soil-conservation-people-religion-and-land.pdf - South West NRM

~ield workers are agreed that the intensity of sampling is
almost invariably dictated by staff resources available and
that constraints on the amount of ground truthing that can
supplement remote sensing are the limiting factor to the rate
of survey. Lay, Bastin and Friedel's papers to this workshop
reflect the problems and alternative approaches concerned. In
simple terms, representativeness, if it is ever achievable in
rangelands, demands special attention.
Since circumstances dictate procedures, in the majority of
cases it is left to the assessors to satisfy themselves that
their sampling assessment area:
a. Has the same ecological potential as the greater
portion of the paddock being assessed.
b. Has been used to a similar degree by the grazing
animals, as the paddock as a whole.
c. Is truly representative of the present condition of
the paddock overall.
Although the requirements of a successful condition assessment
system may differ according to the aim of the assessment, the
size of the areas concerned, and the manpower available,
certain characteristics may be listed as basic to all
successful systems. These would include:
a. Rapidity.
b. Simplicity without loss of repeatability. !
c. Quantitative estimation of criteria.
d. Applicability to grazed and ungrazed sites.
e. Applicability in good and bad years.
f. Usefulness in guiding management decisions.
g. Acceptability to land users.
The quantitative estimation referred to above, has led to
comprehensive use of point methods over the years. The
American Step-Point method and the South African Wheel-Point
method are still widely used but as Friedel points out, they
may have high errors where cover is very low. This error has
led the writer to seek correlations between basal cover and
botanical composition and where these exist, to use such
correlations as a basis for measuring only botanical
composition, by using nearest plant data from Wheel-Point
surveys-and deducing grazing condition solely from
composition.
Irrespective of the region concerned, a number of basic
questions need to be answered before any system of assessment
of condition and trend can be applied in practice. These
questions would usually include the following (Roberts, 1972):
Which species are present?
Which species could or should be present?
. Which species dominate the community?
Which species could or should dominate the community?
. Has the vegetation changed since domestic stock were
introduced?