Agroecology and Agroecosystems

By Stephen R. Gliessman

Jeremy Nelson

IntroAgriculture

◦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

AgroecologyAgriculture 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 qualities4 key qualities

◦Energy flow ◦Nutrient cycling◦Population regulation◦Dynamic equilibrium

ApplicationIndigenous 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

ConclusionAgricultural 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)