198
TABLE 3
Landsat MSS Bands and Transformations Used in Statistical Analysis
Band 4 (B4) Landsat MSS Bands
Band 5 (B5)
Band 6 (B6)
Band 7 (B7)
Band 6
Band 7
Band 5 (BD6) Band Difference
Band 5 (BD7)
Band 6/Band 5
Band 7/Band 5
(R65) Simple Band Ratio
(R75)
(Band 6 - Band 5)/(Band 6 + Band 5) (ND6)
(Band 7 - Band 5)/(Band 7 + Band 5) (ND7)
Normalised Difference
1
(ND6 +0.5)/ABS(ND6
(ND7 + 0.5)/ABS(ND7
0.5) X (ABS(ND6 +
0.5) X (ABS(ND7 +
. 5) ) (TVI6)
.5)) ' (TVI7)
Transformed ^
Vegetation Index
(1.091 B6 - B5 - 5.49) / (1 .091- +
(2.400 B7 - B5 - 0.0l)/(2.400 + 1 ) '
(PVI6) Perpendicular Vegetation
(PVI7) Index 3
4
2.4 B7 - B5 (DVI) Difference Vegetation Index
0.332 B4 + 0.603 B5 + 0.675 B6 + 0.262 B7 (SBI) Soil Brightness Index 5 -
-0.283 B4 - 0.660 B5 + 0.577 B6 + 0.388 B7 (GVI) Green Vegetative Index
First Principal Component (PC1) For each Landsat MSS scene date
Second Principal Component (PC2)
Transformation Sources:
1. Rouse et al. (1973)
2. Perry and Lautenschlager (1984)
Deering et al. (1975)
3. Perry and Lautenschlager (1984)
Richardson and Wiegand (1977)
4. Richardson and Wiegand (1977)
5. Kauth and Thomas (1976)
modified after
modified after
strongest with respect to zinc needle con
tent and weakest with respect to copper nee
dle content. Only the September 1976 scene
produced correlation values greater than
r=-0.65, and then only for MSS bands 5
(r=-0.78) and 6 (r=-0.69) and the soil
brightness index (SBI) (r=-0.70). These values
are significant at greater than the 98 per
cent probability level.
Although no dominant bands or transfor
mations emerged from the statistical analy
sis of the spruce needle data set that show
an overall capability to discriminate dif
ferent levels of metal concentrations in the
needles, the first principal component (PC1),
band differences BD1, BD2, and BD3, TM band
4, and the brightness (TMB) and greenness
(TMG) indices did rank the highest of all
the TM bands and transformations tested,
whereas the soil brightness index (SBI), the
first principal component (PC1), and bands
5, 6, and 7 have the highest ranking of all
the MSS bands and transformations employed
in the analysis.
10. DISCUSSION AND CONCLUSIONS
Two facts stand out from this study:
the amount of copper, lead, and zinc in the
spruce needles differs markedly from their
soil content (especially for copper and
lead), and, except for zinc, the soil and
needle metal contents show essentially no
correlation with each other. The level of
metal availability in the soil substrate
and the regulatory mechanisms operating
within the spruce trees probably account for
these observations. The chemical analysis of
the soil samples from the test site involved
the determination of their total copper,
lead, and zinc content, which is usually
much greater than the amount of metals pre
sent in the soil solution. It is the latter
metals that are available to the plant for
uptake by its root system.
The literature contains numerous refer
ences to plants growing in soils containing
high concentrations of copper, lead, and
zinc, but exhibiting low levels of these
metals in their foliage, except for zinc
(e.g., Holmes, 1964; Nicolls et al., 1965;
Bolviken et al., 1977). The good correlation
found between soil and needle zinc content
and the lack of one between soil and needle
lead and copper are in agreement with the
published data on metal uptake into the
aerial parts of plants. This supports the
thesis that zinc is taken up by the spruce
trees in a more or less unrestricted manner
and subsequently controlled within the tree
system by internal regulatory mechanisms,
whereas the absorption of lead and copper is
controlled by exclusion mechanisms operating
at the soil-root interface. Lead and copper
absorbed by the plant are, for the most part,
deposited within the plant's root system. As
the roots are the medium by which the trees
derive their nutrients and water from the
soil substrate, the detrimental effects that
these highly toxic metals have on a tree's
vascular system can be as serious, if not
more so, than any effects these metals may
have at the active sites of metabolism in
the aerial parts of the tree.
The strong capability of many of the
Landsat MSS and TM spectral bands and trans-