In Galicia, different forest species, mainly pine, eucalyptus and bushes occupy around 2.1 million ha. Shrubs take up about 1 million ha and most of this land could be considered unproductive and constitutes one of the main sources for initiating forest fires that devastate more than 40,000 ha per year. One objective of this study was to establish the role of these species in starting and spreading of forest fires through determination of their risk indices. Another study examined the possibility of using the potential biomass originating from these materials as a source of xyloenergy (energy originating from wood). With this aim, different physical, chemical, and biological parameters were determined over the year for different forest species and geographical zones in Galicia. Bomb calorimetry was used to determine caloric values, one of the key parameters in this study. When caloric values are greater than 22,000 U kg(-1) and very homogeneous over the whole year, make the bush biomass very valuable for energy exploitation. An effective control of this biomass could reduce the number of fires and improve forest ecosystems. The study was carried out using a static bomb calorimeter (caloric values), elemental analysis equipment (C, H, O, N, and S), and an epiradiator (flamabilities), and complemented with the determination of some biological and environmental parameters that are shown together in the form of bioclimatic diagrams.