based
to
ent and
d in the
umber of
um dense
1)
>duced
> photo
ated.
from
we obtain:
Using the given data,
2 5.76177 4.(3.9136)
n,/n =
[em | :
2.9694 . (6.8231) . (4.7680) . 60
or n,/n = 0.08695 and therefore mn /n = 10.15
2p p £f
So for Sv% = 5, with a = 163, now ne = 18.
In Table 2 the number of field plots are given for each of the four
sampling methods for a 5 per cent standard error (Sv%).
Table 2 Number of field plots for Sv% = 5.
Sampling Number of field
method plots (or SU’s)
Unrestricted 55
Stratified 31
Two-stage PPS 46
Two-phase 16
Table 3 shows the calculated number of man-days, for the activities in
field and office, which are necessary to complete the total work included
in each of the methods. In the field the activities are travel (by car,
on foot) and enumeration of plots. Since the area under discussion is
easily accessible, it is assumed that plots can be reached by car to a
distance of 300 m. The office activities are: assembling of orthophoto
sheets, and, depending on sampling method, delineation of various
boundaries, stratifi:ation, grid drawing, area measurements, area
summation list construction, random plot selection and pricking, and final
calculation.
For calculation of fieldwork time, average Speeds were calculated for
calipering trees, for travel by car and for walking. An average number of
trees per plot was calculated and distances were determined - for each
number of plots - based on a systematic distribution. Assuming a circular
10,000 ha forest area with & base camp on its periphery, the first plot,
or PU, is assumed to be at a distance which is always equal to the radius
(= 5643 m).
The distance from parking place to plot is 300 m and the distance between
"total area — à
number of plots
hours. Distances between PU's and distances between SU's within PU's are
calculated similarly. For the latter case total area - PU area (= 225 ha).
The speeds and distances which were calculated are given in Table 3.
plots is \ (m), Enumeration of one plot takes 0.16 crew
