Abstract

Teak [Tectona grandis] plantations in Kerala under the management of the Forest Department occupied around 78 225 ha in 1992. About 17 of this area was under Wildlife Sanctuaries and National Parks management where there is no clear felling. Of theremaining portion, 75 consists of stands 35 yr old. The teak plantations falling under the Territorial Circles were assessed for stocking and site quality distribution in 1992-93 using a stratified sampling procedure, based on Territorial Circles and age groups. The observations on stocking and related parameters were collected from 50X50 m plots laid out in randomly selected plantations in each stratum. Based on teak alone, 36 of the plantation area was understocked, and 45 overstocked. However, when themiscellaneous species present in the teak plantations were considered, the degree of understocking fell to 18 and overstocking increased to 60. With respect to the basal area of teak alone, the stocking pattern did not show significant differences over age groups. Considering the growth of miscellaneous species in terms of basal area, overstocking was more prevalent in older plantations. The site quality distribution approximated to that of normal distribution with a mean site index of 24 m. Young plantations mostly belonged to higher site quality levels. A subset of the sample plots selected for the survey was retained as semi-permanent sample plots to be remeasured periodically. Detailed measurements of tree position, crown width and height of trees were made in such plots in 1992, and they were remeasured in 1997. Data are presented on the status of these plots with respect to stand attributes such as age at measurement, stand density, site quality class etc. However, only when the measurements on successive increments are available for a longer period, can growth projection models can be developed. Efforts were made to work out an optimum thinning schedule for teak based on a simulation exercise. This indicated that there is no need for the firstand second silvicultural or mechanical thinnings currently practised before 12 yr, followed by 50 removal at 30 and 42 yr old. The estimated maximum sustainable harvest for teak plantations under the Territorial Wing in Kerala amounted came to140 000 m3 (timber and smallwood) for the first 14 yr and 200 000 m3 thereafter for a rotation age of 50 yr. The consequence of bringing the plantations to normality in one rotation period was also investigated