The two-phase sampling finally
Estimate of total volume: v - A. X v. x (plot area) i35
p
Plot volumes are obtained from a regression, of the type Y - bc (in
which c =, c', and c' - crown area in per cent per plot; Y - volume,
(4) b = regression coefficient).
n
g
X6
i
Regression coefficient: b = ———
n," Bumber of field plots used for regression calculation
n' = number of photo plots
- 3 E
va = mean volume of Bg plots (m /plot) - b cn
(5) P no sap
pren mere Je,
ce = f lot =
on Ac n mean crown cover o % plots (%) =
p p
ci - V. crown coves per plot (%)
n, = number of photo plots for determination of
v and ©
n n
p p
- 3
Estimate of total volume ve = Ac . b . ca (DB) su Adi een CO)
p
2 2 2 -2 2
(6) Estimate of variance of mean volume: ss = bh" SZ + c i$ . £10)
n n b
p p
2 2
- 2
(7) Dui So e $8
n n v.c
ER RA. P
n, n Ch
g
2 |
in which an estimate of the (standard deviation) of c. |
n 2 |
p |
n S. c |
(8) p 2, ©;
$e 7
=. p
n (n - 1)
p