CLIMATE AND VEGETATION OF STUDY SITE

17

Survey of orchids was carried out from various grasslands,

agricultural lands and forest of Khasi Hills, Garo Hills and adjacent areas

of Meghalaya (Fig. 1). Their habit, habitat and frequency was observed.· Plants

·of different orchid species were collected and maintaine~ on charcoal and

soil mixture, fl11ed in earthen pots. Few epiphytic orchids were grown on

old dead logs under semi-controlled conditions (in net houses) in Botany Depart­

ment, School of Life Sciences, North Eastern Hill University, Shillong. (latitude"

• • 25'34 N and longitude, 91 '56 E, altitude)'1956mm)

The orchids, for the present study, were divided into two

categories:

1) Terrestrial orchids

The orchids, which were found growing in soil of grasslands,

agricultural fields with weeds, grasses and in the forest floor with decaying

rich organic matters.

U) epiphytic orchids

The orchids which occurred on the trunk and branches of

tree species along with or without lichens, mosses and ferns and other epiphytic

vegetation.

SoU

Shillong plateau had mild undulatus topography. The soU

is laterite with reddish brown colour and the texture is sandy-loam at the

surface end and silty-loam at deeper layers. It had originated from the hard

rock representing gncises, schists and granite. Zimba (1977) had proposed

that Shillong plateau and its surrounding hills might have uplifted from sea

bed along with origin of great Himalaya during mesozoic and early tertiary

times. The soU is rich in organic matters and nitrogen but acidic in reaction.

Fig. I Map of Meghalaya showing the place of orchid collection.

(I = Place of collection; • _ study site)

9/0' 9j1- 912'

t MEGHALAYA

N ASS A

."'. .-.!: , '- ,... • .", , 26 .... . ."". . 26' • ...-.~. j j J Burnihot.l" '._0-' '" ,., ~ . j \

o'\. _----, f/'. o~'\. .' ~o • NonQPoh 07

.,-.... . I "C:J ?,.. o-~ i !" t:::.. ~\" Y"· I ." ..... ___ -----~ . I r~ ~ , I V \. c;, \\ .Umsnino , ....... .,.0",-o -~ C) \ ) ':\\,...v y..

v~ I ~ , \. .:t-~cf) / ,) • 8arapani, ."\ ~ • ,C) I ~~ .// ,/ ~HILlONG oJ"., ,.0"; ~o • I WiliiomNagor ~ / 'l.Imp1ino"1 ",

, • ~ .Turo) e f \ -' • Upper Shirllong '1 c, ( Is- Mawph/ono I eJowai ......

." ..... - I r , I" ----- \ EAST KHASI HILLS ) ~. . ~ '- \ "') , ~ \ ~ C)~ ~C)) _ .J ,'I- r • .,.".-,,\. \- ~9'(\C) ,,~ ~\~'''M awsanr~~herrapunjtMf~" l.

~ " ~~o C)c\e~" l,0o,j" ~ " _ '-._ Saghmara Rongra \ ~C)'(\ .". • , • Shell2-. ~'I- ,.

-.- • - • .........-.-.. • ..... -Sal.at ._.. z .'-• ..,., ..... -.... ~.-.--. . ....... r l. • .,.~- ~. • • ." BAN G LAD E S. H Ie 9 tp 2[> 3f> 4p Km. ~.,,- .J

-.J 910· 911· !.l2- STUDY ARE~_

Fig. ,

6 Fig. 2. Meteorological data for minimum and maximum temperature ( C),

relative humidity (96) and rainfall (mm) for the year 1982-83 of study

site in Shillong.

o RAINFALL

(IDJ MAX. TEMPERATURE

• MIN. TEMPERATURE

901 JOr • HUMIDITY

751 "- --"-- ~ 700 2

u om .... ..../ "'- ""V 11111 I I 11111 11111 600 >- 0 .... 560 w 20 ~ ~ 500 ,.... ;::J :J ~ l- E

w45 c( E ~ 15 400 -" w

:! a. ...J ...J

Z ~ 300 <: w LLJ u.. u30 1-10 z IX

w c( 0.. 200 ~

1 5 5 .11111_ 1111- • 1111_ • 1111_ • 1111_ I 1111_ I 1111_ I

100

SEP OCT NOV DEC! I JAN FEB MAR APR MAY JUN JUL AUG SEP I

1982 MONTHS 1983

Fig· 2

18

The vegetation of Meghalaya can broadly be classified into

(i) Subtropical forest

(ii) The mixed evergreen forest

(iii) Temperate forest

(iv) The rolling grassland

The sub-tropical pine forests represent biotic climax, dominated

by Pinus kesiya along with some tree species like Alnus nepalensis, Schima spp.,

Quercus spp., Cedrus deodara, Cryptomaria· japonica etc. and some other trees,

shrubs and herbaceous species like SympLocus spp., Rhododendron arboreum,

Lantana camara, Eupatorium spp., Anaphilis spp., and Desmodium spp. etc.

Mixed sub-tropical forests are confined to restricted areas and are

much disturbed. These are dominated by Schima spp., Quercus spp., Alnus nepale­

nsis, Erythrina arborescens and a number of rosaceae members.

Temperate forests are elavated from 1800 m and above. The true

temperate vegetation which represents the richest flora (in preserved/sacred

forests) and gives an indication that probably the entire area was once covered

by such type of dens·e vegetation but now has been disturbed due to human acti­

vities. In such forests the common trees namely Quercus griffithii, Myrica escu­

lenta, Betula alnoides, Rhododendron arboreum, Castonopsis spp. Photenia notoniam

etc.; shrubs like, Daphne spp., Osbeckia spp. and beautiful orchids like Dendrobium

spp., Coelogyne spp., Cymbidium spp., Oberonia spp., Pleione spp., Pholidata spp.,

Eria spp. etc. are commonly encountered. The epiphytic plant species comprised

of lichens, mosses and ferns as dominant species on the tree trunks and branches

19

of old tree in moist humid forests.

The· grasslands represent most important vegetation type (ground

flora) of this region. Most of the grasslands are in the different stages of sereal

succession. The primitive agriculturtal LPc'.-tlce i.e. shifting cultivation locally

known as Jhuming is commonly used for raising the agricultural crops in the north

eastern region. The extensive use of jhuming is main factor in resulting the genesis

of grasslands in the region. Other biotic and human disturbances have also pro-

moted the process. The grasslands consist of dominant species like Paspalum

dilatatum, Pennisetum cladestinum, Imperata cylindrica, Panicum brevifolium,

Cyperus spp., Fimbristylis spp., Arundinella spp., Trifolium repens, Cassia spp.,

Desmodium spp. etc. and some beautiful terrestrial orchids like Spathoglottis

pubescens, Spirenthus spp., Herminium spp., Habenaria spp., Arundiana spp., Paphi-

opedilum spp. etc.

Climate

Shillong climate is very much influenced by the south-west monsoon

and north-eastern winds.

Therefore, the year can be divided into four seasons:

I Spring season - March and April.

II Summer (Rainy) season - May to September

III Autumn season - October and November

IV Winter season - December to February.

During spring season atmosphere gets warm gradually as compared

to the preceding winter months. The maximum temperature reaches during the

period of April to the June-JUly. The average maximum temperature at Shillong o

recorded during the study period was 24-.8 C and the average minimum temperature

20

o 12.52 C. Rain starts at the end of April and continues upto September. The monthly

average rainfall normally is 212.02. mm. The average humidity (%) ranges between

61 to 88.5 (Fig. 2). October and November represent a typical autumn season

with mild cold and usually with less rain. The winter season can be characterised

by low temperature, from cool to cold one. The temperature drops down to a o

minimum of 1 C in the early period of January and occasional frost can appear.

Sometimes there is rain during the month of March which is helpful for the ger-

mination and development of most of the trees, plants, and herbs.