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Aerial photography, using several photo scales and
film formats, has been an integral part of these
inventories. With one exception, color infrared
(CIR) film has been used exclusively (Table 1).
Aerial photos have been used to identify forested
areas containing a spruce component and classify
them into a series of vegetation types. Vegetation
types were then stratified into a series of
mortality classes. Aerial photos have also been
used to make counts of dead and declining trees on
fixed area photo plots. Overall survey designs and
aerial photographic parameters varied somewhat by
survey area.
4.1 Northeastern United States
In 1984, an extensive inventory of the Adirondack
Mountains and Tug Hill Plateau regions of New York,
and portions of Vermont and New Hampshire was
initiated (Weiss et al. 1986) (Fig. 3). This
inventory was based on estimates made from 55
randomly selected 3150 ha aerial photo sample
blocks. Each block was photographed with CIR film
at a scale of 1:8000. Blocks were stratified into
four vegetation classes which contained a spruce and
fir component (Table 2) and three mortality classes
(Table 3). A series of ca 1 ha. photo plots were
randomly established in each of the mortality
classes within three of the vegetation classes for
tree counts. Aerial photo data was adjusted by a
small sample of ground plots using double sampling
with regression (Wear et al. 1966).
During the following year, selected areas of the
Adirondack Mountains of New York and portions of
Vermont and New Hampshire, including the Green
Mountain and White Mountain National Forests, were
photographed. Complete coverage of these areas with
1:24000 scale CIR film was acquired. These photos
are being used to map the location of concentrations
of moderate and heavy spruce and fir mortality in
vegetation types with a spruce component.
4.2 West Virginia
In 1985, an inventory to estimate levels of red
spruce decline and mortality was conducted on the
Monongahela National Forest and adjoining private
lands in West Virginia (Mielke et al. 1986). Aerial
photography used for this inventory was high
resolution panoramic photography taken the previous
year by a NASA ER-2 high altitude earth resources
reconnaissance aircraft (Nadir scale = ca 1:30000).
This type of photography has been used successfully
for a number of forest damage assessment
applications (Ciesla et al. 1982). Complete
coverage of all of the high elevation red spruce
forests in the state was available.
This photography was used to classify forests with
a red spruce component into vegetation and mortality
classes (Tables 2 and 3). The small scale of the
panoramic aerial photography precluded
identification of tree species and counts of dead
and declining trees on small photo plots. In
addition, exposure variations across each frame
caused a dramatic shift in the color of coniferous
forests and approximately 7 percent of the area
classified as having a spruce component could not be
stratified into mortality classes. Individual
polygons in each vegetation/mortality class were
subsampled with ground plots to estimate levels of
decline and mortality.
4.3 Southern Appalachian Mountains
The high mountains of southwestern Virginia, western
North Carolina, and eastern Tennessee contain six
isolated areas of red spruce and Fraser fir. Total
area is relatively small, ca 24000 ha, and of
limited commercial value; however, these stands
occur in such notable landmarks as Mt. Mitchell
State Park, site of the highest mountain in the
eastern United States, the Great Smoky Mountains
National Park, and along the Blue Ridge Parkway,
whick are areas of major recreational importance.
Complete 1:12000 scale aerial photo coverage was
obtained of these areas during 1984 and 1985. Each
area of spruce-fir forest was stratified into three
mortality classes (Table 3). These mortality
classes differed from the classes used in the other
survey areas and reflect the high levels of Fraser
fir mortality caused by the introduction of the
balsam woolly adelgid into these forests. In
addition, a series of 1:4000 scale CIR photos was
acquired to help monitor tree damage in selected
intensive research sites in these areas.
These inventories have provided a large volume of
baseline data including statistics on the proportion
of spruce-fir forest in each mortality class by
state, data on volume, number of trees, and basal
area on a unit area basis for each vegetation and
mortality class, and data on the relative health of
regeneration. Examples of these data are shown in
Tables 4, 5, and 6.
5 GEOGRAPHIC INFORMATION SYSTEMS
Geographic information systems (GIS) provide a
capability for storage, analysis, and display of
spatial data. They can be used to integrate many
kinds of thematic data and evaluate certain spatial
relationships.
To help identify the causal agents associated with
forest declines and determine the potential role of
anthropogenic pollutants in this decline complex, it
is desirable to relate the location of areas of
decline and mortality to certain topographic
features such as slope, aspect and elevation. In
addition, different forest management objectives and
tactics on various land ownerships might influence
the intensity of decline and mortality, as might the
presence of pest outbreaks or other disturbances.
Spatial data taken from aerial photographs in
conjunction with recent inventories of decline and
mortality in the spruce-fir forests of the eastern
United States includes the location of vegetation
types by damage classes. These data are presently
being digitized for entry into a GIS. Additional
themes, including land ownership, topographic data,
and historical data on the location of fire,
logging, and pest outbreaks such as that compiled by
Pyle, et al. (1985) will also be entered into the
data base.
Presently, data for the northeastern states is
being digitized and entered into a GIS developed and
maintained by the University of Maine. Data for
West Virginia and the southern Appalachian Mountains
Is being stored and analyzed using the Map Overlay
Statistical System (MOSS), a public domain GIS
developed and maintained by the Fish and Wildlife
Service of the U.S. Department of Interior. This
GIS has recently been installed on a Forest Service
Data General MV-4000 at Doraville, Georgia, for this
work.
GIS will also provide the capability to compare
the present spatial distribution of forest decline
and mortality with spatial distributions obtained
from future inventories.
