Agriculture Reference
In-Depth Information
6 Development of Health
and Sustainability
Indicators for a Tropical
Highlands Agroecosystem
6.1 IntRoductIon
Describing agroecosystems, assessing their sustainability and health, and assess-
ing progress toward community goals and objectives has become of great interest
to researchers, development agents, and communities. The agroecosystem health
approach proposes that these descriptions and assessments can be achieved using
a group of carefully chosen indicators (Rapport and Regier, 1980; Gosselin et al.,
1991; Lightfoot and Noble, 1993; Rapport, 1992; National Research Council, 1993;
Cairns et al., 1993; Izac and Swift, 1994; Winograd, 1994; Dumanski, 1994; Rap-
port et al., 1985; Ayres, 1996; Smit et al., 1998). There are numerous definitions of
what constitutes an indicator (Boyle, 1998; Boyle et al., 2000). Gallopin (1994a)
and Smit et al. (1998) described indicators as measurements that can be taken for
a given complex phenomenon to document how it changes over time, how it varies
across space, and how it responds to external factors. In terms of an agroecosystem,
an indicator has been defined as a measurable feature that singly, or in combination
with others, provides managerially or scientifically useful evidence of ecosystem
status (Canadian Council of Ministers of the Environment [CCME], 1996) relative
to a predefined set of goals.
Selection of indicators is complicated by two main difficulties. First, the list
of potential indicators varies from one agroecosystem to another as well as among
levels in an agroecological hierarchy. The second difficulty is that there are virtu-
ally an infinite number of measurable parameters at each hierarchical level of an
agroecosystem (Schaeffer et al., 1988). There are, however, some important guide-
lines in the selection of agroecosystem indicators. A systems approach should be
taken to select a comprehensive set of measures. In addition, the choice of indica-
tors must be explicitly guided by societal issues and values (Kay, 1993) that give
meaning to the description or assessment process. This ensures that selected indica-
tors are practically useful in terms of decision making, setting policy guidelines, or
scientific research. It can be argued that some “nonquantifiable” indicators provide
more important information than more objective ones (Harrington, 1992). But, if the
objectives are to assess the direction or magnitude of change in the status of agro-
ecosystems, to compare one system with another, or to assess the potential impact of
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