Linkages Between Agricultural And Urban Components Of The Landscape

Neuman System Model

Figure 3 The development of an agro-urban sustainable (P/R = 1) landscape. The town marketplace historically was closely linked to the agricultural landscape. Sustain-ability in the modern agro-urban landscape increasingly must be based on the management of suburban areas (ecotones) as natural linkages between urban and agricultural systems.

Figure 3 The development of an agro-urban sustainable (P/R = 1) landscape. The town marketplace historically was closely linked to the agricultural landscape. Sustain-ability in the modern agro-urban landscape increasingly must be based on the management of suburban areas (ecotones) as natural linkages between urban and agricultural systems.

P/R decreases as biological (organic) materials accumulate (Figure 5). This results in a balance between productivity and respiration (P/R = 1) in the climax stage of succession (Odum, 1969). An increase in physical (inorganic) materials in urban systems coincides with a decreasing P/R ratio (i.e., a significant increase in maintenance costs). Thus, the result of urban succession is a city where energy demands greatly exceed productivity. During the past century, the large numbers of people living in urban and suburban areas have led to increased need for food produced in rural areas (Steinhart and Steinhart, 1974; Odum, 1989). This demographic and cultural transition has led to increased reduction of P/R ratios in urban areas, as well as increased subsidization of agriculture (including economic subsidies) to maximize crop yield (National Research Council, 1989; 1996).

More recently, suburban expansion has led to increased pressure on rural land used for agriculture (Lockeretz, 1988). A result of urban sprawl has been an increase in the proportion of the agrolandscape occupied by heterotrophic systems. This has serious implications regarding the conservation of biodiversity from a sustainable agrolandscape perspective (Rookwood, 1995). In addition, urban expansion into agricultural land has important consequences for aesthetic, social, and economic values (Lockeretz, 1988), including the need to understand more fully how human

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