Forest Types

Forest Types occurring in Meghalaya- An overview

 

Due to favourable environmental factors, physiological features, geographical location, biotic influence, human interaction etc. the forests of the State are very rich and diverse. Without reference to Champion and Seth’s subtypes of forest other accredited Botanists have broadly grouped them based on climatic conditions and altitude into tropical, subtropical and temperate types which are easily recognizable and constitute distinct manageable units. These could be further divided into subtypes depending upon the local climatic  factors.

A.      Tropical Forests :-           

           These forests occur in areas where the elevation is upto 1200 meters and with an average rainfall of about 100-250 cm. They are more important from economic point of view and  source of many useful plants. There are grouped into sub-types viz. evergreen, semi-evergreen, deciduous forests.

(i)      Tropical Evergreen Forests:-           

          These forests usually occur in both high rainfall areas and near catchment areas. They seldom form continuous belts due to various exogenous factors. They are complex in structure and rich in species diversity. The trees exhibit clear zonation with dense and impenetrable herbaceous undergrowth. Important tree species are Mesua ferrea, Castanopsis indica, Dysoxylum glabra, Talauma hodsognii, Bischofia javanica, Sapium baccatum, Terminalia curma. T. bellerica, Xerospermum glabratum, Garcinia paniculata, Ficus racemosa, Sterculia roxburghii, Pterospermum lancifolium etc.

The top canopy is composed of mighty trees like Mesua ferrea, Castanopsis indica, Dysoxylum glabra, D. binectariferum, Talauma hodgsonii, Bischofia javanica, Sapium baccatum, Terminalia citrina, T. bellirica, Xerospermum glabratum, Cynometra polyandra, Elaeocarpus robustus, E. rugosus, E. floribundus, Polyalthia cerasoides, Pterospermum acerifolium, Lannea coromandelica, Eriobotrya bengalensis, and Acrocarpus fraxinifolius. Some of the lofty emergent trees are often deciduous in nature and belong to Firmiana colorata, Pterygota alata, Tetrameles mudiflora, etc. Buttressed trunks are characteristic of the majority of the trees of this storey.

The second storey, which is almost obscure is composed of trees like Garcinia paniculata, G. cowa, G. pedunculata, Syzygium operculatum, Vitex glabrata, Premna bracteata, Sarcosperma griffithii, Ficus racemosa, Turpinia pomifera, Nauclea griffithii, Heritiera macrophylla, Saraca asoka, Dimocarpus longan, Pterospermum lancifolium, Sterculia roxburghii, S.hamiltonii, Mangifera sylvatica, Ostodes paniculata, Antidesma acuminata, Knema Linifolia, Chesocheton paniculatus etc. Quite many of these trees are tall but thin boled.

Smaller trees of the third storey consists of Oreocnide integrifolia, Ficus lamponga, F. clavata, Alchornea tiliafolia, Sarchochlamys pulcherrima, Boehmeria hamiltonii, Antidesma bunius, Macropanax dispermus. Ixora subsessilis, Prismatomeris tetrandra, Trevesia palmata, Brassiopsis glomerata, Premna barbata, Saprosma ternatum, Leea umbraculifera, Goniothalamus simonsii, etc.

The shrub layer, where present, is usually of a gregarious nature and comprise of Dracaena elliptica, Leea edgeworthii, Canthium angustifolium Phlogacanthus thyrsiflorus, Ardisia thomsonii, Lasianthus hookerii, Hyptianthera stricta, etc. The forest floor which is heavily covered by humus and litter is occasionally covered by grasses, acanthaceous herbs and some emergent ferns. Wood rotting fungi are abundant on fallen tree trunks and branches.

The climbers and lianas form a characteristic species composition of these forests. To mention a few Hodgsonia macrocarpa, Beaumontia grandiflora, Gnetum scandens, Ventilago madaraspatana, Cayratia pedata, Chonemorpha fragrans, Ampelocissus latifolia, Phanera nervosa. P. Khasiana, Lasiobaema scandens, Combretum roxburghii, Entada purseatha, Schefflera venulosa, etc. These climbers intertwining with each other and entangling over other trees give the interior of the forest a wiry look and render the forests almost impenetrable. Added to this some ferns, obviously epiphytic ones perch over these giant lianas at intervals. A few climbers like Thumbergia grandiflora, Gouania tiliaefolia, Adenia trilobata, Solena heterophylla, Pegia nitida, Desmos longiflorus, etc. associated with lianas, give the forest margins and openings a closed cascade like appearance.

Epiphytes are not very frequent; the high reaches of the lofty trees are often blanketed by a lush growth of epiphytic orchids like Pholidota imbricata, Dendrobium spp., Hoya parasitica, Asplenium spp., Aeschenanthes superba, etc. imparting colour and elegance to the canopy while in bloom. Wherever the canopy is slightly open, ascending epiphytic climbers mainly of the Araceae, as represented by Raphidophora decursiva, R.lancifolia, Pothas scandens, etc. completely mask the sturdy tree trunks.

Even though there is no uniformity in the distribution of dominant tree species in these forests, yet in some places their dominance can be marked. For example, Mesua ferrea in Lailad, Sapium baccatum in Umsamlem, Baghmara, Rongra, Balphakram, etc., Xerospermum glabratum in Rongrengiri and Terminalia myriocarpa in Balat. Along river courses Duabanga grandiflora is more prevalent with understorey trees like Vatica lancifolia.

 

(ii)     Tropical Semi-Evergreen Forests:-  

          This category of forests occupies the north eastern and northern slopes of the State, up to an elevation of 1200 meters where the annual rainfall is 150-200 cm with a comparatively cooler winter. The number of species here is lesser than in the evergreen zone. The main species in this type of forests are Elaeocarpus floribundus, Dillenia pentagyna, D. indica, Hovenia acerba, Garcinia lancifolia, Sapindus rarak, Rhus acuminata, Dalbergia assamica etc.

The top canopy includes Elaeocarpus floribundus, Dillenia pentagyna, D.indica, Hovenia acerba, Ehretia acuminata, Radermachera gigantea, Lithocarpus fenestratus, etc; while the second storey is composed of Micromelum integerrimum, Garcinia lancifolia, Sapindus rarak, Symplocos paniculata, Rhus acuminata, Dalbergia assamica, Bridelia monoica, Vernonia volkamerifolia, Ficus hirta, etc. The shrub layer is not very dense as in the case of evergreen forests. Randia griffithii, Boehmeria sidaefolia, Ardisia thomsonii, A. Floribunda, Clerodendrum bracteatum and Eriobotrya angustissima along with perennial herbs like Costus speciosus, Curcuma domestica, C. zedoaria, Hedyotis spp, etc. are very common.

 

(iii)   Tropical Moist and Dry deciduous Forests:-

This type of forests occurs where annual rainfall is below 150 centimeters and at comparatively low elevations. Typical natural deciduous forests do not occur anywhere in Meghalaya but is only sub-climax or human made forests. Deciduous forests are much more extensive in their distribution in the State and include a host of economically important trees like Shorea robusta, Tectona grandis, Terminalia myriocarpa, Sterculia villosa, Lagerstroemia parviflora, Morus laevigata, Artocarpus chaplasha, Albizia lebbek, Salmalia malabarica, Vitex peduncularis, Gmelina arborea, Schima wallichii, Toona ciliata etc.

B.      Subtropical Pine Forests:-

The pine forests are seen above the tropical zone and are confined to higher reaches of the Shillong plateau in Khasi – Jaintia Hills, in a narrow belt along the east – west direction. The pine forests unlike the tropical forests are less complex in structure and comparatively poorer in respect of species richness. The canopy tree is Pinus kesiya as the principal species, which tend to grow gregariously and often form pure stands. However,in certain places the pines are associated with a few broad leaved species such as Schima wallichii, Acacia dealbata, Erythrina arborescens, Myrica esculenta, Lyonia ovalifolia, Rhododendron arboretum, Quercus spp. etc.

C.      Subtropical Broad-leaved Forests:-

          In the same altitudinal zone with more wet areas, the very dense and complex structured broad leaved forests appear. Though the tier-wise dispersal of trees is not distinct, the canopy trees are Lithocarpus fenestratus, Castanopsis kurzii, Schima wallichii, Rhus javanica, Symplocos glomerata, Elaeocarpus prunifolius, Betula alnoides, Alnus nepalensis, Engelhardtia spicata, Quercus griffithii etc.

D.      Temperate Forests:-

The temperate forests occupy the higher elevations (above 1000 meters) mostly along the southern slopes of Khasi and Jaintia Hills. The rainfall here is very high (200 – 250 centimeters) with severe winter during December to January. These climatic climax forests are usually found in isolated pockets along the valleys, slopes, rivers and streams. The tree species in general show bushy and stunted habit. They form a dense canopy with main components like Lithocarpus fenestratus, Castanopsis kurzii,   Quercus griffithii, Quercus semiserrata, Schima khasiana, Myrica esculenta, Symplocos glomerata, Photinia arguta, Syzigium tetragonum, Ficus nemoralis, Elaeocarpus prunifolius, IIex venulose, Exbucklandia populnea, Betula alnoides, Rhododendron arboretum etc.

 

(i)                East Himalayan wet temperate forest: The forest is situated in high altitudes of East Khasi hills district. Closed evergreen high forest of trees of large girth but medium height, rarely above 25 m and usually with large branching crowns festooned with mosses, ferns and other epiphytes. The forest is rimmed by a dense growth of Castonopsis kurzii trees forming a protective hedge. Deciduous species form a relatively very minor proportion of the crop. Although the forest is essentially a mixed one there is a marked tendency for a few species to predominate strongly, notably the oaks and laurels. Mawphlang sacred grove typifies this kind of forest type.

(ii)             Khasi and Jaintia hills montane wet temperate forests:  This vegetation occurs in Cherrapunje and nearby places like Mawsynrem which experience highest rainfall in the region above 700 cm. The dominant species are oaks and laurels. Subtropical species occur alongside temperate species.

It is seen that the above scheme of classification is more congruent with the actual forest types occurring in Meghalaya and further desirable since the identification characteristics are extremely simple to follow and classify the forests.

Need for reclassification of Forest Types in Meghalaya employing Remote Sensing & GIS technique into identifiable manageable units allowing departure from Champion and Seth’s Forest Subtypes:

 (i)                By way of illustration the relict vegetation of the sacred grove at Mawphlang located near Upper Shillong may be considered: This sacred grove and the vegetation strip extending from it towards southern part of the district have been extensively studied by several investigators. Rao et al., (1990) stated that Quercus dealbata, Q. griffithii, Schima khasiana, Myrica esculenta, Rhododendron arboretum and Manglietia insignis are dominant species in Mawphlang sacred grove. Hajra (1975) listed the species occurring in the sacred grove and proposed a key for their identification. The species composition is distinctly temperate in nature. The area presently does not experience rainfall above 7 months in a year to qualify as wet vegetation. Champion and Seth (1967) regard the vegetation generally in Shillong as Assam subtropical pine which is much of generalization. The vegetation of Mawphlang sacred grove along with the portion beyond the sacred grove stretching towards south of the district qualifies ought to be treated as an exclusive category. There is similar vegetation on the hills along the same latitude towards the eastern portion of the district. It is essential to properly reclassify the vegetation occurring in Mawphlang sacred grove and such similar vegetation occurring along the same latitude.  It would be desirable to rename this forest type as “East Himalayan Wet Temperate Forest” for reasons stated supra.

(ii)             Similarly, the forests occurring in other pockets of Khasi Hills  districts perched on hill tops abutting the northern portion of the district adjoining Barapani, vegetation in Shillong plateau, and the vegetation occurring around Cherrapunje and Mawsmai need to be studied afresh by taking recourse to advanced techniques since the forests occurring in each of these places are unique, and worthy of being regarded as distinct forest types.

(iii)           It is essential to rename the forest types under the broad categories of Tropical , Subtropical, Broadleaved Hill Forest and Temperate forests outlined above since the forest types of Champion and Seth classification are relevant from a national perspective covering large geographical area and lack sufficient relevance from micromanagement point of view.

(iv)           There is much force in the view adopted by the ICFRE that time has come to revisit the Forest Types enunciated by Champion and Seth to enable meaningful and practical management of the Forests at local level. It would be hence desirable to undertake this exercise in the context of Meghalaya considering that grant of Statehood to Meghalaya has made it imperative to adopt management of forests at a scale different from that applicable during pre-statehood years. Meaningful, identifiable and demonstrable Forest Types is the distinct requirement for management prescriptions of our forests.

(v)             With enactment of revised National Forest Policy where a paradigm shift is evident with respect to management of forest from top-bottom approach to bottom-top approach, identification of distinct local forest type units is an indispensable requirement of the day.

(vi)           The introductory meeting conducted by ICFRE has made it clear that inputs regarding forest types under the new scenario applying remote sensing techniques would have to emanate from each State.

(vii)        The ICFRE which has been nominated by MoEF to carry out this gargantuan task appears to be proceeding on a war footing basis and it is imperative for Meghalaya not to lag behind but rather emerge as a front runner since its Remote Sensing & GIS wing has already achieved the distinction of having published in peer reviewed scientific journals the largest number of research papers from any State Forest Department in the Country.

Methodology

 Remote sensing has been recognized as a useful tool for delineation of Forest types. There are numerous reported instances of application of remote sensing for this purpose (Behera et al., 2000; Hirata et al., 2001; Roy and Tomar, 2001; Xiao et al., 2002;  Agrawal et al., 2003; Joshi et al., 2004; Joshi et al., 2006). The present study aims to classify the unique and diverse Forest types occurring in Meghalaya by taking recourse to remote sensing analysis suitably aided by field study.

Satellite imagery

 

The present study is based on mapping land cover from IRS P6-LISS III (23 m spatial resolution) remote sensing data corresponding to Meghalaya State. The imagery is endowed with bands 2, 3, 4 and 5 (green, red, NIR and SWIR). IRS Panchromatic image (6 m resolution) for the corresponding area would be fused with the LISS III image (23 mtrs resolution) to generate a high resolution multispectral imagery. The IRS P6 LISS III sensor data along with PAN data corresponding to the area of interest has been georeferenced and geometrically corrected. The RMS error for geometric correction is secured to 1 pixel. The pixels are resampled to 6 meters using nearest neighbour resampling method. Two season satellite imagery data were analyzed for the purpose of present study. The remote sensing data was ably assisted with field surveys, Forest Survey of India thematic maps drawn in 1978 apart from boundary maps surveyed and drawn by the Meghalaya Forest Department. The Global Positioning System (GPS) receivers were also used during field survey to obtain accurate location of land cover classes for their easy demarcation on geo rectified LISS III images.

 

NDVI layer

 

As the study area is dominated by different types of vegetation,  NDVI was used as an ancillary data layer in the visual interpretation process to enhance the separability among vegetation classes and reduce the shadow effect perpetrated by variations in topography. The NDVI data layer was generated from Red and NIR bands of LISS-III image and is defined as:

NDVI = (NIR-Red)/ (NIR+ Red)

The pixel values of the NDVI data layer range from -1 to +1 and are scaled from 0 to 255 respectively. The higher NDVI values indicate increase in biomass per unit area and vice versa. The positive values indicate different types of vegetation classes, whereas near zero and negative values indicate non-vegetation classes such as water, snow, and barren land.

 

Data processing and delineation of Forest types along with Forest Density Classes

 

The vegetation type maps were prepared using a hybrid technique incorporating the result of both visual interpretation and supervised classification technique. A reconnaissance survey of the study area was made through field visits.  The diverse plant species were correctly identified. The results of the reconnaissance survey were used to correlate the image characteristics and ground features using the standard technique of visual interpretation. Based on image properties viz., tone, texture, size, shape, shadow, and association along with physiography an interpretation key was developed. Simultaneously, a supervised classification employing maximum likelihood classifier was employed and the classification results obtained were used to further refine the boundaries of Forest type classes arrived at through visual interpretation technique. In each of the forest types the dominant species association was determined through field visit. The forest types were categorized into very dense, moderately dense and open forest category following the criteria laid down by Forest Survey of India (2005). Areas having tree cover with canopy density more than 70% were regarded as very dense forest, those with canopy density between 40 – 70% as moderately dense forest and those between 40 – 10% as open forest. Lastly maps were composed district wise depicting both the Forest Types and Density classes of each of the Forest Types to render their management extremely easy.

 

A detailed account of Vegetation Types of Khasi- Jaintia Hills

 

Introduction

The Indo-Burma region of northeast India was considered as the cradle of ancient angiosperms due to the presence of a large number of primitive and ancient flowering plants in the region, (Takhtajan, 1969). Meghalaya, a small state in northeast India, is reported to have 3128 species of flowering plants including 1236 endemic species (Khan et al., 1997). The floristic richness of the state has also been recognized by several earlier workers (Hooker, 1854). Hooker made a huge taxonomic collection for the Kew Herbarium from Khasi & Jaintia hills and remarked that the place was a cradle for angiosperms. A systematic study of the vegetation types occurring in the Khasi-Jaintia hills districts is key to preservation of its astounding floral diversity.

Kanjilal (1934) classified the forests occurring within the present Meghalaya state (then referred to as part of Assam province) into two principal types: evergreen forest and deciduous forest. Evergreen forest was stated to exist in the greater parts of Khasi Hills and as isolated pockets in the deciduous forests. The classification pertained to a date when the region was not granted statehood and did not therefore receive a detailed treatment. The classification is too broad to represent the diversity of vegetation types actually occurring in the State. A detailed treatment of the vegetation types occurring in Khasi hills is lacking.

Rao and Panigrahi (1961) classified the forests in Eastern India on the basis of their occurrence in various altitudes and dominant species occurring within them. Accordingly the forests in RiBhoi district of Meghalaya (stated by the authors to be those in Byrnihat of united Assam) were classed as Tropical Evergreen and Semi-evergreen forest. The forests in Khasi and Jaintia hills were classed as Pine forest. The classification was rendered at a time when Meghalaya did not possess any identity with regard to its present statehood. Its regions were, therefore, referred perfunctorily since it formed a small region within Eastern India with which the investigators were principally concerned.

Joseph (1968) restricted his floristic study to only Ri-Bhoi District of Meghalaya (apart of the then Khasi –Jaintia hills district) and classified the vegetation occurring in the district into only one type. The vegetation was stated to be Tropical mixed Evergreen type with deciduous components dominating the vegetation as one moved northwards i.e., closer to Assam whereas the evergreen component was stated to dominate the vegetation as one moved southwards i.e., towards Shillong. The evergreen component was said to include some subtropical and temperate species. The classification fails to take into account the scenario prevailing in the entire state and therefore vegetation type study pertaining to Khasi hills is more desirable.  Tripathi (2002) classified the forests of Meghalaya into five major types viz subtropical evergreen, subtropical semi-evergreen, broadleaved, sal and pine forests using IRS satellite data.  However, the maps created from remote sensing data could hardly delineate the forest types.

Rajkhowa (1961) mentioned the vegetation types of Meghalaya as occurring in erstwhile greater Assam as two principal climatic formations viz., evergreen including semi-evergreen and deciduous including semi-deciduous. The climatic formations were distinguished with respect to length of their dry periods which were further modified on account of elevation, topography and soil factors. The two principal types of vegetation in Khasi and Jaintia hills were mentioned by him. Oak- Rhododendron forests were classified as a subtype of submontane forests appearing under a further general category called as evergreen type of forests.  This type of forest corresponds to Champion and  Seth’s Type 10b/c2 occurring at a height of 3000 ft and above. These were gradually replaced by subtropical pine forests over a period of time. The second vegetation corresponded to submontane savannah which came about through secondary succession in areas where shifting cultivation was practiced. Savannahs represented climax vegetation in such places. They occurred in places with altitude of 3000 ft and above.

Mehra et al., (1983) for the first time attempted to classify meticulously the forests of Khasi and  Jaintia hills of Meghalaya as a part of larger exercise pertaining to determination of vegetation types occurring in eastern Himlayas. They recognized principally the following vegetation types:

(i)                Khasi and Jaintia hills tropical semi-evergreen forests: This is a sub-category of the broad category named as Tropical semi-evergreen forest which in turn appears under a further general category named as Moist Tropical forests. This subcategory is said to  occur in southern slopes of Khasi and Jaintia hills viz places in and around Shella of the present East Khasi hills district. Rainfall here is very high ranging from 400 cm to 500 cm. Three distinct storeys are visible, trees are tall and scattered. Betel palm is  the most common tree in the middle storey. The tree trunks are covered by epiphytes. There is rich undergrowth.

(ii)             Savannah type of vegetation in Khasi and  Jaintia hills: This is a sub-category of the broader category of vegetation viz., Tropical moist deciduous forests which in turn appears under a further general category named as Moist Tropical forests. This kind of vegetation occurs in areas characterized by high rainfall in the present Jaintia hills district in places like Garampani. There are scattered treess among huge grass stetches.

(iii)           Khasi and  Jaintia hills subtropical wet hill forests: This is a sub-category of the broader category of vegetation viz., Subtropical broad-leaved hill forests which in turn appears under a further general category named as Montane Subtropical forests. This forest was seen in Rait Khwan forest below Shillong plateau where rainfall is 150 to 200 cm. Altitude varies between 600 – 1000 m. There are evergreen trees and the forest is not distinguished into two storeys.

(iv)           Assam subtropical pine forests: This is a sub-category of a general category named as Montane Subtropical forests. This vegetation occurs in Shillong plateau. The maximum height attained is 1800 m. Rainfall is moderately high, about 250 cm. The dominant species is Pinus insularis.

(v)             Khasi and Jaintia hills montane wet temperate forests: This is a sub-category of a general category named as Montane wet temperate forests. This vegetation occurs in Cherrapunje and nearby places like Mawsynrem which experience highest rainfall in the region above 700 cm. The dominant species are oaks and laurels. Subtropical species occur alongside temperate species.

 

The vegetation types proposed by Mehra et al., (1983) in Khasi Jaintia hills of Meghalaya suffer from a major drawback. The forests occurring in and around Cherrapunje have been classified as Khasi Jaintia hills montane wet temperate forest. The justification has been that the area experiences high rainfall above 700 cm and that temperate species such as oaks and laurels dominate the vegetation and occur alongside subtropical species. It is undisputed that the area experiences high rainfall for nearly seven months a year. However, a more recent study of Khiewtam and Ramakrishnan (1993) have concluded that the dominant species are Engelhardtia spicata, Echinocarpus dasycarpus, Syzygium cumini, and  Drimycarpus racemosus. Distribution of Engelhardtia spicata is reported to range between altitude 400 – 1700 m and is widely regarded as a subtropical tree. Distribution of Syzygium cumini is reported to range between altitude 300 – 1200 m and therefore regarded as subtropical. Oaks and laurels though co-existing with the subtropical tree species do not constitute a dominant community.

Similarly, the relict vegetation of the sacred grove at Mawphlang located near Upper Shillong and the vegetation strip extending from it towards southern part of the district have been extensively studied by several investigators. Rao et al., (1990) stated that Quercus dealbata, Q. griffithii, Schima khasiana, Myrica esculenta, Rhododendron arboretum and Manglietia insignis are dominant species in Mawphlang sacred grove. Hajra (1975) listed the species occurring in the sacred grove and proposed a key for their identification. The species composition is distinctly temperate in nature. The area presently does not experience rainfall above 7 months in a year to qualify as wet vegetation. Champion and Seth (1967) regard the vegetation generally in Shillong as Assam subtropical pine which is much of generalization. The vegetation of Mawphlang sacred grove along with the portion beyond the sacred grove stretching towards south of the district qualifies to be treated as an exclusive category. There is similar vegetation on the hills along the same latitude towards the eastern portion of the district. It is essential to properly classify the vegetation occurring in Mawphlang sacred grove and such similar vegetation occurring along the same latitude, the vegetation occurring in other pockets of the district perched on hill tops abutting the northern portion of the district adjoining Barapani, vegetation in Shillong plateau, and the vegetation occurring around Cherrapunje and Mawsmai by taking recourse to advanced techniques since the forests occurring in each of these places are unique, worthy of being regarded as distinct vegetation types.

The conventional approach has led botanists to classify the forests of Khasi Jaintia hills of Meghalaya differently. There is a need to settle the problem of determination of vegetation types occurring in Khasi Jaintia hills which has posed a considerable challenge to field botanists through the ages ever since Kanjilal attempted to classify the forests of Eastern Himalayas.

Remote sensing has been recognized as a useful tool for delineation of vegetation types. There are numerous reported instances of application of remote sensing for this purpose (Behera et al., 2000; Hirata et al., 2001; Roy and Tomar, 2001; Xiao et al., 2002;  Agrawal et al., 2003; Joshi et al., 2004; Joshi et al., 2006). The present study aims to classify the unique and diverse vegetation types occurring in East Khasi hills district as first part of the exercise by taking recourse to remote sensing analysis suitably aided by field study.  The justification for commencing the study with East khasi hills district, within which is located Shillong the capital of Meghalaya state, is that it has been the focal point of several taxonomists starting from Hooker. Further, the district is representative of the diverse vegetation types occurring in all the Khasi Jaintia hills districts viz East Khasi hills district, West Khasi hills district, Ri-Bhoi District and Jaintia hills district. It would not be inappropriate to suggest that the vegetation types occurring in this district is representative of diverse vegetation types occurring in Eastern Himalayas too.

 

The following vegetation types were observed:

1. Khasi subtropical wet broadleaved hill forest:

This vegetation type does not figure in Champion and  Seth classification of vegetation types. It figures in Mehra et al., (1983) scheme of forest types in Eastern Himalayas.

Description.- The forest is situated below Shillong plateau. There are evergreen trees of 15-20 m height. Not distinguished into 2 storeys. The undergrowth is heavy in moist shady places but scant where forest is open.

Distribution.- Rait Khwan forest and adjacent forests on hill tops which are not affected by shifting cultivation.

Locality factors.- Altitude varies from 1000 – 1400 m. The average annual rainfall is 1500-2000 mm. Temperature varies between 6° C (mean minimum) – 27° C(mean maximum).

Floristics.-

Trees – Toona ciliata, Michelia champaca, Schima wallichi.The common trees are Cedrela toona, Euodia fraxinifolia, Castanopsis indica, Betula alnoides, B. nepalensis, Bischofia javanica, Cryptocarya amygdalina, Eurya japonica, Elaeocarpus lancifolius, Myristica kingii, Gynocardia odorata, Quercus dealbata,  Rhus succedaenea, Millingtonia arnottiana, Garuga pinnata, Ostodes paniculata, Chisocheton paniculatus, Machilus odoratissima, Erythrina fusca, Eugenica praecox, Castonopsis tribuloides, Artocarpus lakoocha, Xerospermum noronhianum Litsea umbrosa, Engelhardtia spicata, Alangium chinense, Ixora nigricans, and Sauraja napaulenis, Albizzia lebbek, Lindera cauduta, Ficus hirta, and Mallotus phillipensis

Shrubs – Zanthoxylum scandens, Clerodendrum viscosum, C. serratum, Euphorbia manihot, Phyllanthus glaucus , Rubus ellipticus, Morinda angustifolia, Maesa indica,  Toddalia asiatica, Breynia patens, Symplocos spicata, Erythrina spicata and Debregeasia velutina.

 2.     Subtropical mixed pine forest:

Description.- Similar to Himalayan pine forests, the occurrence of fire reacting in a similar way on the vegetation.

Distribution.- Dominant vegetation occurring throughout the district except the southern portion beyond Mawphlang. This vegetation  type predominates the entire Shillong plateau.

Locality factors.- The type occurs between 800 and 1600 m. The rainfall is between 2000 – 2150 mm.

Floristics.- The floristics pertaining to Upper Shillong protected forest is given hereby as representative of Shillong plateau where mixed pine forest occurs.

Trees – The dominant tree is Pinus kesiya. The other tree species occurring alongside Pine though not growing as tall as Pine are

Quercus griffithii, Q. fenestrata, Lyonia ovalifolia, Rhododendron arboreum, Acer oblongum, Magnolia campbellii, Lindera latifolia, Prunus acuminata, P. nepalensis, Schima wallichii, Myrica sapida, Rhus succedanea, R. griffithii, R. semialata, Docynia indica, Glochidion acuminatum, Glochidion khasicum, Machilus duthei, Castanopsis indica, Cedrella toona, Magnolia grandiflora, and Lindera latifolia.

Shrubs – Elaegnus latifolia, Salix psilostigma, Corylopsis himalayana, Machilus duthiei, Osbeckia crinata, O. nepalensis, O. stellata, Desmodium multiflorum, D. heterocarpon, D. racemosum, Viburnum foetidum, V. simonsii, V. odoratissimum, Lindera melastomacea, Sabia purpurea, Schizandra neglecta, Holboellia latifolia, Daphne cannabina, Gaultheria fragrantissima, Inula cappa, Virburnum coriaceum, V. corylifolium, Ardisia neriifolia, and A. griffithii.

 3.     East Himalayan wet temperate forest:

Description.- The forest is situated in high altitudes of the district. Closed evergreen high forest of trees of large girth but medium height, rarely above 25 m and usually with large branching crowns festooned with mosses, ferns and other epiphytes. The forest is rimmed by a dense growth of Castonopsis kurzii trees forming a protective hedge. Deciduous species form a relatively very minor proportion of the crop. Although the forest is essentially a mixed one there is a marked tendency for a few species to predominate strongly, notably the oaks and laurels. There is typically an evergreen underwood wherever the top canopy is not too dense. Climbers occur and sometimes include large woody forms but are not conspicuous.

Distribution.- Mawphlang and a linear stretch extending southwards, and Nongjrong, Mawsna, and Umshing villages towards eastern border of the district adjoining Jaintia hills district along the same latitude where Mawphlang is situated .

Locality factors.- Altitude varies between 1600 – 1965 m. The total rainy days are approximately 122 days distributed over 7 months of the year. Average annual rainfall is 2500 mm. During winter (December to February) the mean minimum temperature is 3°C and mean maximum temperature is 16°C. This season is also characterized by occasional rain with gusty winds. The period from March to mid-May is usually dry and warm with mean annual maximum and minimum temperatures of 22 C and 16° C respectively. The top soil in the Mawphlang forest is of sandy loam type and shows acidic reaction (pH 5.3).

Floristics (As observed in Mawphlang sacred grove forest).-

Trees.-

I tier.- The foliage is glaucous scattered among which are Quercus griffithi. Other dominant tree species are, Q. glauca, Schima khasiana, Rhododendron  arboreum, Exbucklandia populnea, Engelhardtia spicata, Elaeocarpus lancifolius, Carpinus viminea, Myrica esculenta, Litsaea elongate, Corylopsis himalayana, Zanthoxylum ovalifolium, Pyrus pashia, Pyrus baccata, Manglietia insignis, and

II tier.- Q. dealbata, Taxus baccata, Cinnamomum pauciflorum, Rhododendron formosum, Lithocarpus dealbata, Eurya japonica, Symplocos glomerata,

 

Shrubs.- Symplocos chinensis, Daphne shillong, Sarcococca saligna, Osbeckia stellata, Polygonum chinense, Hedyotis scandens, Smilax aspera, S. roxburghiana, S ferox, Dioscorea pentaphylla, Rosa moschata, Rubus ellipticus, Hedera nepalensis, Pothos cathcartii, Rapidophora calophyllum, Liparis pulchella, Spiranthes australis, Pogonia scottii, Anoeclochilus sikkimensis, Zeuxine goodyeroides, Calanthe mannii, Eria coronoria, Malaxis acuminata, and Eria coronoria.

 4. East Himlayan subtropical wet hill forest:

Description.- Hill forests of good height and density. The dominant species are evergreen but occasional deciduous species also occurs (e.g., Betula spp). The average height is 20-30 m. A middle storey is recognizable. A shrubby undergrowth is visible and grass is absent though herbaceous layer is present. Epiphytes are numerous. Precipitation is above 2000 mm.

Distribution.- Sacred grove of Mawsmai, private forests within and around Cherrapunje Locality factors.- The forests are located on an average elevation of 1484 metres (4872 feet),  yearly rainfall average stands at 11,450 millimetres (450 in). The winter season (November to February) is characterized by low temperature (mean min. 7° C and mean max. 16° C). The mean annual maximum and minimum temperatures are 23° C and 16° C respectively. The soil is sandy loam type.

Floristics.- Dominant species are Oaks and laurels. The species with highest frequency are of subtropical kind but temperate species also occur.

Tree species:

I.- Engelhardtia spicata Echinocarpus dasycarpus Syzygium cumini, S. tetragonum,  Castanopsis indica, Castonopsis tribuloides, C. kurzii, Drimycarpus racemosus, Echinocarpus dasycarpus, Elaeocarpus lanceaefolius, Engelhardtia spicata, Machilus duthei, M. gamblei, Schima khasiana, Quercus lineata, Q. dealbata, Q. glauca, Q. kurzii, Q. spicata, Elaeocarpus braceanus, Symington populnea, Cinnamomum obtusifolium, C. tamala, Garcinia amonola, Acer laevigatum, Rhododendron arboreum.

II .- Ilex venulosa, Castanopsis aarmata, Camellia caudata, Clerodendron bracteatum, C. nutans, Debregeasia wallichiana, Eurya japonica, Helicia erratica, Eurya acuminate, Lindera assamica, Euonymus grandiflorus, Glochidion acuminatum, G. thomsoni, Lingustrum robustum, Lindera melastomacea, Lithocarpus dealbata, Litsea elongata, Myrica esculenta,  Viburnum odoratissimum, V. simonsii,  Ehretia acuminate, Ilex griffithii, Ilex khasiana, I. theaefoia, Lyonia ovalifolia, Wedlandia tinctoria, Syzygium macrocarpum, Symplocos glomerata, S. racemosa, Erythroxylon kunthianum, and Zanthoxylum ovalifolium.

Shrubs.- Ardisia undulate, Berberis wallichiana, Clerodendrum nutans, Daphne cannabina, D. papyracea, D. involucrata, Desmodium floribundum, D. griffithianum, D. racemosum, Elaegnus latifolia, Euonymus grandiflorus, Phlogocantuhus curviflorus, S. coloratus, Gaultheria fragrantissima, Rauwolfia densiflora, Coffea jenkinsii, Euonymous bullatus, Gymnosporia acuminate, and Schoefia fragrans.

 5. Eastern sub-montane semi-evergreen:

Occurs on the lower slopes of southern hills beyond Cherrapunje southwards. It occurs between the mainly deciduous and mainly evergreen forests. The rainfall varies between an annual average of 2500 mm to 5000 mm and the forests occur on well drained slopes from the foot of the range to about 800 m or more.

Description.- Canopy though closed is irregular with evergreen species dominating in the top canopy with a number of deciduous or nearly deciduous species. The lower canopy is mostly evergreen and without bamboos. Two tiers are distinguishable.

Floristics.-

Trees I tier.- Schima wallichii, Bauhinia purpurea, Cedrela toona, Stereospermum tetragonum, Castonopsis indica, Ailanthus grandis, Duabanga grandiflora, Eugenia formosa, Gmelina arborea, Michelia champaca, and Tetrameles nudiflora.

Trees II tier.- Turpinia pomifera, Garcinia stipulata, Mallotus phillipensis, Gynocardia odorata

6.     East Himalayan moist deciduous forest:

Description.- A tall more or less closed forest in which individual trees run to large size. Species well mixed in small groups. Two tiers are visible. There is good underwood and shrubby undergrowth.

Coarse tufted grass species are absent.

Distribution.- Shella, Mawian,  and  Mawiong

Locality factors.- High rainfall over 3000 mm. No frost.

Floristics.-

Tree.- I tier : Sterculia villosa, Bombax ceiba, Toonna ciliata, Artocarpus heterophyllus, Tetrameles nudiflora,  Euphorbia neerifolia, Duabanga grandiflora, Schima wallichii, Dysoxylon binectariferum, Hibiscus macrophyllus, Pterospermum acerifolium, Dillenia pentagyna, Amoora wallichii, Cinnamomum bejolghota, Careya arborea, and Drypetes assamica.

II tier: Aphanamixis polystachya, Bauhinia purpurea, Mallotus phillipensis, Phoebe angustifolia, Callicarpa arborea, Oroxylum indicum, Xerospermum glabratum, Helicia nilagirica, Sapium baccatum, Trema orientalis, Actinodaphne obovata, Litsea glutinosa, Litsea monopetala, Sterospermum chelonoides, Lagerstromia parviflora, and Eurya acuminata.

Shrubs.- Leea indica, Uraria crinata, Morinda angustifolia, Musaenda roxburghii, Eupotarium odoratum, Clerodendron viscosum, C. colebrookianum, Baliospermum spp., Musa india, Grewia microcos, Ardisia paniculata, A. crispa, Calotropis procera, Solanum torvum, and Strobilanthes anisophyllus.

 7.     Tropical Evergreen Forest (Jaintia Hills):

Description.- Four storeyed closed forest averaging 30 m. in height with Mesua strongly dominating in the top canopy. Second storey is 17m. high. Climbers are rare but Ficus is frequent. The occurrence of climbers is rather lesser than those occurring in Upper Assam.

Distribution.- Narpuh Reserved Forest, Saipung Reserved Forest, unclassed private forests upto Sunapur, forests adjoining Khaddum etc. It is confined chiefly to Jaintia hills.

Floristics.-

The top canopy is composed of mighty trees like Mesua ferrea, Castanopsis indica, Dysoxylum glabra, D. binectariferum, Talauma hodgsonii, Bischofia javanica, Sapium baccatum, Terminalia citrina, T. bellirica, Xerospermum glabratum, Cynometra polyandra, Elaeocarpus robustus, E. rugosus, E. floribundus, Polyalthia cerasoides, Pterospermum acerifolium, Lannea coromandelica, Eriobotrya bengalensis, and Acrocarpus fraxinifolius. Some of the lofty emergent trees are often deciduous in nature and belong to Firmiana colorata, Pterygota alata, Tetrameles mudiflora, etc. Buttressed trunks are characteristic of the majority of the trees of this storey.

The second storey, which is almost obscure is composed of trees like Garcinia paniculata, G. cowa, G. pedunculata, Syzygium operculatum, Vitex glabrata, Premna bracteata, Sarcosperma griffithii, Ficus racemosa, Turpinia pomifera, Nauclea griffithii, Heritiera macrophylla, Saraca asoka, Dimocarpus longan, Pterospermum lancifolium, Sterculia roxburghii, S.hamiltonii, Mangifera sylvatica, Ostodes paniculata, Antidesma acuminata, Knema Linifolia, Chesocheton paniculatus etc. Quite many of these trees are tall but thin boled.

Smaller trees of the third storey consists of Oreocnide integrifolia, Ficus lamponga, F. clavata, Alchornea tiliafolia, Sarchochlamys pulcherrima, Boehmeria hamiltonii, Antidesma bunius, Macropanax dispermus. Ixora subsessilis, Prismatomeris tetrandra, Trevesia palmata, Brassiopsis glomerata, Premna barbata, Saprosma ternatum, Leea umbraculifera, Goniothalamus simonsii, etc.

The shrub layer, where present, is usually of a gregarious nature and comprise of Dracaena elliptica, Leea edgeworthii, Canthium angustifolium Phlogacanthus thyrsiflorus, Ardisia thomsonii, Lasianthus hookerii, Hyptianthera stricta, etc. The forest floor which is heavily covered by humus and litter is occasionally covered by grasses, acanthaceous herbs and some emergent ferns. Wood rotting fungi are abundant on fallen tree trunks and branches.

The climbers and lianas form a characteristic species composition of these forests. To mention a few Hodgsonia macrocarpa, Beaumontia grandiflora, Gnetum scandens, Ventilago madaraspatana, Cayratia pedata, Chonemorpha fragrans, Ampelocissus latifolia, Phanera nervosa. P. Khasiana, Lasiobaema scandens, Combretum roxburghii, Entada purseatha, Schefflera venulosa, etc. These climbers intertwining with each other and entangling over other trees give the interior of the forest a wiry look and render the forests almost impenetrable. Added to this some ferns, obviously epiphytic ones perch over these giant lianas at intervals. A few climbers like Thumbergia grandiflora, Gouania tiliaefolia, Adenia trilobata, Solena heterophylla, Pegia nitida, Desmos longiflorus, etc. associated with lianas, give the forest margins and openings a closed cascade like appearance.

Epiphytes are not very frequent; the high reaches of the lofty trees are often blanketed by a lush growth of epiphytic orchids like Pholidota imbricata, Dendrobium spp., Hoya parasitica, Asplenium spp., Aeschenanthes superba, etc. imparting colour and elegance to the canopy while in bloom. Wherever the canopy is slightly open, ascending epiphytic climbers mainly of the Araceae, as represented by Raphidophora decursiva, R.lancifolia, Pothas scandens, etc. completely mask the sturdy tree trunks.

Site specific tree composition.-

Saipung Reserve Forest.-

Palaquim (20%), Diospyros topiosa (9%), Cynometra polyandra (8%), Dipterocarpus turbinatus (7%), Mesua (7.5%), Eugenia (8%), Euphoria longana (8%), Sapium baccatum (3.5%), Vatica lanceaefolia (3%), Canarium (3%), Hydnocarpus kurzii (2.5%), Heritiera acuminata, Persea owdenii, Kayea floribunda.

Narpuh Reserve Forest and adjoining areas till Sunapur.-

Dipterocarpus turbinatus, Artocarpus chaplasa, Mangifera sylvatica, Persea owdenii, Eugenia, Palaquim polyanthum, Mesua ferrea, Castanopsis indica, Dysoxylum glabra, Talauma hodsognii, Bischofia javanica, Sapium baccatum, Terminalia curma. T. bellerica, Xerospermum glabratum, Garcinia paniculata, Ficus racemosa, Sterculia roxburghii, Pterospermum lancifolium etc.

Bamboos- Melocanna bambusoides, Bambusa balcooa

Climbers- Entada phaseoloides, Acacia, Combretum, and Delima

 

 8.     Tropical semi-evergreen forests:

 This category of forests occupy the forests between Lumshnong and Khlerhiat typically up to elevations of 1200 m, where annual rainfall is 150-200 cm with a comparatively cooler winter. The number of species here are fewer than the evergreen zone. There are also a few species in these forests which are deciduous in nature, such as Careya arborea, Dillenia pentagyna and Callicarpa arborea. Again there is a clear stratification of the trees in these forests.

The top canopy includes Elaeocarpus floribundus, Dillenia pentagyna, D.indica, Hovenia acerba, Ehretia acuminata, Radermachera gigantea, Lithocarpus fenestratus, etc; while the second storey is composed of Micromelum integerrimum, Garcinia lancifolia, Sapindus rarak, Symplocos paniculata, Rhus acuminata, Dalbergia assamica, Bridelia monoica, Vernonia volkamerifolia, Ficus hirta, etc. The shrub layer is not very dense as in the case of evergreen forests. Randia griffithii, Boehmeria sidaefolia, Ardisia thomsonii, A. Floribunda, Clerodendrum bracteatum and Eriobotrya angustissima along with perennial herbs like Costus speciosus, Curcuma domestica, C. zedoaria, Hedyotis spp, etc. are very common.

 

9.     Deciduous forests (Ri-Bhoi District):

 This type  of forests occur where annual rainfall is below 150 cm, and at comparatively low elevations. Typical natural deciduous forests do not occur anywhere in Meghalaya but are only sub-climax or man made forests. These forests are characterized by seasonal leaf shedding and profuse flowering of the trees. Recurrent forest fires are a common phenomenon here. Deciduous forests include a host of economically important trees like Shorea robusta, Tectona grandis, Terminalia myriocarpa, Sterculia villosa, Lagerstroemia floss-reginae, L. porviflora, Morus laevigatus, Artocarpus chaplasha, and Gmelina arborea, both as natural and as plantations. Schima wallichii, Artocarpus gomeziana, Tetrameles nudiflora, Lannea coromandelica, Salmalia malabarica, Erythrina stricta, Premna milliflora, Vitex peduncularis, Albizia lebbeck, A. lucida, Terminalia bellirica, etc. are also in abundance. These trees of the deciduous canopy are always lofty and straight boled and with spreading crown.

A distinct second storey can usually be observed in these forests and this zone is composed of Aporusa roxburghii, Croton joufra, C. roxburghii, Pithecelobium sp., Careya arborea, Rhus javanica, Micromelum integerrimum, bridelia retusa, Grewia microcos, G. disperma, Piliostigma malabarica, Mallotus tetracoccus, Glochidion lanceolarium, etc. These trees which reach far below the canopy trees are laxly branched and have a narrow crown.

The shrubby layer is often gregarious and forms an impenetrable thicket during rainy season with profuse growth of stragglers and spreading shrubs interwoven by slender annual climbers. The main component of this layer are Phlogacanthus thyrsiflorus, Desmodium pulchellum, Flemmingia macrophylla, Holarrhena antidysenterica, Costus speciosus, Leea crispa, L. indica, Glycosmis arborea, Allophyllus cobbe, Licuala peltata etc.

Lianas are fewer but scandent shrubs like Bridelia stipularis, Combretum roxburghii, Mussaenda glabra, Hiptage benghalensis, Aspidopteris elliptica, Pottsia laxiflora are frequent. However, lianas like Spatholobus roxburghii, Phanera nervosa. Entada purseatha, etc., make their way high up the canopy and become spectacular but often deforming the main trees. The epiphytic flora is extremely low when compared to the other types of forests. However, massive growth of epiphytic orchids like Pholidota imbricata, Dendrobium moschatum, D. nobile which come to bloom during rainy season and Papilionanthe teres which densely infect trees giving them a pink mosaic appearance during summer are quite common. The tree trunks also provide a favourable habitat for the growth of curious ferns like Drynaria sp., Microsorum sp., etc. Chain-like growth of Hoya lanceolata or Dischidia nummularia are also encountered. Terrestrial ferns are rather very scarce except for Pteris spp.

At places bamboo intruded forests also occur where a good number of bamboos (usually Dendrocalamus hamiltonii) grow interspersed amidst these forests.

The undergrowth of these forests comprises predominantly of Phlogacanthus thyrsiflorus .

 

 10.  Grasslands of West khasi Hills:

Grasslands of Meghalaya are also not a climax type but are only as a result of removal of original forest cover. The rolling grasslands covering large areas can be seen Riangdo, and Ranikor.   The dominant grasses in the grasslands are Saccharum spontaneum, S. arundinaceum, Neyraudia reynaudiana, Thysanolaena maxima, Chrysopogon aciculatus, Narenga porphyrocoma, Panicum atrosanguineum, P. khasianum, Setaria glauca, S. palmaefolia, Oplismenus burmannii, Axonopus compressus, Imperata cylindrica, Paspalum dilatatum, Arundinella bengalensis, etc. These grasses are associated with sedges like Mariscus sumatrensis, Scleria terrestris, and Eriocaulaceae members such as Eriocaulon cristatum, and E. brownianum, etc. A few scattered trees belonging to Emblica officinalis, Helicia nilagirica, Schima wallichii, Engelhardtia spicata, etc. are also noticed in certain places in these grasslands.

Apart from giving a green look to these barren hills these grasslands also support other dicotyledonous species like Eriosema chinensis, Polygonum bistorta, Trifolium repens, Centellaastatica, Hypochaeris radicata, Sonchus asper, Centranthera grandiflora, Hemiphragma heterophyllum, Eusteralis linearis, Plectranthus termifolius, Osbeckia stellata, O. glauca, Impatiens chinensis, I. radicans, Drosera peltata, Utricularia striatula, U. bifida, and ferns like Pteridium aquilinum, Dicranopteris linearis. Lycopodium spp., etc.

 

Forest Types of Garo Hills

 The dense evergreen forests with compact canopy cover are confined to very steep slopes or in the unapproachable localities in interior hills. Whereas, tropical moist deciduous forests are generally found on the alluvial soil or well-drained soil on small hills at lower elevations along river courses. At present small and medium sized patches of these forests are surrounded either by habitations with increasing township and rural establishments or with other artificial landuse systems. The semi-evergreen forests were developed gradually with the course of time with increasing biotic pressure. Large gaps created through traditional jhumming provided chances of establishing deciduous species into large tropical moist evergreen forest patches. Major portion of semi-evergreen forests is present around the periphery of tropical moist evergreen forests. Even few smaller patches exist within the intact large patches of evergreen forests.

 1.    Tropical Moist Evergreen Forest :

 The tree composition is predominantly of  the following tree species: Aphanamixis polystachya, Syzygium operculatum, Castanopsis sp., Schima wallichii, Diospyros variegata, Castanopsis purpurella, Parapentapanax subcordatum, Garcinia cowa, Eurya acuminata, Dillenia pentagyna, Polyalthia simiamum, Walsura tubulata, Syzygium operculatum, Mesua ferrea, Michelia champaca, and Pterospermum lancifolium.

The Tropical moist evergreen forests represent least disturbed primary forests in the interior hills of the study area. These forest patches mainly confine to Tura ridge and around the gorge at Mahadeo River in Balpakram National Park. These forests cover an area of 353 sq km of Garo hills. The largest patch of 180 sq km is situated over the Tura ridge and extends to the north of Rewak area near the eastern boundary of GCA (Garo hills conservation area). BNP and NNP have 115 and 26 sq km area, respectively. These forests form a closed canopy forest and are very rich in species diversity.

The top canopy consists of giant trees like Castanopsis tribuloides, C indica, Mesua ferrea, Schima wallichii, Bischofia javanica, Jantolis hookerii, Dysoxylum species, Cynometra polyandra, Acrocarpus fraxinifolius and Xerospermum glabratum etc. Few deciduous tree species like Tetrameles nudiflora and Firminia colorata etc. also occur in these forests. Second storey is formed by tall but thin boled tree species like Antidesma accuminata, Phoebe attennata, Persia gamblei, Garcinia pedunculata, Vitex glabrata, Premna bracteata, Ficus racemosa, Diospyros, variegata, Mangifera sylvatica, Ixora subsessilis, Prismatomeris tetrandra, Saprosma ternatum etc. Important shrub species are Draecana elliptica, Leea edgeworthii, Canthium augustifolium, Lasianthus hookerii, Tabernaemontana divaricata, Hyptianthera stricata etc. Acanthaceous herbs and some emergent ferns are found on forest floor covered by thick layer of humus and litter.

Lianas and large woody climbers of these forests include the species like Hodgsonia macrocarpa, Beaumontia grandiflora, Gnetum scandens, Ventilago madrasputna, Cayratia pedata, Chonemorpha fragrans, Phanera nervosa, P.khasiana, Shefflera venulosa, Trechelospermum auritum, Combratum roxburghii, Entada purscatta, etc. Among epiphytes, many species of orchids and ferns are prominent in these forests. Important species are Dendrobium sp, Phollidota sp., Aerides sp., Eria sp., Coelogyme sp., Cymbidium sp. etc. Common ferns include the species like Aeschenanthes species, Hoya species Agapetes species Hymenopogon species, Agrostemma species, etc. Ficus trees in these forests start their life as epiphytes but later on establish connection with ground and strangle host to death. On the other hand weak plants Raphidophora decursiva, R. lancefolia, Piper sp. grow robust from ground clasping and covering the trunk of trees.

 Polyalthia simiarum-Walsura tubularis-Syzygium operculatum

These forests cover an area of 353 sq km i.e. 14.4% of the entire landscape, mainly confined to the Nokrek and Balpakram conservation blocks. These conservation blocks form the catchments of Simsang, Mahadeo and Maheshkola rivers in the northern, northeastern, eastern portions. Nokrek Conservation Block, situated over Nokrek ridge run eastwards from ‘Tura peak’ in upper northwest corner to the north of ‘Siju Area’ across river Simsang. The ‘Nokrek Conservation Block’ forms the upper and middle catchment of Simsang, the major river of study area. While ‘Balpakram Conservation Block forms a catchment for Mahadeo and Maheshkola rivers. These conservation blocks are characterised by hilly terrain, steep slopes, moist and sometimes very moist habitat conditions. Average annual precipitation is higher as compared to the surrounding areas. Higher temperature throughout the year results in more humid conditions of wildlife habitats.

Few small patches of dense evergreen forests still exist near habitations. These patches can be seen in the south of Nokrek ridge near ‘Emangiri area’ and also near southern boundary of Balpakram National Park near ‘Shooling area’. Unprotected areas near Chimitab, Nadankol and Shooling are example of tropical evergreen forests.

Syzygium operculatum-Diospyros variegata-Castonopsis sp.

These forests occur on the higher altitude (above 1,000 m) in very moist condition in Nokrek area. It also includes the species from very old (about 60 years) secondary forests, which resembles exactly the old primary forests. The important species are Syzygium operculatum, Diospyros variegata, Castonopsis sp., Castonopsis purpurella, Aphanamixis polystachya, Calophyllum polyanthum, Casearia graveolens, Boehmeria sp., Garcinia kydea and Betula alnoides.

Polyalthia simiarum-Walsura tubularis-Canarium strictum

These forest occur at medium and lower altitude (between 100 to 700 m) inside Balpakram National Park. The limestone area forms the major habitat at the middle altitude. The important species of these forests are Polyalthia simiarum, Walsura tubularis, Canarium strictum, Mesua ferrea, Michelia champaca, Tetrameles nudiflora, Drimycarpus racemosus, Cynometra polyandra, Pterospermum lancifolium and Sapium baccatum.

 Distribution: The distribution in respect of different formations is as indicated above mainly confined to Garo hills conservation area and few pockets of unprotected area.

 2.    Deciduous Forests:

The major portion of these forests occur in the areas affected by human activities, especially jhumming. These forests cover an area of 703 sq km. These forests naturally occur in the alluvial plains and comprise of Sal forests most of which are confined within the boundaries of the existing PA network. The community land has the major portion of TMDF. The tropical moist deciduous forests in community land have resulted gradually due to exploitation of natural forests by local communities.

 This type  of forests occur where annual rainfall is below 150 cm, and at comparatively low elevations. Typical natural deciduous forests do not occur anywhere in Meghalaya but are only sub-climax or man made forests. These forests are characterized by seasonal leaf shedding and profuse flowering of the trees. Recurrent forest fires are a common phenomenon here. Deciduous forests include a host of economically important trees like Shorea robusta, Tectona grandis, Terminalia myriocarpa, Sterculia villosa, Lagerstroemia floss-reginae, L. porviflora, Morus laevigatus, Artocarpus chaplasha, and Gmelina arborea, both as natural and as plantations. Schima wallichii, Artocarpus gomeziana, Tetrameles nudiflora, Lannea coromandelica, Salmalia malabarica, Erythrina stricta, Premna milliflora, Vitex peduncularis, Albizia lebbeck, A. lucida, Terminalia bellirica, etc. are also in abundance. These trees of the deciduous canopy are always lofty and straight boled and with spreading crown.

A distinct second storey can usually be observed in these forests and this zone is composed of Aporusa roxburghii, Croton joufra, C. roxburghii, Pithecelobium sp., Careya arborea, Rhus javanica, Micromelum integerrimum, bridelia retusa, Grewia microcos, G. disperma, Piliostigma malabarica, Mallotus tetracoccus, Glochidion lanceolarium, etc. These trees which reach far below the canopy trees are laxly branched and have a narrow crown.

The shrubby layer is often gregarious and forms an impenetrable thicket during rainy season with profuse growth of stragglers and spreading shrubs interwoven by slender annual climbers. The main component of this layer are Phlogacanthus thyrsiflorus, Desmodium pulchellum, Flemmingia macrophylla, Holarrhena antidysenterica, Costus speciosus, Leea crispa, L. indica, Glycosmis arborea, Allophyllus cobbe, Licuala peltata etc.

Lianas are fewer but scandent shrubs like Bridelia stipularis, Combretum roxburghii, Mussaenda glabra, Hiptage benghalensis, Aspidopteris elliptica, Pottsia laxiflora are frequent. However, lianas like Spatholobus roxburghii, Phanera nervosa. Entada purseatha, etc., make their way high up the canopy and become spectacular but often deforming the main trees. The epiphytic flora is extremely low when compared to the other types of forests. However, massive growth of epiphytic orchids like Pholidota imbricata, Dendrobium moschatum, D. nobile which come to bloom during rainy season and Papilionanthe teres which densely infect trees giving them a pink mosaic appearance during summer are quite common. The tree trunks also provide a favourable habitat for the growth of curious ferns like Drynaria sp., Microsorum sp., etc. Chain-like growth of Hoya lanceolata or Dischidia nummularia are also encountered. Terrestrial ferns are rather very scarce except for Pteris spp.

 3.    Semi-evergreen Forests:

 These forests cover 624 sq km of land. The largest patch covers 113 sq km land extending along the southern side of Tura ridge. The majority of semi-evergreen forest type patches occur in the community owned private land and covers nearly 500 sq km. These forests are mainly confined to the periphery of large contiguous patches of dense tropical moist evergreen forests. BNP and NNP, respectively, have 72 and 14 sq km of semi-evergreen forests.

 Schima Wallichii-Castonopsis purpurella-Shorea robusta

The semi-evergreen forests are well distributed on the hilly portion of all over the landscape. These forests are highly fragmented due to increasing jhum practice. A large belt of semi-evergreen forests spread in the south of Nokrek Conservation unit, starting from Emangiri area to the Rewak area across the river Simsang in Siju area. These forests generally exist on the periphery of dense evergreen forests. A significant proportion of these forests exist in the reserved forests and community owned private land.

The semi-evergreen forests in the study area form upper catchment of Nareng, Bugi and Dareng rivers. Few patches in the central and southern portion of study area form the middle and lower catchment of river Simsang. These patches also form major catchment for Maheshkola river and other small rivers like Rompa and Rongdik, the main tributaris of Simsang- major river of study area.

 Grewia microcos-Schima wallichii-Castonopsis purpurella

These Semi-evergreen forest have more deciduous species. The most important species are Castonopsis purpurella, Shorea robusta, Syzygium cuminni, Aporusa dioica, Dillenia pentagyna, Cynometra polyandra, Sapium baccatum and Polyalthia simiarum.

 Schima wallichii-Castonopsis purpurella-Shorea robusta

 These semi-evergreen forests have more evergreen species. Species are Schima wallichii, Castonopsis purpurella, Shorea robusta, Macaranga denticulata, Dillenia pentagyna, Syzygium cuminni, Tectona grandis, Grewia microcos, Aporusa dioica and Eurya accuminata.

 4.     Important Trees Species in Garo Hills (Haridasan and Rao, 1985)

 Aporusa dioica

Vernacular name-Chamolja, Deciduous(D), 6-12m

high

Euphorbiaceae, Flowers and Fruits (F&F):

November-May

Bangladesh, Burma, and NE India, common in Meghalaya at lower elevations below 800m in deciduous and mixed dec. forest.

Associates:Croton roxburghii

 Diospyros variegata

Bolgisem, (Evergreen), 10-20m high

Ebanaceae, F&F: April-December

Burma and NE India, common in Meghalaya in tropical evergreen forests, often in open places, Tura, Khasi hills.

Diseases: the trees often malfarmed due to disease caused by witches broom.

Michelia champaca:

Bolnabat, (E), large (20-25m)

Megnoliaceae, F&F: May to April

50 Species in tropical Indo-Malayan region 12 in India, 8 in Meghalaya, few cultirated

Indo-Malayan, usually cultivated for fragrant flowers, cultivated as well as wild in foot hills, also in Tura

Uses: Wood durable, used in furnitures and building works.

Schima wallichii:

Boldok, (E), 15-50m large

Theaceae, Fruits and Flowers: February to April;

January to February. (Following year)

16 genera and 500 species in tropics and subtropics,

Mainly in Asia, 8/23 in India 6/13 in Meghalaya, Indo-Burma, Nepal, Bhutan, Bangladesh Eastern Himalaya NE India, throughout Meghalaya in all type of forests.

Uses: Plywood. Bark in allergic

Styrax serrulatum

5-15m

Styracaceae

12/190 in the tropical and temperate region 2/5 in India, 2/3 in Meghalaya 125 species in tropics/ temperate 43 in India,2 m high

Fruits and Flowers in March to December

Indo-Malayan, confined to East and NE India, Common in Meghalaya at lower elevations along forest margins and secondry forests.

Associates: Friesodielsia forniculata, Milletia caudata.

Messua ferrea

Karai, Khmde, large [upto 40m]

Clusiaceae: 35/400 (Genera/Species)

Largely confined to tropics, 6/22 in India 4/11 in Meghalaya. [3 species in world, 1 in Meghalaya]

Flowers and Fruits in April to October.

Indo-malayan, confined to western ghats, and NE India; Important element in evergreen fruits in Meghalaya, at lower elevation

Uses: Wood is very heavy and strong, used for construction proposals handles of agricultural equipment etc.

Castanopsis purpurella

Chako, large tree

Fagaceae: 8/500 in tropical/temperate region, except S. Africa, 5/40 in India, 4/13 in Meghalaya

Burma and NE India; very common in Meghalaya, forming canopy tree in associates with C.tributaris

Castanopsis indica

Fagaceae.

Large tree

Flowers and Fruits in February to December. NE India and neighbouring countries: very common in Meghalaya, in evergreen forest through out the state.

Tetra meles nudiflora

(D), tall upto 50m

Tetramelaceae: A monotypic family of Indo-Malayan region.

Flowers and Fruits in March to June.

Occur in open deciduous forests in Garo hills, associated with Duabanga grandiflora, Gmelina arborea, largerstroemia parviflora, wrightia tomen tosa.

Uses: Wood is useful in match industries, Fast growing tree, easily distinguishabledue to its towering size and nodded branching.

Cynometra polyandra

Chherasu (E), Large (upto 20m)

Caesalpiniaceae 152/2800 in tropics and sub-tropics, 23/80 India, 13/28 in Meghalaya (60 species in tropics, 6 in India and 1 in Meghalaya)

Flowers and Fruits in March to August.

Indo-malayan; confined to north-east India, common in tropical evergreen forests, associates with Premna Latifolia, Garcinia paniculata, Sarchochlamys, Pulcherrima, Schima wallichii, Mallotus, Lutra coccous

Uses: Wood is useful for construction purpose polywood and charcoal.

Trewia nudiflora

Boldiktak, Bol-khap, (D), upto 20 m.

Euphorbiaceae Arugong.

A large cosmopolitan family 300/5000

61/336 in India, 30/90 in Meghalaya

(5 species in Indo-malayan region. 2 in India and 1 in Meghalaya)

Flowers and Fruits in January to September.

Indo-malayan; nearly through out in India; fairly common in Meghalaya in deciduous forests, particularly in along river and water courses, associated with Aesculus assamicus, Vatica lanceaefolia.

Stereospermum chelonoide

Bolsel middle to lofty trees upto 40m.

Bignoniaceae 20/37 in India, majority cultivated; 5 genera and 5 species in Meghalaya [25 species in Afro-Asia, 4 in India, 1 in meghalaya].

Flowera and Fruits in April to March.

Indo-Burma, through out the greater part of India, very common in Meghalaya in tropical evergreen and deciduous forests(below 800m) associated with Vitex species, Dillenia species, Oroxylum indicum, etc.

Uses: Linear fruits, which persist nearly through out year; yield straight boled sturdy and durable timber.

Glycosmis species:

Rutaceae

150 genera/900 species in tropics and temperate region, largely in Asia, Africa and Austraila, 24/86 in India 13/Ca.25 in Meghalaya

[50 species in tropics]

Flowers and Fruits through out the year

Indo-Burma; common; dense evergreen forest of Meghalaya, especially in Garo hills as an undergrowth in wet shady placess.

Callicarpa arborea

Climber, Makhanchi, Middle (upto 15m)

75/3000 in tropics and sub-tropics, 17/96 in India, 13/40 in Meghalaya.

[140 species in tropics and sub-tropics, 10 in India, 6 in Meghalaya]

Flowers and Fruits nearly throughout the year, (more during in April to September)

Indo-malaya; mostly in northern India, Abundant in Meghalaya at all elevations in secondry forest, usually associated with Styrax serrulatum.

Grewia microcos:

(D) Bolchibins, Borsubret (5-15m)

Tiliaceae: 50/450 in tropics and temperate 8/64 nearly through out India, 3/11 in Meghalaya.

(150 species in tropics, 42 in India, 6 in Meghalaya)

Flowers and Fruits in May to February.

Indo-malaya, through out the warmer part of India, in Meghalaya thia species occurs in deciduous forests of lower ranges, associated with Holarrhena antidycenterica, Careya arborea, Embica officinalis, Callicarpa arborea etc.

Uses: Green to fruits purple.

Persea rillosa

Nameaga tall (upto 25m)

Lauraaceae 47/1900 in tropics and sub-tropics 17/175 in India, 11/50 in Meghalaya.

(150 species in tropical Asia and America, 15 in India and 10 in Meghalaya)

Flowers and Fruits in January to May.

NE India and neighbouring countries; very common in Meghalaya, particularly in tropical evergreen and mixed deciduous forests; also in secondry forest at lower elevation, associated with Stereospeesmum chelanoides, Artocarpus chaplasha, Castanopsis species, etc.

 

 

 

 

 

The forests of Meghalaya can be broadly classified into the following types :

  1. Alluvial Sal – This type conforms to type North Indian Tropical Moist Deciduous Kamrup Alluvial
    Sal Forests (3C/C2 d(iv).
  2. Foothill and Plateau Sal – This type conforms to the type North India Tropical Moist Deciduous Eastern Hill Sal Forests (3c/Cla).
  3. Very Moist Sal Bearing Forests – Khasi Hills Sal (3C/C1 a (ii).
  4. Mixed Deciduous Forests – North India Tropical Moist Deciduous (East Himalayan Moist Deciduous Forests (3C/C3 b).
  5. Evergreen Forests – These forests conform to the type Northern Tropical Semi-Evergreen Forests (2B1s1).
  6. Bamboo Forests – This type conforms to the type Northern Tropical Semi-Evergreen Forests (2B1S1).
  7. Grasslands – Northern Tropical Moist Deciduous Forests – Low Alluvial Savannah Woodland (2/ISI).
  8. Assam Sub-Tropical Pine Forests – (9/C2).