Uncertainty in timber assortment estimates predicted from forest inventory data |
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| Authors: | Markus Holopainen Mikko Vastaranta Jussi Rasinmäki Jouni Kalliovirta Antti Mäkinen Reija Haapanen Timo Melkas Xiaowei Yu Juha Hyyppä |
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| Institution: | 1.Department of Forest Sciences,University of Helsinki,Helsinki,Finland;2.Haapanen Forest Consulting,Vanhakyl?,Finland;3.Mets?teho Ltd,Helsinki,Finland;4.Finnish Geodetic Institute,Kirkkonummi,Finland |
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| Abstract: | Uncertainty factors related to inventory methodologies and forest-planning simulation computings in the estimation of logging
outturn assortment volumes and values were examined. The uncertainty factors investigated were (1) forest inventory errors,
(2) errors in generated stem distribution, (3) effects of generated stem distribution errors on the simulation of thinnings
and (iv) errors related to the prediction of stem form and simulation of bucking. Regarding inventory errors, standwise field
inventory (SWFI) was compared with area-based airborne laser scanning (ALS) and aerial photography inventorying. Our research
area, Evo, is located in southern Finland. In all, 31 logging sites (12 clear-cutting and 19 thinning sites) measured by logging
machine in winter 2008 were used as field reference data. The results showed that the most significant source of error in
the prediction of clear-cutting assortment outturns was inventory error. Errors related to stem-form prediction and simulated
bucking as well as generation of stem distributions also cause uncertainty. The bias and root-mean-squared error (RMSE) of
inventory errors varied between −11.4 and 21.6 m3/ha and 6.8 and 40.5 m3/ha, respectively, depending on the assortment and inventory methodology. The effect of forest inventory errors on the value
of logging outturn in clear-cuttings was 29.1% (SWFI) and 24.7% (ALS). The respective RMSE values related to thinnings were
41.1 and 42%. The generation of stem distribution series using mean characteristics led to an RMSE of 1.3 to 2.7 m3/ha and a bias of −1.2 to 0.6 m3/ha in the volume of all assortments. Prediction of stem form and simulation of bucking led to a relative bias of −0.28 to
0.00 m3 in predicted sawtimber volume. Errors related to pulpwood volumes were −0.4 m3 to 0.21 m3. |
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