Stand Damage After Thinning Operations: Does Size and Location of Damages Differ? A Comparison of Logging Operations

Thinning operations are seen as a necessity to obtain stability, produce timber, derive income and promote adapted tree species in even-aged forests. In Austrian forests the highest number of machineries used in forestry are tractors with winches. Different yarder systems, used in combination with excavators with processor heads and with built-in processor units, represent the second most frequent owned machines. Harvester and forwarder are ranked third when numbers of owned machines were compared in 2020, even though in the last years the volume of extracted timber by forwarder increased. These three harvesting technologies were used in thinning operations of coniferous and deciduous dominated stands in central and eastern Austria: Data on damaged trees after a thinning with motor-manual felling and extraction of the timber by tractor with winch was collected at flat to low slope gradients in a coniferous dominated stand. A cable yarder in combination with an excavator was observed in middle steep terrain in beech stands. Data was also collected on residual stand damage after harvester and forwarder, at flat terrain in coniferous stand without traction aid winch and in steeper terrain in combination with a traction aid winch. After the harvesting operations damages on remaining trees were precisely examined by location on the tree, size, intensity and number of damages. The presentation deals with the comparison of various harvesting systems in thinning operations and its effect on the intensity and location of damages.