Classification of Ecosystem
Intended Learning Outcomes
At the end of this Lecture, students will be able to
• Discuss different types of ecosystems
Major Ecosystems
• Earth is a vast ecosystem it is however difficult to handle and thus for convenience we generally study it by making artificial subdivisions into units of smaller ecosystem. (eg. Terrestrial ecosystems as, forest ecosystems, desert ecosystems, grassland ecosystems, manmade ecosystems such as cropland ecosystems, and aquatic ecosystems such as freshwater, marine, etc.)
• An ecosystem thus be separated from each other but it must be remembered that these units of ecosystem are linked with each other forming an integrated system.
Classification of Ecosystem
Different types of ecosystem of the biosphere are artificially categorized as follows:
• Natural Ecosystems
• Artificial ecosystems
Natural Ecosystems
• These ecosystems operate by themselves under natural conditions without any major interference by man. Based on the particular kind of habitat, these are further divided as:
• Terrestrial as forest, grassland, desert etc.
• Aquatic which may be further distinguished as
• Freshwater which may be lotic (running water such as springs, streams, rivers) or lentic (standing water as lake, pond, pools, ditches, swamps, etc.)
• Marine Ecosystems: as an ocean or shallow ones like sea or estuary etc.
Artificial Ecosystems
These are maintained by man where, by the addition of energy & planned manipulations natural balance is disturbed regularly, for ex, croplands like maize, wheat, and rice fields physicochemical environment are artificial ecosystem. etc, where man tries to control the biotic community as well as
Marine Ecosystems
• Pond Ecosystem: A Pond as a whole serves as a good example of freshwater ecosystem
• Abiotic Components: The chief components are heat, light, pH of water, CO2, oxygen, calcium, nitrogen, phosphates, etc.
• Biotic Components: The various organizations that constitute the biotic components are as follows,
• Producers: These are green plants, and some photosynthetic bacteria. The producer fixes radiant energy and converts it into organic substances as carbohydrates, protein etc.
Pond Ecosystem
Producers are of the following type
• Macrophytes: these are large rooted plants, which include partly or completely submerged hydrophytes, eg Hydrilla, Trapha, Typha.
• Phytoplankton: These are minute floating or submerged lower plants eg algae.
• Consumers: They are heterotrophs that depend for their nutrition on the organic food manufactured by producers.
Primary Consumers:
Benthos: These are animals associated with living plants, detrivores, and some other microorganisms
Zooplanktons: These are chiefly rotifers and protozoans, they feed on phytoplankton
• Secondary Consumers: They are the Carnivores that feed on herbivores, these are chiefly insect and fish, most insects & water beetles, they feed on zooplankton.
• Tertiary Consumers: These are some large fish game fish, and turtles, which feed on small fish and thus become tertiary consumers.
• Decomposers: They are also known as micro-consumers. They decompose dead organic matter of both producers and animals to a simple form. Thus they play an important role in the return of minerals again to the pond ecosystem, they are chiefly bacteria, & fungi
Ocean Ecosystem
• Ocean ecosystems are more stable than pond ecosystems, they occupy 70 % of the earth’s surface.
• Abiotic Components: Dissolved oxygen, light, temperature, and minerals.
Biotic Components:
Producers: These are autotrophs and are also known as Primary producers. They are mainly, some microscopic algae (phytoplanktons) besides them there are mainly, seaweeds, as brown and red algae also contribute to primary production.
Consumers: They are all heterotrophic macro consumers
Primary Consumer: The herbivores that feed on producers are shrimps, Molluscs, fish, etc.
Secondary Consumers: These are carnivorous fish such as Herring, Shad, and Mackerel, feeding on herbivores.
Tertiary Consumers: These include, other carnivore fishes like COD, Halibut, Sea Turtle, Sharks etc.
Decomposers: The microbes active in the decay of dead organic matter of producers, and animals are chiefly, bacteria and some fungi.
Estuarine Ecosystem
• An estuary is a partially enclosed body of water along the coast where fresh water from rivers and streams meet and mix with salt water from oceans. This Ecosystems are considered as most fertile ecosystems.
• Abiotic Components: Nutrients such as phosphorus and nitrogen, temperature, light, salinity, pH.
• This ecosystem experience wide daily and seasonal fluctuations in temperature and Salinity level because of variation in freshwater in flow.
• Biotic Components:
• Producers: Phyplanktons- these micro-organisms manufacture food by photosynthesis and absorb nutrients such as phosphorous and nitrogen, besides them, mangroves, sea grass, weeds, and salt marshes.
Consumers:
Primary consumers: Zooplanktons that feed on Phytoplankton, besides them some small microorganisms that feed on producers.
Secondary Consumer: Include worms, shellfish, and small fish, feeding on Zooplanktons
Tertiary Consumer: Fishes, turtles, crabs, and starfish feed on secondary consumers.
Decomposers: Fungi & Bacteria are the chief microbes active in the decay of dead organic matter.
Riverine Ecosystem
• Compared with lentic freshwater (Ponds & lakes), lotic waters such as streams, and river have been less studied. However, the various components of an riverine and stream ecosystem can be arranged as follows.
• Producers: The chief producers that remain permanently attached to a firm substratum are green algae as Cladophora and aquatic mosses.
• Consumers: The consumers show certain features such as a permanent attachment to firm substrata, the presence of hooks & suckers, sticky undersurface, streamlined bodies, and flattened bodies. Thus a variety of animal are found, which are fresh spongy and caddis- fly larvae, snails, flatworms, etc.
• Decomposers: Various bacteria and fungi like actinomycetes are present which act as decomposers.
Land Ecosystem
• Grassland Ecosystem: Grasslands occupy comparatively fewer areas roughly 19 % of the earth’s surface.
• Abiotic Components: These are nutrients present in the soil, and aerial environments, thus the elements like phosphates, sulfates, water, and carbon dioxide, present in soil and air. Moreover, some trace elements are also present.
• Biotic Components:
• Producers: They are mainly grasses a species of Cynadon Desmodium, besides them a few shrubs also contribute some primary production.
Consumers:
Primary Consumers: The herbivores feeding on grasses are grazing animals, such as cows, goats, rabbits, etc. Besides them, there are some insects as termites and millipedes that feed on grasses.
Secondary Consumers: These are carnivores feeding on herbivores these include, animals like foxes, jackals, snakes, frogs, and birds.
Tertiary Consumers: Sometimes hawks, and vultures, feed on secondary consumers, thus occupying tertiary consumers.
Decomposers: The microbes active in the decay of dead organic matter of different forms are fungi and some bacteria
Grassland Ecosystem
Forest Ecosystem
• Forest Occupy roughly 40 % of the land. The different components of the forest ecosystem are as follows:
• Abiotic Components: These are organic & inorganic substances present in the soil and atmosphere. In addition to minerals present in forests we find dead organic debris, moreover, light conditions are different due to complex stratification in the plants.
• Biotic Components:
• Producers: These are mainly trees that show many species and greater degree of stratification. Besides trees, there are also present shrubs and ground vegetation.
• Consumers:
• Primary Consumers: These are herbivores that include animals feeding on tree leaves, ants, beetles, grasshoppers, etc., and large elephants, dears, squirrels, etc.
• Secondary Consumers: These are carnivores, like snakes, birds, lizards, fox, etc. feeding on herbivores.
• Tertiary consumers: These are top carnivores like lions tigers, etc. that eat carnivores of a secondary level.
• Decomposers: These are a wide variety of microorganisms including, fungi, and bacteria.
Desert Ecosystem
• Deserts occupy 17 % of land.
• Abiotic components include light, temperature, and minerals.
• Biotic Components:
• Producers: These are shrubs, especially bushes, some grasses, and a few trees. E.g. Cacti, Xerophytes, mosses
• Consumers: The most common animals are reptiles and insects, there are some rodents and birds, and above all ship of desert camels, feed on tender plants.
• Decomposers: These are very few as due to poor vegetation the amount of dead organic matter is less. They are some fungi and bacteria.
Summary
Ecosystem can be broadly classified as
• Natural ecosystem
Natural ecosystems can be further classified as Land system and Aquatic ecosystem
• Artificial ecosystem
Artificial ecosystems can be further classified as Cropland ecosystem
• Components of an ecosystem are Producers, Consumers, Decomposers
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