COMPLEX FOREST MANAGEMENT SYSTEM BASED ON SMALL SIZE FOREST MACHINES

The aim of this study is to clarify the possibilities for applying compact class logging machines in Latvian conditions. The equipment evaluated in the study is the Vimek harvester and forwarder. The possibility of using both machines in forest operations from ditch clearing to final felling has been evaluated in terms of productivity and economy. The productivity of the Vimek harvester can be characterized by polynomial equations. Statistical significantly higher productivity in pre-commercial thinning was observed in spring trials in forest areas with or without extracted undergrowth trees in comparison to areas with dense undergrowth vegetation. Statistically significant difference was observed in artificially and naturally regenerated stands - in naturally regenerated stands better figures were obtained during the extraction of small trees (D-13 < 17 cm), in artificially regenerated stands - in the extraction of bigger trees. The Vimek harvester was equipped with a specialized felling head with a circular saw and chain (Bracke C.12) in early tending and felling-bunching head with a chain feed roller (Keto-Forest Eco) in thinning The productivity achieved in small ditch clearing was 187 m.h(-1) , while clearing of larger ditches resulted in an average productivity of 107 m.h(-1) , the productivity of early tending is 0.2 ha.h(-1). Harvesting productivity highly depends on the average tree diameter, but the average value is 9.0 m(3) .h(-1). The productivity in final felling in grey alder stands is 11.5 m(3).h(-1). In all cases productivity is expressed as efficient work hours. The prime cost of log production (extraction and delivery) ranges from 22.9 EUR.m(-3), but the cost of ditch clearing and early tending can be estimated from the average hourly cost of 63 EUR.h(-1).