Resin-Tapping Production in Pinus pinaster Ait. Stands in Galicia (NW Spain): Effects of Location, Number of Faces, Wound Width and Production Year

Abstract

Resin or gum is secreted by conifers, mainly members of the genus Pinus, in response to physical and/or chemical stimulation, which can be induced by tapping live trees, i.e., by making repeated wounds in the trees. Resin production could potentially complement timber production (the main economic activity) in pine stands in Galicia (NW Spain). In addition, the particular characteristics of Galician woodlands (smallholdings, sloping land, presence of shrubs, high density of trees) imply different yields and costs than in pine stands dedicated to resin production in other parts of Spain. Therefore, a specific regional management model that is different from the traditional model established for other resin producing areas in the Iberian Peninsula is required. In this study, resin tapping was applied in each of the three years before the trees were felled, in two different locations, with one or two faces tapped and wounds of two different widths (12 and 16 cm) made across the face(s). Tapping two faces yielded more resin than tapping a single face, thus confirming the study hypothesis. When only one face was tapped, the plot location acquired greater importance, with production being higher in the location characterised by a higher mean annual temperature. Increasing the width of the wound did not always increase the amount of resin obtained per tree, which depended on the number of faces open: when two faces were tapped, increasing the width of the wound increased resin production in both locations in each of the three years of the trial. The weather conditions in each year masked the effect of the tapping season, and production did not follow any particular trend over time. The importance of the local weather conditions in the study areas and the environmental conditions in each year are discussed. The study findings are important for decision-making regarding the treatment and selection of areas for resin extraction.