Characterizing the relationship between soil and growth of plantation teak (Tectona grandis L.f.)

Abstract

A study was conducted on modelling the growth of Teak in relation to soil conditions using data from 52 permanent sample plots established in Teak plantations in Kerala, India. The plots were established during 2000-2001 and re-measured during 2004. Diameter increment was computed for all the plots. From each of the plots, soil samples were taken from pits at three depth layers viz., 0-20, 20-40, 40-60 cm and the soils were subjected to analysis for determination of particle size separates, bulk density (BD), particle density (PD), water holding capacity (WHC), soil pH, organic carbon (OC), exchange bases (EB), exchange acidity (EA), cation exchange capacity (CEC), base saturation (BS), Total N, available P, K, Na, Ca and Mg. Process-based modelling approach was tried to characterize the interrelation of tree growth vs soil properties. WHC, in the 20-40 cm depth level, turned out as the foremost soil variable significantly influencing tree growth. The adjusted R2 value for the diameter increment function was 0.55, a reasonable value to expect under uncontrolled conditions. However, this implies that a substantial part of the variation in growth happens on account of factors not included in the model. The results also indicated an almost linear decrease in diameter growth with increase in the soil WHC in 20-40 cm depth level, keeping other factors constant.