Wednesday, August 12, 2009

Analysis of the management issues of Dawatagolla Plantation, Sri Lanka

Analysis of the current management issues of Dawatagolla Forest Plantation to make recommendations towards multiple-use forestry
Fareena Rusaik and Upul Subasinghe

Since 1940, the historical perspective of forest management shows that the management of forests was carried out with the prime objective of obtaining timber. With the increasing demand for timber, forest plantations help to bridge the gap between supply and demand. Therefore the policy makers in Sri Lanka concentrated to involve rural community through social forestry including fast growing tree species. After 1995, the concept of multiple-use forestry became the centre point of forest management.

It was decided to select the Dewatagolla Forest Plantation (DFP) as the study area. It is situated in Alawwa in Kurunegala District and the extent is 30 ha. It contains of mainly jak and mahogany which are divided into jak working circle (JWC) and timber working circle (TWC).

This study was designed with the objectives of identification of the current management issues in the DFP, analysing the present management plan to test the compatibility and provision of suggestions and recommendations through the multiple-use forest management strategies towards the sustainability.

Data were collected by measurements, questionnaire survey, formal and informal interviews and discussions with the villagers and relavent officers.

Results obtained from the survey indicated the necessity of an appropriate multiple-use forest management practices towards the sustainability. Measurements revealed that the 96% of trees to be removed to implement such management pactices. Therefore a constant approach should be made and selective system of timber management was recommended. Several indigenous and exotic tree species provide multipl benefits to the surrounding community were found through the observations. Furthermore, the willingness of the villagers were also identified for the utlisation of the forest in multiple ways.

Tuesday, August 11, 2009

Construction of a stem volume prediction model for E. grandis

Construction of a stem volume prediction model for mature Eucalyptus grandis plantation in Pidurutalagala of Nuwara Eliya, Sri Lanka
Kandiah Selvarathnam and Upul Subasinghe

Timber volume is the most crucial variable in commercial forest plantations. Therefore a precise volume prediction model was constructed for the mature Eucalyptus grandis plantation located in the Pidurutalagala mountain of Nuwara Eliya District, Sri Lanka.

0.02 ha circular samples were used for the data collection. Breast height diameter (dbh) and total height (h) were measured as the preliminary measurements. Then the stems of the standing trees in the sample plots were divided into sections and section lengths, end-diameters and mid-diameters were measured in order to use the Newton's formular for the stem volume estimations. Altogether 14 samples were used for the data collection.

A basic relationship was then developed by assuming the stem volume (v) can be predicted as a function of h, basal area (g) which is calculated using dbh and site quality as given below.

v = f (g, h, site quality)

In order to represent the site quality, top height and top height / age functions were used. Regression analysis (linear) was used to quantify the relationships. In order to obtain the best models, the variables in the above equation were transformed into different forms that can biologically be accepted. R2 and standard residual distrinbution were used to evaluate the model quality. After a careful study, two models were selected to predict the stem volume of E. grandis trees in the selected plantation.