Yuksam-Dzongri
trekking corridor of Khangchendzonga
National Park, Sikkim, India. Journal of Threatened Taxa 10(6): 11753–11759; http://doi.org/10.11609/jott.3911.10.6.11753-11759
Copyright: © Pandey & Badola
2018. Creative Commons Attribution 4.0
International License. JoTT allows
unrestricted use of this article in any medium, reproduction and distribution
by providing adequate credit to the authors and the source of publication.
Funding: Ministry of Environment, Forest and Climate Change (MoEF & CC), Government of India under the National Mission on Himalayan Studies (NMHS) program, through Central Himalayan Environmental Association (CHEA), Uttarakhand, India.
Competing interests: The author declares no competing interests.
Author Details: Aseesh Pandey (PhD, Botany) is associated with the G.B. Pant National Institute of
Himalayan Environment and Sustainable Development, Sikkim Regional Center
(GBPNIHESD-SRC), as a researcher. His research areas are to understand the
patterns of plant diversity, ecological and threat assessment of High-value
Medicinal Plants (HMPs), of the Himalaya. H.K.
Badola is former Senior Level Scientist
(Conservation of Biodiversity) and Scientist in-charge, GBPNIHESD, Sikkim Unit
has over three decades research experience dealing with various aspects
biodiversity conservation and management, especially including the threatened
taxa, in the Himalayas. Presently, he is a freelance expert of Biodiversity, Bioculture and Climate Change.
Author Contribution: Study conceptualized by AP, HKB; extensive field exploratory work done
by AP and AP, HKB developed the manuscript.
Acknowledgements:
We are grateful to the Director, G.B. Pant National
Institute of Himalayan Environment and Sustainable Development for providing
necessary facilities to undertake this research. We highly appreciate the
cooperation from the Forest Environment and Wildlife Management Department,
Sikkim State. We also acknowledge the assistance from Mr
Bhim P. Pandey, Mr B.L. Subba and support
received from the local peoples during field surveys.
Introduction
The Rhododendrons
(family Ericaceae) comprise only 1% of the flowering
plants (Pradhan & Lachungpa
1990). Initially described by Carl
Linnaeus in Genera Plantarum in 1737, worldwide, the
genus Rhododendron encompasses almost 1,000 species (Leach, 1961;
Bhattacharyya & Sanjappa 2014). Over 90% of the world population of Rhododendrons
are mostly concentrated in northwestern Himalaya to southeastern Asia with an extension to Nepal, northeastern India, eastern Tibet, northern Burma and
western and central China (Leach 1961; Pradhan & Lachungpa 1990; Tiwari & Chauhan 2006).
At present, there are 102 species (Bhattacharyya & Sanjappa 2014) and 132 taxa of Rhododendron L. (82
spp., 25 subsp. and 25 var.) in India (Mao et al. 2017a,b). According to Sastry
& Hajra (2010), in India, Rhododendron
species are found in the Himalaya from Kashmir to Arunachal Pradesh and in the
forested mountain tracts of northeastern Indian
states (Fig. 1). Of the total
recorded 129 taxa in northeastern India, the state of
Sikkim harbours the second highest (42) representativeness of the genus Rhododendron
after Arunachal Pradesh (119); however the genus is not reported from Assam and
Tripura (Mao 2010; Sastry & Hajra
2010; Bhattacharyya & Sanjappa 2014; Mao et al.
2017a). Sir Joseph D. Hooker
described 34 new species and details of the 43 species including varieties from
the Indian region in his monograph, Rhododendron of Sikkim Himalaya,
explored during his visits in between 1848 to 1850 (Hooker 1849). These species are naturally grown along
the temperate to alpine zones and beautify the very landscapes (around
1,500–5,000 m).
The
42.55% (3,019km2) of the total geographical area of Sikkim (7,096km2)
is under protected areas (Fig. 2) and represented by various Rhododendron
species. The Khangchendzonga
Biosphere Reserve (KBR) harbours 86.78% of the total protected area and
comprises of: (i) the core zone (1,784km2)
also delineates as Khangchendzonga National Park
(KNP), (ii) the buffer zone (835.92km2) and (iii) the transition zone (311.20km2)
(Badola & Subba
2012). KNP has recently been
notified by UNESCO (on 16.vii.2016) as the only mixed heritage site of India
and is therefore an important conservation area with high ecological,
biological diversity, and also contributes to natural and cultural significance
in the Indian Himalayan region. The
present study focuses on (i) the identification of Rhododendron
species having conservation needs and can be utilized for landscape
beautification, and (ii) identification of the conservation and management
sites for R. falconeri based on its
distribution and status assessment.
Study area
Intensive
literature survey was done for the existing information related to distribution
and availability on Rhododendrons in Sikkim Himalaya. The Yuksam-Dzongri
trekking corridor nestled in the Khangchendzonga
National Park in western Sikkim between 27.38–27.480N &
88.22–88.170E; 1,800-4,100 m, was identified for the present
study (Fig. 3). This trekking
corridor is one of the most fascinating destinations for adventure trekkers in
the northeastern region of the country, for its
picturesque landscapes, ice-clad mountains including the highest peak of India,
Mt. Khangchendzonga, and its wildlife are the top
fascinations. This trekking
corridor is managed as eco-friendly plastic free zone and plucking flowers,
leaves, littering, creating noise and/or disturbance in any form is prohibited
as-per-the national park norms. The
forest guards from state forest department, Himal Rakshak (voluntary mountain guardians) along with state
tourism department keep an eye on these issues.
Material and
Methods
During
the year 2016–2017, different field surveys were conducted in the target
area across different seasons and identified the Rhododendron falconeri Hook.f. as a very valuable and striking species having both the
conservation and aesthetic value.
In the field, we examined various phenophases
of the plant and confirmed species identification by consulting regional floras
such as ÒSikkim Himalayan RhododendronsÓ (Pradhan
& Lachungpa 1990), and ÒFlowers of the HimalayaÓ
(Polunin & Stainton
2001). Photographs of different phenophases were taken for further confirmation. To assess
the status and distribution range in the study corridor, we positioned randomly
a total of 45 (10x10 m2) plots in identified habitats, along
3,000–3,200 m (Fig. 3). In each plot, all the individuals of R.
falconeri were counted along with associated tree
species and the circumference at breast height (CBH) was measured. Individuals with the CBH ³30cm were
considered as tree and the data of each elevation were pooled to calculate
plant (density/hectare), frequency (%), total basal area (m2/hectare)
and important value index (IVI) to estimate the status and availability of R.
falconeri in targeted area. We interacted with different group of
trekkers (local, Indian, foreign), and porters/ guides, etc. and got their
perception/views on the conservation and aesthetic significance of the species.
Results and
Discussion
Species examined
The Rhododendron falconeri Hook.f. known as KorlingaÕ
in Nepali and ÔKalmaÕ by Bhutias,
is a type species of sub-section falconera (Hootman 2003).
The species comprises two subspecies, falconeri and
eximium (Nuttall)
D.F. (Chamberlain 1982). R. falconeri is distributed in
the eastern Himalaya from eastern Nepal through Sikkim and Bhutan, including
the adjacent areas of northeastern India (Arunachal
Pradesh and northern West Bengal).
In the Sikkim Himalaya this species form characteristic Rhododendron
forests between 3,000–3,500 m in coniferous and mixed
deciduous/coniferous forest habitats.
Subspecies falconeri was
first brought to the attention by Sir J.D. Hooker during his famous
1948–50 expedition to Sikkim. Among Rhododendrons, R. falconeri is considered threatened for Sikkim Himalaya
(Pradhan & Lachungpa
1990; Tiwari & Chauhan
2006);
whereas, the subspecies eximium
is restricted to Bhutan between 3,300–3,600 m (Pradhan
& Lachungpa 1990).
Field characteristics
A
medium-sized tree, grows to 10–25 m high, characterized in the field by
its large (15–40 cm long and 7–20 cm broad), rugged, matted, dark
green leaves with deep veins at dorsal surface, which is thickly covered rusty
indumentum beneath (Image 1 b&f) and the peeling
cinnamon coloured bark (Image 1a).
The petiole is 40–60 mm long grooved above, covered with
greyish-white hairs; young leaves are velvety hairy. Flowers are borne in round clusters of
20–25 (Image 1c–e). The
flower colour changes with the growing stages; the juvenile flowers are
pinkish-white (Image 1c), while on maturity they turned in to creamy-white to
yellow blotched with purple colour at base (Image 1d–e). The mature flowers are bell-shaped,
40–60 mm long with 8–10 lobes and swollen at the base on the lower
side (Image 1d–e). Each
hermaphrodite flower contains 12–16 white coloured stamens and large
discoid greenish-yellow coloured stigma lying within the corolla, hairy on the
basal half (Image 1d). Capsules are 16–18-chambered, 40–45 mm long,
erect and woody. Flowering time is
April–May; however, at lower elevations, flowering starts in April which
can be observed up to mid June in higher altitudes.
Ecological status and distribution
Rhododendron
falconeri was observed forming forests with Betula utilis, Michelia lanuginosa [=Michelia velutina],
Rhododendron arboreum and Prunus
species at lower-altitude 2,900m (below Tshoka) and
dominates the forest between 3,100–3,200 m along with Rhododendron barbatum, Rhododendron hodgsonii,
and other associates, Abies densa, Tsuga dumosa,
Acer campbellii, Viburnum nervosum
[=Viburnum cordifolium] in the tree
layer (Table 1), and Berberis and Rosa
spp. in the shrub layer. These
stands offer refuge to various threatened faunal elements such as birds Dendrocopos darjellensis (Darjeeling
Woodpecker), Upupa epops
(Common Hooopoe), Eumyias
thalassinus (Verditer
Flycatcher), Corvus corax
(Common Raven), Psilopogon virens (Great Barbet), Cuculus
micropterus (Indian Cuckoo), Garrulax albogularis (White-throated
Laughing thrush), pheasants like Lophura leucomelanous (Kalij), and
mammals such as Naemorhedus goral
(Himalayan Goral), Muntiacus muntjak (Barking Deer), and Ursus
thibetanus (Himalayan Black Bear). According to the field guides and forest
guards this elevation range was the preferred habitat of Ailurus
fulgens (Red Panda) now no more citing of this
animal is documented since past few years. Above 3,280m, along the trek, R. falconeri is totally replaced by R. hodgsonii. In
some areas, this species is the dominant canopy tree, forming small forests
typically up to 12–15 m in height.
It is a striking tree with bold and rough ornamental foliage, that
people of the Lachung Valley in northeastern
Sikkim use for packaging apples, lighting fires (Pradhan
& Lachungpa 1990). Further, the leaves of R. falconeri are reported as good source of protein,
carbohydrate and possess enzymatic activities such as catalase, peroxidase etc.
(Chhetri & Roy 2007). The un-split woods of R. falconeri, R. fulgens and
R. hodgsonii are used to make cups, spoons and
ladles and handles of Khukri (a local dagger used by
most of the inhabitants) (Tiwari & Chauhan 2006).
The
density and frequency of R. falconeri
varied across the elevational gradient, and the
highest frequency (100%) and average density (103 ind
ha-1) was observed towards higher-elevation (Fig. 4a). The maximum IVI (56.3) was observed in
the lower-elevation sites (P1-P3).
The maximum total basal area (TBA: 12.29 m2 ha-1)
was observed at higher-elevation sites (Fig. 4b). The highest density, frequency and
maximum basal area in high altitude sites are an agreement of the suitable
habitats of R. falconeri for its suitable
adaptation; however, comparatively lower frequency, density and total basal
area at middle elevation might be indicating the light demanding nature of the
species, as the mid-elevation site is dominated by Tsuga
dumosa and Abies
densa in the higher canopy layer. Elsewhere, some Rhododendron
species are also observed to be vulnerable to moisture and light stress, and
that suited better to dry and high radiation environments (Cai
et al. 2014). People perception on
two major issues, (i) whether the conservation
management of R. falconeri is important as
strong forest element, and (ii) how they rate the aesthetic value of the
species for eco-tourism promotion gave interesting ideas. About 50% of trekkers had opinion that
conservation of R. falconeri will help in the
sustenance of wild fauna; whereas, the local porters/guides (80%) viewed these
trees as a potential forest element to be conserved. Overall, the trekkers (83%) had great
admiration for this tree as one of the most aesthetic species (Fig. 5).
Table 1. Details of the associated
species of Rhododendron falconeri along
different elevation sites in Khangchendzonga National
Park
|
Species |
Family |
Vernacular name |
Elevation range (m) |
||
3000 |
3100 |
3200 |
||||
1 |
Abies densa Griff. |
Pinaceae |
Gobre salla |
+ |
+ |
+ |
2 |
Acer campbellii
Hook.f. & Thomson ex Hiern |
Aseraceae |
Kabase |
+ |
+ |
+ |
3 |
Betula alnoides Buch.-Ham. ex D. Don |
Betulaceae |
Saur |
+ |
- |
+ |
4 |
Betula utilis D. Don |
Betulaceae |
Saur |
+ |
- |
+ |
5 |
Eurya japonica Thunb. |
Theaceae |
Jhingeni |
- |
+ |
- |
6 |
Litsea sericea (Wall. ex Nees)
Hook.f. |
Lauraceae |
Siltimur |
- |
+ |
- |
7 |
Michelia dolstopa Buch.-Ham. ex D.C. |
Magnoliaceae |
Champ |
+ |
- |
- |
8 |
Lyonia villosa
(Wall. ex C.B. Clarke) Hand.-Mazz.
[=Pieris villosa
Wall. ex C.B. Clarke] |
Ericaceae |
Angeri |
+ |
- |
- |
9 |
Prunus nepalensis
Ser. |
Rosaceae |
Arupate |
+ |
- |
- |
10 |
Rhododendron arboreum
Sm. |
Ericaceae |
Lali gurans |
+ |
+ |
- |
11 |
Rhododendron barbatum
Wall. ex G. Don |
Ericaceae |
Lal chimal |
+ |
+ |
+ |
12 |
Rhododendron falconeri
Hook.f |
Ericaceae |
Korlinga |
- |
+ |
+ |
13 |
Rhododendron hodgsonii
Hook.f |
Ericaceae |
Gulabi korlinga |
- |
- |
+ |
14 |
Sorbus thomsonii (King ex Hook. f.) Rehder |
Rosaceae |
Pansi |
- |
+ |
+ |
15 |
Symplosos sp. |
Symplocaeae |
Kholme |
+ |
+ |
- |
16 |
Tsuga dumosa (D. Don) Eichler |
Pinaceae |
Tengre salla |
+ |
+ |
+ |
17 |
Viburnum nervosum D.Don [=Viburnum
cordifolium Wall ex. DC.] |
Caprifoliaceae |
Asare |
+ |
+ |
+ |
18 |
Vitex sp. |
Vitaceae |
Panchpatey |
+ |
- |
+ |
+ present; - absent
Conclusion and
recommendations
The
rhododendrons are mostly used in landscaping and woodland planting with the
help of area-specific specimens.
Rhododendrons are among the first to colonize the wasteland, and helps
prevent soil erosion and promotes regeneration of vegetation (Leach 1961). Considering the high tourist influx on
the Yuksam-Dzongri trail, the tracking trails can be
managed as in situ landscaped by conserving and showcasing the forests of R.
falconeri as important biodiversity element of
KNP. Plantation of rhododendron trees
taking the same genetic resource is also suggested in degraded parts of the
trekking corridors according to their elevation range, as one of the precursors
of eco-tourism promotion, until state government wishes to promote the same in
park. This will not only help in the beatification of the trail but also
attract more naturalists/ tourists to this region.
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