photos. Ciesla concluded that "...ultra-small-scale color - IR photographs
comprise a potential tool for detecting and mapping this type of damage...(total
defoliation)...as long as it is restricted to nearly pure stands of host type
with little or no herbaceous vegetation in the under-storey to mask feeding
injury". Harris, (1974), noted that "...boundaries and intensities of a variety
of forest pest infestations can also be delineated on color photographs at some
of the smallest scales (about 1:137,000) available, and at least some infesta
tions that contrast well with surrounding forests can also be seen on ERTS-1
imagery." Beaubien and Jobin (1974) took advantage of such contrast to map
eastern hemlock looper (Lambdina f. fiseellaria (Gn.)) killed balsam fir {Abies
balsamea (L.) Mill) on Anticosti Island, Canada, from ERTS-1 imagery. Murtha
(1973c) showed examples of delineation of SO 2 damage on ERTS-1 imagery. Again,
the primary reason for being able to map the damage comes from initial a priori
knowledge, and contrasts between affected and unaffected vegetation as it is
recorded in various regions of the spectrum by the multi-spectral scanner aboard
the satellite.
DISCUSSION
The preceeding examples have demonstrated that a capability exists
via remote sensing techniques and interpretation ability to transfer detection
and mapping of vegetation damage - (tree mortality and defoliation) from the
research status to the operational status. It is the considered opinion of
this author that vegetation damage surveys for all intents and purposes can
be made operational! The constraints are timing of imagery acquisition, econ
omics, and the ability of the interpreter. He must know what to look for.
Why haven’t remote sensing damage surveys become more common place?
Several reasons can be speculated upon. Perhaps the most important factors are
a need for more effective communication and acceptance of new techniques. To
date, it has been the responsibility of the research community to simply publish
reports of their investigations. All too frequently, the reports are only read
by a select group of other researchers. The responsibility of the research
worker to "sell" his findings or techniques to the people who need to know has
virtually never existed. Perhaps it should. The attitude of staying with an
old technique because it is familiar also has an effect. If the scientist had
the responsibility to "sell" his techniques, perhaps new ideas would be more
readily accepted.
Another reason has been caused by a degree of "bandwagoning". Re
search scientists and others have initially over-emphasized and over-reacted
to a new product, be it a new film, scanner, or airborne platform as the total
answer to all problems. The harm has come because of a tendency to avoid doing
the necessary homework, becoming familiar with the product, and hence familiar
with its limitations, and also because of the quick rewards of researching
a new item, thus avoiding the "hard" selling job mentioned above.
With respect to interpretation of damage to vegetation, "per se"
emphasis should concentrate on damage assessment. In commercial forest areas,
volume lost from timber stands is important. To date we are barely beyond