Crown density assessments, control surveys and reproducibility

作者: Svein Solberg , Lars Strand

DOI: 10.1023/A:1005980326079

关键词:

摘要: This study aims to evaluate the quality of crown density data, based on independent, pairwise tree assessments. The data originates from monitoring forest health (crown condition) in Norway; 250 plots, comprising 12 000 individual trees Norway spruce, have been reassessed by a single observer during 1990–95. Of trees, 2300 were controlled more than twice, providing possibility evaluating assessed temporal changes density. True errors (standard deviation) are estimated be about 10% for and 5% plot means, while real standard deviation differences slightly higher. similar magnitude. Systematic found between sites types, partly resulting bias. However, results suggest that bias is really result each observer's personal style assessment.

参考文章(8)
Sucharita Ghosh, John L. Innes, Combining field and control team assessments to obtain error estimates for surveys of crown condition Scandinavian Journal of Forest Research. ,vol. 10, pp. 264- 270 ,(1995) , 10.1080/02827589509382892
Geir-Harald Strand, Detection of observer bias in ongoing forest health monitoring programmes Canadian Journal of Forest Research. ,vol. 26, pp. 1692- 1696 ,(1996) , 10.1139/X26-191
J. L. Innes, G. Landmann, B. Mettendorf, Consistency of observations of forest tree defoliation in three European countries. Environmental Monitoring and Assessment. ,vol. 25, pp. 29- 40 ,(1993) , 10.1007/BF00549790
John L. Innes, Forest health surveys: problems in assessing observer objectivity Canadian Journal of Forest Research. ,vol. 18, pp. 560- 565 ,(1988) , 10.1139/X88-081
Carl S. Schneider, M. G. Kendall, W. R. Buckland, A dictionary of statistical terms ,(1957)
J. L. Innes, S. Ghosh, C. Hoffmann, Observer variation as a source of error in assessments of crown condition through time Forest Science. ,vol. 41, pp. 235- 254 ,(1995)
Halvor Solheim, Kåre Venn, Dan Aamlid, Skogskader. Veiledning i overvåking av skogskader 53. ,(1991)
E. Joranger, D. Aamlid, R. Horntvedt, A. Rora, Monitoring programme for forest damage an overview of the norwegian programme Norwegian Journal of Agricultural Sciences. ,vol. 6, pp. 1- 17 ,(1992)