downhill cable extraction in whole tree-system
Abstract
For thinning operations on steep terrain the whole tree system (chainsaw tree felling, whole tree cable yarding and delimbing and bucking of the logs on forest roads) is one of the highest level of mechanisation. The goal of this study was to quantify dif-ferences in productivity as well as in number and characteristics of stand damage depending on yarding direction (uphill and downhill in dip line, downhill diagonal) of whole tree cable yarding. The timber was extracted by a tracked-mounted yarder "Syncrofalke" with an integrated "Wolf-processor". To determine the influencing fac-tors on system productivity, time studies were carried out in thinning operations. After harvesting operations stand damages were surveyed and analysed. Only the influ-ence of tree volume and harvesting time was significant on productivity. At an aver-age tree volume of 0.68 m¿ without bark, the system productivity in summer amounts to 8.6 m¿ without bark per PSH15, in winter it amounts to 7.9 m¿per PSH15. This ab-solute productivity difference of 0.9 m¿ per PSH15 responds to an enhancement of 9 % in summer harvesting. Therefore the reason is difficult terrain accessibility caused by snow in winter. In general whole tree cable yarding causes a very high amount of stand damage. 22 % to 32 % of the residual stand was damaged in summer, 25 % to 39 % in winter. But admittedly in summer the damages were about 30 % bigger than in winter. Much more root damages were found in summer because in winter the roots were covered and protected against damage by snow. Independent from yard-ing directions, the trees were wounded more intensively in summer. On the diagonal downhill lines the damaged trees were more regularly distributed within an area of 22.5 m as on the straight lines, where damages along the cable line occurred more cumulatively. Downhill yarding did not cause more damages than uphill yarding.
keywords Agriculture, Forestry forest engineering timber harvesting cable yarding productivity study
Publikationen
Project staff
Karl Stampfer
Univ.Prof. Dipl.-Ing. Dr.nat.techn. Karl Stampfer
karl.stampfer@boku.ac.at
Tel: +43 1 47654-91001, 91501, 91511
Project Leader
01.01.2001 - 31.12.2003