Types of Forests and its Distribution in India – 

Role of forests

On  the  basis  of  climate  the  forests  of  the country could be divided into four major groups.

1.   Tropical forests

2.   Montane Sub -  tropical forests

3.   Montane Temperate forests

4.   Alpine forests

1. Tropical Forests

(i).  Wet  evergreen  forests.  This  is  dense tall  forest  with  height  more  than  45  metre  or  even more. It is entirely evergreen or nearly so.     This type   of   forests   is   mostly   found   in   Arunachal Pradesh,    Assam,    Karnataka,    Kerala,    Manipur, Nagaland,   Tamil   Nadu,   Andaman   and   Nicobar islands and Goa.

(ii).   Semi   –   evergreen   Forests.   These forests  mainly  consist  of  deciduous  species    with certain  number  of  predominant  evergreen  species. Therefore,   these   forests  are   less  dense   than  the typical  evergreen  forests.  The  types  are  found  in Assam,  Gujarat,  Karnataka,  Andaman  and  Nicobar Islands  and Goa.

(iii).  Moist  Deciduous  Forests.  The  cover is mainly of deciduous species but the lower canopy largely consists of evergreen type of vegetation. The overall   canopy   is   rarely  dense   and   even.     The average  height  is  over  25  metre.  This  is  found  in Andhra Pradesh, Assam, Bihar, Gujarat, Karnataka, Manipur, Meghalaya,  Mozoram, Tripura, Nagaland, Orissa, Tamil Nadu, U.P.,  West   Bengal, Andaman

– Nicobar islands, Goa and Dadara Nagar Haveli.

(iv).  Littoral  and  Swamp  Forests.  It    is mainly evergreen of varying density and height   but always   associated   with   wetness.   It   is   found   in Andhra      Pradesh,   Gujarat,   Maharashtra,   Orissa, Tamil Nadu, West Bengal and Andaman – Nicobar islands.

(v). Dry Deciduous   Forests. It consists of entirely deciduous species or  nearly so. The canopy is rather light with height  8 to 20 metres. It exists in Andhra  Pradesh,  Bihar,  Gujarat,  Haryana,  Punjab, Rajasthan,   Tamil   Nadu,   Kerala,   U.P.   and   West Bengal.

(vi)  Tropical  Thorn  Forests.    The  forest cover  is mainly deciduous with thorny tree species. The canopy is more or less broken with height under

10  metres.  It  is  found  in  Andhra  Pradesh,  Gujarat, Haryana,  M.P.,  Karnataka,  Maharashtra,  Rajasthan, Punjab, Tamil Nadu, and U.P.

(vii).  Dry  Evergreen  Forests.  These  are mainly located in Andhra Pradesh and Tamil Nadu. The   forests   consist   of   hard   leaved   evergreens predominantly with some deciduous emergents. The forests are often dense with tree height less than 20 metres.

2. Montane Sub – Tropical Forests

(i).   Sub-   Tropical   Broad   leaved     Hill

Forests.  In this, the  forest cover consists of broad – leaved  species  which  are  largely  evergreens.  This type  is  found  in  Assam,  Maharashtra,  Meghlaya, West Bengal.

(ii).  Sub  –  Tropical  Pine  Forests.  These forests have certain number of pines in association. This type is found in Arunachal Pradesh, M.P., J. & K., Manipur, Meghlaya, Nagaland, Sikkim and U.P.

(iii).   Sub   –   Tropical   Dry   Evergreen Forests. This is low xerophytic forest and scrub and is found in H.P., J. & K. and  Mozoram.

3. Montane Temperate Forests

(i)  Montane Wet  Temperate Forest.  This is evergreen   forest without conifers. This is   found in     Arunachal     Pradesh,     Karnataka,     Manipur, Nagaland, Sikkiam and Tamil Nadu.

(ii). Himalayan  Moist  Temperate Forest. This   is  mainly evergreen  with  oaks   and  conifers. This is found in H.P., J. & K. and U.P.

(iii).  Himalayan  Dry  Temperate   Forest. This       forest    is    open   coniferous    with   spares xerophytic  under  growth.  This  is  found  in  J.  &  K. and Uttar Pradesh.

4. Alpine Forests

(i).  Sub  –  Alpine  Forest.  This  is  stunted deciduous   or  evergreen forest and usually in close formation with or without conifer. This is mainly in Arunachal Pradesh.

(ii). Moist  Alpine  Scrub. These are low in height  but  often  dense  scrub.  This  type  of  forest exists in H.P. and J. & K.

(iii). Dry alpine   Scrub. This is xerophytic scrub  in  open  formation.  This  forest  is  mainly  in Nagaland, Sikkim and U.P.

Role of forest

1. Productive role

1.1. Food:  Forest contribute directly to the diets  of  forest  dwellers  and  of  many  who  live  far beyond the woods. Forest fruits, nuts and berries for instance  are  popular  with  urban  as  well  as  rural consumers. These and many other  forest  foods  add variety and flavour to diets while providing essential vitamins, minerals, fats and proteins.   Tribals derive their   food   form   the   forests   either   directly   or indirectly.  For  example,  Madhuca  indica  saves  the tribals   of   Bihar,   Madhya   Pradesh,   Orissa   and Gujarat.  Animal  foods  include  a  large  variety  of both   invertebrates,   such   as   edible   insects   and vertebrates including mammals, birds and fish.

1.2.  Fodder:  Forest  provides  fodder  and rangelands for millions of   cattle, goats and sheeps. India  need  about  50  million  tonnes  of  fodder  to produce  27  million  tonnes  of  milk  for  its  existing populaiton.     Trees     helps     to     protect     pastoral rangelands, providing shade for cattle and crops and thereby supporting livestock production.

1.3. Fuel: Wood is still peoples main source for   cooking.   World   wide   2000   million   people depend  on  wood  for  cooking.  In  many  developing countries fuel wood supplies as much as 97 per cent of the total energy consumption.  India’s current fuel wood consumption is more than 133 million tonnes. To  cook  one  kg  of  food  1.2  kg  of  fuel  wood  is required.   It   clearly   indicates   that   india   should produce more wood  than  food  if  it  is to  be  cooked before  consumed.  Trees  like  Acacia  sp,  casuarina equisetifolia,  Eucalyptus  tereticornis,  Peltophorum ferrugineum,   etc.,   provide   large   amount   of   fuel wood in India. Besides plant provides firewood and charcoal,     they     also     provide     vegetable     oils

(Renewable   energy).   Vegetable   oils   have   great potential to be used as liquid fuel or as   a source of hydrocarbons.  Some  of  them  can  be  mixed  with disel.  Thus  these  species  are  know  as  Petro-crops, since they can serve as substitutes for supplement to petrochemicals.  Example  for  vegetable  oil  yielding trees – Jatropha curcas, Pongamia pinnata, Maducha indica, Ricinus communis

Latex      yielding      trees      –      Euphorbia antisyphilitica and Calotropis procera

1.4.   Clothing:   Forest   provides   excellent clothing  materials  like  rayon  and  silk.  Example: Rayon   materials   are   produced   from   Eucalyptus galobulus, Accacia mearnsii, Acacia dealbata etc.,

1.5.  Shelter:  Wood  from  forest  is  used  for designing shelter in rural areas. It is the main source of shelter in tribal community.

1.6.  Timber:  In India  forests  provided  45-

60 million m3  of timber annually. Forest timber are used  in  boat  making,  railway  industries,  furnitures etc. Examples are

a). Tectona grandis, Thespesia sp, Pyinkado

(Xylia xylocarpa), Artocarpus heterophyllus,  etc are used in Boat Making.

b). Teak, Terminalias, Mesua ferrea, Cedrus sp are used in making railway carrigaes and coaches c).     Dipterocarpus,     Terminalias,     Xylia xylocarpa  (Pyinkado),  etc.,     are  used  in  making

railway sleepers

d).   Teak,   Delbergia   latifolia   (rosewood), Dipterocarpus  (Gurjan)  etc.,  are  used  in  furniture industry.

e).   Dalbergia   sissoo   (Shisham),   Acacia nilotica,  Albizia  lebbeck,  etc.  are  used  in  making agricultural implements.

1.7.  Industrial  wood:  Many  industries  are depend    upon    forest    wood    for    their    survival. Examples:

a)   Paper industry – Bamboo sp, Eucalyptus sp. b)   Packing   industry   –   silver   oak   (Grevillea robusta), Kanju (Holoptelia integrifolia), etc.

c)   Plywood   industry  –  Teak,   Terminalia   sp, etc.,

d)   Sports goods – Salix alba (white willow) and

Morus alba (white mulberry)

e)   Toy    industry    –    Saffron    teak    (Adina cordifolia), Dalbergia sissoo etc.,

f)   Match  stick  industry  –  Ailanthus  excelsa, Populus nigra (black poplar), etc.,

g)   Musical   instruments   –    Tectona   grandis, Dalbergia latifolia, Dalbergia sissoo etc.,

h)   Pencil  making  industry  –  Alnus  nepalensis, Juniperus virginiana

i)    Wood carving – Albizia lebbeck, Perocarpus indicus

          1.8. Non-wood forest products: Non wood forest products (NWFP) forms a major product from the  forest  and  are  derived  from  over  3000  species. These  products  are  classified  as  leaves,  bamboos, gums,  resins,  oleoresins,  oil  seeds,  essential  oils including oil-yielding  grasses,  tans and  dyes,  drugs and spices, animal products and edible products.

2. Protective role

2.1.   Climate   change:   The   influence   on forest  ecosystem  on  climate  is  particularly through their effects on carbon cycle. Global climate change have been brought about by increased concentration of  heat  absorbing  greenhouse  gases such as  carbon dioxide,        methane,        nitrous        oxide        and chlorofluorocarbons.   Forest   themselves   are   both source and consumer of atmospheric carbon dioxide. As  forest  increases,  trees  absorbs  and  store  carbon dioxide.   But   due   to   deforestation,   especially   by burning a greater amonut of stored carbon dioxide is released   to    atomophere   contributing   to    global warming.        Thus        Affforestation        stabilizes atmospheric     circulation     patterns,     precipitation distribution etc.,

Wind:   Forests   trees    reduces    the   wind velocity and thereby changes the local climate. This principle is used  in  shelterbelts and  windbreaks.   It is mentioned that wind losses 25 to 40 per cent of its velocity if it passes 30 m through a dense forest and it retains only 8  per  cent of  its  velocity if  it passes through 120 m of forest.

Air-Temperature: Forest intercepts the sun’s rays  and make the earth cooler. It act  like a screen

and  prevents  the  sun’s  rays  reaching  the  soil.  The cooling effect is high in summer (up to   9  degrees) than winter (up to 3 degrees).

Precipitation:         Forest    influence    local precipitation.   It  is  believed  that  the  cooling  effect above    a    forest    brought    about    by    the    heavy transpiration  of the canopy increases rainfall by 2 to

3 per cent over that of non-forested area.

2.2. Soil and water conservation:

Forest  plays  a  vital  role  in  soil  and  water conservation,  regulating  of  water  yield  and  rate  of siltation of reservoirs.  Vegetation  helps  to  keep the soil together. Thick canopy of  forest  and  large leaf mass can intercept large amount of water  and thcik layers of humus and leaf litter on forest floor which is  porous  is mainly responsible  for  high infiltration rate and low runoff. The network of numerous roots with root hairs bind the soil. In the absence of root network,   top   soil   is   quickly   washed   away   by rainwater.  Forest  allows  relatively  low  to  silt  free runoff. The estimated runoff decrease by over 200% with afforestation while burning, cutting of trees and shrubs and over  grazing increase runoff up  to 20.3,

72.9 and 23.4 per cent respectively. Forests not only minimize runoff but also help to check soil moisture loss. A forest canopy with no litter layer can reduce evaporation   up   to   50   per   cent   of   that   from   a nonforested  soil  due  ot  shading  and  a  reduction  in wind   movement.   The   presence   of   forest   floor (accumulation   of   litter)   redue   evaporation   even further.For example, the runoff  in bare fallow was

71.1  per  cent  wheras  it  was  only  1.1  and  1.03  per cent    in    Eucalyptus    globulus    and    Acacia    sp affroested area. Forest reduces wind erosion. Forest reduces   the   velocity  of  wind   and   decreases  the turbulence  and  irregularity of  the  movement  of  the wind, thus reducing wind erosion.

2.3. Biological diversity

Forest  are  much  more  than  an  assemblage of    woody    trunks    with    leafy    canopies.    Trees determine  the  structure  and  organisation  of  forest ecosystem,  which provides  habitat  for  multitude  of species of plants, animals and micro-organisms used directly and indirectly by humans. Species diversity itself   may  be   considered  an   indirect   product  of forests, especially in the tropical moist forest, which contain at least one half of all known flora and fauna species.  India  have  about  500  different  species  of mammals  and  1/10th   of  the  total  avifauna  in  the world.

2.4. Purification of atmosphere

Trees  play  a  vital  role  in  ameliorating  the deteriorating   enviornment.   They   are   helpful   in reducing  noise  pollution.  Most  ordinary  sound  we hear falls in the range of 25 decibels. In residentialal area a level of 55 to 60 dBA is desirable druing day time  and  50  to  57  dBA  during  the  evening  hours. Plants  are  known  to  have  some  effects  as  sound barriers.  A  belt  of  5  to  6  m  wide  with  a  tall dense trees  and  shrubs  platnted  close  reduces  sound  5  to 10 dBA

Industrial   development   resulted   in   large amount  of  suspended  particulate  matter,  SO2,  NO2 and heavy metals. Also automobiles exhaust a lot of fumes,  carbondioxide  and  other  harmful  gases  into the air. Forest act as dust collectors and purifies the air,  as they serve as sinks for gaseous pollution, and improves the general environmnetal conditions.

Tree   species   like   Acacia   auriculiformis, Azadirachta     indica,     Artocarpus     heterophyllus Bauhinia    variegata,    and    shrubs    like   Acalypha hamiltoniana,   Casealpinia   pulcherima,   Ixora   sp, Sansevieria  sp.,  and  many  other  species  plays  a major    role   in   enviornmental   conservation   and industrial green belt.