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

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Multivolume work

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:: [TP-4 SOILS]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: COMPUTER DIGITIZATION AND DIGITAL IMAGE ANALYSIS FOR ASSESSING SOIL DISTURBANCE ON CLEARCUTS. Y. Jim Lee

Document type:: Multivolume work

Structure type:: Chapter

COMPUTER DIGITIZATION AND DIGITAL IMAGE ANALYSIS FOR ASSESSING SOIL DISTURBANCE ON CLEARCUTS Y. Jim Lee Pacific Forestry Centre, Forestry Canada 506 West Burnside Road, Victoria, B.C. Canada V8Z 1M5 0.0 ABSTRACT Soil degradation is caused by certain types and degrees of soil disturbance resulting from forest harvesting activities. This soil degradation is known to reduce future productivity of trees. The present method of survey to determine the extent and severity of soil disturbance is a ground-based "grid-point intercept" system which is time-consuming and costly. Developing digital image analysis techniques for estimating soil disturbance on the majority of clearcuts would result in greatly increased efficiency and reduced costs. Aerial photography is useful for determining the area of well defined disturbance caused by landings, roads and skidroads constructed on bare ground. Non-constructed skidroads and winter-constructed skidroads often have narrow surfaces obscured by woody debris. Special digital image analysis techniques allow estimation of these poorly defined types of disturbance. Aerial photographs and ground survey data for two recent clearcuts were processed by a digital image analysis system and estimates made of the proportion of the ground surface in landings, roads and skidroads. These estimates were compared with ground survey data. To date, preliminary work conducted on 1:5000 color aerial photography from the Cariboo Lake area in south-central British Columbia indicated that, with operator assistance, the digital image processing resulted in estimates of the extent of disturbance close to those obtained from ground surveying. In addition, the digital image processing provides areal estimates for (i) "Class A" - "deeply gouged or exposed compacted mineral soil" and (ii) "Class B" - "exposed mineral soil or possibly woody debris". 1.0 INTRODUCTION Certain types and degrees of soil disturbance resulting from forest harvesting activities are known to result in soil degradation and thus in reduced future productivity of trees. Interim soil disturbance guidelines (Lewis and Carr 1989) have been developed by the British Columbia Forest Service (BCFS) and are becoming part of silvicultural regulations. Successful application of these guidelines requires that the BCFS and forest industries conduct soil disturbance surveys on clearcuts. The present survey method is a "grid-point intercept" ground survey system (Krag and Webb 1987; Curran and Thompson 1990). Since ground surveying is time- consuming and costly, the alternate use of digital image analysis technology has been proposed frequently but has not been seriously tested. Ideally, these techniques alone would be used to estimate soil disturbance on the majority of clearcuts and ground surveys would only be required for contentious cases. The result would be increased efficiency and reduced survey costs. A system of computer digitization of aerial photography and digital image analysis is useful for determining the area of well defined disturbance caused by the construction of landings, roads and skidroads. However, soil disturbance guidelines now require a distinction between heavily and lightly used non-constructed skidroads and a tally of winter-constructed skidroads which often have narrow surfaces obscured by woody debris. A system is needed to allow estimates of the less well defined types of disturbance. In addition, future refinement of the guidelines may necessitate consideration of the depth of disturbance. A paper describing the preliminary results of soil disturbance assessment using digital image analysis was published earlier this year (Lee 1990). This paper describes additional computer digitization and a new procedure of computer digital image analysis techniques that provides consistent areal estimates of soil disturbance for clearcut units. 123

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