Agriculture Reference
In-Depth Information
the overall perception of its health. Indicators would be those measurable parameters
that would be expected to change with changes in these attributes.
Productivity (Conway and McCracken, 1990) refers to the range, value, quality,
and quantity of products derived from the agroecosystem. Izac and Swift (1994) dis-
tinguished three types of products that communities derive from an agroecosystem.
The first is harvestable yield, which includes crops, livestock products, medicine,
and the like that farmers deliberately grow. The second type includes amenities—
environmental services provided by the agroecosystem such as drinking water, fuel,
and an aesthetically pleasing environment. The third type includes by-products,
those material outcomes, beneficial or detrimental to the farming communities'
well-being, that are the consequence of the process of production and amenity use
such as soil erosion and water pollution.
Stability refers to the agroecosystem's response to perturbation. The term stabil-
ity encompasses several different properties of the ecosystem (Rutledge, 1974), many
of which have been variously described (Holling, 1973; Orians, 1975; Cairns and
Dickson, 1977; Robinson and Valentine, 1979; Harrison, 1979; van Voris et al., 1980).
The most comprehensive is the description by Orians (1975), which identifies seven
properties related to stability: constancy, persistence, inertia, elasticity, amplitude,
cyclical stability, and trajectory stability. Constancy is lack of change in some param-
eters of the system. Persistence is its survival time, while inertia is the ability to resist
external perturbations. Elasticity refers to the rate at which the system returns to its
former state following a perturbation. The magnitude of normal system oscillations
is its amplitude . Cyclical stability is the property of a system to cycle about some
central point or zone, while trajectory stability is the property of a system to move
toward some end point or zone despite differences in the starting points.
Equitability is defined as the evenness of distribution of agroecosystem resources
and amenities among the stakeholders (Conway and McCracken, 1990). Its impor-
tance is based on the value judgment that an egalitarian distribution is preferable,
and that poverty is likely to force some stakeholders to use unsustainable practices
(Izac and Swift, 1994). A feature of natural environments is that when products and
amenities are supplied to one group of individuals, they are also available to other
groups that were not the intended target (Pearce et al., 1990). This inability to exclude
some stakeholders extends to the by-products of various agroecosystem processes,
such as air and water pollution. Furthermore, exhaustion of natural resources such
as soil nutrient depletion and erosion has major implications on intergenerational
equity. At the farm household level, gender equity is an important social factor.
Self-sufficiency is where local and regional subsistence is derived mainly from
the agroecosystem. Self-sufficiency is related to diversification in the sense that pro-
duction systems must be diversified to satisfy the subsistence needs of all the stake-
holders. More ecogeographical units are utilized, providing more opportunities for
integration and combination of various production processes and the recycling of
nutrients, energy, and wastes. Subordination of surplus production in favor of subsis-
tence encourages resource conservation and a multiuse strategy.
The goal in a multiuse strategy is to obtain a maximum number of necessary
products that each ecogeographical component offers and to maintain this over time.
This favors two desirable (in a value judgment sense) ecological characteristics:
Search WWH ::




Custom Search