Environmental Monitoring and Assessment

, Volume 102, Issue 1–3, pp 167–178 | Cite as

Using slides to test for changes in crown defoliation assessment methods part II: Application of the image analysis system CROCO

  • Matthias DobbertinEmail author
  • Christian Hug
  • Nobuya Mizoue


We tested whether the semi-automatic program CROCO can replace visual assessments of slides to detect changes in defoliation assessment methods. We randomly selected a series of slides of 24 Norway spruce trees with 220 field assessments made between 1986 and 1995. The slides had been randomly arranged and assessed by three experts without knowledge of the tree number or the year when the slide was taken. Defoliation scores were computed with CROCO. Each tree had thus three different defoliation scores, field assessments, photo assessments and CROCO scores.

CROCO scores were less correlated with the field assessments (Spearman’s rank correlation: 0.67) than were the slide assessments with the field assessments (0.79–0.83). However, CROCO was not biased against the field scores, while slide assessments systematically underestimated defoliation.

In a multi-variate mixed effect model none of the variables tree overlap, tree visibility and light conditions was significant in explaining differences between slide assessors and CROCO scores. The same model applied for the differences from the field scores yielded significant effects for poor light conditions (CROCO and all assessors), for crown overlap (CROCO and one assessor) and for visibility (one assessor). We conclude, therefore, that CROCO can be used to detect past and future changes in assessment methods without bias if poor quality photographs are avoided.


CROCO fractals tree defoliation assessment methods quality of photographs 


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  1. Bosshard, W. (ed): 1986, Kronenbilder Eidgenössische Anstalt für das forstliche, Versuchswesen, Birmensdorf, 98 pp.Google Scholar
  2. Bradley, J.V.: 1968, Distribution-free Statistical Tests, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 388 pp.Google Scholar
  3. Brassel, P. and Brändli, U.-B. (eds): 1999, Schweizerisches Landesforstinventar. Ergebnisse der Zweitaufnahme 1993–1995, Birmensdorf, Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft. Bern, Bundesamt f ür Umwelt, Wald und Landschaft. Stuttgart, Wien, Haupt. Bern, 442 pp.Google Scholar
  4. 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.Google Scholar
  5. 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, 84–85.Google Scholar
  6. Dobbertin, M., Hug, C. and Mizoue, N.: (in press), ‘Using slides to test for changes in crown condition assessment methods, Part I: Visual assessment of slides’ Environ. Monitor. Assess. Google Scholar
  7. Durrant, D.: (in press), Recommendations for Quality Assurance Methods using Photographs, in Manual on Methods and Criteria for Harmonized Sampling, Assessment, Monitoring and Analysis of the Effects of Air Pollution on Forests, Part II: Visual Assessment of Crown Condition. UN/ECE and EU.Google Scholar
  8. Ghosh, S., Innes, J.L. and Hoffmann, C.: 1995. ‘Observer variation as a source of error in assessments of crown condition through time’, For. Sci. 41(2), 235–254.Google Scholar
  9. Hall J.P.: 1995, ‘Forest health monitoring in Canada: How healthy is the Boreal forest?’, Water Air Soil Pollut. 82(1–2), 77–85.Google Scholar
  10. Hanisch, B. and Kilz, E.: 1990, Waldschäden erkennen: Fichte und Kiefer—Monitoring of Forest Damage Ulmer, Stuttgart, London, Helms, 334 p.Google Scholar
  11. Innes, J.L.: 1990, Assessment of Tree Condition. Forestry Commission Field Book 12, HMSO, London.Google Scholar
  12. Innes, J.L.: 1993, Forest Health: Its Assessment and Status CAB International, Wallingford, UK, 677 pp.Google Scholar
  13. 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 Eidgenö ssichen Forschungsanstalt für Wald, Schnee und Landschaft 339, 60 pp.Google Scholar
  14. Köhl, M.: 1991, Waldschadensinventuren: mögliche Ursachen der Variation der Nadel/Blattverlustschätzung zwischen Beobachtern und Folgerungen für Kontrollaufnahmen. Allg. For. Jagdtztg. 162(11/12): 210–221.Google Scholar
  15. Landmann, G., Pierrat, J.-C. and Nageleisen, L.-M.: 1999, ‘1995–1997: Période de réajustement á 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, Ministére de l’Agriculture et de la Pêche (DERF-Dé partement de la Santé des Forêts), pp. 63–66.Google Scholar
  16. Little, R.C., Milliken, G.A., Stroup, W.W. and Wolfinger, R.D. (eds): 1996, SAS® System for Mixed Models. SAS Institute Inc., Cary, North Carolina, USA, 633 pp.Google Scholar
  17. 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, 84 pp. + ann pp.Google Scholar
  18. Mizoue, N.: 1999, Development of Image Analysis System for Crown Condition Assessment in Forest Health Monitoring, CROCO, Dissertation, Kyushu University, 89 pp.Google Scholar
  19. Mizoue, N.: 2001, ‘Fractal analysis of tree crown images in relation to crown transparency’, J. For. Plan. 7, 79–87.Google Scholar
  20. Mizoue, N.: 2002, ‘CROCO: semi-automatic image analysis system for crown condition assessment in forest health monitoring’, J. For. Plan. 8, 17–24.Google Scholar
  21. Mizoue, N., and Inoue, A.: 2001, ‘Automatic thresholding of tree crown images’, J. For. Plan. 6, 75–80.Google Scholar
  22. Mizoue, N. and Masutani, T.: 2003, ‘Image analysis measure of crown condition, foliage biomass and stem growth relationships of Chamaecyparis obtusa’, For. Ecol. Manage. 172, 79–88.Google Scholar
  23. 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.Google Scholar
  24. Mizoue, N. and Dobbertin, M.: (in press), Within country accuracy of tree crown transparency estimates using the image analysis system CROCO: A case study from Switzerland. Environ. Model. Software.Google Scholar
  25. 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, 385 pp.Google Scholar
  26. 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.Google Scholar
  27. Schabenberger, O. and Pierce, F.J.: 2002, Contemporary Statistical Methods for the Plant and Soil Sciences. CRC Press. 738 p.Google Scholar
  28. 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.Google Scholar
  29. Wulff, S.: 2002, ‘The accuracy of forest damage assessments—Experiences from Sweden’, Environ. Monitor. Assess. 74, 295–309.Google Scholar

Copyright information

© Springer 2005

Authors and Affiliations

  • Matthias Dobbertin
    • 1
    Email author
  • Christian Hug
    • 1
  • Nobuya Mizoue
    • 2
  1. 1.Swiss Federal Institute for ForestSnow and Landscape Research, WSLBirmensdorfSwitzerland
  2. 2.Faculty of AgricultureKyushu UniversityFukuokaJapan

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