Prices of timber sales in intermediate harvest in Norway spruce stands depending on their age and site index class

The research focused on harvesting timber in intermediate harvest in 2008-2012, in pure Norway spruce stands aged 10-140 at the State Forests National Forest Holding. The data included the following groups of activities: late cleaning, early thinning and late thinning. The assortment structure concerned the following groups of large- (WAO, WA1, WBO, WB1, WCO, WC1, WD), medium- (S10, S11, S2A, S2B, S3A, S3B and S4) as well as small-sized (M1 and M2) assortment groups. Based on the data on the assortment structure of the harvested timber and the prices of individual assortments, the average price of wood was calculated in the age subclasses according to the site quality described with site index class. For each site quality class polynomial equations of the trend line was determined and average timber price for each age subclass was calculated. Approximately 46 thousand hectares of pure spruce stands was analyzed. The largest area was occupied by stands of the I site index class - 41.2% and of the II class - 37.0%. The most important for harvesting was the S2 assortment, whose share ranged from 47.9% in III class to 63.8% in I class. It was shown that the higher the site quality, the higher the prices of assortments in the intermediate harvest.