A terrestrial ecosystem (TE) is a land-based community of organisms (biotic) and their interactions with the abiotic components in a given area. The type of TE found in a particular place is dependent on the following factors:

  1. Topography- valleys, mountains, plains and plateaus
  2. Altitudinal and latitudinal variations
  3. Quality of soil
  4. Amount of light
  5. Amount of precipitation received
  6. Temperature range
Allen’s rule: Animals living in colder regions have shorter limbs (smaller body surface) as an adaptation to control the dissipation of heat.




  • Alpine tundra
  • Arctic tundra

Forest ecosystem

  • Coniferous forest
  • Temperate forest
  • Tropical forest

Grassland Ecosystem

Desert ecosystem


Tundra means a “barren land”. Tundra ecosystems are treeless regions where environmental conditions are very severe.







  •          Harsh climatic conditions (cold and windy): Winters are long and very severe; summers are cool and brief.
  •         Precipitation: Scanty rainfall, precipitation is mainly in the form of snow.
  •          Soil: Permafrost or soil that remains frozen all year round and is also scarce of nutrients.
  •          Low biotic diversity
  •         Types à Arctic Tundra and Alpine Tundra


Distribution: It extends as a continuous belt below polar ice cap and above tree line in the northern hemisphere. In the southern hemisphere, it is limited to some parts of Antarctica and Falkland islands Distribution: It is found at any latitude in a high altitude area.


Examples: Alaska, Canada, Russia, Greenland, Iceland, and Scandinavia. Examples: The Himalayas, the Alps, Tibetan Plateau, The Caucasus Mountains, the American Cordillera etc.
Flora: Mosses, lichens, sedges, cotton grass, sedges, dwarf heath, willows, birches Flora: Mosses, sedges, liverworts, grassy vegetation.


Fauna: Arctic foxes, polar bears, caribou, musk-ox.


Fauna: Pikas, marmots, mountain goat, reindeer, musk ox, arctic hare, caribous, lemmings and squirrel.


  • A forest ecosystem is a dynamic complex of different kinds of biotic components and their abiotic environment interacting as a functional unit, where trees are a key component of this ecosystem.
  • The forest ecosystems have been 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:


·         It is sandwiched between the tundra to the north and the temperate forest to the south.



  •          It stretches in a great continuous belt across North America, Europe and Asia.
  •          Absent in the southern hemisphere because of the narrowness of the southern continents in the high latitudes.


Abiotic components


  •          Well defined seasons– prolonged bitterly cold winter; short cool summer. Presence of local winds like blizzards of Canada and buran of Eurasia.
  •          Precipitation: well distributed throughout the year.
  •          Soil type: Podzolized soil (acidic, excessively leached and mineral deficient)

Biotic components


  •          Natural vegetation/Flora: Consists mostly of conifers- evergreen; conical in shape; thick, leathery and needle-shaped leaves.
  •          Eg: Pine, Fir, Spruce, Larch
  •         Fauna: Mink, Silver fox, Lynx, Wolf






Temperate Forest


  •         It is characterized by broad-leaved trees, which shed their leaves in autumn and grow new foliage in autumn.
  •         It can be further divided into à TEMPERATE DECIDUOUS (mainly in northern hemisphere), TEMPERATE EVERGREEN (found in Mediterranean climatic region) and TEMPERATE RAINFOREST (found in both the hemispheres, coastal region).



  •          Located in the mid-latitude areas, between polar regions (grade into boreal forest) and tropics (grade into Tropical rain forest).
  •          Found in both northern and southern hemisphere.
Abiotic components


  •         Moist, warm summer and frosty or rainy winter
  •          Presence of distinct seasons
  •          Soil type: Alfisol or brown forest soil
Biotic components


  •          Flora: Broadleaf trees (oaks, maples, beeches), shrubs, perennial herbs, and mosses
  •         Fauna: Squirrels, marsupials, brown bear, bats, rodents






Tropical Rain Forest


  •          It is characterized as most luxuriant forest with diverse array of communities and makes up one of the earth’s largest biome.
  •         Found in wet tropical uplands and lowlands around the Equator.

Abiotic components


  •         High humidity and temperature (more or less uniform)
  •         Precipitation: exceeds 200cm, evenly distributed throughout the year
  •         Soil type: Red latosol (high rate of leaching makes it agriculturally useless, but can rejuvenate with nutrients when left undisturbed)

Biotic Components


  •          Flora: Diverse Angiosperms and relatively few Gymnosperms. Besides, liverworts, creepers, ferns, mosses, lichens and algae are also found.
  •          Presence of dense upper canopy and thick undergrowth.
  •          Fauna: Monkeys, rhinos, large number of insects, birds.



It is an act of clearing or thinning forest to fulfill varied purpose of humankind. Following are the prominent causes of deforestation:

  • Shifting cultivation – It is a practice of clearing a patch of land by burning and left abandoned to recover its fertility.
  • Infrastructure expansion: It can be for construction of highways, industries, real estates, communication line, urban outgrowth.
  • Forest fire: It can be of natural cause (high atmospheric pressure and low humidity) or man-made cause (deliberate firing by local inhabitants, discarded cigarettes, electric spark and mining).
  • Logging: It is a process of cutting and processing trees in order to meet the requirements of fuel, fiber, timber, pulp, latex and rubber etc.
  • Large-scale agriculture and overgrazing: Burgeoning population demands for more food (crops and livestock) which in turn encroaches forest land.





Aggravation of

Global warming:


  •          Through the released carbon dioxide.
  •          Forest is a great carbon sink which sequesters as much as 45% of carbon stored on land.
  •          Some 420 million hectares of world’s forest have been lost since 1990 (The State of the World’s Forests-FAO).
Disturbance of hydrological cycle
  •          Causes immediate lowering of ground water level and reduction of precipitation (may lead to drought).
  •          Rapid runoff (may lead to flood).
Loss of biodiversity


  •         Eighty percent of the world’s land-based species live in forests.
  •          Land degradation and soil erosion- may lead to food insecurity
  •         Reduces the ability of forests to provide essential services
Social issues


  •          Loss of livelihood of tribals and other forest dwellers
  •          1.6 billion population has been affected due to forest degradation and deforestation (IUCN).


  • Grassland ecosystem is an area where the vegetation is dominated by continuous cover of grasses and herbaceous (non-woody) plants. It accounts between 20 and 40% of world’s land area. The grasslands are found where rainfall is about 25-75 cm per year, not enough to support a forest, but more than that of a true desert.
  • Typical grasslands are 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 are mainly composed of steppes and savannas.
  • 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.



Savanna/Tropical Grassland: “Big Game Country”




  •          Transitional between the equatorial forests and the trade wind hot deserts.

E.g: Savanna of Africa, Campos of Brazilian highland, Llanos of Orinoco basin.

Abiotic components:
  •          Characterized by an alternate hot, rainy season and cool, dry season.
  •          Local wind: Harmattan in Guinea coast
  •          Soil type: Alfisols and Ultisols
Biotic components:
  •          Flora – tall, elephant grass and short trees that has long roots and water storing devices (e.g: baobabs and bottle trees).
  •          Fauna – Grass-eating Herbivores and flesh-eating Carnivores.


Steppe/Temperate Grassland: “Granaries Of The World”





  •          Found in the interiors of continents, away from maritime influence.
  •          E.g. Prairies of North America, Pampas of Argentina, Downs of Australia etc.
Abiotic components:
  •          Continental climate, not severe in the southern hemisphere.
  •          Local wind: Chinook in Canada and America, Fohn in Switzerland.
  •          Soil type: Chernozem soil

Biotic components:

  •          Flora: Short steppe type of grass, practically treeless (used for extensive wheat cultivation)
  •          Fauna: Mainly domesticated animals- cattle, sheep, pigs are found.



Desert ecosystem is a region of scanty rainfall supporting a community of distinctive plants and animals specially adapted to the harsh environment. Deserts are formed in regions with less than 25 cm of annual rainfall.







Hot Desert




  •         Western coasts of continents between 15 and 30 N and S (lie in the region of Horse latitudes).
Abiotic components:


  •          Extreme diurnal range of temperature. Less than 25cm of annual rainfall.
  •          Soil type: saline, sandy soil with low water holding capacity.
Biotic components:
  •          Flora– Xerophytic or drought resistant scrub, date palms, acacia etc.
  •          Fauna– Diverse array of reptiles, marsupials, mammals (camels, hedgehog, hyenas).


Cold/Temperate Desert


  •         Located interior of the continent, sheltered by the high mountains all around them.
Abiotic Components:


  •          The annual range of temperature is much greater than that of the hot deserts. Continentality accounts for these extremes in temperature (Severe winter with cold wind).
Biotic components:
  •          Flora– Alpine Mesophytic, Grasses, bushes, shrubs and even trees like junipers, birch.
  •          Fauna– Bactrian camel, Asiatic ibex, snow leopard, Tibetan wolf, Tibetan wild ass (kiang) etc.


  • Extensive root system to tap underground water
  • Thick cuticle or sunken stomata to reduce transpiration
  • Leaves- Absent or reduced in size or modified into either thorns, leathery, hard and waxy leaves.
  • Large fleshy (succulent) stems and leaves for water storage
  • Plants lie dormant for years until rain falls.


  • Nocturnal in habit to avoid the sun’s heat
  • Store fat in their humps, thus they can live months without food
  • Excrete concentrated urine to conserve water
  • Camel “the ship of the desert” can travel several days without water (drink gallons of water at one go)
  • Body temperature can change to avoid losing water through sweating. (Remember kharai camel)


DESERTIFICATION – “The greatest environmental challenge of our time”

It is the destruction of biological potential of the land in arid, semi-arid and dry sub-humid areas due to various factors, including climatic variations and human activities.





LAND MANAGEMENT: Deforestation + Overgrazing + Over-cultivation of crops + Developmental activities + Inappropriate irrigation.
CLIMATE RELATED: Natural fluctuations in climate + Global warming as a result of human-caused GHGs.



  •          Land degradation neutrality (LDN) is a condition where further land degradation (loss of productivity caused by environmental or human factors) is prevented and already degraded land can be restored.
  •          Land Degradation Neutrality (LDN) has been defined by the Parties to the Convention as:
  •          A state whereby the amount and quality of land resources, necessary to support ecosystem functions and services and enhance food security, remains stable or increases within specified temporal and spatial scales and ecosystems.



  •         The Bonn Challenge is a global goal to bring 150 million hectares of degraded and deforested landscapes into restoration by 2020 and 350 million hectares by 2030.
  •          Launched by the Government of Germany and IUCN in 2011, the Challenge surpassed the 150-million-hectare milestone for pledges in 2017.


  • It is a biennial publication of Forest Survey Of India, the first being the report of 1987.
  • It is based on the interpretation of LISS III sensor of Resourcesat-2 satellite
  • Total forest and tree cover- 24.56% of the geographical area of the country.
  • Total forest cover- 21.67%; Total tree cover- 2.89%
  • Largest forest cover in India:Madhya Pradesh > Arunachal Pradesh > Chhattisgarh > Odisha
  • Forest cover as percentage of total geographical area: Mizoram (85.41%) > Arunachal Pradesh (79.63%) > Meghalaya (76.33%) > Manipur (75.46%) > Nagaland (75.31%).
  • States/UTs showing significant gain in forest cover: Karnataka > Andhra Pradesh > Kerala > J&K
  • States showing loss in forest cover:Manipur > Arunachal Pradesh > Mizoram.