Secondary logging in natural forests in Central Kalimantan: operational design, production and damage assessment
1999
Supriyatno, N. | Becker, G. (Institute of Forest and Work Science, Freiburg (Germany))
The aim of this study was to define an optimal way to harvest logged-over forest through detailed pre-felling planning and careful logging operations. Three experimental logging plots, each 4 ha, were located within a logged-over lowland dipterocarp forest in Central Kalimantan. Intensity of timber extraction at the first cutting, 11 years prior to the study, was an average of 6.1 stems/ha, with a commercial timber volume of about 38 m3/ha. The density of old skidding trails was 282.5 m/ha. Before secondary logging, all trees (dbh more than or same with 20 cm) were measured, numbered and mapped. Mean tree density and basal area were 170.7 stems/ha and 21.16 m2/ha, respectively. Commercial species represented 41.3 percent of the total tree population and 55.9 percent of the basal area. An average 19.5 stems/ha of harvestable trees (commercial special species, dbh more than or same with 50 cm) were present, but only 15.7 stems/ha (80.4 percent) were of good stem quality. The minimum diameter of trees to be felled was 60 cm with a cutting intensity 20-25 percent of harvestable trees. To minimise soil disturbance and damage to the remaining stand, the skidding trail network and landings were carefully planned, initially on a map and then in the field. Felling direction was prescribed prior to harvesting. A average of 3.6 stems/ha were extracted with a commercial timber volume of 27.75 m3/ha. Dipterocarps contributed 90 percent of extracted timber. Secondary logging damage affected only 8.7 percent of the original tree population or 6.7 percent of the original basal area. Felling was more damaging than skidding. The area of soil disturbed by skidding was 5.6 percent. Density of skidding trails in the secondary logging totalled 123.9 m/ha, consisting of 73 percent old and 27 percent new skidding trails.
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