%0 Research note
%T Simulation of geometric thinning systems and their time requirements for young forests
%A Bergström, Dan
%A Bergsten, Urban
%A Nordfjell, Tomas
%A Lundmark, Tomas
%D 2007
%J Silva Fennica
%V 41
%N 1
%R doi:10.14214/sf.311
%U https://silvafennica.fi/article/311
%X In Fennoscandia, large areas that have not been subjected to  pre-commercial thinning (PCT), and thus support dense stands, are  becoming suitable for harvesting biomass. However, efficient systems for  harvesting biomass from young stands have not yet been developed. In  order to optimise biomass harvesting it is here hypothesized that the  handling unit should not be a single tree but a corridor area, i.e., all  trees in a specific area should be harvested in the same crane movement  cycle. Three types of corridor harvesting approaches (using  accumulating felling heads for geometric harvesting in two different  patterns) were compared in terms of time required to fell a corridor of  standardised size. Corridors are defined as strips of harvested areas  between conventional strip-roads. Harvests were simulated in two types  of stands, first thinning (FT) and delayed PCT stands, in which the  spatial positions of the trees had been mapped. The differences in  simulated time consumption per corridor were minor when the only  variable changed was the corridor pattern. However, there were ca.  2-fold and 3-fold differences in simulated time consumption per corridor  between the harvesting approaches for the FT stand and the PCT-stand,  respectively. Furthermore, area handling (felling head accumulating all  trees corridor-wise, with no restrictions on the accumulated number of  trees except for a certain load limit) was found to give up to 2.4-fold  increases in productivity compared to a single-tree (reference) approach  for the FT stand. In conclusion, the simulation results clearly show the benefits of  applying area-harvesting systems in young, dense stands.