Validating timber harvesting productivity and cost information in Michigan loggers' survey using field-based studies

Abstract. A survey was developed in 2010 for Michigan’s logging industry especially within the 150-mile radius of Kinross, MI. This survey included loggers’ report about current timber harvesting machinery and productivity information. In order to have more confidence when using the results from loggers’ survey, a series of field-based studies was designed to evaluate harvesting productivity and cost of a mechanized whole tree harvesting system for both hardwood stand clearcut and softwood stand 70% selective cut in Michigan. Detailed time and motion study results showed that at hardwood clearcut site, under the conditions of average target tree size (DBH) of 8.5 inches and average skidding distances of 515 feet, the system presented harvesting production rates of 28.00 BDT/PMH and 29.19 BDT/PMH for the feller-buncher and skidder, respectively. In the case of softwood 70% selective cut, when average target tree size was 5.36 inches and average skidding distances was 319 feet, the harvesting productivity was 9.59 BDT/PMH for the feller-buncher and 14.16 BDT/PMH for the skidder. The total felling and skidding production costs were determined to be 3.72 $/BDT and 9.19 $/BDT at site 1 and site 2, respectively. Comparison between survey-based and field-based harvesting system productivity showed that loggers’ survey underestimated the production rate in hardwood stand clearcut, and overestimated the production rate in softwood stand selective cut. Missing of tree size information in the loggers’ survey could be one reason that led to the difference between survey-based and field-based production rates. Use of assumed 50% green wood moisture content could also make the survey-based production rates measured in BDT/PMH deviate from their real value when wood moisture content was significantly different from 50%.