TheImprovement ofTropical and Subtropical Rangelands

REGIONAL RESOURCE ASSESSMENT 79
specific types of land use (for example, forest and rangeland). Both
types of agencies conduct their own mapping activities. Thus, in a
range improvement project, it is common to find that one or more
land characteristics (for example, geology) have been mapped already
for much of the project area. With this pattern established, a project
will likely continue mapping land characteristics individually in the
interests of consistency and economy. Moreover, project mapping
may be carried out by several groups on a component basis because
of the distribution or resource responsibilities among participating
agenCIes.
Because it is difficult to map certain land characteristics individually,
some characteristics often will be combined in one map
(for example, climate and vegetation; vegetation and land use/land
cover). Because of the constraints ofscale, mapping units will tend to
be IIOmewhat heterogeneous, but will be designed around naturally
linked groupings of land characteristics (for example, associations of
soil or vegetation).
Landscape Approach
The need to adopt a systems approach during most phases of a
range improvement project is emphasized throughout this volume.
Two considerations argue for the systems approach at the resource
assessment level. First, as noted above, the region should be understood
in terms of its differences in land capability. This quality of
the land is derived from physical and biological characteristics such
as climate, soils, and vegetation. Although these characteristics may
be surveyed individually, they must be considered together to determine
land capability. Moreover, the units of land that are mapped
function more or less like systems and not simply as a collection of
independent components. Change in anyone of the components will
affect or be affected by other components in varying degrees. Thus,
at the resource assessment level, it is desirable to consider the units
of land to be managed as integrated "landscapes" with a distinct set
of related characteristics.
Second, from a practical standpoint, significant economies of
effort and improvements in product quality can be achieved by combining
related or complementary aspects of the resource assessment.
For instance, in a landscape approach, an interdisciplinary team (perhaps
a soil scientist, geomorphologist, and plant ecologist) performs
the mapping and analysis tasks as a group, rather than producing a