EVALUATION OF DOUBLE ENTRY CABLE LOGGING FOR FOREST RESIDUE RECOVERY IN NORTHERN IDAHO

A double entry residue recovery cable logging study was done in northern Idaho. Results were compared to conventional logging methods of sawlog removal and slash disposal. Methodology, analysis, results and discussion are presented in an introductory section and three separate papers.; Double entry logging is a means of yarding merchantable and unmerchantable material from a site in two entries. It implies using one machine for both entries or two different size ones. A larger system would be used to yard sawlogs and a second smaller one to yard unmerchantable pieces later. By removing large sawlogs in the first entry, the efficiency and productivity of the large yarder is improved. By removing the rest of the material, the entry of the smaller yarder may be justified.; Conditions of the stand will help dictate the effectiveness of two entries. Double entry can be justified in stands that have a wide range of timber sizes and a significant portion in large sawlong classes.; Double entry yarding increased volume recovery in sawlogs and gross return per acre. The increase in product recovery resulted in a significant increase in recovery costs. The higher costs are a result of the higher cost associated with the second entry yarding system and a decrease in piece rate production during the first entry on the double entry site. Hourly costs of the small, second entry yarder were higher than those of the larger, first entry yarder because the small one required a wheeled skidder to move material away from the yarder and a bucker to process material at the skidder's landing.; Total cost per piece yarded was lower in the double entry yarding but costs per acre and per cunit were higher. The added cost of a second entry could not offset all the traditional costs of slash disposal. If all material is scheduled for yarding as a means of slash disposal, however a double entry technique could produce lower total costs per acre.; Double entry logging in the Intermountain region will not be cost effective unless it results in increased volume recovery from the site and unless there is a market for the residue portion of the volume.