Processing logging residues at a centralised yard and at the landing site was compared.

Ground-based full-tree systems can generate large quantities of logging residues on landings. Due to the nature of the terrain and difficult road conditions, it is sometimes not possible for large biomass transport trucks to access these residues. A recent research article examined the harvesting of Douglas-fir, true firs and western redcedar. The two systems studied were as follows:
 

1. Forwarding residues to a concentration yard where they were stored and then ground directly into chip vans (termed “slash forwarding”). The equipment used was a grapple loader, end dump tractor/trailer, grapple loader and horizontal grinder (Peterson 7400, wheeled)
2. Grinding residues on the landing and then forwarding the hogged material to a concentration yard where it was stored and then reloaded into a chip van (termed “in-woods grinding”). The equipment used was a grapple loader, horizontal grinder (Peterson 4710B), dump truck (modified with high walls) and a front-end loader.

The average moisture content of the logging residue was 24%. The travelling distances for both systems were normalised to enable accurate comparison. The table below provides the productivity results, measured as bone-dry tons (BDT) per scheduled machine hour (SMH), for the various machines within the two systems.
 

 
The cost results showed that the slash forwarding system was US$ 23.62 per BDT, while the in-woods grinding was US$ 24.52 per BDT. Where logging residues were densely piled on the roadside, the in-wood grinding system was the most suitable, but when the residues were more scattered, the slash forwarding was preferred.

The research was published in the Forest Products Journal 2012, Vol. 62(3), and was titled “A productivity and cost comparison of two systems for producing biomass fuel from roadside forest treatment residues”. The authors were N Anderson, W Chung, D Loeffler and J Jones. Source: http://www.fs.fed.us/rm/pubs_other/rmrs_2012_anderson_n002.pdf