Biomass equations for sessile oak (Quercus petraea (Matt.) Liebl.) and hornbeam (Carpinus betulus L.) in aged coppiced forests in southwest Germany

摘要

Over-aged coppice forests (older than 40 years) occur all over Europe as a result of the abandonment of traditional harvesting practices during the last 60-100 years. With the increasing demand for bioenergy, there is renewed interest in coppicing, which typically aims at maximizing biomass production. For the sustainable management of these forests, accurate estimates of their biomass potential are needed. Therefore biomass equations for the two most common tree species traditionally managed in Central European coppice systems were developed in this study. In total, 24 oak (Quercus petraea) and 24 hornbeam (Carpinus betulus) trees from two different, aged coppice stands in Rhineland-Palatinate (southwest Germany) were felled and separated into various biomass compartments which were directly weighed in the field. From every compartment, samples were taken to the laboratory to determine wood density and water content. Based on dendrometric parameters (diameter at breast height (dbh)) and compartment dry mass, allometric equations were developed. Power functions provided the best fits for relationships between dbh and biomass in tree compartments and whole trees (R~2 = 0.97 and 0.92 for oak and hornbeam, respectively). These allometric equations for oak differ considerably from those developed for trees grown in high forests, pointing to the need to use equations that are specific to silvicultural systems, in this case for aged coppice forests.