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Validation of saw log and technological wood assortment recovery and reduction predictions based on cut-to-length harvester data Cover

Validation of saw log and technological wood assortment recovery and reduction predictions based on cut-to-length harvester data

By: Allar Padari and  Ahto Kangur  
Open Access
|Apr 2024

Figures & Tables

Figure 1.

Proportion of damaged trees depending on tree species and age.
Proportion of damaged trees depending on tree species and age.

Figure 2.

Locations of cutting areas.
Locations of cutting areas.

Figure 3.

Log volume reduction (A, C, E and G) and firewood volume increase (B, D, F and H) depending on stand age and site index class (A, B – Scots pine; C, D – Norway spruce; E, F – Birch spp.; G, H – European aspen).
Log volume reduction (A, C, E and G) and firewood volume increase (B, D, F and H) depending on stand age and site index class (A, B – Scots pine; C, D – Norway spruce; E, F – Birch spp.; G, H – European aspen).

Figure 4.

Birch veneer log recovery depending on site index class and stand element age.
Birch veneer log recovery depending on site index class and stand element age.

Figure 5.

Black alder (left) and grey alder (right) firewood increase, and log volume reduction proportion depending on site index class and stand element age.
Black alder (left) and grey alder (right) firewood increase, and log volume reduction proportion depending on site index class and stand element age.

Figure 6.

Distribution of Scots pine assortments calculated by diameter classes according to actual data, the old model and new model.
Distribution of Scots pine assortments calculated by diameter classes according to actual data, the old model and new model.

Figure 7.

Distribution of Norway spruce assortments calculated by diameter classes according to actual data, the old model and new model.
Distribution of Norway spruce assortments calculated by diameter classes according to actual data, the old model and new model.

Figure 8.

Distribution of birch species (silver and downy birch) assortments calculated by diameter classes according to actual data, the old model and new model.
Distribution of birch species (silver and downy birch) assortments calculated by diameter classes according to actual data, the old model and new model.

Figure 9.

Distribution of European aspen assortments calculated by diameter classes according to actual data, the old model and new model.
Distribution of European aspen assortments calculated by diameter classes according to actual data, the old model and new model.

Figure 10.

Distribution of black alder assortments calculated by diameter classes according to actual data, the old model and new model.
Distribution of black alder assortments calculated by diameter classes according to actual data, the old model and new model.

Figure 11.

Distribution of grey alder assortments calculated by diameter classes according to actual data, the old model and new model.
Distribution of grey alder assortments calculated by diameter classes according to actual data, the old model and new model.

Figure 12.

Old and new model prediction comparison residuals for volumes of Scots pine and Norway spruce assortments.
Old and new model prediction comparison residuals for volumes of Scots pine and Norway spruce assortments.

Figure 13.

Old and new model prediction comparison residuals for volumes of silver and downy birch, and European aspen assortments.
Old and new model prediction comparison residuals for volumes of silver and downy birch, and European aspen assortments.

Figure 14.

Old and new model prediction comparison residuals for volumes of black and grey alder assortments.
Old and new model prediction comparison residuals for volumes of black and grey alder assortments.

Figure 15.

Average model residuals by tree species.
Average model residuals by tree species.

Figure 16.

Saw log proportions of the total volume of all roundwood assortments by tree species and sources.
Saw log proportions of the total volume of all roundwood assortments by tree species and sources.

Average model residuals for different models for calculating assortment volumes by tree species_

Tree speciesAssortmentAverage model residuals, %

old modelnew model
Scots pinesaw log6.74−0.01
firewood−1.33−0.82

Norway sprucesaw log7.782.40
firewood−3.67−2.55

Birch speciessaw log11.831.23
firewood2.21−0.16

European aspensaw log0.750.42
firewood22.48−2.34

Black aldersaw log−17.98−7.84

Grey aldersaw log−33.45−2.99

Saw log proportion reduction_

Tree speciesAge used in the Estonian modelMalinen et al. 2007Estonian model (Figure 3)

MELA-96MELA-05Bucking simulation
Pine60–10016.0424.2518.179–28%
Spruce60–802.3517.796.3810–29%
Birch50–7030.2729.3541.4638–64%

Site index classes and site index H100 relationship_

Site index H100, mSite index classSite index class in calculations
< 11.55A6
11.5…15.555
15.5…19.544
19.5…23.533
23.5…27.522
27.5…31.511
> 31.51A0

j_fsmu-2023-0013_tab_008

Relative diameter of a tree in relation to the diameter of a stand elementNumber of trees, per mille
0.411
0.534
0.659
0.796
0.8131
0.9154
1.0154
1.1132
1.296
1.364
1.435
1.518
1.610
1.74
1.82

General data on felled elements included in the analysis_ Site index class and site index H100 relationship are described in Table 2_

Tree speciesNo. of elementsAge, yearsSite index class

minimummaximummaximumminimum
Scots pine (Pinus sylvestris L.)14,013212191A5A
Norway spruce (Picea abies (L.) H. Karst.)3,045161771A5
Silver and downy birch (Betula pendula Roth, Betula pubescens Ehrh.)7,145221531A5
European aspen (Populus tremula L.)1,862231401A3
Black alder (Alnus glutinosa (L.) Gaertn.)679371381A4
Grey alder (Alnus incana (L.) Moench)77018751A4

Total27,514162191A5A

Parameters of timber assortments (roundwood) used in the analysis_

Tree speciesAssortmentTop diameter, cmLength, m

minimumstepMaximum
Scots pineLog28–…3.10.36.1
Log23–283.10.36.1
Log18–233.10.36.1
Log13–183.10.36.1
Log10–133.10.36.1
Pulpwood53.0 3.0
Firewood33.0 3.0

Norway spruceLog25–…3.10.36.1
Log18–253.10.36.1
Log13–183.10.36.1
Log10–133.10.36.1
Pulpwood53.0 3.0
Firewood33.0 3.0

Silver and downy birchLog14–…3.10.36.1
Pulpwood53.0 3.0
Firewood33.0 3.0

European aspenLog14–…3.10.36.1
Pulpwood53.0 3.0
Firewood33.0 3.0

Black alderLog18–…3.10.36.1
small log14–183.10.36.1
Firewood33.0 3.0

Grey alderLog18–…3.10.36.1
small log14–183.10.36.1
Firewood33.0 3.0

Equation parameters obtained by comparing roundwood assortment volumes_

Tree speciesAssortmentabcdfiR2p-value
Scots pineLog volume reduction−0.4560−6.7947−46.80169910010.0356< 0.0001
Firewood increase2.78171.0015267.01569910010.0233< 0.0001
Norway spruceLog volume reduction0.21456.7871−0.06561201.10.0158< 0.0001
Firewood increase−3.108617.2571−91.944449500.10.0195< 0.0001
Silver and downy birchLog volume reduction1.06229.15950.3487105010.0945< 0.0001
Firewood increase0.17333.23630.00630,1110.0052< 0.0001
Veneer log−3.639610.4272−2.648110200.10.1445< 0.0001
European aspenLog volume reduction1.052212.658715.8415495010.1991< 0.0001
Firewood increase−1.060728.4761−0.09690.10.20.10.0381< 0.0001
Black alderLog volume reduction0.610622.1975−0.08371210.0789< 0.0001
Grey alderLog volume reduction−6.10612.485−61.4859010010.03530.0257

The parameter n of the volume change Equation 3 and the parameters of the Equation for calculating its coefficients a, b and c (Equation 5)_

Tree speciesFormulaConstantEquation coefficients
klmn
Scots pinelog volume reductiona−2.2590.24693−0.013453
b11.35752−2.100760.1712
c894.235−304.76628.869
firewood increasea−3.35030.0159−0.00132
b1.5375−0.02710.0022
c1.5328−0.02610.0021
Norway sprucelog volume reductiona−0.89371−0.138860.010494
b29.46034.36432−0.33114
c−366800−228124−4093
firewood increasea−1.66542−0.060810.00124
b29.592240.278170.09189
c−115756−2406389.533
Silver and downy birchlog volume reductiona−0.396070.06595−0.00325
b28.784−1.0880.042
c382931688511280082
firewood increasea−1.675910.01012−0.000974
b25.21899−0.217770.02076
c−2119857782.9−749.88
veneer block recoverya−2.7282−0.2457−0.06834
b30.28112.921−1.639
ln(-c)12.6550.82260.2254
European aspenlog volume reductiona0.090150.01429−0.000614
b27.49482−0.06593−0.01049
c−1503697285−387
firewood increasea−1.34789−0.013860.00115
b46.312250.04688−0.00447
c10507971920148−82200
Black alderfirewood increasea0.1209−0.091110.0119810
b73.66109−4.701720.78866
c−2.703·1015−5.258·10156.974·1014
Grey alderfirewood increasea−0.82187−0.301290.004347
b58.03680−0.133255.87003
c3.048·1011−2.887·10114.242·1012
DOI: https://doi.org/10.2478/fsmu-2023-0013 | Journal eISSN: 1736-8723 | Journal ISSN: 1406-9954
Language: English
Page range: 66 - 89
Published on: Apr 13, 2024
Published by: Estonian University of Life Sciences
In partnership with: Paradigm Publishing Services
Publication frequency: 2 issues per year

© 2024 Allar Padari, Ahto Kangur, published by Estonian University of Life Sciences
This work is licensed under the Creative Commons Attribution 4.0 License.