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Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986
Spruce budworm infestation detection using an airborne
pushbroom scanner and Thematic Mapper data
H.Epp
Canada Centre for Remote Sensing, Ottawa, Ontario
R.Reed
Saskatchewan Parks and Renewable Resources, Prince Albert, Canada
ABSTRACT: Damage to white spruce stands in Saskatchewan by spruce budworm (Choristoneura fumiferana) has
increased in the last three years. Due to dwindling wood supplies, loss of merchantable spruce and perhaps
more importantly, regeneration, future spruce stands must be protected by limiting budworm spread. Forest
managers, therefore require data of current year damage to softwood stands by spruce budworm larvae. Tradi
tionally, federal and provincial forestry agencies conduct annual aerial sketch mapping suveys to record the
extent and severity of damage to growth which gives the attacked trees a reddish-brown appearance. Useful
information about the status of the spruce budworm is gathered but more reliable surveys related to individual
stands could provide better timber forecasts.
This paper reports on the results of a project undertaken to investigate the potential of high resolution
MEIS-II pushbroom scanner and Thematic Mapper data for detecting current year spruce budworm infestation.
In the summer of 1985 the Canada Centre for Remote Sensing and the Forest Inventory Section of Saskatchewan
Parks and Renewable Resources assessed the capability of an airborne multispectral pushbroom scanner and
Thematic Mapper data to detect current year spruce budworm damage. On July 4, 1985 data were acquired with an
electro-optical pushbroom scanner of approximately 5 m resolution and 6 km swath width of a test site in east-
central Saskatchewan. Thematic Mapper data of the same area were acquired on August 26, 1985 while independent
infrared aerial photography was acquired on July 21, 1985 with a 240 mm mapping camera.
From the aerial photography and natural colour images created from the pusbhroom scanner data it was possible
to detect and identify areas of spruce budworm damage. One level of budworm infestation, with indications of a
second level, was possible in some parts of the study area with the MEIS-II scanner. The lower resolution
Thematic Mapper data was only able to identify the severely affected spruce budworm areas but there was confu
sion with other vegetation types. The biowindow, where the foliage turns reddish-brown, is usually very short,
lasting only four to eight weeks. It is, therefore, difficult to obtain cloudfree imagery of affected spruce
budworm areas.
Classifications performed on the MEIS-II and TM data indicate that only the real-time parallelipiped classi
fier will give satisfactory results, but only in the drier areas. Other enhancements such as principal compo
nent and Martin Taylor did not improve on the initial contrast stretched images.
Spatial resolution was not a significant factor in determining which sensor could differentiate budworm
infestation. The higher radiometric resolution with the higher signal-to-noise ratio in the MEIS-II sensor and
the narrower band widths did make a significant improvement in budworm detection.
The results of the study suggests the possibility of a spruce budworm infestation survey which could provide
more accurate data of current year damage than those presently produced by aerial sketch mapping. Improved
data could help program planning and assessment and ultimately improve wood supply.
INTRODUCTION
The current spruce budworm (Choristoneura fumiferana
Clem.) epidemic although limited in extent, is the
first significant occurrence in Saskatchewan, Canada,
since 1968. The current epidemic began in 1982 when
2000 ha of white spruce (Picea glauca, Moench) were
severely defoliated. This increased to 4800 ha in
1983. At the same time two new infestations resulted
in moderate to severe defoliation of an estimated
7900 ha. As a result timber harvesting and salvage
operations were stepped up in an attempt to reduce
the infestation (Stanley and Reed, 1986). Infesta
tion areas had increased to 8300 ha by 1985
(Table 1). Areas of infestation in Saskatchewan are
small compared to eastern Canada where
189.9 million ha were affected in 1983 (Kucera and
Taylor, 1984).
This paper reports the results of a remote sensing
project jointly undertaken by Saskatchewan Parks and
Renewable Resources (SPRR) and the Canada Centre for
Remote Sensing (CCRS). The goal of the study was to
investigate the potential of the high resolution
MEIS-II pushbroom scanner (McColl et al., 1984) and
LANDSAT Thematic Mapper (TM) data for detecting
current year spruce budworm infestation.
Spruce budworm outbreaks cause growth loss and
increased mortality, thereby reducing harvestable
yields (McLean and Erdle, 1984). Because decisions
Table 1. 1985 spruce budworm infestations in
Saskatchewan (in ha).
Location
Light
Moderate
Heavy
Severe
Total
Red Earth
1093.0
1802.3
1356.3
134.8
4386.4
Tall Pines
1114.8
726.9
753.6
475.4
3070.7
Tenant Lake
981.3
807.4
246.5
575.0
2610.2
Woody Tower
477.3
119.9
0.0
2.3
599.5
Total
3666.4
3456.5
2356.4
1187.5
10666.8
(after Stanley and Reed, 1986)
and management plans on forest utilization are based
on forecasts of forest development, it is important
that known outbreaks of spruce budworm are mapped
accurately.
The Canadian Forestry Service and the Forest
Inventory Section of Saskatchewan Parks and Renewable
Resources monitor the activities of the spruce bud
worm in Saskatchewan. The Canadian Forestry Service
records the extent and severity of current year
infestation by aerial sketch mapping surveys on the
basis of 1 km units. This is carried out in July by
which time damage to current year growth is quite
evident.
In 1985, personnel from the Forest Inventory
