Use of Systems Theory, Directed Graphs, and Pulse Process Models in an Adaptive Approach to Agroecosystem Health and Sustainability - Integrated Assessment of Health and Sustainability of Agroecosystems - page 91

4 Use of Systems Theory,

Directed Graphs, and
Pulse Process Models
in an Adaptive Approach
to Agroecosystem Health
and Sustainability

4.1 IntRoductIon
Attempts to understand the interrelationships between, on the one hand, goals and
objectives of communities living in an agroecosystem and, on the other hand, their
planned actions, stated needs, and concerns require the understanding of a com-
plex system. Such a system involves many variables interacting with each other in a
dynamic process. Furthermore, the definition of these variables and their relation-
ships depend on how the communities perceive their world. In attempting to model
such a complex system, one faces a trade-off between the accuracy of the model's
predictions and the ability to obtain the detailed information needed to build the
model (Roberts and Brown, 1975).
A system , better referred to as a holon to distinguish it from a real-world assem-
blage of structures and functions, is a representation of a situation and consists of an
assembly of elements linked in such a way that they form an organized whole (Flood
and Carson, 1993). An element is a representation of some phenomena by a noun
or a noun phrase. Links between elements represent a relationship between them.
A relationship can be said to exist between two elements if the behavior of one is
influenced or controlled by the other (Flood and Carson, 1993). Behavior refers to
changes in one or more important attributes of an element. Systems thinking involves
formulating a holon and then using it to find out about, gain insight into, or engineer
a part of the perceived world.
The difficulty in formulating a holon to study the interrelationships among com-
munity values, community goals, planned actions, and perceived problems arises
from three predicaments. The first is that values, goals, and problems are socially
constructed based on the perspectives of the stakeholders, and these are sometimes
divergent or conflicting (Ison et al., 1997). No one such perspective is sufficient or
complete, and none can be said to be right or wrong. Furthermore, problems and
concerns in the agroecosystem are often part of what has been referred to as a mess

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