Geography (Biosphere, Ecosystem and Biomes of the world)

1. Prologue

2. Biosphere

3. Biotic Regions

4. Ecology and ecosystem

5. List of Biomes (Tundra in detail)
Note This article comes under the salient features of Worlds physical geography and some portions of Ecology.

Biosphere

Before getting into detail in Biosphere, a quick glance on the Types of sphere of the earth. The area near the surface of the earth can be divided up into four inter-connected "geo-spheres:" the lithosphere, hydrosphere, biosphere, and atmosphere. Scientists can classify life and material on or near the surface of the earth to be in any of these four spheres.

The names of the four spheres are derived from the Greek words for stone (litho), air (atmo), water (hydro), and life (bio).

Lithosphere

The lithosphere is the solid, rocky crust covering entire planet. This crust is inorganic and is composed of minerals. It covers the entire surface of the earth from the top of Mount Everest to the bottom of the Mariana Trench.

Hydrosphere

The hydrosphere is composed of all of the water on or near the earth. This includes the oceans, rivers, lakes, and even the moisture in the air. Ninety-seven(97) percent of the earth's water is in the oceans. The remaining three percent is fresh water; three-quarters of the fresh water is solid and exists in ice sheets

Atmosphere

The atmosphere is the body of air which surrounds our planet. Most of our atmosphere is located close to the earth's surface where it is most dense. The air of our planet is 79% nitrogen and just under 21% oxygen; the small amount remaining is composed of carbon dioxide and other gasses.

All four spheres can be and often are present in a single location. For example, a piece of soil will of course have mineral material from the lithosphere. Additionally, there will be elements of the hydrosphere present as moisture within the soil, the biosphere as insects and plants, and even the atmosphere as pockets of air b


Life Affects the LandscapeThe life forms that make up the biosphere do more than just live on Earth. They also interact with it and are responsible for making great changes in the way that the Earth has evolved.

Consider the atmosphere. Our atmosphere is comprised of approximately 21% oxygen. Where did that oxygen come from?

The early Earth did not have very much oxygen in the air. Most of it had been trapped by the seas, and locked up in the rocks and soil. Slowly over millions of years, plants released oxygen into the air, greatly increasing its abundance, and making animal life possible.







So now with the idea of the other three sphere I feel it is easy to determine what a biosphere is?



Biosphere

The biosphere is defined as the sphere or area around the planet Earth where life exists. This zone of life is vast.

Most life forms live on or near the surface of Earth. However, some live deep within the hydrosphere (oceans, lakes and streams), while others thrive in the depths of the lithosphere (solid portion of Earth).

Biosphere is the largest part of ecosystem (But whats ecosystem?)



Ecology



It is the scientific study of the inter relationship among organism, between organism and all aspect living and non-living of the environment. The branch of biology that deals with the relations of organisms to one another and to their physical surroundings. Ernst Haeckel is usually given the credit for coining the word ecology in 1866



Ecosystem

The plants and animals that are found in a particular location are referred to as an ecosystem. These plants and animals depend on each other to survive. In a delicate balance, these life forms help to sustain one another in regular patterns. Disruptions to an ecosystem can be disastrous to all. Organisms within the ecosystem (And most of the disruptions done by mankind( word mankind used sarcastically).



Ecosystem is a term used by A G Tensely in 1935, to describe a discrete unit that consists of living & non-living parts, interacting to form a stable system

NOTE The diagram for this is given below



Community The term is applied to any grouping of population of different organisms found living together in a particular environment



Population - A group of organism all of the same species, which occupies a particular area



EcoSystem in Semi-detail form (This is self explanatory just refer the diagram below)

Plants and animals depend on each other to survive. This connection of living things to each other is called biodiversity.

An ecosystem, short for 'ecological system', includes all the living organisms existing together in a particular area. These plants and animals within an area interact with each other and with the non-living elements of the area, such as climate, water, soil and so on.

An ecosystem can be very small, such as a puddle or an area under a large rock, or it can be vast, such as an ocean.

The balance of an ecosystem is delicate, and a disruption such as the introduction of a new element can damage it.





Micro: A small scale ecosystem such as a pond, puddle, tree trunk, under a rock etc. Messo: A medium scale ecosystem such as a forest or a large lake



Biome:(Explained below)



Just a small point I am adding here

Function in an ecosystem is of two types

1. Flow of Matter(cyclic) 2) Energy(suns energy uni-directional )



Energy uni-directional means the energy given by sun to us is not taken back.





Biomes

A very large ecosystem or collection of ecosystems with similar biotic and abiotic factors such as an entire Rain forest with millions of animals and trees, with many different water bodies running through them.

Ecosystem boundaries are not marked(separated) by rigid lines. They are often separated by geographical barriers such as deserts, mountains, oceans, lakes and rivers. As these borders are never rigid, ecosystems tend to blend into each other.

This is why a lake can have many small ecosystems with their own unique characteristics. Scientists call this blending ecotone(explained in brief)

Ecosystems can be put into 2 groups. If the ecosystem exists in a water body, like an ocean, freshwater or puddle, it is called an aquatic ecosystem. Those that exist outside of water bodies are called terrestrial ecosystems.















Listing of Biomes

Three important regions of the earth

1) Tropical zone

2) Temperate zone

3) Frigid zone







Note very important diagram for the whole explanation of Biomes (Only for starters like me.) Figure 1



I am listing the biomes one after another will explain the most important ones in terms of exam



1) Forest

2) Grasslands

3) Desert Biome

4) Chaparral/Mediterranean Biome

5) Tundra Biome











Forest

Forest Biome divided into two types of biome

1. Tropical Forest

2. Temperate Forest (Refer above fig)





(a)Tropical Forest again divided into two types

(i) Tropical Rain Forest (TRF)/Tropical Evergreen Forest (They are also called Selvas) Most nutrients in the tree in TRF and not in the soil.

(ii) Tropical Deciduous Forest/Tropical Monsoon Forest (TMF)

Location: Near the equator in Central and South America, parts of Africa and Asia. Characteristics: Hot, humid with equatorial climate and biggest biodiversity. Almost half of the worlds species (plants and animals) live there. The trees are mostly hardwood.



Note Difference between Evergreen vegetation and Deciduous Forest

Deciduous = A term referring to the ability of some plants to lose their leaves annually. In TMF the trees shed their leaves during the dry summer months (March - May)

In the temperate zone the deciduous tree shed their trees during autumn

Evergreen trees = is one which retains its leaves throughout the year it does shed its leaves but not completely at any time of the year



(b) Temperate Forest again divided into two parts

(i) Temperate deciduous Forest West European type (Hard-Wood type)

(ii)Temperate Coniferous forest Soft-Wood type (In Russia it is called Taiga)



Grasslands

(i)Tropical Grassland (Nothing but combination of Grass + Scattered trees). Tropical grasslands are tall, thick rough, coarse & lack nutrients



Savannah/TropicalGrasslands:Location: Central Africa (Kenya, Zambia, Tanzania), northern Australia and central South America(Venezuela/Brazil).Characteristics: Hot and dry, mainly grass, scrub and occasional trees. This biome has two distinct seasons a dry season and a rainy season. During the dry season the vegetation dies and re-appears rapidly during the rainy season.



(ii)Temperate Grassland

Here the grasses are short + soft + nutritious

Location: Mainly found in the Pustaz in Hungary, the Veldt in South Africa, the Pampas in Argentina and the Prairies in the USA.Characteristics: Many grass and trees with little large bushes. Climates are temperate continental with mild weather and moderate rainfall.



Different regional names for grasslands

Praries in North America

Pamper in Argentina

Campos in Brazil

Lamos in Venezuela

Pustaz in Hungry

Steppes in Russia

Velds in South Africa

Downs in Australia



Tundra Biome

Tundra biome is naturally speaking the most fragile biome as it lacks diversity. The tundra is near the North Pole. Winters are very cold. Summers last for a very short time.

Under the soil (Permafrost soil explained below) the earth is frozen and never melts.

About 1/5 of the Earth is tundra. Tundra is the coldest of all the biomes. The word comes from a Finnish word and means 'treeless plain'. There is arctic tundra and alpine tundra. But in Russian Language is means Marshy Region

Permafrost Soil Permafrost(Permanently frozen) a layer of permanently frozen ground in areas where temperatures are too low to permit complete thawing(ice becoming liquid or soft as a result of warming up). Permafrost underlies most of the tundra regions

Talik is an area of unfrozen ground surrounded by permafrost.



Permafrost generally begins at a depth less than a meter from the surface.(Here active layer is the surface). When the upper Ice Cover melts during summer the sub-soil still remains frozen & the result is wetlands throughout the region.

Tundra has areas lying roughly beyond 65 Degrees North. These areas are very cold & have annual rainfall less than or equal to 25 cm (mostly in summer). Tundra is the most continuous of all biomes as it occurs unbroken along the margins of northern continents

Summer isotherm of 10 degrees marks the beginning & 0 degrees marks the limit on the pole wards side Winters are very long(9-10 months) with very severe temperature(-35 to -40 degrees). In summer season, because of the long day length & continuous insolation but the suns rays are very inclined so that theres very diffused heating.

Regions under tundra biomes

1. Iceland

2. Green Land

3. Alaska

4. Siberia

5. Northern most parts of Canada

6. Northern Scandinavian parts

Ecotone

Note Rarely the boundaries between 2 adjacent or neighboring biomes are discrete or distinct, instead they blend with the neighboring biomes through a transitions zone known as ecotone. This transition zone has high species diversity & density as compared to any of the neighboring Biomes.

Ecotone arises naturally for e.g.

Ecotone may also reflect human intervention for e.g. the agricultural clearance of formerly forested areas.



Bush trees - Tundra

A similar Ecotone is built between Southern Part of tundra and temperate coniferous forest (Temperate zone) (Refer figure 1). It consists of short height trees E.g. Alders and Junipers

Grass Tundra

Next to bush tundra there is grass tundra it consists of e.g. mosses, lichens and Rhododendrons (small plants with multicolored flowers)

Note (The vegetation is well adopted to withstand extreme cold & to survive on a minimum moisture. It can also remain alive beneath the snow in winter)

Chaparral/Mediterranean Biomes

The chaparral biome is found in small sections of most continents, including the west coast of the United States, the west coast of South America, the Cape Town area of South Africa, the western tip of Australia and the coastal areas of the Mediterranean.

The chaparral is characterized as being very hot and dry. The winter is very mild and is usually about 50F (10C). Most of the rain in this biome comes in the winter. The summer is hot and dry at up to 100F (37.5C). This makes fires and droughts very common.

Desert Biome

A desert is a place that gets just a bit of rain every year. Some deserts get almost no rain at all. A desert can be very hot in daytime and cold at night.Some deserts are cold all the time. A desert is a dry area where less than 50 cm of rain falls each year. About one fifth of the Earth's surface is desert.

Deserts can be hot or cold. The Australian Desert is one example of a hot desert, and the Gobi Desert in Mongolia is an example of a cold desert. Antarctica is the world's largest desert.

The Atacama Desert of Chile and the Sahara Desert in Africa receive less than 1.5 cm a year, if at all.

Although rain doesn't fall very often in deserts, sometimes not for years, there can be sudden, heavy rains that cause flooding.

Deserts can be found along coastlines, such as the Atacama Desert, or in the interior of continents, such as the Great Basin Desert of North America.

Note A desert biome represents the adaptations of the life most admirably.

And this you can make out by just reading the facts mentioned above.







By Arun Chettiar

References -

1. G C Leong Book (Comprehensively explained)

2. www.google.com

3. Atlas Map