This method involved identifying plant
species within selected 1metre squares (or quadrats) in each of the six areas. Each
of the six distinct areas was a strata which was sampled separately. A zero
co-ordinate point ((0,0) or origin) was selected for each area. (by convention, this
is usually the bottom left-hand corner, this was the point chosen for the Wet Woodland
Survey). By taking pairs of random numbers from a random number table, selected one
metre squares could be obtained. If pairs of random numbers gave a point lying
outside of the area, they were ignored and the next pair of numbers were selected from the
number table.
A 10x10 metre area is split into an imaginary grid of 100x1m².
The origin is chosen, by convention this is usually the bottom left-hand corner.
The origin in the actual area could be marked by placing a cane in the ground.
Then, a pair of two-digit random numbers are taken from a random number table, in this
case, 0507. Using a transect line (a long rope marked at 1 metre intervals), 5
metres is measured out horizontally from the origin. From this new point 7 metres is
measured vertically. Now a 1m² quadrat (square wooden frame of side 1metre) can be
placed on the ground at this point and the species within it identified (shown as the
black square above).
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The reason that 1 m² squares were selected was to
allow for the size of the largest ground cover plants growing in any of the six distinct
areas. If a smaller quadrat square had been used i.e. 0.25m², it would not have
been suitable for areas with larger plants. Once selected, 1m² quadrats had to be
used throughout the survey so as to maintain consistency in the results. |