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Accuracy of visual tree defoliation assessment: a case study in Finland

Finnish Forest Research Institute|Metsäntutkimuslaitos
2014
mwp307.pdf
1.49 MB

URI

Tiivistelmä

Defoliation (crown thinning) is widely used as a rapid method of tree condition assessment. As a method that is based on subjective visual observation it might be influenced by statistically significant observer bias. Significant observer bias has been discovere in some countries. We analyzed the significance of observer bias occurring in the Finland's forest condition monitoring system. We analysed the data of three training courses held to the field personnel (2006, 2007, 2008). Our results indicate that some inconsistencies occur between observers, but these are still not systematic in nature. In conclusion, the detected observer biases are independent incidents, caused mainly by the observer perception during the single events. Therefore there is no need to make any systematic corrections for Finnish national visual tree defoliation assessments. We suggest that the best way to improve field assessments is the proper education and guidance of field personnel.

ISBN

OKM-julkaisutyyppi

D4 Julkaistu kehittämis- tai tutkimusraportti taikka -selvitys

Julkaisusarja

Metlan työraportteja|Working Papers of the Finnish Forest Research Institute

Volyymi

Numero

307

Sivut

22 p.

ISSN

1795-150X

DOI

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