Abstract
In this study we used photographs of tree crowns to test whether the assessment methods for tree defoliation in Switzerland have changed over time. We randomly selected 24 series of slides of Norway spruce with field assessments made between 1986 and 1995. The slides were randomly arranged and assessed by three experts without prior knowledge of the year when the slide was taken or the tree number. Defoliation was assessed using the Swiss reference photo guide. Although the correlations between the field assessments and slide assessments were high (Spearman's rank correlation coefficient ranged between 0.79 and 0.83), we found significant differences between field and slide assessments (4.3 to 9% underprediction by the slide assessors) and between the slide assessments. However, no significant trends in field assessment methods could be detected. When the mean differences between field and slide assessments were subtracted, in some years, field assessors consistently underpredicted (1990, 1992) or overpredicted defoliation (1987, 1991). Defoliation tended to be overpredicted in slides taken against the light, and underpredictedfor trees with more than 25% crown overlap. We conclude that slide series can be used to detect changes in assessment methods.However, potential observer bias calls for more objectivemethods of assessment.
Similar content being viewed by others
References
BFL/EAFV: 1985, Ergebnisse der Sanasilva-Waldschadeninventur 1985, BLF/EAFV, Bern und Birmensdorf, pp. 47.
Bradley, J. V.: 1968, Distribution-free Statistical Tests, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, pp. 388.
Brang, P. {on(ed.)}: 1998, Sanasilva-Bericht 1997. Zustand und Gefährdung des Schweizer Waldes–Eine Zwischenbilanz nach 15 Jahren Waldschadenforschung, Berichte. Eidg. Forschungsanstalt für Wald, Schnee und Landschaft, Birmensdorf, 345, pp. 102.
Burger, H.: 1939, ‘Baumkrone und Zuwachs in zwei hiebsreifen Fichtenbeständen’, Mitt. Schweiz. Anst. f. d. forstl. Vers. Wesen. 21, 5–58.
Burkman, W. G. and Hertel, G. D.: 1992, ‘Forest Health Monitoring–A national program to detect, evaluate, and understand change’, J. For. 90(9), 27–28.
Dobbertin, M., Hug, C. and Schwyzer, A.: 1999, Aufnahmeanleitung für die Sanasilva-Inventur,Version 6.3, intern. document, pp 53.
Dobbertin, M., Hug, C. and Mizoue, N.: 2004, ‘Using slides to test for changes in crown condition assessment methods. Part II: Application of the image analysis system CROCO’, Environ. Monitor. Assess. (submitted)
Dobbertin, M. and Ghosh, S.: 1998, ‘Vergleich zwischen zwei Beobachtern bei der Inventur 1997’, in P. Brang (ed.), Sanasilva-Bericht 1997. Zustand und Gefährdung des Schweizer Waldes–Eine Zwischenbilanz nach 15 Jahren Waldschadenforschung, Berichte, Eidg. Forschungsanstalt für Wald, Schnee und Landschaft, Nr. 345, pp. 84–85.
Dobbertin, M., Landmann, G., Pierrat, J. C. and Müller-Edzards, C.: 1997, ‘Quality of Crown Condition Data’, in C. Müller-Edzards, W. De Vries, and J.W. Erisman, (eds), Ten Years of Monitoring Forest Condition in Europe. Studies on Temporal Development, Spatial Distribution and Impacts of Natural and Anthropogenic Stress Factors. Technical Background Report’, Geneva and Brussels, United Nations Economic Commission for Europe/European Commission, pp. 7–22.
Flückiger, W. and Braun, S.: 1999, Wie geht es unserem Wald? Untersuchungen in Walddauerbeobachtungsflächen von 1984 bis 1998, Institut für angewandte Pflanzenbiologie, Schönenbuch.
Gertner, G. and Köhl, M.: 1995, ‘Correlated observer errors and their effects on survey estimates of needle-leaf loss’, For. Sci. 41(4), 758–776.
Ghosh, S., Innes, J. L. and Hoffmann, C.: 1995, ‘Observer variation as a source of error in assessments of crown condition through time’, Forest Sci. 41(2), 235–254.
Hall, J. P.: 1995, ‘Forest health monitoring in Canada: How healthy is the boreal forest?’, Water, Air, Soil Pollut. 82(1–2), 77–85.
Hanisch, B. and Kilz, E.: 1990, Waldschäden erkennen (Fichte und Kiefer). Monitoring of Forest Damage (Spruce and Pine). Reconnaître les dommages forestiers (épicéa et pin), Ulmer, Stuttgart/Helm, London, pp. 334.
Innes, J. L., Böhm, J. P., Bucher, J. B., Dobbertin, M., Jansen, E., Kull, P., Rigling, A., Walthert, L. and Zimmermann, S.: 1994, Sanasilva-Bericht 1993. Der Zustand des Schweizer Waldes, Berichte der Eidgenössichen Forschungsanstalt für Wald, Schnee und Landschaft 339, pp. 60.
Köhl, M.: 1991, ‘Waldschadensinventuren: Mögliche Ursachen der Variation der Nadel/Blattverlustschätzung zwischen Beobachtern und Folgerungen für Kontrollaufnahmen’,Allg. Forst-Jagdtztg. 162(11/12), 210–221.
Landmann, G., Pierrat, J.-C. and Nageleisen, L.-M.: 1999, ‘1995–1997: Période de réajustement à la hausse de la notation de l’état des cimes des arbres forestiers en France’, in Département de la Santé des Forêts (eds), La santé des forêts (France) en 1998, Paris, Ministère de l’Agriculture et de la Pêche (DERF-Département de la Santé des Forêts), pp. 63–66.
Lorenz, M., Müller-Edzards, C., Becher, G., Fischer, R. and Dibbern, B.: 1999, ‘Forest Condition in Europe. Results of the 1998 Crown Condition Survey 1999’, Technical Report, Brussels, Geneva, EC-UN/ECE, p. 84 + ann. pp.
USDA Forest Service: 1998, Forest Health Monitoring 1998 Field Methods Guide, USDA Forest Service, National Forest Health Monitoring Program, Research Triangle Park, NC 27709.
Mizoue, N.: 1999, ‘Development of Image Analysis System for Crown Condition Assessment in Forest Health Monitoring, CROCO’, Dissertation, Kyushu University, pp. 89.
Mizoue, N.: 2002, ‘CROCO: Semi-automatic image analysis system for crown condition assessment in forest health monitoring’, J. For. Plann. 8, 17–24.
Mizoue, N. and Dobbertin, M.: 2003, ‘Detecting differences in crown transparency assessments between countries using the image analysis system CROCO’, Environ. Monitor. Assess. 89, 179–195.
Müller, E. and Stierlin, H. R.: 1990, Sanasilva Kronenbilder mit Nadel-und Blattverlustprozenten, Eidgenössiche Forschungsanstalt für Wald, Schnee und Landschaft, 2. überarbeitete und erweiterte Auflage, pp. 129.
Müller-Edzards, C., De Vries, W. and Erisman, J. W. (eds): 1997, ‘Ten Years of Monitoring Forest Condition in Europe. Studies on Temporal Development, Spatial Distribution and Impacts of Natural and Anthropogenic Stress Factors’, Technical Background Report, Geneva and Brussels, United Nations Economic Commission for Europe/European Commission, pp. 385.
Redfern, D. B.: 1997, ‘National Report. United Kingdom’, in C. Müller-Edzards, J. W. Erisman and W. De Vries, (eds), Ten Years of Monitoring Forest Condition in Europe. Studies on Temporal Development, Spatial Distribution and Impacts of Natural and Anthropogenic Stress Factors. Technical Background Report, Geneva and Brussels, United Nations Economic Commission for Europe/European Commission, pp. 174–177.
Solberg, S.: 1999, ‘Forest Health Monitoring: Evaluation of Methods, Trends and Causes Based on a Norwegian Nationwide Set of Monitoring Plots’, Dr. Agric. Thesis, Agricultural University of Norway. ISBN 82-7169-897-4.
Solberg, S. and Strand, L.: 1999, ‘Crown density assessments, control surveys and reproducibility’,Environ. Monitor. Assess. 56, 75–86.
Strand, G.-H.: 1996, ‘Detection of observer bias in ongoing forest health monitoring programmes’,Can. J. For. Res. 26, 1692–1696.
Strand, L.: 1990, ‘Crown density and fractal dimension’, Communications of the Norwegian Forest Research Institute 43.6 Norwegian For. Res. Inst., Oslo-Aas.
Wulff, S.: 2002, ‘The accuracy of forest damage assessments–Experiences from Sweden’, Environ. Monitor. Assess. 74, 295–309.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Dobbertin, M., Hug, C. & Mizoue, N. Using Slides to Test for Changes in Crown Defoliation Assessment Methods. Part I: Visual Assessment of Slides. Environ Monit Assess 98, 295–306 (2004). https://doi.org/10.1023/B:EMAS.0000038192.84631.b6
Issue Date:
DOI: https://doi.org/10.1023/B:EMAS.0000038192.84631.b6