58 
independence states that the distribution of the classes in 
one band is random to the distribution of the classes in the 
the other band. If there is no independence, as is shown 
by a large calculated chi-square value, an interaction is 
said to be present. Critical chi-square values are avail 
able in most statistical text books, although a more re 
liable rule-of-thumb can be used: if the calculated value 
exceeds three times the number of degrees-of-freedom, the 
distribution is dependent. This rule is preferred because 
of the random noise that is introduced between bands due to 
different mapping scales, projections, and orientations. 
By examining the results summarized in Table 2, it is appar 
ent that there was a high degree of dependence between the 
vegetation band and the soil, contour, aspect, and slope 
bands, respectively. None of these results are startling, 
for plant ecologists have known for years that there is a 
close interaction between the distribution of soils, veg 
etation, aspect, elevation, and slope. 
Selection of the stratification scheme. Although the 
chi-square analyses indicated a high degree of dependence 
between the vegetation, slope, aspect and contour bands, we 
selected the vegetation band for the stratification because 
this band best represented the range of ground conditions 
present in the Park to the highest ground resolution. Use 
of the hypsographic bands was rejected due to relatively 
poor horizontal accuracy; and use of the soil band was re 
jected due to relatively poor horizontal accuracy; and use 
of the soil band was rejected due to its large minimum map- 
ping areas. A 
total of 
402 ground 
plots were proportion- 
ately allocated 
to the 
19 spectral 
classes 
(Table 3). 
SPECTRAL 
NUMBER OF 
PERCENT OF 
NUMBER OF 
STRATIFICATION 
PIXELS* 
TOTAL AREA 
GROUND PLOTS 
VEGETATION TYPE 
Conifer-1 
300 
2 
8 
Conifer-2 
1106 
7 
28 
Conifer-3 
1824 
11 
46 
Redwood Forest 
Conifer-Hardwood-1 
1994 
12 
50 
8379 acres 
Conifer-Hardwood-2 
2151 
14 
54 
Hardwood-Conifer 
2040 
13 
51 
Hardwood-1 
1538 
10 
39 
Hardwood-2 
885 
6 
22 
Hardwood-3 
308 
2 
8 
Douglas Fir Fori 
Hardwood-Woodland-1 
84 
1 
2 
Hardwood-Woodland-2 
546 
4 
14 
4379 acres 
Hardwood-Woodland-3 
484 
3 
12 
Hardwood-Woodland-4 
192 
1 
5 
Hardwood-Woodland-5 
562 
4 
14 
Hardwood-Woodland-6 
321 
2 
8 
99 
1 
2 
Chaparral 
Brush-2 
543 
3 
14 
Shrub 
436 
1 
11 
1444 acres 
Grassland 
545 
3 
14 
15958 
100 
402 
1 pixel = .89 acres 
Table 3. Allocation of 402 ground samples to the 19 spec 
tral class stratification, and the grouping of 
these classes into three vegetation types based 
on these samples.