Evaluation of Salvage Logging Productivity and Costs in Windthrown Norway Spruce-Dominated Forests

Abstract

Different abiotic and biotic disturbances are expected to become more common in the future due to a warming climate. Globally, post-disturbance salvage logging is becoming more predominant to recover economic value from timber in disturbed forests. This study collected comparative time-study data and analyzed the productivity of cutting for windfalls in clear cuttings and determined the cutting costs of windfalls. Furthermore, the logging (i.e., cutting and forwarding) costs of wind-damaged trees and those of undamaged standing Norway spruce (Picea abies (L.) Karst.) trees in clear cuts were calculated in Finland. The results revealed that the cutting productivity of windfalls was 19-33% lower than that of undamaged stems. The cutting costs of windthrown stems with a volume of 0.3-1.5 m 3 were 35-64% higher and the logging costs of windfalls were 10-30% higher than those of undamaged standing stems. The study provided new understanding regarding the productivity and costs of salvage logging operations under Finnish conditions. Even if the logging of windfalls is expensive and laborious, salvage logging operations are important for forest stands and their health to minimize post-disaster damage outbreaks in coniferous forests, such as the damage caused by bark beetles-mainly Ips typographus L.

Forwarder Productivity in Salvage Logging Operations in Difficult Terrain

“…Total time studies covered 57.90 PMH 15 Forests 2020, 11, x; doi: FOR PEER REVIEW www.mdpi.com/journal/forests slope of the regression was also tested for the significance as appropriate. A likelihood ratio test was used to evaluate the significance of the individual variables; the significance level of the statistical analysis was set to 0.05.…”

“…Some authors report that salvage logging interventions must be planned considering the site-specific characteristics [13,14]. When salvage logging is appropriate to be applied, the most suitable technological solutions are those based on fully mechanized systems as these guarantee high productivity and above all a lower risk for operators as they work exclusively on the machines [15,16].In complex terrain and in mountain areas, with a low density of forest roads, the use of fully mechanized systems in salvage logging operations is difficult. In these conditions, the main system remains the semi-mechanized system based on motor-manual felling with a chainsaw and timber extraction by cable yarders or skidders [17].…”

“…Previous studies mentioned productivity related to ordinary harvesting conditions or salvage logging operation in gentle terrain, while there is a lack of knowledge about the productivity of forwarders in non-ordinary conditions, such as salvage logging, in complex and steep terrain. For example, in Finland cutting costs in salvage logging operations were estimated to be about 35-64% higher than ordinary clearcutting and the logging costs were 10-30% higher than normal standing stems [15,17]. Although harvester productivity in salvage logging operations are lower, compared with normal clearcutting, Bergkvist [30] does not detect any significant difference in forwarder productivity in salvage logging operations compared to normal clearcutting.…”

“…Some authors report that salvage logging interventions must be planned considering the site-specific characteristics [13,14]. When salvage logging is appropriate to be applied, the most suitable technological solutions are those based on fully mechanized systems as these guarantee high productivity and above all a lower risk for operators as they work exclusively on the machines [15,16].…”

“…To convert the delay-free productive machine hour (PMH 0 ) into productivity machine hour including delays shorter than 15 min (PMH 15 ), a correction factor k should be applied. The k factor can be derived from the study observations if the study is based on a long observation time.…”