Resin tapping: A review of the main factors modulating pine resin yield

Abstract

Pine resin is a non-wood forest product that has been used for multiple purposes since ancient times throughout the world. In recent years, resin tapping activity has increased in countries that were historically producers, but in which it had practically disappeared since the late 1980 s, and is expected to grow in importance due to its bio-product nature. The aim of this review is to provide an overview of the research work on the main factors modulating resin yield. A total of 205 papers were selected and classified according to their main topics. The species and its intraspecific genetic variation are two of the main factors influencing both the production and the quality of the resin obtained. The environmental factors most commonly studied and which in turn were the most successful when related to resin production, were temperature and water availability. Diameter at breast height was the most investigated dendrometric variable, although other variables such as total height or crown ratio were also studied, generally obtaining positive relationships between them and resin production. The resin ducts, which produce, secrete and transport resin through the tree, are the most influential anatomical variable and the focus of the anatomical research. Other factors that can modulate resin production are the presence of pests, which induce the tree’s immune response, and fire, with contradictory results on their effects. Finally, the extraction method and the stimulant paste used influence resin production, research is focusing on new extraction methods and more efficient and cheaper stimulant pastes with lower proportions of sulfuric acid. Although interest in and knowledge about resin tapping has increased in recent years, research needs to further develop and deepen the relationships between resin production and the different factors involved.