An Assesment of Resin tapping from Pinus caribaea trees grown in Kwale district

Abstract

Rosin Kenya Ltd. has tapped P. caribaea trees grown in Kwale District for oleoresin since 1992. There had been reports that some of these trees were dying probably due to some stress from the resin tapping operations leading to the Forest department halting these operations in this District. An assessment of the tapping operations in this district was therefore done to establish if they had any adverse effects on the trees and if there was any evidence of wood loss and incidence of insect attack associated with the operations in order for the Forest department to make informed decision on future tapping operations. Tree samples used in the study were obtained randomly from the oldest, medium aged and youngest pine plantations in Shimba block and represented four diameter classes (<15, 15-24, 25-34 and >35 cm). For each tree selected, incidence of insect attack was observed, width and number of working faces, vertical height of face, height of clear bole, Dbh, bottom, mid and top diameters of the chipped channels were measured and circumference of tree chipped and portion of clear bole so far chipped computed. Data on pine resources in Kenya for potential resin tapping were also compiled from Inventory section. The mean number of working faces was 3 and the mean face width was 11.6 cm. Number of faces and face width varied significantly (p<0.001) with diameter class and compartment (age of the tree). The overall mean circumference of the tree exposed due to the bark chipping operation for the whole period of tapping was 48.8 %. The mean height of vertical face was 2.0 m while the mean height of clear bole was 8.2 m and percentage of clear bole so far chipped being 27.8 %. Vertical height of face and clear bole height varied significantly with compartment but not with diameter class. It is concluded that resin tapping as currently practiced does not have any observable effect on growth and health of the trees tapped and also does not expose the tapped trees to additional stress from insect attack and that the drying up or death of the tapped trees may be more as a result of climatic, environmental, site and pathological factors as opposed to resin tapping per se. A number of recommendations are made on future resin tapping operations including the establishment of permanent sampling plots for obtaining reliable data on effect of tapping on growth. It is also recommended that FD allocates additional pine plantations to Rosin Kenya for resin tapping to help in easing the pressure on the plantations already being tapped and that FD incorporates a pine resin tapping cycle in its management plan in the short term. It is further recommended that FD puts in place a medium to long-term plan for the establishment of plantations with species suitable for pine resin tapping.