WET LAND ECOSYSTEM

 

Areas of marsh, fen, peatland/water, whether natural (or) artificial, permanent (or) temporary with water that is static (or) flowing, fresh, brackish (or) salt, including areas of marine

water the depth of which at low tide does not exceed 6 mtrs.

Wetlands Classification-

  1. Inland wetland-

a)Natural- Lakes / Ponds, Ox-bow Lakes, Waterlogged, Swamp/marsh

  1. b) Manmade- Reservoirs Tank, Ash pond
  2. Costal Wetland-
  3. A) Natural- Coral reef, Tidal flat, Mangroves, Salt marsh, Estuary, Lagoon, Creek,

Backwater, Bay

b)-manmade -• Salt pans, Aquculture

Functions of Wetlands-

  • Habitat to aquatic flora and fauna, birds
  • Filtration of sediments and nutrients from surface water,
  • Nutrients recycling, Water purification Floods mitigation,
  • Ground water recharging, Buffer shorelines against erosion,
  • Genetic reservoir for various species of plants(rice)
  • the National Lake Conservation Programme (NLCP) considers lakes as standing water
  • bodies which have a minimum water depth of 3 m, generally cover a water spread of more than ten hectares, and have no or very little aquatic vegetation.
  • Wetlands (generally less than 3 m deep over most of their area) are usually rich in nutrients (derived from surroundings and their sediments) and have .abundant growth of aquatic macrophytes

India’s Wetland

Wetlands occupy 18.4% of the country’s area of which 70% are under paddy cultivation.

Inland wetlands >Costal Wetlands

 

National Wetlands Conservation Programme (NWCP)

  • NWCP was implemented in the year 1985-86.
  • Under the programme, 115 wetlands have been identified by the Ministry which require urgent conservation and management interventions.

Aim

  • Conservation of wetlands to prevent their further degradation and ensuring their wise
  • use for the benefit of local communities and overall conservation of biodiversity.

Objectives

  • to lay down policy guidelines for conservation and management of wetlands in the country.
  • to provide financial assistance for undertaking intensive conservation measures in the identified wetlands
  • The Central Government is responsible for overall coordination of wetland
  • conservation programmes and initiatives at the international and national levels. It also provides guidelines, financial & technical assistance to state govt.
  • State Governments/UT Administration are responsible for management of wetlands and implementation of the NWCP for ensuring their wise-use

 

Criteria for Identification of Wetlands of National Importance

Criteria for identification of wetlands of national importance under NWCP are same as those prescribed under the ‘Ramsar Convention on Wetlands’ and are as given below:

  1. Sites containing representative, rare or unique wetland types

example of a natural or near-natural wetland type’ found within the appropriate biogeographic region.

  1. Criteria based on species and ecological communities
  • If it supports vulnerable, endangered, or critically endangered species; or
  • threatened ecological communities.
  • If it supports populations of plant and/or animal species important for maintaining the biological diversity of a particular biogeographic region.
  • If it supports plant and/or animal species at a critical stage in their life cycles, or provides refuge during adverse conditions.

 

  1. Specific criteria based on water birds
  • If it regularly supports 20,000 or more water birds.
  • If it regularly supports 1% of the individuals in a population of one species or subspecies of waterbirds.

 

  1. Specific criteria based on fish
  • If it supports a significant proportion of indigenous fish subspecies, species or families, life-history stages,  species  interactions  and/or  populations  that  are representative of wetland benefits and/or values and thereby contributes to global biological diversity.
  • If it is an important source of food for fishes, spawning ground, nursery and/or migration path on which fish stocks, either within the wetland or elsewhere, depend.
  1. Specific criteria based on water/life and culture
  • If it is an important source of food and water resource, increased possibilities for recreation  and eco-tourism, improved scenic values, educational opportunities, conservation of cultural heritage (historic or religious sites)

 

LAKE ECOLOGY

 

Any – body of standing water, generally large enough in area and depth, irrespective of its hydrology, ecology, and other characteristics is generally known as lake.

Ageing of Lakes

The nutrient enrichment of the lakes promotes the growth of algae, aquatic plants and various fauna. This process is known as natural eutrophication.

Similar nutrient enrichment of lakes at an accelerated rate is caused by human activities and the consequent ageing phenomenon is known as ‘cultural eutrophication’.

In India, natural lakes (relatively few) mostly ile in the Himalayan region, the floodplains of Indus, Ganga and Brahmaputra.

Lake ‘Sudarshan’ in Gujarat’s Girnar area was perhaps the oldest man-made lake in India, dating back to 300 BC.

Lakes are also classified on the basis of their water chemistry. Based-on the levels of salinity, they are known as Freshwater, Brackish or Saline lakes (similar to that of classification of aquatic ecosystem).

On the basis of their nutrient content, they are categorized as Oligotrophic (very low nutrients), Mesotrophic (moderate nutrients) and Eutrophic (highly nutrient rich).

Removal of the nutrients from a lake

  • Flushing with nutrient-poor waters.
  • Deep water abstraction.
  • On-site P-elimination by flocculation/flotation with water backflow, or floating Plant
  • NESSIE with adsorbents.
  • On-site algae removal by filters and P-adsorbers.
  • 0n-site algae skimming and separator thickening.
  • Artificial mixing / Destratification (permanent or intermittent).
  • Harvest of fishes and macrophytes.
  • Sludge removal

EUTROPHICATION

a syndrome of ecosystem, response to the addition of artificial or natural substances such as nitrates and phosphates through fertilizer, sewage, etc that fertilize the aquatic ecosystem.

The growth of green algae which we see in the lake surface layer is the physical identification of an Eutrophication.

Some algae and blue-green bacteria thrive on the excess ions and a population explosion covers almost entire surface layer is known as algal bloom.  Nitrogen testing is a technique to find the optimum amount of fertilizer required for crop plants. It will reduce the amount of nitrogen lost to the surrounding area.

 

 

HARMFUL ALGAL BLOOMS

Algae or phytoplankton are microscopic organisms that can be found naturally in coastal waters. They are major producers of oxygen and food for many of the animals that live in these waters.

Algal blooms can be any color, but the most common ones are red or brown.

Most algal blooms are not harmful but some produce toxins and do affect fish, birds, marine mammals and humans.

Use of algae

Most species of algae or phytoplankton serve as the energy producers at the base of the food web, without which higher life on this planet would not exist.

Why Red Tide is a misnomer?

“Red Tide” is a common name for such a phenomenon where certain

phytoplankton species contain pigments and “bloom” such that the human eye perceives the water to be discoloured.

Blooms can appear greenish, brown, and even reddish orange depending upon the type of organism, the type of water, and the concentration of the organisms.

The term “red tide” is thus a misnomer because blooms are not always red, they are not associated with tides, they are usually not harmful, and some species can be harmful or dangerous at low cell concentrations that do not discolour the water.

What are the causes of these blooms?

Two common causes are nutrient enrichment and warm waters.

AQUATIC ECOSYSTEM

 

Fresh water ecosystems- The salt content of fresh bodies is very low, always less than 5 ppt  (parts per thousand). E.g lakes, ponds, pools, springs, streams, and rivers

Marine ecosystems – the water bodies containing salt concentration equal to or above that of sea water (i.e., 35 ppt or above). E.g shallow seas and open ocean   Brackish water ecosystems- these water bodies have salt content in between 5 to 35 ppt. e.g. estuaries, salt marshes, mangrove swamps and forests.

 

AQUATIC ORGANISMS

The aquatic organisms are classified on the basis Of their one of occurrence and their ability to cross these zones. can be classified on the basis of their life form or location into five groups

  1. Neuston:

These are unattached organisms which live at the air-water interface such as floating plants, etc.

Some organisms spend most of their lives on top of the air-water interface such as water striders, while others spend most of their time just beneath the air-water interface and obtain most of their food within the water.

E.g., beetles and back-swimmers.

  1. Periphyton:

These are organisms which remain attached to stems and leaves of rooted plants or substances emerging above the bottom mud such as sessile algae and their associated group of animals.

  1. Plankton

This group includes both microscopic plants like algae (phytoplankton) and

animals like crustaceans and protozoans (zooplankton) found in all aquatic

ecosysteins, except certain swift moving waters

The locomotory power of the planktons is limited so that their distribution is

controlled, largely, by currents in the aquatic ecosystems.

  1. Nekton:

This group contains animals which are  swimmers.

The nektons are relatively large and powerful as they have to overcome the water currents.

  1. Benthos:

The benthic organisms are those found living in the bottom of the water mass.

Practically every aquatic ecosystem contains well developed benthos

Factors Limiting the Productivity of Aquatic Habitats

  1. Sunlight :

Sunlight penetration rapidly diminishes as it passes down the column of water.

The depth to which light penetrates a lake determines the extent of plant distribution.

Based on light penetration and plant distribution they are classified as photic and aphotic zones

Photic zone:

It is the upper layer of the aquatic ecosystems, up to which light penetrates and within which photosynthetic activity is confined.

The depth of this zone depends on the transparency of water.

photic (or .”euphotic”) zone is the lighted and usually well-mixed portion that extends from the lake surface down to where the light level is 1% of that at the surface.

Aphotic zone:

The lower layers of the aquatic ecosystems, where light penetration and plant growth are restricted forms the aphotic zone.

Only respiration activity takes place.(photic-both respiration and photosynthesis take place )

Aphotic zone is positioned below the littoral and photic zones to bottom of the lake where light levels are too low for photosynthesis.

This deep, unlit region is also known as the profundal zone.

Dissolved oxygen:

Oxygen enters the aquatic ecosystem through the air water interface and by the photosynthetic. average concentration of dissolved oxygen as 10 parts per million by weight.

Dissolved oxygen escapes the water body through air-water interface and through respiration of organisms (fish, decomposers, zooplanktons, etc )

The amount of dissolved oxygen retained in water is also influenced by temperature.

Other limiting factors which influence on aquatic productivity are

Transparency:

Transparency affects the extent of light penetration.

Suspended particulate matters such as clay, silt, phytoplankton, etc make the water turbidity. Consequently it limits the extent of light penetration and the photosynthetic activity in a significant way.

Temperature:

The water temperature changes less rapidly than the temperature of air because water has a considerably higher specific heat than air.

Since water temperatures are less subject to change, the aquatic organisms have narrow temperature tolerance limit.

DESERT ECOSYSTEM

 

Deserts are formed in regions with less than 25 cm of annual rainfall, .or sometimes in hot regions where there is more rainfall, but unevenly distributed in the annual cycle.

Lack’ of rain in the mid latitude is often due to stable high pressure zones; deserts in temperate regions often lie in “rain shadows”, that is where high mountains block off moisture from the seas.

The climate:of these biomes is modified by altitUde and latitude. At greater distance from the equator the deSerts are cold and hot near equator and tropics.

As the large volume of water passes through the irrigation system, salts may be left behind that will gradually accumulate over the years until they become limiting, unless means of avoiding this difficulty are devised

Adaptations

(i)  These plants conserve water by following methods:

They are mostly shrubs. Leaves are absent or reduced in size.

Leaves and stem are succulent and water storing.

In some plants even the stem contains chlorophyll for photosynthesis.

Root system is well developed and spread over large area.

The annuals wherever present germinate, bloom and reproduce only during the short rainy season, and not in summer and winter.

(ii) The animals are physiologically and behaviorally adapted to desert conditions.

They are fast runners.

They are nocturnal in habit to avoid the sun’s heat during day time.

They conserve water by excreting concentrated urine.

Animals and birds usually have long legs to keep the body away from the hot ground.

Lizards are mostly insectivorous and can live without drinking water for several days.

Herbivorous animals get sufficient water from the seeds which they eat.

Mammals as a group are poorly adapted to  deserts

Indian Desert — Thar desert (hot)

The climate of this region is characterised by excessive drought, the rainfall being scanty and , irregular.

The winter rains of northern India rarely penetrate into the region.

The proper desert plants may be divided into two main groups.

  1. i) depending directly upon on rain and
  2. ii) those depending on the presence of subterranean water.

The first group consists of two types:

the ‘ephemera’s’ and the rain perennials’.

The ephemera’s are delicate annuals, apparently free from any xerophilous adaptations, having slender stems and root-systems and often large Flowers.

They appear almost immediately after rain, develop flowers and fruits in an incredibly short   time, and die as soon as the surface layer of the soil dries up.

The rain perennials are visible above the ground only during the rainy season, but have a perennial underground stem.

The second group – depending on the presence of subterranean water

By far the largest number of indigenous plants are capable of absorbing water from deep below the surface of the ground by means of a well-developed root system, the main part of which generally consists of a slender, woody tap root of extraordinary length.

Generally, various other xerophilous adaptations are resorted to such as reduced leaves, thick hairy growth, succulence, coatings of wax, thick cuticle, protected stomata, etc., all having for  their object of reduction of transpiration.

 

Fauna

It is home to some of India’s most magnificent grasslands and sanctuary for a charismatic bird, the Great Indian Bustard. Among the mammal fauna, the blackbuck, wild ass, chinkara, caracal, Sandgrouse and desert fox inhabit the open plains, grasslands, and saline depressions.

The nesting ground of Flamingoes and the only known population of Asiatic wild Ass lies in the remote part of Great Rarm, Gujarat.

It is the migration flyway used by cranes and flamingos.

Some endemic flora species of Thar Desert includes Calligonum Polygonoides, Prosopis cineraria, Tecomella undulate, Cenchrus biflorus and Sueda fruticosa , etc

 

Cold Desert/ Temperate Desert

Cold desert of India include areas of ladak, leh and kargil of kashmir and spiti valley of Himachal  Pradesh and some parts of northern Uttaranchal and Sikkim. Lies in rain shadow of Himalaya Oak, pine, deodar, birch and rhododendron are the important trees and bushes found there. Major  animal include yaks, dwarf cows, and goats.

Severe arid conditions – Dry Atmosphere

Mean annual rainfall less than 400mm

Soil type – sandy to sandy loam , Soil pH – neutral to slight alkaline.

Soil nutrient – Poor organic matter content ,low water retention capacity

Bio-diversity

Cold desert is the home of highly adaptive, rare endangered fauna, such as

Asiatic Ibex, Tibetan Argali, Ladakh Uriyal, Bharal, Tibetan Antelope (chiru),

Tibetan Gazelle, Wild Yak, Snow Leopard, Brown Bear, Tibetan Wolf, Wild

Dog and Tibetan Wild Ass (‘Kiang’ a close relative of the Indian wild ass) ,

Woolly hare, Black Necked  Crane, etc.

India as a signatory to United Nations Convention to Combat Desertification

(UNCCD) has submitted four National Reports to UNCCD

in the years 2000, 2002, 2006 and 2010

Some of the major programmes currently implemented that address issues related to land degradation and desertification is:-

  1. Integrated Watershed Management Programme (IWMP),
  2. National Afforestation Programme (NAP),
  3. National Mission for Green India (GIM),
  4. The Mahatma Gandhi National Rural Employment Guarantee Scheme
  5. (MGNREGS),
  6. Soil Conservation in the Catchment of River Valley Project and Flood Prone River,
  7. National Watershed Development Project for Rainfed Areas (NWDPRA),
  8. Desert Development Programme (DDP)
  9. Fodder and Feed Development Scheme-component of Grassland Development including
  10. Grass Reserves, Command Area Development and Water Management (CADWM)  programme etc

 

 

GRASSLAND ECOSYTEM

 

found where rainfall is about 25-75 cm per year, not enough to support a forest, but more than that of a true desert.

vegetation formations that are generally found in temperate climates.

In India, they are found mainly in the high Himalayas. The rest of India’s grasslands aremainly composed of steppes and savannas.

Steppe formations occupy large areas of sandy and saline soil; in western Rajasthan, where the climate is semi-arid,

The major difference between steppes and savannas is that all the forage in the steppe is  provided only during the brief wet season whereas in the savannas forage is largely from grasses that not only grow during the wet season but also from the  smaller amount of regrowth in the dry season.

 

Types of Grasslands

  1. semi-arid zone (The Sehima-dichanthium type)

It covers the northern portion of Gujarat, Rajasthan (excluding Aravallis), western Uttar Pradesh, Delhi and Punjab.

The topography is broken up by hill spurs and sand dunes.

senegal, Calotropis gigantia, Cassia auriculata, Prosopis cineraria, Salvadora oloides and zizyphus Nummularia which make the savanna rangeland look like scrub.

  1. dry sub humid zone (The Dichanthium- cenchrus-lasitrrus type)

It covers the whole of peninsular India (except Nilgiri).

The thorny bushes are Acacia catechu, Mimosa, Zizyphus (ber) and sometimes fleshy Euphorbia, along with low trees of Anogeissus latifolia, Soymida febrifuga and other deciduous species.

Sehima (grass)is more prevalent on gravel and the cover maybe 27%. Dichanthium (grass) flourishes on level soils and may cover 80% of the ground.

3)  moist subhumid zone(The Phragmities- sacchrum-imperata type)

It covers the Ganga alluvial plain in Northern India.

The topography is level, low lying and ill-drained.

Bothriochloa pertusa, Cypodon dactylon and     Dichanthium annulatum are found in transition zones.

The common trees and shrubs are Acacia arabica, hogeissus, latifolia, Butea monosperma,

Phoenic sylvestris and Zizyphus nummularia.

Some of these are replaced by Borassus sp in the palm savannas especially near Sunderbans.

4) The Themeda – Arundinella type

This extends to the humid montane regions and moist sub-humid axeas of Assam, Manipur,West Bengal, Uttar Pradesh, Punjab, Himachal Pradesh and. Jammu and Kashmir.

The savanna is derived from the humid forests on account of shifting cultivation and sheep grazing.

Indian Grasslands and Fodder Research Institute, Jhansi and Central Arid Zone Research institute, Jodhpur

Role of fire

fire plays, an important role in the management  of grasslands.

Under moist conditions fire favours grass over trees, whereas in dry conditions fire is often necessary to maintain grasslands against the invasion of desert shrubs.

Burning increases the forage yields, e.g. Cynodon daotylon

FOREST ECOSYSTEM

 

 

Forest ecosystem includes a complex assemblage of different kinds of biotic communities. Optimum conditions such as temperature and ground moisture are responsible for the establishment of forest communities.

Forests may be evergreen or deciduous which are distinguished on the basis of leaf into broad-leafed or needle leafed coniferous forests in the case of temperate areas. classified into three major categories: coniferous forest, temperate forest and tropical forest.

All these forest biomes are generally arranged on a gradient from north to south latitude or from high to lower altitude

 

Coniferous forest (boreal forest):

Cold regions with high rainfall, strong seasonal climates with long winters and short summers

evergreen plant species such as Spruce, fir and pine trees, etc and by animals such as the lynx, wolf, bear, red fox, porcupine, squirrel, and amphibians like Hyla, Rana, etc.

Boreal forest soils are characterized by thin podozols and are rather poor. Both because, the weathering of rocks proceeds slowly in cold environments and because the litter derived from conifer needle (leaf  is decomposed very slowly and is not rich in nutrients.

These soils are acidic and are mineral deficient.

This is due to movement of large amount of water through the soil, without a significant counter-upward movement of evaporation, essential soluble nutrients like calcium, nitrogen and potassium which are leached sometimes beyond the reach of roots. This process leaves no alkaline oriented cations to encounter the organic acids of the accumulating litter.

The productivity and community stability of a boreal forest are lower than those of any other forest ecosystem.

Temperate deciduous forest:

The temperate forests are characterised by a moderate climate and broad-leafed deciduous trees, which shed their leaves in fall, are bare over winter and grow new foliage in the spring.

The precipitation is fairly uniform throughout.

Soils of temperate forests are podozolic and fairly deep.

Temperate evergreen forest:

Parts of the world that have Mediterranean type of Climate are characterised by warm, dry summers and cool, moist winters. low broad leafed evergreen trees.

Fire is an important hazardous factor in this ecosystem and the adaptation of the plants enable them to regenerate quickly after being burnt.

Temperate rain forests:

seasonality with regard to temperature and rainfall

Rainfall is high, and fog may be very heavy. It is the important source of water than rainfall itself

The biotic diversity of temperate rain forests is high as compared to other temperate forest.

the diversity of plants and animals is much low as compared to the tropical rainforest.

 

Tropical rain forests:

 

Near the equator.

Among the most diverse and rich communities on the earth.

Both temperature and humidity remain high and more or less uniform.

The annual rainfall exceeds 200 cm and is generally distributed throughout the year.

The flora is highly diversified The extreme dense vegetation of the tropical rain  forests remains vertically stratified with tall trees often covered with vines, creepers,   lianas, epiphytic orchids and bromeliads.

The lowest layer is an understory of trees,  shrubs, herbs, like ferns and palms.

Soil of tropical rainforests are red latosols, and they are very thick

Tropical seasonal forests:

also known as monsoon forest occur in regions where total annual rainfall is very high but segregated into pronounced wet and dry periods.

This kind of forest is found in South East Asia, central and south America, northern Australia, western Africa and tropical islands of the pacific as well as in India.

Subtropical rain forests:

Broad-leaved evergreen subtropical rain forests are found in regions of fairly high rainfall but less temperature differences between winter and summer

Epiphytes are common here.

Animal life of subtropical forest is very similar to that of tropical rainforests.

 

INDIAN FOREST TYPES

Forest types in India are classified by Champion and Seth into sixteen types.

 

Tropical Wet evergreen forests

are found along the Western Ghats, the Nicobar and Andaman Islands and all  along the north-eastern region.

It is characterized by tall, straight evergreen trees.

The trees in this forest form a tier pattern:

Beautiful fern of various colours and different varieties of orchids grow on the trunks of the trees.

Among the following States, which one has the most suitable climatic conditions for the cultivation of a large variety of orchids with minimum cost of production, and can develop

Tropical Semi-evergreen forests

found in the Western Ghats, Andaman and Nicobar Islands, and the Eastern

Himalayas.

Such forests have a mixture of the wet evergreen trees and the moist

deciduous trees. The forest is dense

Tropical Moist deciduous forests

found throughout India except in the western and the north -western regions.

The trees are tall, have broad trunks, branching trunks and roots to hold them firmly to the ground.

These forests are dominated by sal and teak, along with mango, bamboo, and rosewood.

Littoral and swamp

found along the Andaman and Nicobar Islands and the delta area of the Ganga and the Brahmaputra.

They have roots that consist of soft tissue so that the plant can breathe in the water.

Tropical Dry deciduous forest

The northern part of the country except in the North-East. It is also found in Madhya Pradesh, Gujarat, Andhra Pradesh, Karnataka, and Tamil Nadu. The canopy, of the trees does not normally exceed 25 metres.

The common trees are the sal, a variety of acacia, and bamboo.

Tropical Thorn forests

This type is found in areas with black soil: North, West, Central, and South India. The trees do not grow beyond 10 metres. Spurge, caper, and cactus are typical of this region.

Tropical Dry evergreen forest

Dry evergreens are found along Tamil Nadu Andhra Pradesh and Karnataka coast. It is mainly hard-leaved evergreen trees with fragrant flowers, along with a few  deciduous trees.

Sub-tropical Broad-leaved forests

Broad-leaved forests are found in the Eastern Himalayas and the Western Ghats, along the Silent Valley.

There is a marked difference in the form of vegetation in the two areas.

In the Silent Valley, the  poonspar, cinnamon, rhododendron, and fragrant grass are predominant.

In the Eastern Himalayas, the flora has been badly affected by the shifting cultivation and forest fires.

There are oak, alder, chestnut, birch, and cherry trees. There are a large variety of orchids, bamboo and creepers.

Sub-tropical Pine forests

found in Shivalik Hills, Western and Central Himalayas, Khasi, Naga, and Manipur Hills.

The trees predominantly found in these areas are the chir, oak, rhododendion, and   pine as well as sal, amla, and laburnum are found in the lower regions.

 

Sub-tropical Dry evergreen forests

hot and dry season and a cold winter. It generally has evergreen trees with shining

leaves that have a varnished look.

found in the Shivalik Hills and foothills of the Himalayas up to a height of 1000 metres.

Montane Wet temperate forests

In the North, found in the region to the east of Nepal into Arunachal Pradesh, receiving a minimum rainfall of 2000 mm. In the North, there are three layers of    forests: the higher layer has mainly coniferous, the middle layer has deciduous trees such as the oak and the lowest layer is covered by rhododendron and champa.

In the South, it is found in parts of the Niligiri Hills, the higher reaches of Kerala.

The forests in  the northern region are denser than in the South. Rhododendrons and a

variety of ground flora can be found here.

Himalayan Moist temperate Forest

This type spreads from the Western Himalayas to the Eastern Himalayas. The trees

found in the western section are broad-leaved oak, brown oak, walnut,

rhododendron,

Eastern Himalayas, the rainfall is much heavier and therefore the vegetation is also more lush and dense. There are a large variety of broad-leaved trees, ferri, and  bamboo.

Himalayan Dry temperate Forest

This type is found in Lahul, Kinnaur, Sikkim, and other parts of the Himalayas.

There are predominantly coniferous trees, along with broad-leaved trees such as the oak, maple, and ash. At higher elevation, fir, juniper, deodar, and chilgoza are found.

 

Sub alpine forest

Sub alpine forests extend from Kashmir to Arunachal Pradesh between 2900 to 3500 metres.

In the Western Himalayas, the vegetation consists mainly of juniper, hododendron, willow, and black currant.

In the eastern parts, red fir, black juniper, birch, and larch are the common trees.

Due to heavy rainfall and high humidity the timberline in this part is higher than that in the West.

Rhododendron of many species covers the hills in these parts.

Moist Alpine scrub

Moist alpines are found all along the Himalayas and on the higher hills near the Myanmar border. It has a low scrub, dense evergreen forest, consisting

mainly of rhododendron and birch. Mosses and ferns cover the ground in patches. This region receives heavy snowfall.

Dry alpine scrub

Dry alpines are found from about 3000 metres to about 4900 metres. Dwarf plants predominate, mainly the black juniper, the drooping juniper, honeysuckle, and willow.

   TERRESTRIAL ECOSYSTEMS

 

 

The interrelations between organisms and environment on the land constitute “Terrestrial Ecology”.

The most important limiting factors of the terrestrial ecosystems are moisture and temperature.

 

 

TUNDRA

The word tundra means a “barren land” since they are found where environmental conditions are very severe. There are two types of tundra- arctic and alpine.

Distribution:

Arctic tundra extends as a continuous belt below the polar ice cap and above the tree line in the northern hemisphere. It occupies the northern fringe of Canada, Alaska, European Russia, Siberia and island group of Arctic Ocean.

On the south pole, tundra is very small since most of it is covered by ocean .

Alpine tundra occurs at high mountains above the tree line. Since mountains are found at all latitudes therefore alpine tundra shows day and night temperature variations.

Flora and fauna:

Typical vegetation of arctic tundra is cotton grass, sedges, dwarf heath, willows, birches and lichens.

Animals of tundra are reindeer, musk ox, arctic hare, caribous, lemmings and squirrel.

They are protected from chillness by the presence of thick cuticle and epidermal hair.

Mammals of the tundra region have large body size and small tail and ear to avoid the loss of heat from the surface.

The body is covered with fur for insulation.

ECOLOGY

 

 

Ecology is  defined “as a scientific study of the relationship of the living organisms with each other and with their environment.”

The classical texts of the Vedic period such as the Vedas, the Samhitas, the Brahmanas and the Aranyakas-Upanishads contain many references to ecological concepts .The Indian treatise on medicine, the Caraka- Samhita and the surgical text Susruta-Samhita. contain classification of animals on the basis of habit and habitat, land in terms of nature of soil, climate and vegetation; and description of plants typical to various localities.

Caraka- Samhita contains information where air, land, water and seasons were indispensable  for life and that polluted air and water were injurious for health.

The environment is defined as ‘the sum total of living, non-living components;  influences and events, surrounding an organism.

Components of Environment

  1. Abiotic – Energy, Radiation, TEMP, Water, etc.
  2. Biotic- plants, animals, man, DECOMPOSER ETC.

Diesel engine exhaust fumes can cause cancer, humans” and it belong to the same potentially deadly category as asbestos, arsenic and ‘mustard gases.

Six main levels of organisation of ecology are:

  1. Individual- Organism is an individual living being that has the ability to act or function independently.
  2. Population-Population is a group of organisms usually of the same species,

occupying a defined area during a specific time,

  1. Community- Communities in most instances are named after the dominant plant form

(species). A community is not fixed or rigid; communities may be large or small.

Types of Community-

On the basis of size and degree of relative independence communities may be divided into two types-

(a)  Major Community

These are large-sized, well organized and relatively independent. They depend

only on the sun’s energy from outside and are independent of the inputs and

outputs from adjacent communities.

E.g: tropical ever green forest in the North-East

 

(b) Minor Communities

These are dependent on neighbouring communities and are often called societies.

They are secondary aggregations within a major community and are not therefore completely independent units as far as energy and nutrient dynamics are concerned.

e.g: A mat of lichen on a cow dung pad.

The environmental factors determine the characteristic of the community as well as the pattern of organisation of the members in the community

The characteristic pattern of the community is  termed as structure which is reflected in the roles played by various population, their range, the  type of area they inhabit, the diversity of species in the community and the spectrum of interactions between them

Eco-System-An ecosystem is defined as a structural and functional unit of biosphere consisting of community of living beings and the physical environment, both interacting and exchanging materials between them. It includes plants, trees, animals, fish, birds, micro-organisms, water, soil, and  people.

When an ecosystem is healthy (i.e. sustainable) it means that all the elements live in balance and are  capable of reproducing themselves

 

Components of Ecosystem

The components of the ecosystem is categorised into abiotic of non-living and biotic of living components. Both the components of ecosystem and environment are same.

 

  1. Abiotic Components

the inorganic and non-living parts of the world.  consists of soil, water, air, and light energy etc.  involves a ,large number of chemicals like oxygen, nitrogen-, etc. and physical processes including volcanoes, earthquakes, floods, forest fires, climates, and weather conditions.

Abiotic factors are the most important determinants of where and how well an organism exists in its environment. Although these factors interact with each other, one single factor can-limit the range of an organism.

 

  1. a) Energy

Energy from the sun is essential for maintenance of life. Energy determines the distribution of organisms in  the environment.

  1. b) Rainfall
  2. c) Temperature :-Temperature is a critical factor of the environment which greatly influences survival of organisms. Organisms can tolerate only a certain range of temperature and humidity.
  3. d) Atmosphere :It is made up of 21% oxygen, 78% nitrogen , 0.038% carbon dioxide and other inert gases (0.93% Argon, Neon etc).
  4. e) Substratum :Land is covered by soil and a wide variety of microbes, protozoa, fungi and small animals (invertebrates) thrive in it
  5. f) Materials:

(i) Organic compound

Such as proteins, carbohydrates,  lipids,  humic  substances are formed from inorganic compound on decomposition.

(ii) Inorganic compound

Such as carbon,   carbon dioxide, water, sulphur, nitrates, phosphates, and ions of various metals are essential for organisms to survive.

  1. g) Latitude and altitude

Latitude has a strong influence on an area’s temperature, resulting in change of climates such as polar, tropical, and temperate. These climates determine different natural biomes. From sea level to highest peaks, wild life is influenced by altitude. As the altitude increases, the air becomes colder and drier, affecting wild life accordingly.( wild life decrease as altitude increase)

 

  1. Biotic Components :Biotic components include living organisms comprising plants, animals and microbes and are classified according to their functional attributes into producers and consumers.

Primary producers – Autotrophs (self-nourishing) Primary producers are basically green plants (and certain bacteria and algae). They synthesise carbohydrate from simple inorganic raw materials like carbon dioxide and water in the presence of sunlight by the process of photosynthesis for themselves, and supply indirectly to other non- producers.

In terrestrial ecosystem, producers are basically herbaceous and woody plants, while in aquatic ecosystem producers are various species of microscopic algae.

 

  1. b) Consumers — Heterotrophs or phagotrophs (other nourishing)

 

Consumers are incapable of producing their own food (photosynthesis).

They depend on organic food derived from plants, animals or both.

Consumers can be divided into two broad  groups

 

(i) Macro consumers- They feed on plants or animals or both and are categorised on the basis of their food sources.

Herbivores are primary consumers which feed mainly on plants e.g. cow, rabbit.

Secondary consumers feed on primary consumers e.g. wolves.

Carnivores which feed on secondary consumers are called tertiary consumers e.g. lions which can eat wolves.

Omnivores are organisms which consume both plants and animals e.g. man.

 

(ii) Micro consumers – Saprotrophs (decomposers or osmotrophs)

 

They are bacteria and fungi which obtain energy and nutrients by decomposing dead organic substances (detritus) of plant and animal origin.

The products of decomposition such as inorganic nutrients which are released in the ecosystem are reused by producers and thus recycled.

Earthworm and certain soil organisms (such as nematodes, and arthropods) are detritus feeders and help in the decomposition of organic matter and are called detrivores.

Classification of Eco-system

 

  1. Natural Ecosystem-

Terrestrial- Forests, Grasslands, Deserts

Aquatic- Fresh Waters, Saline Waters, Marine Waters

Ecotone :- a zone of junction between two or more diverse ecosystems. For e.g. the mangrove forests represent an ecotone between marine and terrestrial ecosystem.

Characteristics of Ecotone

It may be very narrow or quite wide. It has the conditions intermediate to the adjacent ecosystems. Hence it is a zone of tension.

It is linear as it shows progressive increase in species composition of one in coming community and a simultaneous decrease in species of the other out going adjoining community.

A well developed ecotones contain some organisms which are entirely different from that of the adjoining communities.

Sometimes the number of species and the population density of some of the species is much greater in this zone than either community. This is called edge effect For example the density of birds is greater in the mixed habitat of the ecotone between the forest and the desert.

 

Niche

a  description  of  all  the  biological,  physical  and  chemical  factors  that  a  species needs to survive, stay healthy and reproduce. No two species have exact identical niches. Niche plays an important role in conservation of organisms.

Types of Niche

  1. Habitat niche – where it lives
  2. Food niche – what is eats or decomposes & what species it competes with
  3. Reproductive niche -how and when it reproduces.
  4. Physical & chemical niche – temperature, land shape, land slope, humidity & other requirement.

Biome

The terrestrial part of the biosphere is divisible into enormous regions called biomes, which are characterized, by climate, vegetation, animal life and general soil type.

No two biomes are alike.

The most important climatic factors are temperature and precipitation.

  1. Tundra- Northern most region  adjoining the ice bound  poles. Devoid of trees except stunted shrubs in the southern part of tundra biome, ground flora includes lichen, mosses and sedges.

The typical animals are reindeer, arctic fox polar bear, snowy owl, lemming, arctic hare,  ptarmigan. Reptiles and amphibians are almost absent

 

  1. Taiga- Northern Europe, Asia and North America. Moderate temperature than tundra. Also known as boreal forest.

The dominating vegetation is coniferous evergreen mostly spruce, with some pine and firs. The fauna consists of small seed eating birds, hawks, fur bearing carnivores, little mink, elks, puma, Siberian tiger, wolverine, wolves etc.

 

  1. Temperate Deciduous Forest- Extends over Central and Southern Europe, Eastern North America, Western China, Japan, New Zealand etc.

Moderate average temperature and abundant  rainfall. These are generally the  most  productive agricultural areas of the earth The flora includes trees like beech, oak, maple and cherry. Most animals are the familiar vertebrates and invertebrates.

  1. Tropical rain forest- Tropical areas  in  the equatorial regions, which is  a bound  with  life.  Temperature and rainfall high.

Tropical rainforest covers about 7% of the earth’s surface& 40% of the world’s plant and animal species.

Multiple storey of broad-leafed evergreen tree species are in abundance.

Most animals and epiphytic plants(An epiphyte is a plant that grows harmlessly upon another plant)  are concentrated in the canopy or tree top zones

  1. Savannah- Tropical region: Savannah is most extensive in Africa

Grasses with scattered trees and fire resisting thorny shrubs.

The fauna include a great diversity of grazers and browsers such as antelopes, buffaloes, zebras, elephants and rhinoceros;  the carnivores include lion, cheetah, hyena; and mongoose, and many rodents

 

  1. Grassland- North America, Ukraine, etc . Dominated by grasses. Temperate conditions with rather low rainfall. Grasses dominate the vegetation. The fauna include large herbivores like bison, antelope, cattle, rodents, prairie dog, wolves, and a rich and diverse array of ground nesting bird

 

  1. Desert- Continental interiors with very low and sporadic rainfall with low humidity. The days are very hot but nights are cold. The flora is drought resistance vegetation such as cactus, euphorbias, sagebrush. Fauna : Reptiles, Mammals and birds.

Aquatic Zones

Aquatic systems are not called biomes,

The major differences between the various aquatic zones are due to salinity, levels  of dissolved nutrients; water temperature, depth of sunlight penetration.

 

  1. Fresh Water Ecosystem-Fresh water ecosystem are classified as lotic

(moving water) or lentic (still or stagnant water).

 

  1. Marine Ecosystem-
  2. Estuaries-Coastal bays, river mouths and tidal marshes  form  the

estuaries.  In estuaries, fresh water from rivers meet ocean water and the two are mixed by action of tides.

Estuaries are highly productive as compared to the adjacent river or sea

 

Biosphere

a part of the earth where life can exist.

represents a highly integrated and interacting zone comprising of atmosphere (air), hydrosphere (water) and lithosphere (land) Life in the biosphere is abundant between 200 metres (660 feet) below the surface of the ocean and about 6,000 metres (20,000 feet) above sea level. absent at extremes of the North and South poles. Living organisms are not uniformly distributed  throughout the biosphere

 

FUNCTIONS OF AN ECOSYSTEM

ENERGY FLOW- Energy is the basic force responsible for all metabolic activities. The flow of energy from producer to top consumers is called energy flow  which is unidirectional.

Energy flows through the trophic levels: from producers to subsequent trophic levels. There is a loss of some energy in the form of unusable heat at each trophic level.

The trophic level interaction involves three concepts namely :-

  1. Food Chain
  2. Food Web
  3. Ecological Pyramids
  4. FOOD CHAIN- A food chain starts with producers and ends with top carnivores. The sequence of eaten and being eaten, produces transfer of food energy and it is known as food chain.

Grazing food chain-The consumers which start the food chain, utilising the plant or plant part as their food, constitute the grazing food chain.

This food chain begins from green plants at the base and the primary consumer is herbivore

For example, In terestrial ecosystem, grass is eaten up by caterpillar, which is eaten by lizard and lizard is eaten by snake.

In Aquatic ecosystem phytoplanktons (primary producers) is eaten by zoo planktons which is eaten by fishes and fishes are eaten by pelicans

Detritus food chain- The food chain starts from dead organic matter of decaying animals and plant bodies to the micro-organisms and then to detritus feeding organism called detrivores or decomposer and to other predators.

 

Litter —■Earthworms —■Chicken—■Hawk

Detritus food chain

The distinction between these two food chains is the source of energy for the first level consumers.

  1. FOOD WEB

“A food web illustrates, all possible transfers of energy and nutrients among the organisms in an ecosystem, whereas a food chain traces only one pathway of the food”.

  1. ECOLOGICAL PYRAMIDS

The steps of trophic levels expressed in a diagrammatic way are referred as

ecological pyramids.

 

The food producer forms the base of the pyramid and the top carnivore forms the tip. Other consumer trophic levels are in between.

The pyramid consists of a number of horizontal bars depicting specific trophic levels which are arranged sequentially from primary producer level through herbivore, carnivore onwards.  The length of each bar represents the total number of individuals at each trophic level in an ecosystem.

The ecological pyramids are of three categories-

1.Pyramid of numbers,

2.Pyramid of biomass, and

3.Pyramid of energy or productivity

  1. Pyramid of Numbers

This deals with the relationship between the numbers of primary producers and consumers of different levels. Depending upon the size and biomass, the pyramid of numbers may not always be upright, and may even be completely inverted.

(a) Pyramid of numbers – upright

In this pyramid, the number of individuals is decreased from lower level to higher trophic level.

This type of pyramid can be seen in grassland ecosystem.

(b) Pyramid of numbers – inverted

In this pyramid, the number of individuals is increased from lower level to higher trophic level.

A count in a forest would have a small number of     large producers, for e.g. few number of big trees.   This is because the tree (primary producer) being

few in number and would represent the base of the pyramid and the dependent herbivores  (Example – Birds) in the next higher trophic level and it is followed by parasites in the next trophic level. Hyper parasites being at higher trophic level represents higher in number.

A pyramid of numbers does not take into account the fact that the size of organisms being counted in each trophic level can vary

the pyramid of number does not completely define the trophic structure for an ecosystem.

  1. Pyramid of Biomass

In this approach individuals in each trophic level are weighed instead of being counted. This gives us a pyramid of biomass, i.e., the total dry weight of all organisms at each trophic level at a particular time.

Biomass is measured in g/m2.

 

(a) Upward -pyramid For most ecosystems on land, the pyramid of biomass has a large base of primary producers with a smaller trophic level perched on top

 

(b) Inverted pyramid-In contrast, in many aquatic ecosystems, the pyramid of biomass may assume an inverted form

  1. Pyramid of Energy

To compare the functional roles of the trophic levels in an ecosystem, an energy pyramid is most suitable.

An energy pyramid, reflects the laws of thermodynamics, with conversion of solar energy to chemical energy and heat energy at each trophic level and with loss of energy being depicted at each  transfer to another trophic level.

Hence the pyramid is always upward, with a large energy base at the bottom.

POLLUTANTS AND TROPHIC LEVEL :-

Movement of these pollutants involves two main processes:

 

  1. Bioaccumulation

refers to how pollutants enter a food chain. there is an increase in concentration of a pollutant from the environment to the first organism in a food chain.

 

  1. Biomagnification

refers to the tendency of pollutants to concentrate as they move from one trophic level to the next.  there is an increase in concentration of a pollutant from one link in a food chain to another.

In order for biomagnification to occur, the pollutant must be: long-lived, mobile, soluble in fats, biologically active.

If a pollutant is not active biologically, it may biomagnify, but we really don’t worry about it much, since it probably won’t cause any problems Examples : DDT.

BIOTIC INTERACTION

The interaction between the organisms is fundamental for its survival and functioning of ecosystem as a whole.

Type of Biotic Interaction

  1. Mutualism:

both species benefit.

Example: in pollination mutualisms, the pollinator gets food (pollen, nectar), and the plant has its pollen transferred to other flowers for cross-fertilization (reproduction).

 

  1. Commensalism:

one species benefits, the other is unaffected.

Example: cow dung provides food and shelter to dung beetles. The beetles have no effect on the cows.

 

  1. Competition:

both species are harmed by the interaction.

Example: if two species eat the same food, and there isn’t enough for both, both may have access to less food than they would if alone. They both suffer a shortage of food

 

  1. Predation and parasitism:

one species benefits, the other is harmed.

Example : predation—one fish kills and eats ..parasitism: tick gains benefit by sucking blood; host is harmed by losing blood.

 

  1. Amensalism :

One species is harmed, the other is unaffected.

Example: A large tree shades a small plant, retarding the growth of the small plant. The small plant has no effect on the large tree.

 

  1. Neutralism :

There is no net benefit or harm to either species. Perhaps in some interspecific interactions, the costs and benefits experienced by each partner are exactly the same so that they sum to zero

 

BIOGEOCHEMICAL CYCLE

 

The elements or mineral nutrients are always in circulation moving from non-living to living and then back to the non-living components of the ecosystem in a more or less circular fashion. This circular fashion is known as biogeochemical cycling (bio for living; geo for atmosphere).

  1. Nutrient Cycling:

The nutrient cycle is a concept that describes how nutrients move from the physical environment to the living organisms, and subsequently recycled back to the physical environment.

It is essential for life and it is the vital function of the ecology of any region. In any particular environment, to maintain its organism in a sustained manner, the nutrient cycle must be kept balanced and stable.

 

Types of Nutrient Cycle

Based on the replacement period a nutrient cycle is referred to as Perfect or Imperfect cycle.

A perfect nutrient cycle is one in which nutrients are replaced as fast as they are utilised.

Most gaseous cycles are generally considered as perfect cycles.

In contrast sedimentary cycles are considered relatively imperfect, as some nutrients are lost from the cycle and get locked into sediments and so become unavailable for immediate cycling.

Based on the nature of the reservoir, there are two types of cycles namely Gaseous and sedimentary cycle

Gaseous Cycle — where the reservoir is the atmosphere or the hydrosphere, and

Sedimentary Cycle — where the reservoir is the earth’s crust.

 

  1. Gaseous Cycles:

Water Cycle (Hydrologic)

The hydrologic cycle is the continuous circulation of water in the Earth-atmosphere system which is driven by solar energy.

Water moves from one reservoir to another by the processes of evaporation,

transpiration, condensation, precipitation, deposition, runoff,

infiltration, and groundwater flow.

 

  1. The Carbon Cycle

without carbon dioxide life could not exist, because it is vital for the production of carbohydrates through photosynthesis by plants. It is the element that anchors allorganic substances from coal and oil to DNA(deoxyribonudeic acid: the compound that caries genetic information) Carbon cycle involves a continuous exchange of carbon between the atmosphere and organisms. Carbon from the atmosphere moves to green plants by the process   of photosynthesis, and then to animals. By process of respiration and decomposition of dead organic matter it returns back to atmosphere.

 

  1. The Nitrogen Cycle

an essential constituent of protein and is a basic building block of all living tissue. It constitutes nearly 16% by weight of all the proteins.

There is an inexhaustible supply of nitrogen in the atmosphere but the elemental form cannot be used directly by most of the living organisms needs to be ‘fixed’, that is, converted to ammonia, nitrites or nitrates, before it can be taken up by plants. on earth it is accomplished in three different ways:

(i) By microorganisms (bacteria and blue-green algae)

 

(ii) By man using industrial processes (fertilizerfactories) and

(iii) To a limited extent by atmospheric phenomenon such as thunder and lighting

The amount of Nitrogen fixed by man through industrial process has far

exceeded the amount fixed by the Natural Cycle.

As a result Nitrogen has become a pollutant which can disrupt the balance of

nitrogen. It may lead to Acid rain, Eutrophication and Harmful Algal Blooms.

Certain microorganisms are capable of fixing atmospheric nitrogen into

ammonium ions. These include free living nitrifying bacteria (e.g. aerobic

Azotobacter and anaerobic Clostridium) and symbiotic nitrifying bacteria living in  association with leguminous plants(pulse etc) and symbiotic bacteria    living in non leguminous root nodule plants (e.g. Rhizobium) as well as blue green algae (e.g. Anabaena, Spirulina).

Ammonium ions can be directly taken up as a source of nitrogen by some plants, or are oxidized to nitrites or nitrates by two groups of specialised bacteria:

Nitrosamines bacteria promote transformation of ammonia into nitrite. Nitrite isthen further transformed into nitrate by the bacteria Nitrobacter.

The nitrates synthesised by bacteria in the soil are taken up by plants and converted into amino acids, which are the building blocks of proteins.

These then go through higher trophic levels of the ecosystem.

During excretion and upon the death of all organisms nitrogen is returned to the soil in the form of ammonia.

Certain quantity of soil nitrates, being highly soluble in water, is lost to the system by being transported away by surface run-off or ground water. In the soil as well as oceans there are special denitrifying bacteria (e.g. Pseudomonas), which convert the nitrates/nitrites to elemental nitrogen. This nitrogen escapes into the atmosphere, thus  completing the cycle.

The periodic thunderstorms convert the gaseous nitrogen in the atmosphere to ammonia and nitrates which eventually reach the earth’s surface through precipitation and then into the soil to be utilized by plants.(Better if You Check Diagram)

  1. Sedimentary Cycle

Phosphorus, calcium and magnesium circulate by means of the sedimentary cycle.

(a) Phosphorus Cycle

Phosphorus plays a central role in aquatic ecosystems and water quality.

Phosphorus occurs in large amounts as a mineral in phosphate rocks and enters the cycle from erosion and minning activities.

This is the nutrient considered to be the main cause of excessive growth of rooted and free-floating microscopic plants in lakes.

The main storage for phosphorus is in the earth’s crust.

On land phosphorus is usually found in the form of phosphates.

By the process of weathering and erosion phosphates enter rivers and streams that transport them to the ocean.

In the ocean once the phosphorus accumulates on continental shelves in the form of insoluble deposits

After millions of years, the crustal plates rise from the sea floor and expose the phosphates on land.

After more time, weathering will release them from rock and the cycle’s

geochemical phase begins again.

(b) Sulphur Cycle

The sulphur reservoir is in the soil and sediments where it is locked in organic

(coal, oil and peat) and inorganic deposits (pyrite rock and sulphur rock) in the

form of sulphates, sulphides and organic sulphur.

 

It is released by weathering of rocks, erosional runoff and decomposition of organic matter and is carried to terrestrial and aquatic ecosystems in salt solution.

The sulphur cycle is mostly sedimentary except two of its compounds hydrogen sulphide

(H2S) and sulphur dioxide (SO2) add a gaseous component to its normal sedimentary cycle.

Atmospheric sulphur dioxide is carried back to the earth after being dissolved in rainwater as weak sulphuric acid.

sulphur in the form of sulphates is take up by plants and incorporate through a series of metabolic processes into sulphur bearing amino acid which is incorporated in the  proteins of autotroph tissues. It then passes through the grazing food chain.

Sulphur bound in living organism is carried back to the soil, to the bottom of ponds and lakes and seas through excretion and decomposition of dead organic material.

 

SUCCESSION

a universal process of directional change in vegetation, on an ecological time scale. occurs when a series of communities replace one another due to large scale destruction either natural or manmade.

continously -one community replacing another community, until a stable, mature community develops.

The first plant to colonise an area is called the pioneer community. The final stage of succession iscalled the climax community.

The stage leading to the climax community are called successional stages

or seres. characterised by the following: increased productivity, the shift of nutrients from’ the reservoirs, increased diversity of organisms with increased niche development, and a gradual increase in the complexity of food webs.

Primary Succession

In primary succession on a terrestrial site the new site is first colonized by a few hardy pioneer species that are often microbes, lichens and mosses.

The pioneers through their death any decay leave patches of organic matter in which small animals can live.

The organic matter produced by these pioneer species produce organic adds during decomposition that dissolve and etch the substratum releasing nutrients to the substratum. Organic debris accumulates in pockets and crevices, providing soil  in which seeds can become lodged and grow.

As the community of organisms continues to develop, it becomes more diverse and competition increases, but at the same time new niche opportunities develops.

The pioneer species disappear as the habitat conditions change and invasion of new species progresses, leading to the replacement of the preceding community.

Secondary Succession

Secondary Succession occurs when plants recognize an area in which the climax community has been disturbed.

Secondary Succession  is the sequential development of biotic communities after the complete or partial destruction of the existing community.

This abandoned farmland is first invaded by hardy species of grasses that can survive in bare, sun-baked soil. These grasses may be soon joined by tall grasses and herbaceous plants.

These dominate the ecosystem for some years along with mice, rabbits, insects and seed- eating birds.

 

Eventually, some trees come up in this area, seeds of which may be brought by wind or animals. And over the years, a forest community develops. Thus an abandoned farmland over a period becomes dominated by trees and is transformed into a forest.

The differences between primary and secondary succession, the secondary succession starts on a well-developed soil already formed at the site. Thus secondary succession is relatively faster as compared to primary succession which may often require hundreds of years.

Autogenic and Allogenic Succession

When succession is brought about by living inhabitants of that community itself, the process is called autogenic succession, while change brought about by outside forces is known as allogenic succession.

Autotrophic and Heterotrophic succession

Succession in which, initially the green plants are much greater in quantity is known as autotrophic succession;  and the ones in which the heterotrophs are greater in quantity is known as heterotrophic succession.

Succession would occur faster in area existing in the middle of the large continent. This is because, here all prop gules or seeds of plants belonging to the different seres would reach much faster, establish and ultimately result in climax community.

 

Environmental Impact Assessment (EIA)

Notification on Environmental Impact Assessment (EIA) of developmental projects 1994 under the provisions of Environment (Protection) Act, 1986 making EIA  mandatory for 29 categories of developmental projects. One more item was added to the list in January, 2000. environmental impact assessment statutory for 30 activities

Environment Impact Assessment Notification of 2006 has categorized the developmental projects  in two categories, i.e., Category A and Category B

‘Category A’ projects are appraised at national level by expert appraisal committee

India has constituted the State Level Environment Impact Assessment Authority (SEIAA) and State Level Expert Appraisal Committee (SEAC)  to decentralize the environmental clearance process

The objective of EIA is to foresee and address potential environmental problems/  concerns at an early stage of project planning and design.

The EIA notification establishes four stages for obtaining Environmental Clearance.

  1. Screening
  2. Scoping and consideration of alternatives Baseline data collection
  3. Impact prediction
  4. Assessment of alternatives, delineation of mitigation measures and environmental impact statement
  5. Public hearing
  6. Environment Management Plan Decision making
  7. Monitoring the clearance conditions

Screening- It is only for Categories B

Screening Criteria are based upon:

  • Scales of investment; •       Type of development; and, •      Location of development

B1 Categories project require Environmental Impact Assessment while B2 category projects are exempted from EIA.

State Level Expert Appraisal Committee determine about project categories

Waste minimization

Waste minimization is an appropriate strategy to address the problems of industrial pollution. The objective of the scheme is to assist the small and medium scale industries in adoption of cleaner production processes.

• A scheme on adoption of clean technology and promotion and establishment of waste minimization circles in small and medium scale industries is being implemented at the initiative of Ministry of Environment & Forests.
• So far, 118 waste Minimisation Circles have been established in 41 sectors in 17 geographic locations in the country.
• A “Waste Minimization Circle (WMC)” is a small group (5 to 7 units) of entrepreneurs in the small scale sector, whose units manufacture similar products and employ the same processes voluntarily meeting periodically and regularly in the premises of each member unit, one after another, to analyze the current operations of the host unit.