Difference equations derived on the basis of the McDill-Amateis differential functions and from the integral form of the Bertalanffy, Richards, and Korf growth functions were used to model the dominant height growth of young European aspen (Populus tremula L.) stands on Athos Peninsula (northern Greece). | K. KITIKIDOU, M. KAYMAKIS, E. MILIOS Research Article Turk J Agric For 36 (2012) 55-63 © TÜBİTAK doi: Site index curves for young Populus tremula stands on Athos Peninsula (northern Greece) Kyriaki KITIKIDOU*, Minas KAYMAKIS, Elias MILIOS Department of Forestry and Management of the Environment and Natural Resources, Democritus University of Thrace, Pantazidou 193, 682 00 Orestiada - GREECE Received: Abstract: Difference equations derived on the basis of the McDill-Amateis differential functions and from the integral form of the Bertalanffy, Richards, and Korf growth functions were used to model the dominant height growth of young European aspen (Populus tremula L.) stands on Athos Peninsula (northern Greece). Data from stem analysis were used for fitting. Both numerical and graphical analyses were used to compare alternative models. The cross-validation approach was used to analyze the predictive ability of the models. The algebraic difference form of the differential function proposed by McDill and Amateis resulted in the best compromise between biological and statistical aspects and produced the most adequate site index curves. Therefore, it is recommended for height growth prediction and site classification of European aspen stands on Athos Peninsula. This equation is base-age invariant, so any number of points (A1, H1) on a specific site curve can be used to make predictions for a given age A2 and the predicted height H2 will always be the same. Key words: Algebraic difference equation, height growth, site index Introduction The classification of forest land in terms of its productivity is an important issue for forestry managers as well as for forestry enterprise administrators. An index that expresses this productivity is a required variable for the modeling of present and future growth and yield and can also be used for forest land stratification for the purposes of forest inventory and forest exploitation on a .
