DEVELOPMENT OF YOUNG STANDS AFTER WHOLE TREE HARVESTING AND WHOLE TREE HARVESTING COMBINED WITH STUMP BIOMASS EXTRACTION.

Forest management pressures on ecosystems are expected to rise due to increased use of renewable resources and environmental, economic and political reasons. Extraction of nutrient rich logging residues from felling sites has become a common practice, therefore risks of negative impact on the nutrient cycling as well as site future productivity must be assessed. To evaluate effect of whole-tree harvesting (WTH) and whole-tree harvesting combined with stump biomass extraction (WTH+SB) on productivity of next rotation young stands measurements were carried out in eight sites for four to six years in typical forest site types in Latvia (Oxalidosa turf. mel. – eutrophic peat soil site; Hylocomiosa, Oxalidosa – mesotrophic mineral soil sites, Mytrillosa – oligotrophic mineral soil site). Harvesting in the sites was carried out in 2012-2013 and regeneration was carried out after one to two years with Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L. (Karst.)) and black alder (Alnus glutinosa L. (Gaertn.)). Comparing conventional harvesting or so-called stem only harvesting (SOH) to WTH no statistically significant differences were observed regarding tree height, but in eutrophic Norway spruce site WTH plot smaller stem diameters were observed. Comparing WTH to WTH+SB statistically significantly higher Norway spruce and black alder heights in mono-stands were observed in WTH plots, while no significant differences were detected in Norway spruce and black alder mixed stand. No explicit differences were found regarding height/diameter ratio between WTH and WTH+SB treatments. [ABSTRACT FROM AUTHOR]