OPTIMIZING MANAGEMENT OF EVEN-AGED TEAK STANDS USING GROWTH SIMULATION MODEL: A CASE STUDY IN KERALA

Abstract

JAYARAMAN, K. & RUGMINI, P. 2008. Optimizing management of even-aged teak stands using growth
simulation model: a case study in Kerala. A growth simulation model was developed for even-aged teak
stands to derive optimal density management plans. The optimal rotation age and effects of understorey
species on the growth of teak were ascertained. The growth model consisted of five modules, i.e. effects of
site index, unrestrained growth, ageing, density of teak and density of miscellaneous species. The model
was calibrated based on data gathered from 69 permanent sample plots established in teak plantations in
Kerala, India. A model was developed in order to identify the optimum density trajectory that maximized
the net present value (NPV) of cash flows. Optimum density regimes were worked out for different interest
rates in all the site quality classes, with and without miscellaneous species (understorey) in the stands. The
relative initial density that maximized the NPV varied from 0.41 for site quality I to 0.21 for site quality IV
regardless of interest rate. The rate of increase in initial density required for attaining the optimum was
3% every five years. For any particular interest rate, the optimal rotation age remained the same under
all site quality classes. However, the optimal rotation age changed from 65 to 40 years as the interest rate
changed from 2 to 5%. Understorey species in teak plantations had a significant effect on the growth of
teak trees. The percentage increase due to the absence of miscellaneous growth was about 16% for crop
diameter and 23% for mean annual increment of volume over a rotation period. Consequently, there was
an increase of 56% in NPV for all the site quality and interest levels.