Biomass Harvesting from Salvage Clearcuts on Young Eucalypt Stands and Post-Wildfire Pine Thinnings with Fixteri FX15a Feller-Bundler in Spain

Abstract

We studied two Eucalyptus globulus salvage clearcuts—after a wildfire and a Gonipterus attack—and a strong thinning on a dense Pinus pinaster stand which was regenerated 20 years after a wildfire and also affected by a Matsococcus pest. Biomass harvesting was performed using the feller-bundler Fixteri FX-15a, which was time-studied during several weeks using GNSS combined with an automatic weight/time registration system (WNexus-2®). Detailed in situ time studies were applied during shorter periods as well. The productivity equations found as main explanative factors for the salvage clearcuts the unit weight per tree and the felling reason (wildfire vs. pest); for the thinning, besides the unit weight, the percentage of extracted basal area explained the productivity. Biomass collection did not allow an economic positive balance: in the Gonipterus-affected plantation the cost was reduced to 125 €·ha−1, reaching a zero balance for unit weights greater than 33 kg (dry matter) per tree; the restoration cost in the pine stand was 265 €·ha−1, much lower than the cost without biomass harvesting. In the burned eucalypt, the zero cost would be achieved for a dry unit weight much greater than the observed values. Although Fixteri performance and utilization were remarkable, recommendations about possible improvements of its design and operation were concluded from the detailed time studies.