Teak (Tectona grandis) was introduced to Sri Lanka in 1680 by Dutch. Since then teak was grown mainly as monocultures and as a mix with Jak, Margosa, Eucalypts and Mahogany. The popular methods of establishing teak plantations were Taungya System and Participatory Forestry Programmes (PFPs) so that the Forest Department can share the benefits with local people. Therefore, this paper evaluates the growth and financial benefits of a teak plantation managed under PFP.
A 12.5 ha teak land was selected from Rambapokuna village in Kurunegala district for the data collection. It was partitioned into 0.4 ha blocks and given to the farmers under 25 year lease agreement in 1999. As the entire plantation is homogeneous, one block in this land was randomly selected and a transect was demarcated along the diagonal. 0.02 circular plots were then demarcated at 5m intervals to collect data. Breast height diameter (dbh) and total height of all the trees were measured (42 stems) and the tree basal area and volume were calculated using standard methods.
The results revealed a poor growth of teak (Class III) when compared with the Provisional Yield Tables. The average tree dbh, height and volume values were 11.2cm, 8.8m and 0.051m3 respectively. Pre-commercial thinning has been done in 2007 without a scientific study.
In order to calculate the income and cost by time series analysis, the current volume was projected using the Class III yield table. The estimated volume in 2049 including the thinnings is 48.895m3 with the predicted income of USD 28,584 (assuming 75% timber recovery in harvesting) for the 0.4 ha block. Total extraction and replanting cost was estimated as USD 5,874. The Net Present Value of the total income and cost will be Rs USD 1,501 assuming the present discount rate as 10%.
The reason of poor growth rate is due to the site quality and lack of proper silvicultural practices. Therefore, it is recommended to apply proper management practices to obtain a higher volume which can generate a higher profit.
K M T S Jayarathne and S M C U P Subasinghe
Department of Forestry and Environmental Science, University of Sri Jayewardenepura, Sri Lanka