PART I
SOME ECOLOGICAL OBSERVATIONS ON MIRIK AND ITS
ENVIRONS IN DARJEELING DISTRICT, WEST BENGAL ·.
- 13 -
INTRODUCTION
Since 1866 when the term Ecology was employed first by Ernst Hae ckel, who ,invented the word oekologie for "the relation of the animal to its organic as well as its inorganic environment, particularly its friendly or hostile relations to those animals or plants with which it comes in con tact," ecology has been variously defiQed by other investigators (Warming, 1909; Daubenmire, 1947; Tansley, 1949; Odum, 1971; Kendeigh, 1980; etc.).
At present, the scope of ecology in botany is vast and useful in the realm of applied sciences. Ecology needs field study which consists of re cording and examining plant species growing in a vegetation of covered area.
The estimates and accounts are . made of the environmental. conditions under which plants are growing. Thus, the plant taxonomic study, described in
th~ subsequent chapter becomes very much complementary to the study on ecology of the region. •
During the last few decades, Mirik and its a?joining areas specially in 'the catchment part have been subjected to drastic deforestation with in adequate_ a forestation, the soil surface has become devoid of any plant cover and due to over insolation of the soil. Leaching of minerals has been in creased tremendously (De, 1977). As a result, the f~rtility status of the soil has been decreased.. Thus, the obser:--ation on some· ·of the ecological factors, such as, soil, tl;lmperature, rainfall in the region is very essential. Moreover, due to rapid urbanization the human population has been in creasing day by day. It is also very necessary to study the present day sic tuation of human population in the region. The development of the plant depends on the topographical relief of a particular area. This part of con sideration has also been taken into account during investigation.
Recently, the study on landuse becomes the part of the programme during ecological study in' a region (Odum, 1971 ). It is essential for purpose ful utili'7.alion of land in an area. Thus, attempt h~s been made to survey - 14 -
the nature. or landuse in the region under study with special· reference to the observation on vegetation types.
REVIEW OF LITERATURE
Information in connection with the earlier records on history, human population, agriculture and forestry of Darjeeling district are· available in some of the literature (Hooker, 1854; Hunter, 1876; O'Malley, 1907; Dash, 1947). In later period all these information about the same region have been dealt with in several rep~rts (Mitra, 1954; Ray, 1967; Census, 1971; Banerji rt a!., 1980). Physiography, geological aspect and soil have been critically represented by Wadia (1966) specially with reference to India as a whole. The geology of Himalayas has been thoroughly discussed .by some of' the authors (Garwood, 1903; Gansser, 1964). De (1977) discussed the . . economy of North Bengal with special reference to agriculture, forestry and plantation. Puri (1960) represented in details about the forest types and vegetation in India a~ a whole.
Whitmore (1982) discussed·critically about the management of the forest. Chaudhuri (1969) dealt with the critical quantitative analysis and special ecological features of the ·vegetation of. North Bengal. The. ecology of Himalaya .has recent)/ been discussed critically by Kalapasi (i980) with a view to understanding the present day situation of tfie environment.
Impact of climatic; factors on plant community has been well elabo rated by Daubenmire (1947, 1974), Etherington (1975), Whitmore (1982), though earlier records on the sketch of climate and vegetation of Hima- . . layas were described by Thomson (1852), Hooker (1854) and O'Malley (1907). Later on, a number of authors (Biswas, 1966; Hara, .1966 & 1971) reflected the environmental conditions of some of the' places in the Eastern Himalaya other than Mirik P.S. with special reference to. rainfall, temperature, humi~ dity and soil factors. - 15 -
METHODOLOGY
The work was carried out on the following lines of investigation
1. Survey in connection with the accumulation of various information:
Information in connection with .physiography, drainage, soil, climate, human population and landuse have been carried out after being contacted with local people, office of Gram Panchayat, local Police Station, Govern ment Offices, specially the Directorate of Agriculture and Forestry and local tea gardens.
Meteorological data was collected specially from the record of tea gardens and Meteorological stations at Siliguri and Calcutta (Alipur). In formation collected after survey were compiled and worked in collabora tion with the National Atlas and Thematic Mapping Organisation, Govern ment of India.
2. Collection and identification of different plant materials :
Collection of various plant materials was performed specially during the study on vegetation. !"roper identification of collected materials was done after comparing the prepared herbarium sheets. with those available in various herbarium sections of North Bengal University, Lloyd Botanic Gardens in Darjeeling, Central National Herbarium (Botanical Survey of India, Howrah, Calcutta) and Indian Museum (Calcutta).
Vegetation types were classified according to physiognomy and stru ctural features of the plant specially in relation to the altitude of the hill and climatic condition.
10656'7 ?. 2 DEC 10.90 LOCATION MIRIK POLICE STATION, DARJEELING DISTRICf, W.B.
88' 89'
NEPAL
• Phopar Kheti 27' 27' WEST BENGAL
,··· ~· '
Z6"Ll~~---L~------~------L------~------·~'J______-Ja•• 88C Knh. 1U II Ill 20 Km"- 89° L_ Fig. 1. ~·~~--~~~~~--~~ MIRIK & ITS ENVIRONS r--~;;.---.....:;.::~~~~~~~89-=-.-.. -----......
26"
' L ------~--~---.:"'~'~"='="""="===;;;'"==~1U=d,l ====~=---~----~--~~~~------_j:d.'lll Knh. i~
Fig. 2. MAP OF MIRIK LAKE ~U~~~i[\~~·lA\ DARJEELING DISTRICf, W.B. REFERENCES
Agricullural Land ~ Forest area ~ Jhoras & Conservation Area V~.::-:::,::;:.1 Fellow & Grassland [II]
Unmetalled Road
Dam Spring
Area of the Lake 143000 Sq. mts. Mean height of the Lake 1580 mts. above M.S.L.
Fig. 3. RELIEF MIRIK POLICE STATION DARJEELING DISTRICT, W.B.
26° 50' REFERENCES Heights in metres Less than 300 bd 300-600 m 600-900 ~ 900-1200 am . 1200-1500 ~·lore than 1500 •m 1 1 I
88° 10' 15'
,----, Fig. 4. TOPOGRAPHIC SECTION FROM THE HIGHEST ELEVATION OF MIRIK P. S. TO THE BASE LEVEL AT BALASON VALLEY
~
0 "~ ~ 00"'
0 mts. L------__Jl
< 700 mts.---Lower Erosional Surface 700-1000 mts. ---Middle Erosional Surface > 1000 mts. - -- Upper Erosional Surface of the Mountains
Scale : Horizontal II 1 Cm. ~ 500 mts Vertical ·•
' Fig. 5• . rL DRAINAGE ' i ,.-·--' MffiiK POLICE STATION, 55' J \ /-· DARJEELING DISTRICf, W.B. I...__ _ _,. /
26' 50'
88° 10' 15' J Fig. 6. .
cg ---- .
•
• r SLOPE 55' r- if/3 I--~\ MIRIK POLICE STATION - .!_:,J -~ / DARJEELING DISTRICf, W.B. "' ~ f_y.; ..__
® Mirik "' ~
--~
I~~: -..----"-"'-"'-"CE_s ------, Slope zones in % Pc.
Less than 20
20-30
30-40 40-50
More than 50
\l,·n.- ((Uf ;m II
IS'
( ' 1 Fig. 8. SOIL MffiiK POLICE STATION DARJEELING DISTRICT, W.B.
REFERENCES
Red Podsol
Brown Earth Ash-Grey Soils with association o:' Red Soils. =~ Whitish-Grey Soils []IDI Grey Soils with association rmm1mm ·'' ofYellowish Brown Soils lWlli!llil
88'
l L __ J Fig. 9. POPULATION DENSITY 1981 . MIRIK POLICE STATION, DARJEELING DISTRICT, W .B . . .,,.
50'
REFERENCES Persons ha Less than I
1~3 / 4-6 J-9
More than 9 \_
I
I i 1
1S'
Fig. 10. ·.
P. S. MIRIK GROWI'H OF POPULATION 1901-1981
25
! :o' 20 c
"';:l .o .s;;: !-< .5 IS ~
5 ! '.
0+---~r----r----~--~r----r----~--~----~; 1901 '11 '21 '31 '41 '51 '61 . '71 '811 Census Years
' Ffig. 11. 88° 10' 15' .---~--~~~------· SUKHIAPOKRI P. s. ADMINISTRATIVE ( ,...... MIRIK POLICE STATION, 55' ~' ) __.....--·,.. \_,PARJEELING DISTRICT, W.B. 55'
,~~ ~--·""'' 1 .-...;,~ _,. 1 I /ill/1K~q~~- ~ · I I •«~-· i OKAYTI T.G.I I .....,;;;, ~- t'(RONGDONG) ~ rJ MIRIK KIIASMAHAL
--~ ·. I MIRIK @)';- \\ I I '''Q. 1 II ·,_ I ·. ..._..._...... ~ BUKIM T.G. tTharbol "<;/ .,....---··\-- ..... , __ I I PHUGURI\ 1 -..:;: •• I ( FQREST J l )'~ 1\l'- I \ ~-. I \ ',_~ ~) ~------j \ SAORENI / ...... --,.._ __ \~ ··- \ I II ...... _ I I I \ I < ' -< I. PASCH 1M I I I i PHUGURI T.G. \ 1 \ MANJWA .. , I ·., ') I I ' : /\ ,,--\ ~ .. ,, ,' \ , __ J \ tr '-....._ //\ SINGBALI T.G. / ...... --t__ / \ / - ' __ ,.. \ / PURBA,PHUGURJ_ __..... -,_..,.--.( '- T.G.t ...... _ ~ ...... \ \ ...... TINGLING T.G. \I ..... 'i NEW FALLODI T.G. 26' ..... -J.. IGAYABARII 50' (----<:,...... \ ', ' ) \ ...... _...... - ..... ,_... I ', \ \ ' '- REFERENCES ., MANJHA FOREST \ -....._ .,.-z (PANIGIIATA F. R.) \I ----- Boundanes: \ / PATONG T.G. International I Police Station ~! '\ : Village r ., I --- ...... ·- \ -----;;;-- Police Station HQrts. ® i ·,., \_----- ( ~ Important Roads _, "" PANIGHATA M B ,.,.; \ / \ r·---·/ . I \ f",/' ~- \ NAXALBARI P. S. \ 88' 10' 15'
m~tnos HU) .'al 1 Km•.
/"'---~ '· Fig. 12. LAND USE MIRIK POLICE STAUON DARJEELING DISTRICf, W.B •
. I
·'.
AEFEAEI Rural Settlements Croplands Plantations (Tea Gardens) Forests Scrubs Wastelands Important Roads Mme. 1000. 500 1 Km•. l .( Fig. 13.' - 16 - OBSERVATION AND DISCUSSION. Physiography with special reference to slope, river system, drainage, water shed and soil : The district of Darjeeling lies between 26°31' and 27°13' N. lat. and qetween 87°59' and 88°53'' E. long. and its total area is about 3108 sq.kms (Figs. 1 & 2) in which Mirik P.S.with its geographical area 97.4 sq.kms com prises of 15"villages, out of which two are uninhabited (Fig.12). Mirik being the head quarters of the P.S.lies on its north-central part. It is interesting to note that most villages are named after tea garden of respective area. The principal town and administrative headquarters of the district is Oar jeeling town at 27°3' N• .lat. and 88°16' E. long. (Fig.1). On the west the district is bounded by Nepal. From Phalut-Sa.nda kphu the western boundary follows the southward ridge until it joins the. Mechi river which <::ontinues as the boundary right up to the plains, thence by the boundary of Nepal upto the south-western ·corner of the district. On the. south lies the districts of Purnea and West Dinajpur being inter cepted by the Mahananda river and on the east the district is bounded by. Bangladesh and the Jalpaiguri district (Fiqs. 1 & 2). Mirik P. S. claims its special identity in respect of its strategic posi tion in the Sub-Himalayan hilly region of West Bengal.. It is bounded by Mechi and Balason rive~s in the west and east respectively lying adjacent to the border of Nepal. In the north it is separated from ·sukhiapokri by the river Rangbang. The plains of Naxalbari P.S.Jies in the south (Fig.2). The district falls naturally into two distinct tracts, the Tarai imme diately beneath the hills, and the ridges and deep valleys 9f the lower Hima layas. The Tarai portion of the district is a low-lying belt of the country, traversed by numerous rivers and streams rushing down from the hills and by the upland ridges which mark their courses. Behind the Tarai, the moun tains tower abruptly from the plains, which are here only ·about 91.4 m _) - 17 ·_ above sea-level, in lofty spurs' reaching to 1828.8m and 3048.0m and cul minate in a series of long ridges and valleys. The rocks of the Darjeeling district are subdivided by Mr. Mallet into five groups, i.e. gneiss, the Daling Series, the Buxa Series, the Gond wanas and the Tertiary system (O'Malley, 1907). The outcrops of these form a series of bands, running. more or less parallel to the general trend of the Himalayas and dipping one beneath the other into the hills. ·The hi gh_est ground is in the north-west where the Singalila ridge enters the di strict at Phalut. From. there, it descends· southwards to the level of the plains first as the boundary and then as the top of slopes ori the left bank of the Mechi river. Mirik is situated on a ridge at an elevation of 1700m above sea-level (Fig. 2). Here lies a large depression which turns into a natural lake (Figs. 3 & 14). This picturesque pool set amidst charming plantation of Cryptomeria japonica (Japanese Ceder) has a potential of developing into an attractive tourist resort. The Mirik itself lies in the highest part of the region in Mirik P.S. The height gradually slopes down towards south-east having average height of 300m-600m above sea-level. More precisely, it represents the central part of the region under study having the highest alti~ude which slopes down towards both the sides, west and· east boundary rivers Mechi and Balason respectively (Fig.4). .A topographic section from the highest ele vation·of the region to the base level of Balason river valley with the limits of erosional surface points to the real character of surface confi guration of the region. The surface configuration of this area undoubtedly presents a complex physical environment' due to different geomorphic .pro cesses (Fig. 5 ). In connection with the study on the drainage system in the area under study, it has been noted that the central part of the region acts as main water divide line. ln the west, tributaries like Kiyang Khola, ' . - 18 - . Ashli Jhora, Mana Jhora drain out the western highlands merge into the main stream the Mechi. In the eastern region, Marma NaJa, Manjwa Jhora, Dudhia Jhora, Chenga NaJa drain out the east merge with th~ river, Bala son (Fig. 6). In the north also the drainage systems follow slope towards north and touch the river Rangbang. The Balason river rises from the Lepchajagat Peak on the Ghum saddle and flows south almost parallel to the 88°15' meridian till it reaches the plain -at an altitude of 304.8m and then turns south-east. On entering the Tarai, it divides itself into two channels, one called the New Balason which joins the Mahanadi, the other- river in the district, just below Siliguri and the other, the Old Balason, continues southward and passes out of the district to join the Mahanadi lower down. At the base of the hills the BaJa- son is flanked by three terraces - the first one only a few metres higher than the present riverbed, the second one 6,09m higher than the first and the third 45. 72m higher than the second. There is an excellent exposure of stratified sand and gravel rising to 12.19m on the west bank. The valley of Balason is larger than that of Mahanadi, although the catchment basin does not receive much heavy rainfall as that of the latter. The Mechi river forming the Indo-Nepal boundary rises at an alti tude of 1905m south of the west. facing Rangbang spur of the Singalila range at about 26°55' North, follows through a deep gorge throughout its hilly course an9 descends into the Bhabar tract where the bed suddenly wi den~ to about 335.3m. Below this point, there is a long stretch of loose and water-worn gravel intersected with water channels. Te~races flank the Mechi as well as the Balason at the point where the Singalila slopes abruptly on to the _plains. The Mechi eventually joins the Mahananda (Figs. Z & 6). A transect chart (Fig. 7) has been flrepared to show the relation of variation of relief with that of drainage pattern. - 19 ~ The study of relief and drainage leads to determine the slope of the area which is shown in figure B. The northern portion of the P. S. ad joining to headquarter, Mirik is. more or Jess flat though the height is maxi mum. The water divide area is having a slope of less than 20 percent as calculated from the relief. It has· been seen that the slope is maximum where the land is merging with the boundary rivers. Thus -along both the r.ivers, the Mechi and the Balason as well as Rangbang in the north also, the slope increases ~o more than 50 per cent. The map (Fig. 9) represents different zones of soil that has been worked out during survey in the region. On the basis of the colouration and texture, soils of the region have been Classified as (i) Red Podosol, distributed in the northern part of the area, (ii) Brown Earth, representing the major part of the area, (iii) Ash-Grey soil with association of Red soil, representing a narrow strip towards the southern part, (iv) Whitish--Grey soil adjacent to the previous one in southern part and (v) Grey soil with the association of. Yellowish-Brown soil representing the extreme southern part of the police station. The· soils of the upland is noted to be red and gritty while that of plain is dark and more fertile. Climate : The Mirik and its environs consist of two distrinct tracts, the ridges and the deep valleys of the Himalayas and· the level country at their base. The elevation of the latter is only about 300m above sea-level and the mountains tower abruptly from the plains ·in spurs reaching about 2630m, many of them densely' clothed with forests upto their summits. In a country of such varying topography, the climate also varies from place to place. The climate of t~e Tarai and the lower vaJJeys resembles very much to that of the adjoining districts in West Bengal and Bihar. The hilly tracts in the north show a cool and bracing climate. March to May roughly con stitute the summer in this district. Monsoon lasts till about the beginning - 20 - of October, then with a short gap of a month and a half as the post-mon soon season, the winter appears and lasts till the end of February; The vapour laden monsoon wind first strikes the outer hills which receive high rainfall annually. This gradually decreases in the inner valleys and lower hill slopes. From the earlier meteorological records available in the observa tories at Darjeeling, Bagdogra, in various tea gardens in the region and in Calcutta (Alipore Observatory), it appears that during the period from 1850-1988, the rainfall in the region has been found to decrease in con siderable amount (Tables I &II). There is no doubt that such a decrease in rainfall has affected the ecology of the region and which is reflected by the increase of drought and drying up of a number of hill streams (Jho ras). It is expected that such a drastic decrease of rainfall· has a role on the change of adaptation of various plants in the vegetation. TABLE- I Average rainfall data (in mm) during the period from 1850-1987 in the region of Mirik and its environs (each figure represents the average rainfall of five years) Year 1850-1855 1900-1905 1950-1955 1970-1975 1982-1987 Rainfall 3477.51 3182.62 2671.57 2760.00 2560. QO (in mm) ====== Over the northern tracts of the region, the atn-osphere is highly humid throughout the year, the relative humidities ranging between 90% and 95% during the rainy season.' In the low lying tracts to the south, relative humi dities are slightly less, the driest months are being March and April when the relative humidity varies between 45% and 60%. ' - 21 - TABLE- II Numbe r of rainy days and total rainfall data (in mm) throughout the year of 19BB in Mirik and its environs Months No. of rainy days Total rainfall (in mm) January 8 22. 4 February 3 26.1 March 4 38. 5 April 4 22. 9 May 8 34. 4 June 23 335. 9 J ul y 25 637.9 Augus t 28 715.2 Septe m ber 10 176. 3 October 3 29. 8 November Nil Decembe r Nil Total 116 days 2039. 4 mm ~======~====== During the monsoon season the sky is heavil y ·overcast while for the rest of the year, it is highly or mode rately clouded. C loudiness increases in May. In winte r mornings, lifted fog freque ntly covers the hill y regions. Fog occurs occasiona ll y in the Tarai from December to March. In hilly r egion, fog or mist is ver y com mon in J ul y and August and· is fairl y fre quent in June and September. In summer from Mar c h to May, the heat in the plains and low vc:ll c ys is a s oppressive as in other Sub-Himalayan di stric ts of West Bengal. The mean dail y m aximum temperature 33. 5°C t ouches the highest level in May. The night te mperatures are, however, highe r during the south-west monsoon - 22 - season than that in summe r. In lhe hilly region both day and night temp e ratures a re higher during the ra ins than those in summer. After the with drawal of the south- west m onsoon boll! dn} nnd night LPmprrnl urPs IH'rJlll I o fal l throughout the region, the decrease being more rapid from November. January is the coldest m onth of the year when, in the plains, the mean dail y maximum t emperature is 24. 2°C and the minimum 8. 6°C, the corres ponding fi gure for the highly e levated ar ea (2630m) being 8. 6°C and 1. 9°C. Frosts are fa irly common throughout the cold .season in the hilly part of the region. In association with the passage of western disturbances, cold waves occasionally visit the district between November and early March when the m inimum tempera ture may fall below 0°C, especially in the hi ghly e levated area~ Human population and Biotic influence The growth of the area under study affords the most remarkable instance of the expansion of human population. According to O'Malley (1907) when t he British fi rst acquired the hill territory, it was almost entire ly under forest and what small population it had, had been driven out by the oppression of the petty ruler whom they replaced. The first regular census of Oarjeeling district was carried out in the year of 1871-72 and the result gave a total population of 94,712 persons, the average density of the population being 0. 3 persons/ha and in the subsequent years the population increased tremendously due to t wo main causes - (i) the deve lopment of the tea industry and (ii ) the influx of settle rs to exploit the wastelands of the district. The census at that time showed that the tea garden c oolies and their children accounted for more than two-thirds of the total population. Afte r that rapid expansion was due entirely to the immigration of Agr i cultu ri st~ At that time the forest and the hill top were inhabited by the aborigines (Lepchas) of the country. It was r esolved to keep a certain portion as a reserve for native c ultivators, who flocked into t hi s la nd of promise; so that, with the exception of the forest reserves - 21 - and some trees grown along the slopes of hills, the forest has been largely cleared away and the land was brought under cultivation. The bulk of the population was Nepalese, the continued immigration from Nepal being due to pressure of the population on the land in the eastern portion. They bought up good lands or clear holdings from jungle. The Lepchas li ved in the more thi ckly populated parts of the d istrict. Now-a-days, the popula tion of this area is exceedingly heterogeneous, i. e Nepalese, Lepchas, Bho tias, Tibetans. Besides, Ma rwari merchants, Bengali officials, Punjabi tra ders and even Chinese carpenters are also present. According to the Census (1961 ), the density of human population has been noted to be 1. 3 persons/ha in 1901 attained 2. 2 persons/ha in 1961 in Mirik. In 1988 it has been noted that Mi rik with its adjoining villages has a dens ity of 4 to 6 persons/ha. The fi gure 10 shows that the villages in south-central part of Mir ik i.e. the villages like Tingling T. G., Patong T. G., New Falodi T. G . etc. have the density of 1 to 3 persons/ha. The villages at forest covered southern region is totally uninhabited. The Ma rma T. G.village and Phuguri forest are sparsely populated having less than 1 person/ha. There is no doubt that due to rapid spread of urbanizat ion and in crease of human population (Fig. 11 ), the biotic factors play a very important role in moulding the vegetation. The growth of human population in Mirik P.S. has been compiled from the data in various literature avai lable in the region from 1901 to 1981 and which has been shown in the figure 11 . The emergence of natural f lora is out of question in the thickly populated ;-Jreas Most of the plants introduced by people for various reasons have been natu rn i i!C'd nncl with the progress of time have become wild in a steadfast fa shion. The plants that prove to be obnoxious weeds in the cultivated areas have been controlled by constant vigilance and are cleared every year. Moreover, due to inc rease of domestic animals' graz ing influe nces t he vege tation re markably. Destruction by fire is anothe r problem in this area. Moreover, construc tion of new houses and other similar projects also c heck the na tural growth of the vegetation. - 24 - Landuse : Conservation of nat ural resources in the br oadest sense has always been one of the most importa nt applicat ions of ecology. According to Odu•n (1971) when the huma n populat ion of a n a rea is small, poor landuse m ay a ffect only t he people who a re guil ty of bad judqnw nt. As the popu- la t ion increases, ho·Never, everyone suffe rs when land is im pr operl y used, because ever yone eventually pays for r eha bilita tion or, as is now too often t he c ase, ever yone suffe rs a permanent loss of resources. A vary signifi cant feature recorde d here in t he study of landuse is the exte nsive existence of tea ga rde ns whic h a re re prese nted in figure 12. These pl a ntations appear to have been mere ly experimenta l plots, but by t he year 1856 the indust ry began to be developed on an ext ensive scale, specia ll y on the lower slopes, as it was be li eved that e levation of Darjee ling was t oo high for t he plant t o be very productive. Accor ding l o t he account of O' Malley (1907) t ea plants had t:J een sown and ra ised by the end of t hat year a t Kurseong fl a ts, bet ween Kurseong and Pankhabari by Capt ain Sam le r, the Agent of t he Darjeeling Tea Concern. At the same time Government endeavoured to supplem ent the e ffort of the pioneer of the industry by di stributing tea seed among t he na tive c ultivat ors. The deve lopm ent of the indust ry in the hills had been even more r a pid as the suit abili t y of the soil a nd c lima te t o the growth of tea became apparent. Most of the ar eas in the region have been pla nted wi th the China vari ety whic h was for many years conside red the only kind suited for the pro duction of f ine tea. Of la te years, the variety known as "Assam indigenous" has been m uch in favour, and it is certa inly capable of produc ing the very f inest t eD. The establishment of tea gardens for obvious reason ha s checked the natura l growt h of vegetation. The figure 13 a lso shows that the c rop land occupies a very little area in comparison to tea gardens. The distri bution of crop land is mostly in t he nor the rn part of the region and t he r est are distribut ed most irre gularly throughout the area. Fig. 14. Mirik Lake with plantation of Cryptomeria japonica (L.f.) D. Don in the background. Fig. 15. Mirik Lake Garden. Fig. 16. Mirik Bazar - 2 '1 - Ve getation t ypes : The vegetation and 1'\'o lc )(!~ of Darjeeling district, West Bengal, is rather broadly known through the accounts of Hooker (1854), C hampion (1 936), Calder (1937), Puri (1960), Rao & Panigrahi (1961) a nd Legris (1963). But references particularly to the vegetation of Mirik and its en virons are scanty. Hooke r (1854) has given picturesque word-portraits of the vegetation in the hills, but these a re scattered, and laborious effort is involved in piecing together the full spread of his vegetation picture. The c lassification of vegetation t ypes, especially with regard to the tropical areas is in a n unsatisfactory state, m a inl y due to the floristic com plexi ty and variations in botani cal composition, even within a small area. C hampion's c lassif ication of vegetation t ypes (1936), and also those of Puri (1960), were more general than specific, pertaining to the entire Indian subcontinent. Its inadequacy is fe lt when a small area is taken up. Rao & Panigrahi (1961 ) classifie d t he vegetation t ypes of t he Eastern Himalaya inc luding Bihar and Orissa on the basis of altitude and latitude. However, the data avai lable to them were only frcrr, c-rrt a in selected a reas under study. The voluminous work of Legris (1963) dealing with Indian vegeta tion c ontains m eagr e data on the region under study. According t o Gomez -Pompa (1967), the term 1 'Tropical Rain Forest" was first coined by Schimper (1903) and later used by many authors includ ing R ic hards (1952), has no real meaning, as it is too broad, encompassing tropica l evergreen and semi -evergreen, sL6 1r opic-e~ l c~ \ erl]fPen and semi-ever green as well as temperate forests. The present study of the flora o f Mirik and its e nvirons has m3de it possible to obtain a Tl::Jre intimate gli mpse of the vegetation and its vari ous forms. The c lassification presented here is mainly based on phy siognomy and s tructural h'ill 1m~; of the plant specia lly in re lation to the altitude of th ~ hill a nd c lima tic condition. Thus, four vegetational zon~s have been proposed a nd whic h are represented in the following Table Ill. - 26 - TABLE - III Major Vegetational Zones in Mirik and its e nvirons in Darjeeling district, West Bengal C li matic Zone Altitude in Vegetational Zones metres Tropical 100-500 Tropical Deciduous Sal forests (Plantations) 500-1200 Tropical Evergreen Subtropical 1200-1800 Subtropical Evergreen Te mperate 1800-2630 Temperate Mixed The distribution pattern of the zones of vegetational types in Mirik and its e nvirons has been represented in figure 13 which shows the distri bution of forest area covering the southern part of the region a long the river Balason in the eclstern zone. Patches of wasteland can be seen along the Balason rive r, Rangbang river and parts of Mechi river near the junction of Mana Jhora. Scrubs are seen in the northe rn part of the region near crop-land. I. Terrestria l Vegetation A. Primary Vegetation 1. Tropical Deciduous Sal forest : This zone li es be tween a lti tude of 1 00-500m and is characte rised by heavy rainfall and the relative humidity is about 60% to 80%. SCJ I S h~ robust a' is gregarious on ridges and spurs having we ll dr ained soil and is mainly confined to the southern and east ern slopes of modera t e gradient. It grows as pure or mixed with other species, suc h as, Tectona gra ndis, Schima wallic hii, Mallotus philippi nens is, Litsea sali ci folia. Among the shrubs, Clerodendrum brac teatum, ~ viscosum and among the li anas Dioscorea bulbifera, !2:_ glabra and Smilax perfol ia ta are common in the forests. In this zone Amaranthus spin osus, Lantana camara, Sida acuta and Eupatorium odora tum form thickets on sunny forest paths. - 27 - 2. Tropical Evergr een Zone : Tropical evergreen vege tation occurs upto an a ltitude of 1200 m above sea-le vel. This zone re cei ves heavy rain fall and the relative humidity is usually above 80o/o. Winter is m ild, followed by a comparatively dry season from F e bruary to April. The sloping area ensures qui c k drainage. One striking f eature of these tropical forests is the extremely mixed dominance, so that no singl e tree specie s can be marked as dominant. Some of the component trees may shed their lea ve s indi vidually every year, but no tree remains c ompletely leafl ess for any part of the year. Smooth bark, plank buttresses and large glossy thick leaves are characteristics of the trees of this a rea. The outstanding component species of this zone are : Castanopsis indica, ~ tribuloides, Syzygium tetragonum, Ficus auriculata, F icus semicordata, Macaranga pel t CJ I a. Symplocos glomerata, ~ panic ulata, Alcimandra _calhcarli i, l laeocarpus lanceifolius, Lithocarpus fenestratus, Vitex negundo and occasionally Vernonia volkameri ifolia. Although sunli ght falls directly on the uppe rmost canopy, this is soon filtered off by the successive tree canCJ pies and a sort of gloom preva ils inside the for est~ Nevertheless, there is a dense herbaceous ground layer, wi t h Triumfe tta rhomboidea, Hedyotis auricularia, Ophiorrhiza nutans, Begonia spp., Pilea umbrosa, Le ucas mollissima, C rotalaria a lb ida, Amorpho phalus bulbifer and Hedychium spp. Among shrubs Mussaenda roxburghii and C lerodendrum spp. are a lso found here and ther~ The climbing herbs Diplocyclos palmatus, C issampelos pare ira and climbing shrubs like Jasminum ample >.. ic aul e. - ~ nepalense and Smilax lanceifolia are not un co!Tlmon in this zone. There are also num ~ rous species of ferns, Se laginellas, Lycopodiums and fungi. Near streams, wate r-fa ll s and moist marshy places, Impatiens tripetala grows gregariously in la rge populations. On we t rocks and boulders in fairly sunny places, Elatostema rupeslrc, assoc iated with Peperomia pellucida, grow profusely. A few spec ies of li anas like Cala mus acanthospat hus and Derris monticola can be seen in these forests, usually c limbing up to the top-most canopy of trees. - 2H - Among the less woody climbers which are often gregarious in forest borders and in fa irly sunny forest openings, the outstanding species are Thunbergia coccinea, Gouania tiliaefolia, Dioscorea spp. Piper thomsonii, Hoya edenii and H. linearis a r·e also very commJn, climbing over trees, by their roots. Mucuna macrocarpa, a large woody climber, is not uncommon in t his zone. The epiphytic flora is not rich as compared to the subtropical zones. Most of t hem a re fe rns, Selaginellas and Lycopodiums. Among the flowering plants, which are by no means gregarious or abundant, mention m3y be m 3. Subtropical Evergreen Zo ne : Subtropical evergreen forests occur between a ltitude 1200-1800m. This zone is characterised by very heavy ra infa ll, moderate ly cold temperature and high humidity spread over most of the year. Being c loudy for most of the t ime, incid ent sunli ght is Jess. There is not iceable differ ence between summer a nd winter, ground frost s being common in December-January. These woodlands of climatic climax forests are seen scattered in deep sheltered valleys and occasionally in plain areas. The trees are gene rally of a bushy appearance and shorter than those in the t ropical zone. The leaves are usually s imple, smaller in size and often toothed, but at the same t ime firmer a nd more leathery. Plank buttresses a re rare. The tree layers are less distinguishable into strat a. The reduction in tree strata, coupled with lowering of canopy is associated with the increase in altitude. The shrubby and herbaceous layers are well marked. These moist-loving forests are characterised by the rarity of lianas and the predominance of epiphytes. Mosses and li verworts are abundant. Undergrowth is so dense as t o make it necessary to c lear the way at ever y step, when traversing - 29 - these forests. The forest floor is soft a nd dark with humus detritus, g1vmg it a cushion-like texture, where different types of mosses, fungi, Balanophora and orchids grow. The floristic composition exhibits exceptional richness in species which are different from those of the tropical evergreen, although some of its components are generically and even specifically identical with lowland species. In its great multiplicity of trees, these forests agree with the tropical forests, but a single species or a group of species showing domi nance is much more common. The usual trees of the uppermost storey are Lithocarpus elegans, Engelhardia spicata, Exbucklandia populnea, Prunus napaulensis, P. cerasoides, Michelia doltsopa, M. velutina, Rhododendron arboreum,Alnus nepalensis, Betula alnoides, Castanopsis hystrix, C. tribuloides, Litsea elong ata, Ficus hookeriana and Alcimandra cathcartii. Occasionally Schima wallichii, Mallotus philippinensis and Castanopsis indica can also be seen in the forests of this zone. This storey of tall trees is discontinuous and scattered. It is also noticeable that in many places these trees are smaller in stature a nd merge w ith those of the second storey, composed of Viburnum cylindricum, Y..:_ erubescens, Quercus glauca, Euonymus hamiltonianus, Lindera neesiana, Helicia nilagirica, Daphne involuc rata, Styrax serrulatum, Symplocos racemosa, ~ dryophila, ~ theaefolia, Acer oblongum, ~ laevigatum, A. thomsonii, Schefflera elata, Debregeasia wallichiana, Vernonia volkame riifolia and Ligustrum confusum. Tree ferns are very common in these forests. In deep valleys, as well as in sheltered slopes of hills, where wind velocity is less, the trees grow taller and in these forests large lianas like Tetrastigma serrulatum, T. rumicispermum a nd T. bracteolatum climb over the trees to the upper most layer. The re are also many large scandent shrubs which do not reach such a height. These are Embelia floribunda, ~ vestita, Toddalia asiatica and Elaeagnus conferta. Amongst the shrubby species Dichroa febrifuga, Sarcococca hooke riana, Melastoma malabathricum, ~ normale, Osbeckia stellata, Oxyspora paniculata, Baliospermum ca!ycinum, Neillia thyrsiflora7 Maesa - j[l - chisia, Mycetia longifolia, Camellia kissi, Eurya acuminata, Boehmeria ~ yphylla, Ficus sarmentosa, Lyonia ovalifolia, Clerodendrum colebrookianum, Ardisia mac rocarpa. Psychotri a cn·alica, Mussaenda macrophylla,Rubus spp. and var ious species of Araliaceae and Acanthaceae are common. Among the edges of these forests and in fairly open places, Jasminum humile, Solanum indicum, ~ torvum, ~ vi arum, Polygala arillata, Sida rhombifolia, Urtica a rdens, U. dioica and Urena lobata, Achyrospermum densiflorum, Colg..trunia cocc.inea, Phyllanthus parvifolius1 Pogostemon tuberculosus can be seen. The forest floor is densely covered with fungi, mosses, ferns, Selagi nellas, Lycopodiums and various herbaceous angiosperms, represented by Anisadenia saxatilis, Adenostemma lavenia, Myriactis nepalensis, Senecio cappa, ~ wall ichii, Begonia hat acoa, B. megaptera, B. palmata, Impatiens spp., Chirita macrophylla, C. pumila, Didymocarpus albicalyx, D. podocarpus, Loxost igma griffithii, Lysionotus serratus, Te ucrium guadrifarium, Viola pilosa, V. thomsonii and various species of Zingiberaceae, Commelia'laceae and Araceae. On rocks and boul ders near streams and moss-covered cliffs, Ela t ostema platyphyllum, E. rupestre, E. sikkimense, Pilea anisophylla, ~ bracteosa, P. t e rnifolia, P. umbrosa, Girardinia palmata, Sarcopyramis napalensis, Begonia hatacoa, Impatiens spp., usually grow profusely. Many terrestrial orchids, such as, Anoectochil us spp., Arachnis spp., Calanthe spp., Goodyera spp., Liparis bit uberculata, _'=._ nervosa, Malaxis. khasiana, Thunia alba, Zeuxine goodyeroides, Phaius spp., etc. are common in shaded humus covered soil inside the forest. Root parasite like Balanophora dioica is also comm:m. There are many species of c limbe rs spreading over bushes and shrubs and the usual ones are species of Clematis, Dioscorea, Smilax, members of Menispermaceae, C ucurbitaceae and occasionally Holboellia lat ifoli a. Along the borders of forests spreading over bushes, thick masses of Parana race mosa, Rubia manjith, Trichosanthes spp., Paederi.a fo etida and Passi flora napalensis are dominant. Among the large climbers Chonemorpha fra grans and species of Trache lospermum can also be mentioned - 31 - Innumerable species of orchids, mosses and ferns also harbour on the branches of the trees in the forests of this zone. The epiphytic orchid flora in these forests are the richest in the area, with almost every other tree forming a veritable hanging garden of orchids and ferns. Species of Aeschynanthes, Agapetes, Piper, Hoya a nd Medinella are also very common. Many Loranthaceous hemiparasites like Helixanthera parasit ica, Dendrophthoe falcata, Viscum album a nd V. a rticulatum can also be seen in the forests of this zone. 4. Temperate Mixed Zone : This zone lies between altitude of 1800-2630m and receives heavy rainfall and is characterised by the prevail ing high humidity and very cold temperature. Temperate deciduous forest does not occur in this region as a conti nuous vegetational zone, it is usually found only in small patc hes on the northern or eastern slope in the evergreen oak and t he Rhododendron forest zones. Rhododendron, as an individual tree, is found even at an elevation of 1200 m in tropical or subtropical evergreen forests but the actual forest of Rhododendron is found in this zone and continues to the timber line (Hara, 1966). The different species of Rhododendron found in this zone are Rhododendron arboreum, R. grande, R. gri ffi thianum, R. falconeri, etc. which a re also associated with other trees like Magnolia campbelli. Miche ~ doltsopa, Acer campbelli, A. hookeri, A. sikkimense, A. pectinatum, A. caudatum, Eriobotrya hookeriana, E. petiolata, Prunus undulata, Actinodaphne sikkimensis, Neolitsea cassia, Litsea elongata, Cinnamomum bejolghota, Photinia integri folia, Daphniphyllum himalense, Quercus pachyphylla, Q. semecarpifolia, Brassaiopsis alpina, B. mitis and Symplocos spp. Among the climbing shrubs Jasminum dispermum and the species of Lonicera and Senecio are fairly common in t he forests and among the epiphytic shrubs, the species of Pentapanax and Vaccinium are also common in this zone. Berberis insignis, Mahonia acanthifolia, M. napaulensis, Gaultheria griffi thiana, G. nummularioides, Daphne bholua, Pteracanthus a latus, P. boerhaa vioides, P. urophyllus, etc. a re common shrubs in this zone. The c ommon herbs in the regions are Lysionotus serratus1 Chirita macrophyll a, Didymo- carpus albicalyx, Sanicula e lata, Selinum te nuifolium, Primula peliola ri s, - 32 - Anaphalis spp., Gynura cusimbua, Begonia spp., Arisaema concinnum, A. consanguineum, Viola thomsonii and various species o f Zi ngiberaceae and Commelianaceae. Ferns,epiphytic m osses and lichens are qui te luxuriant on rocks and trunks of trees of the forests. Species of Selaginella and Lycopodium are also found everywhere in this zone. B. Secondary Vegetation : There is a succession of several edaphic formations, in many dist urbed spots within the primary forests. These can be observed in various stages of development depending on the extent of disturbance and the span of time during which the succession of secondary vegetation is taking place. These may include scattered herbaceous growth of several weed species or homogeneous grasslands or woody vegetation of shrubs, dwarf trees or even quit e t all trees, e ither belonging to several species or sometimes to a single species. This secondary vegetation developed as a consequence of the disturbance of primary vegetation can also be partially and para- llely classified into 1. Tropical Deciduous and Evergreen Zone, 2. Subtropical Evergreen zone and 3. Temperate Mixed Zone. 1. Tropical Deciduous and Evergreen Zone : The herbaceous type forms the first succession stage and among the pioneers, mention may be made of Cassia tara, f:_ occidentali s, Mimosa pudica,. Euphorbia hirta, Oxalis corniculata, Sonchus arvensis, Eupatorium odoratum and various grasses like Garnotia stricta, Paspalum conjugatum, Oplismenus burmannii and g_ composi tus. In due course, certain shrubby species make their way and invade such herbaceous regrowth. Among them the usua l ones are Lantana camara, Desmodium multiflorum and grasses like Thysanolaena maxima. Subsequent ly, such places may e ither remain purely shrubby or, if destroyed by frequent fires, may develop into grasslands or in places where the soil layer is thick and where frequent fires do not occ ur, may develop into secondary forests. In grasslands the common SJX'CIPS of grasses are Imperata cylindrica, Chrysopogon aciculatus, C. gryllus, Digitaria cruc iata, D. longiflora, - 53 - Dicha nthium a nnulatum, Brachi aria distachya, Panicum psilopodium and Saccha rum spontaneum. These grasses a re usually associated with herba ceous plants like C rot a laria bialat.a, _Ca rdamine scutat a, Commelina paludosa, Cyanot is c rist at a1 C. vaga, Cyperus spp., Mariscus aristatus, M. cyperinus, Kyllinga brevi folia, ~ nemorali s and Mosla dianthe ra. Very rarely, such places may develop into bamboo forests, wi th the most common species li ke Arundinella l?erqalensis and Ba mbusa pa llida. If the vegetation develops into secondary forests, t rees like Casta nops is indica, Mallotus philippinens is and Sy mplocos paniculata become pre dominant. The undergrowth in these forests comprises elements like Sida rhombifolia, Age ratum conyzoides, Chenopodium a mbrosioides, Jatropha c urc as, Hedychium spp. a nd C le rodendrum spp. The common climbers are Smilax lanceifolia, ~ perfoliata, Mukia n-eceraspata na and Cyclea bicristata. 2. Subtropical Eve rgreen Zone : The main types of secondary vege ta t ion in this zone a re the tree a nd shrub Savannas. These formations are def ined as grasslands with scatte red trees a nd shrubs. The grasses of these for mations a re normally 1 m high, often reach ing upto 3-5 m a nd form a continuous layer domina ting over a lower strata of herbs and small grasses. These grasslands a re often burnt during dry season. The trees, whe rever t hey occur in scattered. patches, have thin round canopies permit t ing suffic ient light for the sun- loving grasses to grow we ll under the m, a nd in many places where the soil is reduced to li thosols, the ecology in such places is not conducive to the development of trees a nd in those places pure for mations of grasses develop. Wherever the t op soil is deep, many a rborescent fo rms develop, forming t ra nsilion to woodlands and these play an important role in the formation of trees and shrub Savannas. Under long term.favourable conditions, a nucleus of these tree species can be seen ma intained at certain places, which are precursors for mature well developed secondary forests. Among the tall grasses, the common ones are Agrostis pilosula, Apluda mutica, Dichanthium assimile, Erianthus longisetosus, . ~ rufipilus, - 34 - Impera te c ylindrica, Mi scanthus n:palensis . . Phragmites karka and Thysano laena rmxima. Among the grasses of lesser he ight, me ntion may be made of Eragrostis nigra, Eulalia le sche na ultiana, Digit a ri a spp., Alloterops is semialata, Axonopus c ompressus, Garnotia stricta, Isachne albe ns, Micro stegium nudum M. vimine um, Mi sca nthus nudipes, Oplismenus W etc. Among smaller grasses Poa annua and Eleusine indica sometimes form pure patches in many places. The common shn..bby and herbaceous plants assoc iated with t hese grasses are Piptanthus nepalensis, Neillia thyrsiflora, Rubus spp., Buddleja asiatica, lnula spp., Hype ricum patulum, H. japonicum, H. elodeoides, Urena lobata, Smithia ciliata, D esmod ium spp., Bide ns pilosa, B. biternata, Anaphalis adnata, A. contorta, A. margaritacea, Erigeron karvinskianus, Young ia japonic a, Emilia sonchifolia, Conyza spp., Duchesnea indica, C: linopodium umbrosum, C ra niotome furcata, Rumex nepalensis, Artemisia spp., Elsholtzia strobilifera, Cerastium fontarun sub. sp. triviale, C. glomera tum, Stellaria sikkimensis, S. medi a, P lantago e rosa, Neanotis spp., Origanum vulgare,Mazus spp., Agrimonia pilosa, Astragalus sikkimensis, A. st ipularis, Pot e ntilla spp., Gera nium nepalense, Hydrocotyle himalaica, Oenanthe thomsonii, Dichroce phala integrifolia, Galinsoga parviflora, Gnaphalium luteoalbum, Galium asperifolium, Rorippa nasturtium-aguaticum, Oxalis spp., He miphragma he terophyllum a nd species of Cyperus, Fimbristylis, Hypoxis, Amisc hophacelus and Cyanotis. Eupatorium ·adenophorum, a Cen tral American annual-perennial he rb with white flowe r-heads usually occupy suc h places much earli e r a nd est ablishes very well, spreading over bushes and scrubs forming gregarious carpets. It is also interesting to note that in rore places of t his zone Ac hyranthes bide ntat a and Pupali a lappacea forming scrub jungles where othe r vege t ations ~re e ntirely lacking. The common trees met with in these grasslands a re Castanopsis tri buloides, Lithocarpus e legans, Prunus cerasoides, Acer spp., Exbucklandia populnea, Alnus ne pa le nsis and F icus spp. Bamboo forests are also best developed in this zone, espec ially at lowe r e levations. Ofte n large clumps of bamboos could be seen in patches - 35 - a long the borders of forests and in c leared forests. The common species are Arundinaria mati ng, Arundinella nepale nsis and De ndrocalamus hami ltonii. Among the orc hid fl ora some orc hids growing along the grassy slopes are common. These are Anthogonium grac il e, Sat yrium nepalense, Bulbo phyll um striatum, Mala xis acuminata, C re mastra appe ndicula ta, Galeola falcone ri and various spec ies o f Habenaria a nd Herminium. 3. Temperate Mixed Zone : The seconda ry vegetation in this zone is not well m arked as the previous zones. Vast are as of Temperate Zone are rea lly occupie d by primar y fore:;ts, only in a scattered form the secondary vegetation developed. On gradual ext ension of altitudes, pri ma r y veget ations are disturbed in a lower de gree. If t he vege ta tion develops into seconda ry forests, a fe w pat ches of trees like Daphniphyllum himale nse, Quercus pacll yph) !Ia. Cast a nopsis hystrix, C. tribuloides a nd even the species of Symplocos and Acer ca n a lso be seen. Species of R ubus are the chief unde rgrowth in these forests a nd the c limbing shrubs like C le ma tis buchana ni ana and Tre utle ra insignis a re commonly found in this zone. The herbaceous plants me t within this zone are Fra garia nubicola, Anemone rivularis, A. vitifolia, Adenoste mma lavenia, Artemisia japonica, Edga ria da rjeelingensis, Geranium nepale nse, Lobelia pyram ida lis, Codonopsis infla ta, ~ javanica, Begonia megaptera, ~ pa lmata. Among the grasses Panic um khasianum, Agrostis micrantha, Er ianthus sikkimensis, Miscanthus nepale nsis, Poa a nnua a nd e ven Eragrost is nigra a re common in this zone. Species of Carex, Fimbrist ylis and Cautleya can a lso be seen in moist forest floors, a long the fo rest borders and in shady places of ravines. Among the bamboos Arundinaria mali ng is only the common species in this zone. - 36 - IL Marshland Vegetation : While studying the terrestrial vegetation in Mirik and its environs, the marshland vegetation also parallely observed in the respective zones and are dealt with separately below. In Tropical Zone the aquatic vegetation is very poorly developed. Along the edges of ditches and water courses marsh-loving plants like Commelina paludosa, C. sikkimensis, Kyllinga brevifolia and species of Cyperus usually occur in isolated populations. In some marshy areas Colo casia esculenta grows in large populations. In Subtropical Zone there are many spots where water-logged condi tions facilitate the development of marshy grasslands, where Acarus calamus, Colocasia esculenta, Fimbristylis dichotoma, F. miliacea, Eragrostis gange tica, ~ unioloides, Isachne albens, Drosera peltata and Oenanthe javanica grow profusely. Schoenoplectus mucronatus often grows in large popu- lations in marshes, along the stream sides and periphery of lake in the re gion under study. Along the margins of lake, monsoonal ponds, ditches and watercourses, marsh-loving plants like Carex filicina, Kyllinga brevifolia, Juncus l eschenaulti~ Pycreus diaphanus, Potamogeton spp., Arthraxon quartinianus, Commelina sikkimensis, Cyperus spp., Garnotia stric ta, Setaria glauc~ Paspalum disti&um, Microstegiurn vimineum, Polypogon fugax, Utricularia striatula, Mimulus nepalensis, Rorippa nasturtium-agua ticum, ·Hypericum elodeo i~and Polygonum hydropiper usually grow in large populations. In Te mpe rate Zone many of the marsh-loving plants are identical with those of the subtropical zone. So, only those species needs mention here whic h are common and abundant in the region. These a re Fimbristylis dichotoma, F. miliacea, £.ycreus diaphanus, Oenanthe javanica and Pimpinell a s ikki mensis. - )7 - IlL Cultivated and Other Useful Plants The physical configuration of the region makes agricultural condi tions extremely diverse. It may be broadly divided into two parts : the mountainous region to the north forming its greater part and the alluvial plain to the south known as the Tarai. While the Tarai contains stretches of alluvia l ooil admirably suited for rice (Oryza sativa) cultivation, there are a lso poor sandy tracts which cannot be brought under plough. Nothing except scrub jungle grows on the stony inclines, but the land is of good fer tility on the gentler slopes and in the upper valleys. Formerly, the system of cultivation was that common to nomadic tribes which is locally known as "jhuming". The word Mirik itself has its meaning, the burnt hill, "mi-rek" being the Lepcha name for the burning of jungle. The rude hill tribes used to burn down the jungle and grew their scanty crops on the land thus cleared. This process is no longer in vogue now-a-days. Terraces have been cut out in the hill side on easy slopes within reach of some stream or spring, the water of which is ingeniously diverted into tiny fields. The fertility of land on a hi ll side depends largely on the aspect. An eastern or southern aspect is best, as such land gets the benefit of the morning and midday sun, while a northern aspect is cold and sunless. The staple food crops in the region under study are Oryza sativa and Zea mays, which are cultivated with considerable effort in different regions. Recently, high-yielding varieties of these ~raps developed in the experimental farms of the district with different code names, such as, "Kalimpong-1", "Kalimpong-Il", "NC-678", "Taichung_ Native-I" for Oryza sativa a nd "Ganga-101", "Himalayan-123" for Zea mays are now popular among the farmers. Some of these varieties are now being sown in other districts of West Bengal as well (Source : District Agricultural Officer, Dar jeeling). Apart from t f--nse food c rops, various vegetable crops in scattered plots and kitchen gardens are also raised. Of these the common ones are Sechium edule, Lycopersicon lycopersicum,Solanum melongena, S. tuberosum, Oaucus carota, Raphanus sativus, Avena sativa, Cyclanthera pedata, Pisum sativum and Lablab purpure us. The important spice yielding plants like Amomum subulatum, Zingiber offirirwle and Capsicum frutescens are c ulti- vated in diffe rent areas. Among these, Amomum subulatum is a very - 58 - valuable crop grown upto an altitude of 1700 m above sea-level. It requires shade, moderate warmth, a good supply of irrigation water and ric h soil. Saccharum officinarum a nd Ricinus communis are also grown in the lowe r elevations. The last crop of any importance calling attention is Ele usine coracana, from the seed of which the mild native beer is obtained Fruit orchards and t ea gardens are scattered throughout the valley and hill slopes in the region unde r study. The common .commercially impor tant fruit plants in the orchards are Citrus aurantium var. aurantium, C. medica, Prunus persica and Pyrus connunis. Among plantation crops, Camellia sinensis is a nother most important and common Crq:l in the region. The ra infall of the district, although varying from place to place, is on the whole favourable for the growth of this beverage-yielding plant. Some of the shade plants that are c ultivated in the tea gardens are Albizia chinensis, Indigofera stachyodes and Erythrina a rborescens. The noteworthy ornamental plants that are cultivated along roadsides and in gardens and publi c parks are : Hydrangea hortensea, Sambuc us adnata, ~cana den s i s, .?:.._ hookeri, Abutilon indicum, Acacia mearnsii, Agave ame ri cana, Dracaena angustifolia, Spiraea bella, ~ cantoniensis, Salix babylonica, Hibisc us mutabilis, H. rosa-Sinensis Dahlia excelsa, D. imperialis, Deutzia c re nata, Pyracantha crenulata, Ligustrum lucidum, Catharanthus roseus, Solanum jasminoides, Digitalis purpurea, Fumaria par viflora, Iberis amara, Viola tricolor, Dianthus c hinensis, Rosa indica, Biden.s forn:'osa, Helianthus annuus, Tagetes erecta, ~ patula, Zinnia elegans, Bellis perennis, Calendula officinal is, Linaria bipartita, Antirrhinum majus, Salvia leucantha, .?:.._ splende ns, Cotoneaster integrifolius, C elosia arge ntea, Gomphrena globosa, C hrysan themum spp., Zephyranthes carinata and Hemerocallis fulva. Duranta repens, Jatropha curcas and Prinsepia ut il is are usually culti vated as hedge-plants. Many wild plants are use d by local people as vege tables. The leaves or young shoots of Stellari a media, Gonat anthus humilus, Sonc hus a rvensis, - 39 - Pol ygonum molle, F agopyrum esculentum, Oxalis corniculata, Sauropus and rogynus, Ela l oslema platyphyllum, Girardinia palmata, Laportea termi nalis, Dr ymaria diandra, tubers of Amorphophallus bulbifer and Colocasia escule nta are often cooked with meat and fi sh. F ruits of many wild plants are eaten by local people and among them me ntion m ay be made of Toddalia asiatica, Parthenocissus semicordata, Tetrastigma spp., Duc hesnea indica, Eriobotrya dubia, Rubus spp., Sorbus cuspidata, Eugenia kurz ii, Syzygium tetragonum, Agape tes serpens, Ardisia macrocarpa, P hysalis peruviana, Solanum indicum, ~ nigrum, Litsea cubeba, Hel ic ia nilagirica,Elaeagnus conferta, Pyrularia edulis, Debregeasia walli chiana, Ficus auriculata, ~ oligodon, F. semicordata, Morus australis, Casta nopsis hystrix, C. indica and C. tribuloides. Fruits of Euodia fraxinifolia, and Zanthoxylum nitidum are a lso used for the preparation of "Chutney" by the local hill people. Leaves of Camellia kissi and seeds of Borreria articularis are sorne tirres used by t he paharias (hill people) as a substitute for tea and coffee respectively. The region ~nde r s tudy owing to its location, topography, etc. is quite rich in medicinal plants. There is ample scope for introduction and c ultivation of several useful indigenous a nd exotic species which are re quired byj the Pharmaceutical and Phytoche mical firms of West Bengal and which have already been planned for their cultivation and propagation from comme rcial point of view. Such exploitation of indigenous plants for medi cinal purposes would be ver y useful for economic growth of the country. Many species like C issampelos pareira, Berberis chitria, Polygala a rillata, ~ c rotalario ides, Drymaria diandra, Schima wallic hii,Glycosmis arborea, Celastrus paniculatus, Gouania tiliaefolia, Rhamnus napalensis, Rhus spp., Crotalaria albida, Smithia sens itiva, Cassia spp., Potentilla fulge ns, Melastoma malabathricum, Osbeckia nepalensis, Diploqclos ~ matus, Trichosanthes tric uspida t e, Valeriana hardwickii, Hydrocotyle - 40 - himala ica, Bidens pilosa, Conyza canadensis, Eclipta alba, Taraxacum offi cinale, Rhododendron arbor eum, Paederia foetida, Symplo cos racemosa, Heliotropium indicum, Swertia chirayita, Lantana camara, Vitex negundo, Solanum nigrum, Elsholtz ia blanda,Amaranthus spi nosus, Chenopodium ambrosioides, Rumex nepa lensis, Lindera neesiana, Dendrophthoe falcata, Juglans regia, Hedychium spicatum, Dioscorea bulbifera, Ophiopogon inter me dius, Acarus calamus, etc. well known for their medicinal value, grow under natural conditions in different vegetational zones under study. During the present studies an attempt has bea n made to present the data on the medic it:l a l plants of the district, particularly with reference to those plants which a re medicinally used by the local Adivasis (Tribes). Local Adivasi practitioners and other plant collectors trained in that field are often seen collecting the roots, barks, leaves, fruits,seeds, etc. of various species of medicinal importance like Dichroa febrifuga, Ageratum conyzoides, Artemisia ni lagirica, Emilia sonchifolia, Achyranthes aspera, Viscum a lbum, Urtica ardens, ~ dioica etc. The close relationship of several useful plants, particularly of the medic inal value with the Adivasis and the possibility of building up better economy after introducing them to cultivate systematically selected medicinal plants on large scale in their natural forest zones could be developed as an interesting basis for the future Ethnobota nical s tudies of this ar ea. There are also many types of natural fibres used as ropes for build ing huts, carrying baskets and for other purposes. Among the common plants which yield fibres are Sida acuta, ~ rhombifolia, Urena lobata, Tri umfe tta rhomboidea, Boehmeria platyphylla and Debregeasia longifolia. The forests of the region under study with their rich vegetation harbour a number of timber plants which a re of immense economic impor tance. The climatic conditions and location of the district support the growth of the timber yieldinCl trees like Shorea robusta, Tectona grandis, Magnolia campbellii, Michelia doltsopa, Sloanea dasycarpa, Acer campbelli, A. laevi gatum, Engelhardia spicata, Alnus nepa lensis, Que rcus lamell osa, Q. leuco trichophora, etc. which are used for house-building and also for making - 4 l - furniture, tea-boxes and agricultural implements. It is also interesting to note that recently the local Forest Di vision has taken different progressive plantations programme for the timber yielding trees like Shorea robusta, Tectona grand is, Cryptomeria japonica, e tc, a mong which Shorea robust a plantations are not growing as fast as those of Tectona grandis and Cr y ptomeria japonica (Source : Divisional Forest Officer, Darjeeling Division). SUMMARY In connection with some ecological observations on Mirik and its environs in Darjeeling district, Mirik, which is derived from the term "mi-rek" bein g the Lepcha name for tre burning of jungle and which is the headquarter of the P. S., now-a-days has its geographical position at 27°3'N. la t. and 88°16'E.long. Boundaries and drainage system have been worked out to observe that Balason and Mechi are the two main rivers in the region under study. The courses of different branches and tributaries have a lso been marked out. Mirik is observed to be situated on a ridge at an elevation of 1700m above sea level. The map of the Mirik lake has been prepared to cover 143000 sq.m having the mean height of 1580m above sea level. A topographic section from the highest e levation of the region to the level of Balason river valley with the limits of erosional surface has been prepared. In this connection less than 700 m elevation shows the lower erosional surface, 700-1 DOOm, the middle erosional rurface and above 1 DOOm represents upper erosional surface of the mountains. A t ransect chart has been prepared to show the relation of varia tion of relief with that of drainage patte rn. Five diffe rent zones of soil has been prepa red for Mirik P. S. These are Red Podosol, Brown Earth, representing the major part of the area, Ash Grey Soi l with association of Red So il, representing a narrow strip towards the southe rn part, Whitish Grey Soil adjacent to the previous one - 42 - and Grey Soil with association of Yellowish Brown Soil representing the extreme Southern part of the police station. Out of the study on the earlier records on c limatic factor, it has been noted that s ince 1850 the rainfall has been gradually declining from 3477. 51 mm (1850-1855) to 2560. 00 mm (1982-1987). Total rainfall in the year of 1988 has been observed to be 2039.4 mm. Besides, the average relative humidity and temperature throughout the year have been recorded. After consulting the· different doc uments available in the region the recent developme nt of human population has been take n into account and the relative population de nsities in diffe rent parts of Mirik P. S. have been worked out. A very significant feature is noticeable here in the study of land use is the extensive existence of tea gardens. C ropland occupies a very litt le area being distributed mostly in the northern part of the region. Relative position of rural settle ment s, fo rests,scrubs and wastelands have bee n marked out in the maps. Vegeta tion of this a rea has been c lassified on the basis of physiognomy and struc tural features of the plant in relation to the a ltitude of the hill and climatic condition. Four vegetational zones, i. e . Tropical Deciduous Sal Forest s (Plantations), Tropical Evergreen, Subtropical Evergreen and Te mperate mi xed Zone have been m a rked out a nd different plant species in various zones of the prima ry forests have been worked out. Besides, the cha nge of vegetational structure for secondary forest formation due to the influence of various factors has been pointed out. Marshla nd vegetation in different zones of Tropical, Subtropical and Temperate regions has been described. C ultivated a nd othe r useful plants with spec ial re fe re nce to food, medicinal and ornam enta l vaiL£ available in the region have a lso been studie d. Besides, the common trees yie lding timber, fibre and fruits and those having comme rcial potentia li ty have been identified. Fig. 17. Plantation of Cryptomeria japonica (L.f.) D. Don Fig. 18. Scanty undergrowth of Crrptomeria japonica (L.f.) D. Don Fig. 19. A close-up view of Diplopterigium giganteum (Wall. ex Hook.) Nakai Fig. 20. Schoenoplectus mucronatus (L.) Palla a dominant species m the marshland b y the side of Mirik Lake. Fig. 21. Association of EuSatorium adenophorum Spreng. and Erian bus rUfipilus (Steud.) Griseb. with Cryptomer1a Japonica (L.f.) D. Don in the background. Fig. 22. Thysanolaena maxima (Roxb.) Kuntze - an economicaJJy important plant of the region. Fig. 23. Ana~halis contorta (D. Don ) Hook f. - a ominant species in the scrub jungles. Fig. 24. An association of Dendrocalamus hamiltonii Nees & AiD. ex Munro, Ipomoea congesta R.Br. and Eupatorium adenophorum Spreng.