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:: [WP-3 FOREST INVENTORY APPLICATIONS]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: USE OF DIGITAL SATELLITE DATA FOR STAND DELINEATION AND ESTIMATION OF STAND VARIABLES BY REGRESSION ANALYSIS AND FIELD INVENTORY. Olle Hagner

Document type:: Multivolume work

Structure type:: Chapter

information and digital elevation models (DEM). Alternatively digitized aerial photos can be used instead of satellite data. The result of segmen tation is checked and edited interactively on a workstation monitor. When the operator is satis fied with the result, a hardcopy is printed for field use. 2.1.2 Stand data estimation. Estimates of stand characteristics are obtained by applying regression functions to the spectral signatures within each delineated stand (Tomppo 1986),(Hagner 1989). The regression functions are derived from NFI-plot data and corresponding multispectral satellite data. Techniques developed by Holmgren (1990) are used to model site type parameters from soil map information and digital elevation models. 2.1.3 Field inventory. A simplified version of the subjective field inventory method used in Sweden today is used to collect stand data. The surveyor describes all variables frcm one spot within each stand. Only a few supporting measure ments are made. The surveyor concentrates on variables that can not be described by remote sensing, such as: Treatment recommendations, environmental considerations, etc. Hand-held field computers are used for data entering and checking of consistency and completeness. During field inventory errors and corrections of the delinea tion are noted. A few (10-15) stands are selected for an objective reference survey, in order to determine correction factors for personal bias of the ground crew. 2.1.4 Combined estimation. The results of field inventory are used together with the estimates obtained from NFI- and satellite data, to calcu late new estimates for each stand. If random errors are uncorrelated and if field and satellite estimates are weighted according to the inverse of their variances, then combined estimates will have higher precision than any of the separate input sources. Also other sources of information, such as aerial photo interpretation, previous field inventory data, etc., can be included in the combined estimates. 2.1.5 Map production. Once the combined esti mates of stand data have been calculated, a second automatic merging pass is started. Adjacent stands with minor differences are joined into larger units, according to criteria for desired size of final stands and acceptable within-stand varia tion. Also the result of this second merging pass is checked and edited by the operator. Finally the result is transferred to a GIS for storage, analy sis, and presentation. 2.2 Test sites Five test sites were used. They are located near the city of Umea in Northern Sweden (63°.9 N, 20°. 1 E) (Figure 1). The sites are representative of the forest types found in most parts of North ern Sweden, dominated by natural stands of Scots pine and Spruce (Pinus sylvestris, Picea abies) in various mixtures with broadleafs, mainly birch (Betula pubescens and B. verrucosa). The sites are owned by private owners (site 1) and forest com panies (sites 2-5). The relative proportions of age and cutting classes are fairly normal for Northern Sweden, with approximately 50% being old mature stands. 2.2.1 Test site no. 1. The main objective for the used site no. 1 was to evaluate the perfor mance of various methods for stand delineation. The specific location was selected because of the diversity of forest types, age, and cutting classes represented in the area. Also a wide range of site types are found, with several types of moraine and sediment soils. The topography is rather flat, with an altitude ranging from 45 up to 120 meters. A dense grid of 1468 sample plots (2 plots/- hectare) were surveyed. The variables measured on each plot were: wood volume/hectare, mean tree diameter, tree species mixture, and various site type variables, such as: soil type, moisture, vegetation, type etc. A manual stand delineation of the test site was made by means of visual interpretation of black and white aerial photos, at the scale of 1:30 000. The delineation was checked and corrected in situ. 2.2.2 Test sites no. 2-5. These test sites were used to evaluate the precision of stand character istics estimated frcm satellite data and NFI- sample plots. A total of 80 reference stands, were located in 4 separate sites (Figure 1). The characteristics of each stand were determined frcm 20 circular (radius: 10 meters) sample plots, distributed according to a systematic square grid. Also, subjective estimates of stand variables were obtained for each stand by professional surveyors, using the traditional inventory methods, see section 1.1.1. TEST SITE CLUSTER OF 8 NFI - PLOTS Figure 1. location of test sites and National Forest Inventory plots used in the study. Each dot represents a cluster of eight NFI sample plots. The area shewn corresponds to the Landsat 5 quarter scene acquired 21 06 89. 2.3 National Forest Inventory sample plots The Swedish NFI is a continuous inventory. Approx imately 18 500 plots are surveyed each year. Of these, 40% are permanent and revisited every 5 years. More than 200 stand and site variables are recorded for each plot (Ranneby et al. 1987 ). A total of 740 permanent NFI-sample plots, sur veyed during the period of 1983-1987, and corre sponding spectral signatures frcm a satellite acquisition (Landsat 5 TM, 1989) were used to construct regression functions for estimation of stand characteristics frcm spectral signatures. The location of NFI-plots is shown in Figure 1. 394

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