Background: Biomass assessment of young forest stands is important because of their role in the carbon cycling. The aim of this study was to develop biomass equations for young broadleaved species growing in natural conditions in Albania. Methods: Five forest stands were investigated using circular sample plots. Diameter at breast height (DBH) and height (H) from 58 sampled trees ranging in age from 4 to 34 years old of Turkey oak (Quercus cerris L.), sweet chestnut (Castanea sativa Mill.), European hornbeam (Carpinus betulus L.) and manna ash (Fraxinus ornus L.) were measured in situ. Logarithmic regression equations were used and tested for their performance to estimate aboveground and tree-components biomass for each species using DBH, H and their combination DBH2 x H as predictors. Results: We found that DBH was a reliable predictor for estimation of aboveground and components biomass for young trees but the inclusion of height in biomass allometry did not improve the biomass estimation. We observed differences in scale (β0) and exponent (β1) coefficients of biomass models, not only between broadleaved species, but also among tree-components within species. Both coefficients were strongly species-specific and their values reflect differences in biomass stocking rate due to different growth strategies of each species in early development phases. Conclusions: Allometric equations to estimate aboveground and tree-component biomass appeared to be species-specific, meaning that such models are applicable for species growing at sites with similar ecological conditions. From the tree variables used, DBH was the most reliable predictor of aboveground and individual components biomass, whereas height proved to be a promising predictor for stand biomass. These allometric equations developed for young trees will improve the accuracy of current estimates of forest carbon stock in Albania.

The study objective was the determination of allometric relationships to estimate aboveground biomass in young Q. cerris stands growing in various sites in Albania. The equations described here are developed for Q. cerris forest stands managed as coppice. The total aboveground biomass of sampled trees varied from 10.67 to 19.71 kg with a stem diameter at 1.3 m (DBH) from 7.65 to 9.7 cm, and height from 5.26 to 7.6 m. Stem biomass comprised, on average, 69.6 %, while branch biomass was 24.3 %, and leaf biomass,6% on the total aboveground biomass of the sampled oak trees. Total aboveground biomass was predicted with the highest accuracy from linear and non-linear regression equations. Total aboveground biomass and the biomass of tree compartments were predicted with a notable accuracy from DBH where the allometric model efficiency exceeded 93%. Biomass expansion factors (BEFs) showed a stronger dependency on diameter at breast height and a weaker relationship with age. The age-dependence relationship found in our study was closely related to site productivity. The variability in aboveground biomass among sampled sites indicated that local site conditions cause this difference. These new equations for Q.cerris might be applicable in the framework of the Albanian National Forest Inventory for estimation of carbon accounting from forest ecosystems and will contribute to the sustainable management of oak forests.

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