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:: Spectral response from thinning cuttings measured by multitemporal satellitedata. Hâkan Olsson

Document type:: Multivolume work

Structure type:: Chapter

grown-up coniferous forest and water, but not agricultural land and young forest. Areas covered by clouds, cloud shadows or technical errors in any of the 36 channels used were excluded from the mask. Under the mask median values were extracted from all the 36 channels in 1730 systematically located windows of 2 by 2 pixels. All the field surveyed thinnings, except the two stands with more than 50 % deciduous forest and the seed tree stands after cutting, were covered by the mask. The calibration functions, and with them the measured DN changes, will thus be less representative for deciduous forest and seed tree stands. For each channel at the Landsat acquisitions 1985- 1989, the same channel the previous year were used as regressor in a linear regression. The calibration functions where thus of the type: X(t2,ch i ) = a + b * X(tl,ch i ) (1) Where: X = a DN value 0..255 t2 = an aquisition year 1985-1989 tl = t2-l ch^ = one of the used TM channels The influence of different definitions of forest masks and calibration algorithms was tested on the field surveyed stands before thinning. The functions finally used were estimated with robust regression, procedure RREG;NORMAL in Minitab version 7.2. This procedure is less sensible for outliers than least squares regression. 2.5 Calculation of standwise spectral changes The analysis of change in DN values was in this first version only made when a field surveyed stand had a valid acquisition both the first summer before (tl) and the first summer after (t2) the reported month of cutting. By use of the calibration fuctions (1), was a mean value at (t2) predicted from the stand mean value at (tl), for each stand and channel. This was done for all valid pairs of aquisitions. The number of cuttings observed was 41. The number of valid change measures on the field surveyd stands before cutting was 105. The changes in DN is the difference between the actually measured mean values at (t2) and the predicted values. Since the stands were cut in different years, the change values obtained are mean values for the 5 pairs of summer acquisitions used. 3. RESULTS 3.1 DN change as a function of thinning grade Table 3 shows a summary of the field inventory and the changes in DN. The table is grouped by degree of thinning. The differences in DN mean values between the three groups of thinning is small. The standard deviations fore the thinnings are of the same order as standard deviations before cut. The measured DN changes as a function of thinning grade is illustrated in figure 1. Table 3. Summary of field inventory and DN changes, grouped by thinning grade. The measured DN differences for all stands before the year of thinning are shown in the left column. All stands unthinned Thinnings, grade 19.0 - 30.0 - 29.9 % 39.9 % 40.0 - 51.2 % Seed tree stands 74.1-90.4% Number of observations: 121 15 14 7 5 Before cutting: Basal area (m /ha) 24.0 22.1 26.3 26.5 18.3 Spec. dist. pine 63 % 68 % 56 % 47 % 76 % spruce 25 % 23 % 30 % 25 % 20 % deciduous 12 % 9 % 14 % 28 % 4 % After cutting* Basal area (m /ha) - 16.7 17.0 14.4 3.3 Spec. dist. pine - 72 % 64 % 59 % 100 % spruce - 23 % 28 % 26 % 0 % deciduous - 5 % 8 % 15 % 0 % Mean height (m) - 14.9 15.6 15.4 16.1 Measured-Predicted DN: TM 1 mean -0.08 0.43 0.50 0.58 7.84 std 1.30 0.80 1.14 0.98 3.66 TM 2 mean 0.25 0.51 0.35 0.49 4.37 std 0.82 0.63 0.59 0.60 1.12 TM 3 mean -0.03 1.57 1.12 1.45 14.48 std 0.73 1.26 0.72 1.39 8.86 TM 4 mean 0.46 -0.92 -3.09 -1.81 5.53 std 2.64 2.38 3.74 2.88 2.28 TM 5 mean 0.34 4.82 3.55 4.38 29.80 std 1.36 2.45 2.20 3.41 8.18 TM 7 mean 0.01 2.15 2.00 2.55 13.79 std 0.60 1.17 2.70 1.80 3.72 852

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