Proceedings of the Symposium on Global and Environmental Monitoring: Proceedings of the Symposium on Global and Environmental Monitoring

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Persistent identifier:: 856665355

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts ; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856665355

Language:: English

Document type:: Multivolume work

Volume

Persistent identifier:: 856669164

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Scope:: XIV, 912 Seiten

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856669164

Illustration:: Illustrationen, Diagramme, Karten

Signature of the source:: ZS 312(28,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: International Society for Photogrammetry and Remote Sensing, Commission of Photographic and Remote Sensing Data

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [FA-3 FOREST DAMAGE]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: CAN MOUNTAIN PINE BEETLE GREEN ATTACK BE DETECTED ON HIGH RESOLUTION DATA FROM A DIGITAL AIRBORNE IMAGER? PRELIMINARY RESULTS. I. D. Kneppeck, F. J. Ahern

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Structure type:: Chapter

847 beetle infestation with an accuracy of 91 percent using 1:3000 scale photographs. Encouraging results have also been given in another report (Murtha, 1985) in which colour infrared large-scale photography (1:2000) was used to help distinguish between healthy and unattacked Engelmann spruce (Picea englemannii Parry). The objective of this study was to differentiate between green attacked and unattacked trees using imagery acquired with an airborne MEIS (Multi element Electro-optical Imaging Sensor). A previous study showed that MEIS data at 1.4-m resolution was sufficient to permit the detection of more trees with the appearance of red attack than 3.4-m resolution MEIS imagery and conventional aerial photography (Kneppeck and Ahern 1989), emphasizing the need for data with high resolution. 2. STUDY AREA The area chosen for the Investigation is located approximately 35 km southeast of Cranbrook, British Columbia near latitude 49° 23’ N, longitude 115° 17’ W in the Elk Forest. The terrain is fairly flat with elevations ranging from 823 m to 884 m above sea level. During the site selection process several areas containing red attacked trees were monitored during the summer months for signs of beetle spread to adjacent trees. Image data was then acquired over those areas exhibiting extensive green attack (symptoms, as mentioned earlier, included pitch tubes and boring dust found near the base of trees). Trees under attack were mainly lodgepole pine. Other species, not attacked by the mountain pine beetle, were black cottonwood (Populus trichocarpa Torr. & Gray), white spruce (Picea glauca (Moench) Voss), western larch (Larix occidentalis Nutt.), and douglas fir (Pseudotsuga menziesii (Mirb.) Franco). 3. DATA ACQUISITION Four lines of MEIS data were acquired on high- density tape September 1, 1989 from 579 m, 1539 m, and 3414 m above ground level. The corresponding instantaneous field of view was 0.4 m, 1.0 m, and 2.2 m, respectively. The MEIS data consisted of a blue band (448 nm), a green band (549 nm), a red band (676 nm) and five infrared bands (711, 722, 735, 751, and 875 nm). The minimum and maximum limits of each band are provided in Table 1. These bands closely resembled those determined by Ahern (1988) to have potential for detecting mountain pine beetle stress at an early age. Colour infrared aerial photography was obtained concurrent with the MEIS data. The overflight was timed such that it was subsequent to the period of beetle spread, which is usually from mid to late July. One month following the MEIS data acquisition trees were checked on the ground for mountain pine beetle green attack. A tree was considered at the green attack stage if all of the following conditions were met: needles were still green reddish coloured boring dust was found at the base of trees and pitch tubes were formed around entrance holes on the bark by cutting into the tree with an axe, blue stain fungi was found in the sapwood. A total of 256 green attacked trees and 250 healthy trees were identified in four principal areas which we shall refer to as Galloway, Jaffrey, Rosen Lake and Elko. Every tree was tagged with a number, and its location was marked onto an acetate sheet attached to a colour infrared photograph. A record was kept of each tree which included its location, tag number, and general health and a 35 mm photograph of each tree was obtained. 4. DATA ANALYSIS This section reports on the analysis conducted to date for the 0.4 m resolution MEIS imagery acquired over Jaffrey and Galloway. The MEIS data for all lines were copied from high- density tape to computer compatible tape. Subscenes were made of each of the four areas mentioned earlier and histograms were generated for each band. A colour infrared image was made using bands corresponding to the infrared (751 nm), red (676nm), and green (549 nm) portions of the spectrum, displayed as blue, green and red respectively. The data were linearly contrast stretched before display. Training areas were made for 156 trees whose locations had been marked on the colour infrared photographs. The training area for each tree included only fully sunlit pixels, and excluded shadowed or partially shadowed pixels. Statistics extracted for each tree included the mean digital signal level for each band. Table 2 provides a summary of the number of attacked and unattacked trees used in the analysis. For each tree the mean digital signal level per band was transferred into the RS/1 statistical package. It was apparent from the data that the digital signal level (DSL) of attacked and unattacked trees was generally highest in the 711 nm band. To reduce variations caused by differing illumination between trees, the DSL of each band was divided by the DSL of the 711 nm band for every tree. Using this normalized data, the average DSL for the attacked and unattacked trees was calculated. Figures 1 and 2 show the average DSLs of attacked and unattacked trees in Jaffrey and Galloway respectively. The standard deviations of the DSLs for each band were also calculated and displayed on Figures 1 and 2 as the average of the standard deviation for the attacked trees and the unattacked trees. Figures 1 and 2 show that there are noticeable differences between attacked and unattacked lodgepole pines at both sites. However, the differences in digital signal level between the two sites are larger than the differences between attacked and unattacked trees within a single site. While the Galloway trees generally exhibit a spectral shape which is typical for healthy green vegetation (see Ahern, 1988 for samples of foliar spectra of attacked and unattacked lodgepole pine), the Jaffrey trees have higher visible wavelength Intensities and lower near infrared intensities than one would expect. This difference between the Galloway trees and the Jaffrey trees is also visible on the colour infrared photography acquired during the mission: the Jaffrey trees have, in general, an appearance which is more gray and less pink than the Galloway trees. These differences suggest a lower level of vegetation vigour for the Jaffrey sample, which may be related to different growing conditions. Additionally, the differences between attacked and unattacked trees are generally smaller than the standard deviation of an individual measurement.

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