10 
minary investigation of the site classification accuracy by ocular esti- 
mation. Two land surveyors performed the estimation by studying 
aerial photographs in mirror stereoscope. They compared every sec- 
tion with a few sample plots, which earlier were studied in the field. 
The results were referred to 6 separate rectangular areas, each of 
them about 39 hectare. ( Compare 2.4 and the figures 1, 2, 3 and 4.) 
3.3. The treatment of the primary material 
'The investigation was concentrated on 98 sample plots with stands of 
scots pine, for the main part of pine, or of one half pine and onehalf 
Norway-spruce. One test serie refers to measurement in the field and 
the other to measurement in the photographs. 
The mathematical symbols used are, 
Di = the ideal site quality of a sample plot expressed in cub.metre 
per hectare and year, 
h = the mean height of trees within a sample plot expressed in 
metre, read from a height curve 
D = the mean crown diameter of sample plot, expressed in metre. 
5 = the crown closure within sample plot, expressed in tenths. 
T = forest type according to the scheme by Arnborg (1) 
The following functions were visualized in graphs (not reproduced 
here) 
a) Di — f (h), one curve for each of the years 40, 60, 80, 100 and 
120, according to the height-age system generally ased in Sweden. 
b) Bi — f (D) for each age-class 50—70 years, 70—90 years and 
900—110 years. 
c) B1 — f (D) for each height-class — 15 metres, 15—17.5 metres, 
17.5—20 metres, 20—22.5 metres. 
Lh 
d) Bi = f | =) without any distribution in classes. 
\ / 
oh E 
e) Bi = f | D ) for each age-class 50—7/0 years, and 90—110 years. 
\ LJ 
f D : 
PD D-—Í | D without any distribution 1n classes. 
Th? | Bass , 
g) Bi — 1 D for each age-class 50—/70 years, /0—90 years and 
90—110 years. 
h) Age = f [5^ 
D, 
i? s 
1) Bi = f D | without any distribution in classes 
(PB,