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Articles containing the keyword 'spherical densiometer'
Category : Research article
article id 315,
category
Research article
(2006).
Estimation of forest canopy cover: a comparison of field measurement techniques.
Silva Fennica
vol.
40
no.
4
article id 315.
https://doi.org/10.14214/sf.315
Keywords:
canopy cover;
forest canopy;
canopy closure;
Cajanus tube;
line intersect sampling;
spherical densiometer;
digital photographs
Abstract |
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Author Info
Estimation of forest canopy cover has recently been included in many forest inventory programmes. In this study, after discussing how canopy cover is defined, different ground-based canopy cover estimation techniques are compared to determine which would be the most feasible for a large scale forest inventory. Canopy cover was estimated in 19 Scots pine or Norway spruce dominated plots using the Cajanus tube, line intersect sampling, modified spherical densiometer, digital photographs, and ocular estimation. The comparisons were based on the differences in values acquired with selected techniques and control values acquired with the Cajanus tube. The statistical significance of the differences between the techniques was tested with the nonparametric Kruskall-Wallis analysis of variance and multiple comparisons. The results indicate that different techniques yield considerably different canopy cover estimates. In general, labour intensive techniques (the Cajanus tube, line intersect sampling) provide unbiased and more precise estimates, whereas the estimates provided by fast techniques (digital photographs, ocular estimation) have larger variances and may also be seriously biased.
-
Korhonen,
University of Joensuu, P.O. Box 68, FI-68101 Joensuu, Finland
E-mail:
lauri.korhonen@joensuu.fi
- Korhonen, University of Joensuu, P.O. Box 68, FI-68101 Joensuu, Finland E-mail: ktk@nn.fi
- Rautiainen, University of Joensuu, P.O. Box 68, FI-68101 Joensuu, Finland E-mail: mr@nn.fi
- Stenberg, University of Joensuu, P.O. Box 68, FI-68101 Joensuu, Finland E-mail: ps@nn.fi
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