Desert ecosystem, Mountain, Cave & Tundra ecosystem: EVS Notes
EVS Notes Unit I Multidisciplinary nature, Natural Resources, Forest resources, Water resources, Mineral resources, Food resources, Energy resources, Land resources, Role of an individual Unit II Introduction structure-function, Forest eco-system; Grassland ecosystem; Desert ecosystem; Aquatic ecosystems Unit III Air pollution, Water pollution, Soil pollution
THE DESERT ECOSYSTEM
The areas with an annual rainfall of less than 25 cm come in deserts. They occupy about 17% of the land. Due to extremes of both, water and temperature factors, the biota is much more varied and is poorly represented. The various components of the ecosystem are:
Abiotic components
In deserts, ecosystem temperature is found to be very high and rainfall is very low. A dry atmosphere, high temperature, and intense illumination favor the rate of transpiration.
Biotic components
These are as follows:
a) Producers
These are shrubs, especially bushes, some grasses, and a few trees. The shrubs have a widespread branched root system with their leaves, branches, and stems variously modified. Sometimes a few succulents like cacti are also present. Some lower plants like lichens and xerophytic mosses may also be present.
b) Consumers
Insects, reptiles, nocturnal rodents, birds, camels, etc. are the main consumers.
c) Decomposes
These are very few, as due to poor vegetation the amount of dead organic matter is correspondingly less. They are some fungi and bacteria, most of which are thermophilic.
THE MOUNTAIN ECOSYSTEM
The chief components of the ecosystem are:
Abiotic components
It is the altitude that provides different climates.
Biotic components
These are as follows:
a) Producers
They differ to the difference in climatic conditions even on the same mountain e.g., in the forests, trees are the main producers, while in the desert the chief producers are shrubs, herbs, and only a few trees.
b) Consumers
They vary with the type of producers in the area.
CAVE ECOSYSTEM
A cave is a natural hollow opening under the surface of the earth, or a mountain or a hill. Many caves are found in North America and Europe, e.g., Mammoth cave in North America. The main components of the cave ecosystem are as follows:
Abiotic components
The absence of light is the most striking feature since it has a telling effect on the cave-dwelling organisms. Temperature is nearly uniform, except for some fluctuations with the depth of the cave. Several fluctuations in moisture levels occur. Atmospheric pressure varies from that of the terrestrial environment.
Biotic components
These are as follows:
a) Producers
They are almost absent.
b) Consumers
Both vertebrates and invertebrates of cave-dwelling existence are found. They may be temporary, such as bats, owls, etc., or permanent, such as turbellarians, Leeches, insects, etc., (invertebrates). Mammals are rare; birds are absent.
c) Decomposers
Fungi and bacteria are present
TUNDRA ECOSYSTEM
Tundra means a barren land or hostile territory. Tundra biomes occur in the polar regions in northern Canada, Greenland, other islands of the Arctic oceans, and northern Europe (northern hemisphere). Since the Antarctic Ocean has not been exploited much; this biome has been designated as Arctic Tundra. The Tundra biome also occurs on the peaks of the High mountains of the world and has been called the Alpine Tundra. The chief components of the Tundra ecosystem are as follows:
Abiotic components
These include temperature, light, moisture, pressure, soil, etc. This temperature exerts a very powerful influence so that only a few organisms have successfully got adapted to the Tundra conditions. In the Arctic Tundra, the winters are very long and cold, during which the ground remains frozen. The summer is short and sharp during which snow melts to some depth only, hence the deeper layer of soil remains permanently frozen and is known as permafrost. Due to this Tundra soil is very shallow. In the Alpine Tundra, the Alpine climate prevails.
Biotic components
These are as follows:
a) Producers
Suitable conditions for plant growth exist only for about 60 days. The dominant producers are the hardiest of plants like bushes, lichens, mosses, grasses, and grass-like herbs.
b) Consumers
These include mammals like carbou, hares, reindeer, foxes, and polar bears, amphibians and reptiles are totally absent. However, some species of birds and insects are present. The insects are represented by black flies, bumble bees, etc. The birds are migratory and are represented by arctic loon, goose, hawks, gulls, larks, etc. The South Pole has only marine birds and penguins. The fauna of the Alpine Tundra varies with the type of vegetation.
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