INFLUENCE OF STRIP ROADS ON THICKNESS OF TREES GROWING IN CLOSE VICINITY

Transcription

1 INFLUENCE OF STRIP ROADS ON THICKNESS OF TREES GROWING IN CLOSE VICINITY Włodzimierz Stempski Krzysztof Polowy Krzysztof Jabłoński Poznań University of Live Sciences FORMEC 2016 From Theory to Practice: Challenges for Forest Engineering 49 th International Symposium on Forestry Mechanization, 4-7 September 2016, Warsaw

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4 Width of a strip road: 3,5-4 meters (for extraction by forwarder) Distance between the strip roads: 30 m (with motormanual cutting) or 20 m (for harvesters)

5 National State Forests Decree no. 35 of the General Director of the State Forests of 29 June 2016 on opening of stands by a network of strip roads in State Forests organizational units. Guidelines for opening of stands by a network of strip roads : Width of a strip road: 4-5 meters (in case of extraction by horse 2,5 m) Distance between the strip roads: basically 20 m (for Short Wood System) or multiples of 20 m (for Long Wood System)

6 Research area Oborniki Forest District (Regional Directorate of State Forests in Poznań) eastern part of Notecka Forest; subcompartment 47d; Scots Pine, 33 years old; fresh coniferous site; density 0,9; coverage moderate. Measurements were conducted in spring 2014, second thinning conducted in June and July First thinning (and cutting the 12 strip roads) conducted in 2008.

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9 The aim of the study Evaluation of DBH structure of trees neighboring to the strip roads, a year after second thinning and six years after cutting the roads. The scope of the study Trees growing along all 12 strip roads in 4 zones: Directly by the strip road 1,5 m of the strip road 3 m of the strip road Half way between the strip roads (control) Cross measurements of DBH

10 Four of the strip road were narrower (2,9 m) than the others (3,6 m). This fact was taken into account in the analysis of results. Measured diameters were analyzed statistically. First test of compatibility of measured distribution with a normal distribution. Next assessment of differences between four zones. Due to lack of compatibility of measured distribution with normal distribution, the non-parametric Kruskal-Wallis test was applied. Calculations were performed using Statistica 12 software. The significance level of α=0,05 was assumed.

11 Results Average DBH of trees in all distance zones wider strip roads Strip road number Distance zone ,27 13,70 13,90 13, ,37 14,68 14,73 14, ,57 14,23 13,89 13, ,53 14,52 15,10 14, ,15 13,65 13,36 12, ,85 13,99 14,42 13, ,09 12,73 13,37 11, ,32 12,07 11,78 10, ,26 13,64 13,75 12,87

12 Average DBH of trees in all distance zones thinner strip roads and both widths together Strip road number Distance zone ,80 11,68 11,73 10, ,32 12,07 11,78 10, ,95 11,63 11,71 12, ,06 10,70 10,99 11, ,80 11,19 11,21 11, ,37 12,79 12,86 12,33

13 Kruskal-Wallis test showed statistically significant difference in trees DBH between distance zones. p-value for all strip roads and for wider strip roads: 0,0000 p-value for narrower strip roads: 0,0003 Strip roads 1-12 Distance zone p-values for multiple comparisons , , , , , , , , , , , ,001026

14 Strip roads 1-8 Distance zone , , , , , , , , , , , , Strip roads 9-12 Distance zone , , , , , , , , , , , ,000000

15 Kruskal-Wallis test for each strip road: significant differences were found in 8 strip roads: 2, 4, 5, 6, 7, 8, 9, 12. Strip road 2 (p=0,0222) between zones 1 and 4 Strip road 4 (p=0,0111) between zones 1 and 2 Strip road 5 (p=0,0040) between zones 1 and 4; 2 and 4 Strip road 6 (p=0,0082) between zones 1 and 4; 2 and 4 Strip road 7 (p=0,0005) between zones 1 and 3; 1 and 4 Strip road 8 (p=0,0000) between zones 1 and 4; 2 and 4; 3 and 4 Strip road 9 (p=0,0000) between zones 1 and 2; 1 and 3; 1 and 4 Strip road 12 (p=0,0001) between zones 1 and 2; 1 and 3

16 SUMMARY 1. DBH distribution of trees neighboring to the strip road before the second thinning and after this treatment was not significantly changed. After the thinning for 10 out of 12 strip roads, trees growing next to the road were thickest, and in 8 cases differences with trees growing further were significant. 2. The edge trees were significantly thicker than in control zone. Differences between second zone and control were found in 4 cases. 3. For most strip roads the thinnest trees were found in control zone, but in only one case diameters were diminishing evenly towards the control zone. In most cases second thickest were trees in third zone (about 3 m of the strip road).

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