The Effect of harvesting intensity in single-tree selection on biomass of hornbeam - ‎Persian ironwood stand

The impact of logging and tree harvesting on the ecological function and the future of Hyrcanian forests structure is a continuing debate topic. The information is currently available does not support firm conclusions about the impact of forest harvest intensity on forest structure and biomass. The present study aims to evaluate the effect of single-tree selection harvest intensity on biomass of hornbeam-Persian ironwood stand. For this purpose, information on all trees and dead trees were collected in 70 half-hectare plots. The 35 sample plots were in single-tree selection stands with three harvest intensities and the same sample plots were in control stand. Trees litter fall were measures from September to February and the storage of soil organic carbon was determined through organic carbon and bulk density. Then, tree biomass, litter biomass, dead tree biomass and total biomass were finally calculated. The results showed with increasing the rate of harvest intensity up to 13.5% the total biomass had rising trends, although harvest intensity had no significant effect on aboveground and belowground biomass and soil organic carbon. The aboveground biomass was higher in single-tree selection stand than control stand. The average of total biomass was 147 and 144 ton/ha in harvest and control hornbeam-Persian ironwood stands respectively and harvesting increased two percent of mean total biomass. The medium harvest intensity (3.6-9.5% of stand volume) was finally determined as appropriate selective logging intensity. The correspondence of litter biomass and dead tree biomass as bio indicator indicated that tree marking in the single-tree selection system was advisable.