Download ecosystems and agroecosystems

ECOSYSTEMS AND
AGROECOSYSTEMS
6/09/2010
Definition
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Individual (species)
Population
Community
Ecosystem
Landscape
Individuals and Population
• No population exists as an isolated entity
• Individuals not only interact among
themselves but also interact with other
population individuals
• This interacting web of populations is called a
community
• Population + community + environment =
ecosystem
COMMUNITY
• Communities are groups of organisms
(populations) that maintain persistent
associations with each other.
• The members of a typical community include
plants, animals, and other organisms that are
biologically interdependent through
predation, parasitism, and symbiosis.
• Ecology: is the scientific study of the
interactions that determine the distribution
and abundance of organisms.
• Ecosytem: The assemblages of individuals,
communities, and physical environments.
– Ex. Ponds, lakes, forests etc.
• Ecosystems are ultimate unit for study in
ecology
• Life sytems: subdivision of ecosystems
Concept of Agroecosystem
• Agriculture + ecosystem =Agroecosystem
• Any ecosystem largely created and maintained
to satisfy a human want or need is called an
agroecosystem
• Agroecological
research is the idea that, by
understanding ecological relationships and
processes, agroecosystems can be manipulated
to improve production and to produce more
sustainably, with fewer negative environmental or
social impacts and fewer external inputs
Difference between manipulated Agroecology
and Natural Ecology
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Six ways difference :
Maintenance at an early succession state
Monoculture
Crops generally planted in rows
Simplification of biodiversity
Plough which exposes soil to erosion
Use of genetically modified organisms and
artificially selected crops
• Semi-domesticated ecosystems that fall on a
gradient between ecosystems that have
experienced minimal human impact, and those
under maximum human control.
• E.g.- Integrated pest management aims to control
problematic pests through introduction of other
species, not application of pesticides or
herbicides to kill that pest.
Method of
intercropping.
• Elimination of unsustainable practices such as
increasingly intensified pesticide use.
SUSTAINABLE AGROECOSYSTEMS
• Maintain their natural resource base.
• Rely on minimum artificial inputs from
outside the farm system.
• Manage pests and diseases through
internal regulating mechanisms
• Recover from the disturbances caused by
cultivation and harvest
Interactions Among Ecosystems
– Destruction of ecosystems:
• Natural to agricultural to urban succession.
• Agricultural vs. natural – farmers concerned pests
will come out of the woods (not true).
• Urban vs. natural – environmental losses
• Urban vs. agricultural – concerned about pesticide
issues.
Nat.
Ag
Urban