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Fig. 1. Location of the research areas. The research was conducted in mature stands (Staszów Forest District) and in post-disaster areas (Dąbrowa Tarnowska Forest District and Przedbórz Forest District).

Table 1. Characteristics of the research areas. View in new window/tab.
Table 2. Flow chart presenting the classification of harvester operation times during work in standard areas and in post-disaster stands. Numerical codes referring to the classification applied were used to construct time series.
D W t – Direct Work time Main Work time M W t Numerical code of time category 1,1 Crane out, positioning, cutting, felling
1,2 Pulling tree into machine, debranching, cross-cutting
Auxiliary Work time C W t 2,1 Travelling time on worksite
2,2 Worksite prepartion time – removing disturbing branches and log fragments hindering access to tree stem being cut
2,4 Time of log arrangement and timber sorting
Unavoidable Delay time U D t 2,3 Technological downtime – breaks due to work organisation, route setting and tree cutting order
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Fig. 2. Structure of harvester work time in areas of standard utilization and with windbreaks. The activities noted were grouped in respective time categories in accordance with Table 2.

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Fig. 3. Significance of differences in the duration of harvester work activities in standard stands and those with windbreaks. Larger differentiation of activity duration in post-disaster stands is visible.

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Fig. 4. Fragment of a time series of harvester operations – TP (late thinning). The points at which the line is broken indicate the occurrence of a given time category. The cycles described in this paper are marked with grey color.

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Fig. 5. Fragment of a time series of harvester operations – WL-R (post-disaster mature). The points at which the line is broken indicate the occurrence of a given time category. The cycles described in this paper are marked with grey color.

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Fig. 6. Fragment of a periodogram of harvester work in late thinning stands (TP). The highest peak of the periodogram shows the strongest operational cycles.

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Fig. 7. Fragment of a periodogram of harvester work in mature stands (R). The highest peak of the periodogram shows the strongest operational cycles.

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Fig. 8. Fragment of a periodogram of harvester work in stands of the late thinning age class with windbreaks (WL-TP). The highest peak of the periodogram shows the strongest operational cycles. Variation of operation which is slightly larger in comparison with post-disaster stands is visible.

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Fig. 9. Fragment of a periodogram of harvester work in stands of the mature age class with windbreaks (WL-R). The highest peak of the periodogram shows the strongest, shortest operational cycles which overlap with longer cycles (the peak for the length of a five-activity cycle).

Table 3. Average duration of a harvester operational cycle in standard stands and in post-disaster areas.
Variant, stand Sample size – number of observations Number of
analysed cycles 		Mean duration of work cycle
[s] 		Difference in relation to standard stands
[%]
Name Symbol
Late thinning TP 3214 957 88  
Mature R 3132 925 60  
Post-disaster mature WL-R 6761 1252 113 +28
Post-disaster thinning WL-TP 5639 988 93 +55