Ráðunautafundur - 15.02.1989, Síða 12

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manage rangelands, not to conduct research that in essence attempts to plan for the
planners.
To develop the base of knowledge upon which to manage rangelands, range
scientists must understand the methods of science. Moreover, we must begin to use
the methods of retroduction and hypothetico-deduction routinely to study processes
that are of importance in grazing management. This will facilitate the movement of
range science from the what to the how and why stages of development. This must
occur if we are to manage based upon understanding of processes important to
grazing management.
IMPLICATIONS FOR GRAZING MANAGEMENT
Many biological processes are important in range management, but plant antecology,
plant synecology, diet selection and habitat use by livestock are of particular
importance to grazing management. Here, I briefly describe the role of each process
in grazing management and the potential for enhanced management if we understood
each process.
Plant antecology is the study of a single organism or of a single species of
organisms. Its importance to grazing management lies in its ability to provide
insights into what caracteristics enable plants to tolerate or avoid grazing. Genetic
variation among and within plant species accounts in part for the ability of plants
to tolerate/avoid grazing. In addition, environmental factors such as soil nutrient
status, season, intensity and frequency of grazing affect the ability of plants to
tolerate/avoid grazing. To the extent that we can understand the mechanisms that
underlie tolerance/avoidance, we can change them via both genetic and
environmental manipulations (Caldwell, 1984; Malechek et al., 1986; Bryant et al.,
1987).
This area of range science has received a great deal of attention historically
(Stoddart et al„ 1975). Much effort has gone into describing the responses of
different species of plants to factors such as season, intensity and frequency of
grazing. More recently, scientists have begun to propose alternative explanations for
how and why these processes occur, and to subject their explanations to critical
experimentation (e.g. Caldwell, 1984; Bryant et al., 1987). While antecology has
facilitated our understanding of important factors governing the response of
individual plants to herbivory, the importance of such factors at the population and
community levels of organization is speculative (Archer and Tieszen, 1986).
Plant syneclogy is the study of the interactions among different plant species
within plant communities. Its importance to grazing management lies in its ability to
predict changes in the abundance of different plant species as a result of grazing
practices. The value of rangelands for grazing depends upon the abundance of