Herbage production and chemical characteristics for bioenergy production by plant functional groups from semi-natural grasslands

The current paper is devoted to biomass yield and proportion, chemical composition and energy yield by functional groups in different semi-natural grassland types. The study was performed for three grassland types in Estonia which were represented by five NATURA 2000 meadows each. The highest yield was obtained from alluvial meadows followed by mesic and wooded meadows. Hence, the largest amount of other herbs was found from alluvial meadows, even if the proportion of this functional group was dominant in wooded meadows. The contribution of the sedges&rushes was the largest in alluvial meadows. The grasses were prevalent in mesic meadows. The legumes were growing in all studied grassland types in small amounts. Nitrogen content in legumes differed significantly from other studied functional groups, but no significant differences between functional groups in other chemical (Cl and S) contents were found. The other herbs had the highest ash content and the lowest calorific value contrary to the sedges&rushes with the lowest ash content and the highest calorific value. The highest area-specific energy potential was calculated for alluvial meadows followed by mesic and wooded meadows. The energy potential depends more on the amount of biomass than the calorific value of particular functional group. Improved knowledge about the functional groups and their chemical content enables to promote and optimise alternative usage of this late harvested mixed biomass from semi-natural grasslands for bioenergy production.