engleski

Pedotransfer functions for bulk density estimation of forest soils

The data of 45 soil profiles from a 16 × 16 km grid across Slovenia was analysed to develop a local pedotransfer function (PTF) for bulk density (ρb) estimation. In total, 106 soil horizons were considered. Concentration of organic carbon (OC) was found to be well correlated (r = -0.861, p < 0.001) with ρb. Two separate line segments were fitted to the data, which was partitioned into two intervals, based on OC content (below 36.0 g/kg and above 36.0 g/kg). Nearly 80 % of the variability in ρb is explained with segmented regression. The local PTF was compared with published PTFs and four validations indices (MPE, SDPE, RMSPE and R2) confirmed the highest prediction quality of the local PTF. The differences of carbon stock (Cpool) estimation, based on usage of different PTFs could be higher than 160 t OC per hectare. Prediction of carbon stocks could be substantially improved by calibration of the models coefficients with data stratified according to each unique soil type.

pedotransfer function PTF; organic carbon OC; segmented regression; forest soil; carbon stock Cpool

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