Structure and functions of Grassland Ecosystems

GRASSLAND ECOSYSTEM (TERRESTRIAL ECOSYSTEM)

Introduction

^v   Grasslands (also called Greenswards) are areas where the vegetation is dominated by grasses and other herbaceous (non-woody) plants.

^v   Grasslands occupy about 24% of the earth’s surface.

^v   Grasslands occur in regions too dry for forests and too moist for deserts

^v   The annual rainfall ranges between  25- 75 cm, Usually seasonal

^v   The principal grasslands include:

^Ø   Prairies (Canada, USA),Pampas (South America),Steppes (Europe & Asia) Veldts (Africa)

^v   The highest abundance & greatest diversity of large mammals are found in these ecosystems.

^v   The dominant animal species include

^v   Wild horses, asses & antelope of Eurasia,

^v   Herds of Bison of America; and

^v   The antelope & other large herbivores of Africa.

Structure and functions of Grassland Ecosystems

I. Biotic components

1) Producer Organisms

^v   In grassland, producers are mainly grasses; though, a few herbs & shrubs also contribute to primary production of biomass.

^v   Some of the most common species of grasses are:

^v    Brachiaria sp., Cynodon sp., Desmodium sp., Digitaria sp.

2) Consumers

^v   In a grassland, consumers are of three main types;

a) Primary Consumers

^v   The primary consumers are herbivores feeding directly on grasses. These are grazing animals such as

^v    Cows, Buffaloes, Sheep, Goats, Deer, Rabbits etc.

^v   Besides them, numerous species of insects, termites, etc are also present.

b) Secondary Consumers

^v   These are carnivores that feed on primary consumers (Herbivores)

^v   These include;-Frogs, Snakes, Lizards, Birds, Foxes, Jackals etc.

c) Tertiary Consumers

^v   These include hawks etc. which feed on secondary consumers.

3) Decomposers

^v   These include wide variety of saprotrophic micro- organism like: Bacteria; Fungi; Actinomycetes

^v   They attract the dead or decayed bodies of organisms & thus decomposition takes place.

^v   Therefore, nutrients are released for reuse by producers.

II. Abiotic components

^v   These include basic inorganic & organic compounds present in the soil & aerial environment.

^v   The essential elements like C, H, N, O, P, S etc. are supplied by water, nitrogen, nitrates, sulphates, phosphates present in soil & atmosphere.