ECOSYSTEMS

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.

 Most of them have long.
 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.

#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.
 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.