Diversity, distribution
pattern and seasonal variation in moth assemblages along altitudinal gradient
in Gangotri landscape area, Western Himalaya, Uttarakhand, India
Abesh Kumar Sanyal1, V.P. Uniyal 2, Kailash Chandra 3 & Manish Bhardwaj 4
1,2,4 Wildlife Institute of India,
P.O. Box-18, Chandrabani, Dehra Dun, Uttarakhand 248001, India
3 Central Zone Regional Centre,
Zoological Survey of India, 168-189 Vijaynagar,
Jabalpur, Madhya Pradesh 482002, India
1 abesh@wii.gov.in, 2 uniyalvp@wii.gov.in (corresponding
author), 3 kailash611@rediffmail.com, 4 manish@wii.gov.in
doi: http://dx.doi.org/10.11609/JoTT.o2597.3646-53 | ZooBank: urn:lsid:zoobank.org:pub:B071F0A8-BD65-41F8-B120-9FADD54BB996
Editor: Peter Smetacek,
Butterfly Research Centre, Bhimtal, India Dateof publication: 26 February 2013 (online & print)
Manuscript details: Ms # o2597
| Received 04 October 2010 | Final received 26 November 2012 | Finally accepted
14 January 2013
Citation: Sanyal,
A.K., V.P. Uniyal, K. Chandra & M. Bhardwaj (2013). Diversity, distribution pattern and
seasonal variation in moth assemblages along altitudinal gradient in Gangotri landscape area, Western Himalaya, Uttarakhand, India. Journal of Threatened Taxa 5(2):
3646-3653; doi:10.11609/JoTT.o2597.3646-53
Copyright: © Sanyalet al. 2013. Creative Commons Attribution 3.0 Unported 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: Training Research and Academic
Council (TRAC), Wildlife Institute of India.
Competing Interest: None.
Acknowledgements:The authors are grateful to Director and Dean, Wildlife Institute of India and
Director, Zoological Survey of India for guidance and support. Thanks to Uttarakhand Forest Department and field staff of Gangotri and Govind National Park
for necessary permission and logistics for conducting the study. Staffs of Central Zone Regional Centre,
Zoological Survey of India, Jabalpur are highly
thankful for assisting during identification and literature consultation.
Abstract: Field survey was conducted at different altitudes and land-use
areas in the two protected areas, viz., GangotriNational Park and Govind National Park of Uttarkashi District, Uttarakhand,
India. A total of 475 specimens of
moth representing 436 morphospecies were collected
using light trap method during the survey conducted between
September 2008–May 2010. Preliminary findings show a decreasing diversity with increasing
altitude. Subalpine areas were
least diverse and subtropical areas had the highest diversity of moths. The greatest number of
specimens were collected during the summer and post-monsoon period. The lunar phase had a significant effect
on catch success with new moon days resulting in the largest catches and full
moon days resulting in the least number of species as well as individuals. Of the thirty twospecies mentioned in Appendix 1, nine species are first time record from the
state Uttarakhand. Four species are new record from Western
Himalaya within Indian Territory, and also first time recorded from
entire Himalayan landscape. As
there was no previous comprehensive study on the moth diversity of Gangotri landscape area, all the 32 species described could
be regarded as new record from these two protected areas.
KeyWords: Altitudinal distribution, catch success, Gangotri landscape area, moths, seasonal variability.
For
figures, images, tables -- click here
An inventory of biodiversity
is of primary importance as part of biodiversity conservation for sustainable
development, particularly in threatened and fragmented landscapes like Western
Himalaya that harbours unique assemblage of flora,
fauna of considerable conservation importance. In comparison with higher plants and
larger animals, the inventory of insects in Western Himalayan landscape is
still fragmentary and incomplete.
Recent estimates reveal the
report of over 127,000 species of moths from the world, of which over 12,000
species are recorded from India (Chandra 2007). The comprehensive work
on moths of different regions of Western Himalaya within the Indian Territory
was mostly carried out by Hampson (1892, 1894, 1895,
1896) and Bell & Scott (1937) in their “Fauna of British India”
series and Cotes & Swinhoe (1886) in “A catalogue
of moths of India”. Since then not
much work has been carried out on moth fauna of Western Himalaya except Arora (1997, 2000) who had published some moth species from
the Nanda Devi Biosphere Reserve, Garhwal Himalaya, Uttarakhand and Smetacek (2008)
who published 887 species of moth from different elevations in Nainital District, KumaonHimalaya, Uttarakhand. So far no comprehensive work on moth
fauna in Gangotri landscape area
which is an important wildlife refuge in high altitudes of UttarakhandState has been done.
Study site
The study was conducted in
two high altitude protected areas of Uttarakhand(Fig. 1) Gangotri National Park (30050’–31012’N
& 78045’–79002’E) and GovindNational Park (31002’–31020’N & 77055’–78040’E),
which represents the biogeographical zone - 2B West
Himalaya (Rodgers & Panwar 1988). They are situated in UttarkashiDistrict of the Uttarakhand State. The altitude varies from 1200–6000
m. The GangotriNP covers an area of 2,390km2 harbouringthe Goumukh Glacier, the origin of the river Ganges
and Govind NP covers an area of 953.12km2encompassing the upper catchment of river Tons. The climate of the area is typically
Himalayan with medium rainfall during July–August at lower
altitudes. The average rainfall is
1,500mm, extreme cold with three to four month snowfallin winter with permanent snowline in the higher reaches.
The vegetation pattern in the
study area resembles the broad pattern of vegetationalzones of northwestern Himalaya. The
lower altitude represents montane subtropical type
with Chir Pine (Pinus roxburghii Sarg. (Pinaceae) dominating with tree rhododendron (Rhododendronarboreum Smith (Ericaceae),Rohini (Mallotus philippensis Lam. (Euphorbiaceae),
Alder (Alnus nepalensisD. Don (Betulaceae), Wild Pear (Pyrus pashia Buch.-Ham. (Rosaceae), Indian Laburnum
(Cassia fistula Linn. (Caesalpiniaceae), Amla (Emblica officinalis Gaertn. Euphorbiaceae), Toon (Toona ciliata, M.J.Roem (Meliaceae). Shrub layer is dominated by Musk Rose (Rosamoschata Miller (Rosaceae),
Raspberry (Rubus sp. (Rosaceae),
Wig plant (Rhus sp. (Anacardiaceae),Dodonea viscosa Linn.
(Sapindaceae), Colebrooka oppositifoliaSmith (Labiatae), Pyracantha crenulata M. Roemer (Rosaceae),Ziziphus mauritiana Lam.(Rhamnaceae). The mid altitude regions were
represented by montane moist and dry temperate type
of vegetation. Moist temperate
vegetation consists of Grey Oak (Quercus leucotrichophora A. Camus (Fagaceae),
Blue Pine/kail (Pinus wallichiana A.B. Jackson (Pinaceae),
Western Himalayan Fir (Abies pindrow Royle (Pinaceae), Deodar (Cedrus deodara G. Don (Pinaceae),
Horse Chestnut (Aesculus indica Hook. (Hippocastanaceae),
Himalayan Cypress (Cupressus torulosa D. Don (Cupressaceae),
and Yew (Taxus baccata Pilger (Taxaceae). The shrub layer was
dominated by Viburnum continifolium D. Don (Sambucaceae), Hippophae rhamnoides Rousi (Elaeagnaceae) and Berberissp. (Berberidaceae). The montanedry temperate vegetation zone was predominantly coniferous along with
broad-leaved trees like oak, ash, maple. There were also deodar, juniper, high
level fir (Abies spectabilis Mirbel. (Pinaceae) and
Silver Birch (Betula utilisD. Don (Betulaceae). The subalpine zone around 3000m had
dense coniferous forest represented by the species like Pinus wallichiana A.B. Jackson), Himalayan Yew (Taxus wallichiana Pilger (Taxaceae)) with
intermixed broad-leaved trees like Kharsu oak (Quercus semecarpifoliaSmith (Fagaceae)). The common shrubs were Rosa webbiana Wallich (Rosaceae, Cotoneaster sp.(Rosaceae) and Berberis sp.
etc. The herbaceous species like Delphiniumsp.(Ranunculaceae), Swertia sp. (Gentianaceae)
and Pedecularis sp. (Scrophulariaceae)
were found common.
Materials & Methods
The moths were collected using
light trap running for four hours from 19:00–23:00 hrin the three seasons, viz, summer (April–May),
monsoon (June–July), and post Monsoon (August–September). Wherever electricity was available,
light traps were set by placing a 120W Tungsten filament bulb in front of a
white 10’x 6’ cloth sheet hung between two vertical poles in a way that it
touches the surface and extends forward over the ground slightly and the data
collected by this method were used for the inventory purpose, not for diversity
analysis. In higher areas of
subalpine zone, light traps were set by solar powered lantern
which had significantly low light intensity than tungsten filament
bulb. After collecting, moths were
killed by Benzene vapour in killing jar. The collected specimens were processed
for pinning, setting and preserved in air-tight wooden
boxes. First the specimens were sorted into morphospecies.
Identifications were done with the help of available literature and also by
comparing with the reference collection available at Zoological Survey of
India. The classification used mainly follows Hampson(1892, 1894, 1895, 1896) and subsequent changes in the families based on Kristensen (1999).
Result
Altitudinal distribution: Diversity of moth fauna in terms of morphospeciescollected showed a decreasing trend along increasing altitude. For comparison between different nightly
catches at different altitudes, species were collected in same season, weather
condition and moon phase. The data
provided in Table 1 shows the average number (total morphospeciescollected/sampling night) of moth species collected in the four different
altitudes with their respective broad vegetation type.
The four
altitudinal zones sampled were categorized into three elevational ranges: The lower zone is represented by
500–1500 m which is characterized by montanesubtropical and moist temperate type of forest. This zone came out as the most diverse
zone (Fig. 2) in respect to moth species collected. The mid altitude zone is represented by
1500–2500 m, which is characterized by montanedry temperate type of forest. This
zone had medium diversity. The
higher altitude zone is represented by 2500–3500 m, which is
characterized by subalpine vegetation. This zone contained significantly less diversity of moth species.
Seasonal variation: The
data provided in Table 2 shows the total number of specimens collected in
different seasons. For comparing
the catch success in different season, the average value of catch success per
night were used as a simple mean of total species collected by total trap
nights.
Catch success was highest in
summer months (April–May) followed by post monsoon
(August–September) and monsoon (June–July) (Fig. 3).
Effect of moon phase: To
observe whether the moon phase has any significant effect on catch success, a
light trap was run on daily basis for one month period in the month of April at
an altitude of 1440m from 20:00–24:00 hr. The result of the observed species catch
and individual catch per day in a complete lunar cycle is shown in Fig. 4. Most species as well as individuals were
attracted in and around no moon nights and declined as the ambient moon light
started to increase and came to a minimum around full moon nights when the ambient
moon light was at its best.
Species list: Although
a total of 475 specimens were collected representing 436 morphospeciesin different seasons, only 32 were identified up to species rank representing
six superfamilies and nine families within the short
span of study time. The identified
species list with their collection locality (GVNP: GovindNational Park, GTNP: Gangotri National Park) and
altitude at which they were collected is given in Table 3. Current valid names are provided after
consulting from LepIndex (Global Lepidoptera Species
Database 2007 & The Natural History Museum, London).
Discussion
In tropical or subtropical
landscapes, two patterns of diversity are typically reported on altitudinal
gradients: diversity either declines (linearly or nonlinearly) with increasing
altitude, or, more commonly, unimodal patterns
(mid-elevation peak) are found (Rahbek 1995, 2005;
McClain et al. 2007). Our study
result, although a preliminary one, has indicated the previous trend, i.e.,
moth diversity declining linearly with increasing altitude. As the study does not cover the entire elevational range, it is hard to predict the underlying
cause of such pattern. The lower
altitude zone represented by montane subtropical and
moist temperate type of forest is in comparatively better condition than the
upper reaches, which are under pressure from increasing human settlements and
grazing-related problems. The
sampling related issues may also have a significant effect on this pattern as
setting up light traps in lower altitude zone was easier than the alpine areas
due to availability of good logistic support like electricity. Whereas in lower areas the light trap
was run by tungsten filament bulb run from main power source, for sub-alpine
areas solar powered light was the only feasible option with much lower intensity.
Significant seasonal
variation in catch success per night was observed with the highest catch
success in summer time followed by post-monsoon season and the monsoon time which had significantly lowest success. High rainfall in monsoon months resulted
in low catches, suspecting that flight may be restricted in such
conditions. Post-monsoon months
observed a significantly high moth abundance and species richness perhaps by
increased availability of fresh plant material stimulated by rain. Summer (April–May) was the best
season for sampling. Moon phase or
the monthly lunar cycle had a significant effect on the light trap catch
success. Yela& Holyoak (1997) from their study recommended to
restrict the light trapping to periods without strong moonlight because moths
are not attracted to artificial light in the presence of high ambient
moonlight, though their activity remains at it’s peak. Our study documented the same phenomenon
where maximum number of species as well as individuals were attracted to light
traps in the beginning and end of lunar cycle, i.e. from 3rd to 6thday and 24th to 28th day when there was apparently no
ambient moon light. Catch success
eventually dropped as the ambient moon light started
to increase and became almost zero in the full moon period from 14thto 18th day. One factor
that masked this general pattern was the presence of cloud cover evident from
the slightly increased catch success in 12th day when there was
strong moon light but its effect was nullified by the
clouds.
The present work gives an
idea about previous and new distribution record of the 32 species mentioned
(Table 3). Of these, nine species are first records from UttarakhandState, viz., Goniorhynchus signatalis, Lista haraldusalis, Trichopterigia rufinotata, Psyra similaria, Nordstromia lilacina, Spilosoma obliqua, Diarsia albipennis, Cyana horsfieldi and Spilosoma strigulata.
As the area is under
tremendous pressure from the threat of loss of biodiversity due to various
anthropogenic activities like increasing human population, conversion of
forested land to agricultural patch, shifting cultivation and livestock grazing
of pastoral people, it is very important to know about the overall picture of
diversity of an important indicator group like moth calling for the need of a
more thorough investigation.
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