Allometric relationships for biomass and leaf area of beech (Fagus sylvatica L)

The objectives of this study were i) to establish allometric relationships among stem and crown dimensions, biomass, and leaf area, ii) to determine the relative aboveground biomass distribution, iii) to quantify the relationship between leaf area and the water-conducting cross-sectional stem area, iv) to determine the vertical gradient of the specific leaf area (SLA) and v) to estimate aboveground stand biomass and leaf area index (LAI). Thirty-eight trees were sampled, ranging in age from 8-59 years. Tree biomass amounts increased with increasing diameter at breast height (dbh). Nonlinear models on dbh explained more than 90% of the biomass variance; regressions improved when tree height was used as well. Crown dimensions increased with stem size. A linear relationship was found between basal area and crown length. Crown projection area was nonlinearly related to leaf area and crown biomass. The fraction of dry matter present in the stem generally increased with tree biomass, but differently for trees from different diameter classes. The ratio between leaf and branch biomass decreased significantly with increasing tree size. The ratio between leaf biomass and leaf area (SLA) was relatively constant for whole trees, amounting on average to 172 cm(-2) g(-1). SLA generally increased from the tree top down to the crown base; this pattern did not significantly differ among trees within a stand. The rate of change decreased with decreasing canopy closure. A strong linear relationship existed between leaf area and sapwood area: the ratio was affected by the height of the crown base. Aboveground stand biomass ranged from 6 to 167 ton ha(-1), and increased linearly with stand age. LAI reached a maximum of seven; the leveling off was ascribed to self-thinning.