Ecosystem Processes

B.Sc (Hons) Agriculture

College of Agriculture

BZU, Bahadur Sub Campus,

Layyah

2012-16

EcosystemAn ecosystem is a community of living organisms in conjunction with the nonliving components of their environment interacting as a system.

Ecosystem processes• There are four ecosystem Processes.

Water cycleThe constant process of precipitation, transpiration,

evaporation, and surface and ground water flow is

called the water cycle.

• Water (H20) is the most abundant molecule on Earth.

• It is the only one thatcan be found naturally insolid, liquid and gas.

Water cycle

• The continuous movement of water on,above and below the surface of the earth.

• The water moves from one reservoir toanother, such as from river to ocean, orfrom the ocean to the atmosphere, by thephysical processes of evaporation,condensation, precipation,runoff, andsubsurface flow.

Mineral cycleThe mineral cycle may also be referred to as the nutrient cycle.

• Nutrients follow cyclical patterns as they are used andre-used by all living organisms.

• The nutrient elements is essential for the living organisms.

Mineral cycle

• Carbon is found in the atmosphere.

• Plants take carbon dioxide from theatmosphere and convert it intocarbohydrates and, in this form, a large partof global carbon is stored in forests and soil.

• Carbon returns to the atmosphere throughrespiration of organisms, organicdecomposition, combustion.

Succession

Ecosystems are dynamicand their compositionand structure changesover time.• Periodic disturbances

such as fires, droughts, floods, and pests occur and these can substantially alter the grasslands, forests, and other communities.

Succession TypesSuccession have two types.Primary Succession:• When the change of environment has

been total, as in the case ofcompletely erases the originalenvironment, or when a completelynew environment is created, theprocess is called primary succession.

Secondary Succession:• When the change has only been

partial and some of the originalspecies remain, the process is calledsecondary succession.

Energy PyramidAnother way of showing the transfer of energy in an ecosystem is theEnergy pyramid.

• Living organisms require energy to perform the basic functions of growth, reproduction and survival.

Energy pyramids show

• That the amount of available energy decreases down the food chain

• It takes a large number of producers to support a small number of primary consumers

• It takes a large number of primary consumers to support a small number of secondary consumers