Forest residue extraction levels in Greece are currently very low, but logging residues have the potential to be an important component of the wood energy supply chain. Forests are a major supplier of renewable energy. Exploring the possibilities of utilizing the biomass of logging residues for energy requires analysis and knowledge of its properties. In this research work the properties (ash, volatiles, fixed carbon, carbon, hydrogen, oxygen, nitrogen and calorific value) of the various constituents of the biomass of fir (Abies borisii - regis), pine (Pinus nigra), oak (Quercus frainetto) and beech (Fagus silvatica) logging residues were determined. Bark and ash content increased with decreasing diameter of branches. Ash content was higher in bark than in wood of branches in all species. Ash and nitrogen content was several times higher in bark and in foliage or needles than in wood of branches. Oak branches and twigs of all species had ash and nitrogen content higher than that required by the EN ISO 17225-2 standard for domestic pellets and they should not be used for energy, at least for pellets production. Volatile mater, fixed carbon, carbon and hydrogen content were in the range given by other researchers. Heating value is higher in softwood (fir and pine) than in hardwood (oak and beech) and ranged from 18.72 MJ/kg to 21.00 MJ/kg. In addition, Duncan's multiple range test was used to compare the means between the various constituents in all species.

This work examined the enhancement of bending strength properties of two wood species, namely fir and pine, reinforced with two carbon fibre fabrics (CFF) of different areal weight, in two different layouts. CFF applied in the bottom surfaces of the specimens ('F'-type) and in the second wrapped in the bottom surfaces and up to the half of the lateral surfaces ('U'type).The results indicated that samples which are reinforced with CCF show higher MOR and MOE values than the controls and this improvement was found to be significantly different. The reinforcement layout affected the bending properties of both pine and fir wood, since the corresponding values are higher in U-shaped reinforcement than in F-type reinforcement, at identical CFF areal weights. In the case of fir wood, the CFF areal weight did not significantly affect the bending properties.