Agroecology and Agroecosystems
By Stephen R. Gliessman
Jeremy Nelson
Intro

Agriculture
◦ more than an economic activity to maximize
production and profit
◦ Environmental and social components too

Sustainability as a means to balance the
interactions
◦ Agroecology as a way to achieve sustainability
Agroecology

Agriculture as a stream, individual farms
are points along it
◦ Upstream impacts on farms
 Labor availability and cost
 Market access for goods produced
 Legislative policies – water & pesticide use, animal
care
◦ Downstream effects of farms
 Soil erosion and groundwater depletion
 Pollution of water, air, soil, food
Agroecology cont.

Ecosystems:
◦ Functional system of relations between
organisms and environment
◦ Maintain relative equillibrium; thus sustainable

Agroecosystems work to balance
biological, physical, chemical, ecological,
cultural interactions
◦ To achieve and sustain yields
◦ Created through human manipulation of an
environment for ag production
Agroecosystems cont.

Created through human manipulation of
an environment for ag production
◦ Changes key aspects of the natural ecosystem;
called emergent qualities

4 key qualities
◦
◦
◦
◦
Energy flow
Nutrient cycling
Population regulation
Dynamic equilibrium
Application

Indigenous farm systems are sustainable
agroecosystems
◦ Example of how cultures and local
environments coevolved to balance all the
needs of people
 Ecological, technological, soio-economic

Illustrates importance of…
◦ Intimate knowledge of local ecology
◦ Perceiving the farm as part of a much larger
system
Conclusion

Agricultural systems cannot be regarded
solely as production driven by economic
forces
◦ Nor can we disregard interrelations of agriculture
and ecosystems

“By properly selecting and understanding the
‘upstream’ inputs into agriculture, we can be
assured that what we send ‘downstream’ will
promote a sustainable future”
(Gliessman 2004: 113)