Table 1. The statistical characteristics of tree species specific regression models for height and DBH in which the stump diameter (x_{1}, x_{2}, x_{3} and x_{4} for the stump diameters of birch, spruce, pine and other broadleaves in respective order) is the independent variable. | ||||||||||

Tree model | Dependent variable | R^{2} | F-test | N | Term | Constant/Coefficient | t-test | |||

F-value | p | Estimate | Std. error | t-value | p | |||||

DBH | DBH_{Birch} | 0.946 | 521.531 | <0.001 | 31 | Constant | –1.268 | 4.359 | –0.291 | 0.773 |

x_{1} | 0.830 | 0.036 | 22.837 | <0.001 | ||||||

DBH_{Spruce} | 0.936 | 824.357 | <0.001 | 57 | Constant | –5.009 | 2.404 | –2.083 | 0.042 | |

x_{2} | 0.897 | 0.031 | 28.712 | <0.001 | ||||||

DBH_{Pine} | 0.965 | 2029.299 | <0.001 | 75 | Constant | –3.075 | 1.923 | –1.599 | 0.114 | |

x_{3} | 0.875 | 0.019 | 45.048 | <0.001 | ||||||

DBH_{Other broadleaf} | 0.989 | 3342.685 | <0.001 | 39 | Constant | –5.847 | 1.289 | –4.536 | <0.001 | |

x_{4} | 0.933 | 0.016 | 57.816 | <0.001 | ||||||

Height of the tree | Height_{Birch} | 0.764 | 97.260 | <0.001 | 31 | Constant | 2.432 | 0.746 | 3.261 | 0.003 |

x_{1} | 0.061 | 0.006 | 9.862 | <0.001 | ||||||

Height_{Spruce} | 0.827 | 263.788 | <0.001 | 57 | Constant | 0.159 | 0.279 | 0.571 | 0.570 | |

x_{2} | 0.061 | 0.004 | 16.242 | <0.001 | ||||||

Height_{Pine} | 0.965 | 196.838 | <0.001 | 75 | Constant | 2.083 | 0.324 | 14.030 | <0.001 | |

x_{3} | 0.046 | 0.003 | 6.419 | <0.001 | ||||||

Height_{Other broadleaf} | 0.911 | 391.037 | <0.001 | 39 | Constant | 1.751 | 0.253 | 19.775 | <0.001 | |

x_{4} | 0.063 | 0.003 | 6.922 | <0.001 |

Table 2. Work elements with detailed definitions in harvesting roadside brushwood with the harwarder. | |

Work element | Definition of the work element |

Moving between the working locations | Begins when the harwarder starts to move (wheels are turning) and ends when the harwarder stops moving to perform another activity at the working location, e.g. positioning to cut. |

Positioning to cut | Begins when the boom starts to swing towards the first tree and ends when the empty harwarder head is resting on the tree before the felling cut at stump height begins. With tall trees (higher than 8 m), the harwarder head is first placed halfway along the tree to be felled. |

Accumulating the felling | Begins when the felling cut starts (either at the stump height or halfway of the tree) and ends when the accumulated tree bunch starts moving to the load space of the harwarder. With tall trees the top is cut first, after which the harwarder head is moved vertically downward and the tree is cut again at the stump height. The number of trees in each harwarder head bunch is observed and recorded. |

Loading | The harwarder loads directly felled trees to the load space of the harwarder. Begins when the accumulated tree bunch starts moving to the load space of the harwarder and ends when the empty harwarder head start positioning to cut, the load is full or harwarder starts to move to the next working location. |

Driving loaded or unloaded | Driving with load begins when the brushwood is harvested from the time study plot (harwarder head is positioned for driving loaded and wheels are turning) and ends when the harwarder stops to begin unloading at the landing area. Driving unloaded begins when the load is empty, the harwarder head is positioned for driving unloaded and its wheels are turning. Driving unloaded ends when the harwarder stops at the working location and positioning to cut starts. |

Sorting of trees placed in the load space of the harwarder | Sorting of trees placed in the load space of the harwarder before the final grip for unloading. |

Unloading | Starts when the harwarder stops at the landing for unloading and ends when the load is empty and harwarder head is positioned for driving unloaded. The number of harwarder head loads during unloading is recorded. |

Table 3. Work elements with detailed definitions in roadside brushwood clearing with the spiral cutter. | |

Work element | Definition of the work element |

Continuous clearing of brushwood | The mini-excavator is driving forward at a steady pace, brushwood is fed continuously to the blades by rotating spirals, brushwood is cut down in a desirable direction (backwards) and the work is not interrupted |

Slow down clearing of brushwood | The mini-excavator has to slow down the driving speed or stop because brushwood is cut down slowly, improperly or fell in an undesirable direction (towards mini-excavator). The clearing work is partly interrupted, but the spirals continue to rotate either forward or backwards |

Table 4. Regression model statistics for harvesting with the harwarder (x_{1} = number of harvested trees per hectare, x_{2} = the average volume of the harvested trees (dm^{3}), x_{3} = grapple load size during loading (m^{3}), x_{4} = grapple load size during unloading (m^{3}), x_{5} = forwarding distance (m)). | ||||||||||

Work phase model | Dependent variable | R^{2} | F-test | N | Term | Constant/Coefficient | t-test | |||

F-value | p | Estimate | Std. error | t-value | p | |||||

Moving | T_{Moving} | 0.881 | 576.779 | <0.001 | 80 | Constant | 0.168 | 0.045 | 3.721 | <0.001 |

1/x_{1} | 4351.5 | 181.2 | 24.016 | <0.001 | ||||||

Cutting | T_{Cutting} | 0.724 | 204.102 | <0.001 | 80 | Constant | –4.571 | 0.680 | –6.719 | <0.001 |

ln(x_{2}) | 3.400 | 0.238 | 14.286 | <0.001 | ||||||

Loading | T_{Loading} | 0.848 | 434.187 | <0.001 | 80 | Constant | –8.222 | 5.176 | –1.588 | 0.116 |

1/x_{3} | 7.237 | 0.347 | 20.837 | <0.001 | ||||||

Number of trees in the grapple | N_{Number of trees} | 0.487 | 73.960 | <0.001 | 80 | Constant | 1.163 | 0.411 | 2.830 | 0.006 |

1/x_{2} | 53.675 | 6.241 | 8.600 | <0.001 | ||||||

Unloading | T_{Unloading} | 0.203 | 19.919 | <0.001 | 80 | Constant | 99.030 | 8.259 | 11.990 | <0.001 |

x_{4} | –140.211 | 31.416 | –4.463 | <0.001 | ||||||

Forwarding | T_{Forwarding} | 0.900 | 757.519 | <0.001 | 85 | Constant | 24.154 | 3.688 | 6.549 | <0.001 |

x_{5} | 0.691 | 0.025 | 27.523 | <0.001 |