Grassland ecosystem: Environmental sciences Notes, MCQ, Books, PDF
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
Grasslands ecosystem occupy roughly 24% of the earth’s surface (Shantz, 1954). Whyte (1957) divided grassland into 8 types based on the floral characteristics. The different components of a grassland ecosystem are:
Abiotic components
These include nutrients present in soil and the atmosphere. Thus the elements like C, H, O, N, P, S, etc. are supplied by carbon dioxide, water, nitrates, phosphates, and sulfates present in the air and soil of the area.
Biotic components
These are as follows:
a) Producers
They are mainly grasses, as species of Dichanthium, Cynodon, Desmodium, Dactyloctenium, Digitaria, Setaria, Sporobolus, etc. Besides them, a few forbs and shrubs also contribute to primary production.
b) Consumers
These are as follows:
i) Primary consumers
The herbivores feeding on grasses are mainly such grazing animals as cows, buffaloes, deers, sheep, rabbits, mice, etc. Besides them, there are also present some insects such as Leptocorisa, Dysdercus, Oxyrhachis, Cicindella, Coccinella, some termites and millipedes, etc. that feed on the leaves of grasses
ii) Secondary consumers
Snakes, lizards, birds, jackals, foxes, etc. are common secondary consumers which feed on herbivores.
iii) Tertiary consumers
These include hawks that feed on secondary consumers.
c) Decomposers
Several fungi (Mucor, Aspergillus, Penicillium, Cladosporium, Rhizopus, Fusarium, etc.), actinomycetes, and bacteria decay the dead organic matter of different forms of higher life. They bring about minerals back into the soil, thus making them available to the producers.
CROPLAND ECOSYSTEM
This is an artificial or man – engineered ecosystem aimed primarily to grow a single species of one’s choice. To secure maximum production, man makes much-planned manipulation in the physicochemical environment. These include the addition of fertilizers to the soil, use of chemicals for disease control, proper irrigation practices, etc. This may include the dominant species like maize, sugar cane, jowar, paddy, vegetables, etc.
The following are the main components of a maize cropland ecosystem:
Abiotic components
These include the climatic conditions of the region, where the crop may grow most successfully, and the various minerals and gaseous elements such as C, H, O, N, P, K in soil and atmosphere. Maize generally grows best in slightly alkaline soil with good aeration.
Biotic components
These occur in the following order:
a) Producers
In the field, in addition to dominant species of maize, a number of weeds like Cynodon dactylon, Launaea nudicaulis, Euphorbia hirta, Cyperus rotundus, Digitaria species., and Alysicarpus also contribute to the primary production of the field.
b) Consumers
These are as follows:
i) Primary consumers
These are herbivores. The smaller animals include chiefly insects such as aphids, thrips, beetles, etc., which feed and lay their eggs on maize leaves. The larger animals include birds, rats, rabbits, and men feeding on leaves, flowers, and fruits on the crop.
ii) Secondary consumers
These are carnivores like frogs and some birds that eat insects.
iii) Tertiary consumers
Snakes and hawks belong to this category which can eat frogs and small birds, respectively.
c) Decomposers
Several microbes such as actinomycetes, fungi, and bacteria found in soil and climate decompose dead organic matter of plants as well as animals and help in the circulation of minerals making available them to producers again
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