Site Quality Estimations Based on the Generalized Algebraic Difference Approach: A Case Study in Çankiri Forests

Abstract

In this study, it is aimed that the dynamic site index models were developed for Crimean Pine stands in Sarikaya-Cankiri forests located in middle northern Turkey. The data for this study are 153 sample trees obtained from the Crimean Pine stands. In modeling relationships between height and age of dominant or co-dominant trees, some dynamic site index equations such as Chapman-Richards (M1, M2, M3), Lundqvist (M4 and M6), Hossfeld (M5), Weibull (M7) and Schumacher (M8) based on the Generalized Algebraic Difference Approach (GADA) were used. The estimations for these eight-dynamic site index model parameters with well as various statistical values were obtained using the nonlinear regression technique. Among these equations, the Chapman-Richards’s equation, M3, was determined to be the most successful model, with accounted for 89.03 % of the total variance in height-age relationships with MSE: 1.7633, RMSE: 1.3279, SSE: 1165.6, Bias: -0.0380. After determination of the best predictive model, ARMA (1, 1) autoregressive prediction technique was used to account autocorrelation problems for time-series height measurements. When ARMA autoregressive prediction technique was applied to the Chapman-Richards function for solving autocorrelation problem, these success statistics were improved as SSE: 868.7, MSE: 1.3183, RMSE: 1.1482, Bias: -0.06369, R2: 0.918. Also, Durbin-Watson statistics displayed that autocorrelation problem was solved by the use of ARMA autoregressive prediction technique; DW test value=1.99, DW<P=0.5622, DW>P=0.4378. The dynamic site index model that was developed has provided results compatible with the growth characteristics expected in the modeling of height-age relations, such as polymorphism, multiple asymptote, and base-age invariance.

New dynamic equation of dominant height and site index for Pinus chiapensis (Martínez) Andresen in Puebla and Veracruz, Mexico

“…The usual way to reference productivity is to use the dominant height-age relationship using the site index (SI), which is defined as the average height reached by the dominant trees in a stand at a given base age (Quiñonez-Barraza et al, 2015). With SI equations, curves are constructed that show the height growth pattern of trees of a species in an ecoregion (Akbas & Senyurt, 2018).…”

“…La forma habitual para referenciar la productividad es utilizar la relación altura dominante-edad mediante el índice de sitio (IS) que se define como la altura promedio que alcanzan los árboles dominantes de un rodal a una edad base determinada (Quiñonez-Barraza et al, 2015). Con las ecuaciones de IS se construyen curvas que muestran el patrón de crecimiento en altura de los árboles de una especie en una ecorregión (Akbas & Senyurt, 2018).…”