Growth and climate drive resin production in Pinus pinaster and Pinus pinea

Key messageResin production and growth in Pinus pinaster and Pinus pinea show a trade-off under varying environmental conditions, impacting future resin yields under climate change.AbstractResin production in pines constitutes an important defense mechanism against biotic and abiotic factors, and it is also an important forestry product. In Portugal, resin is mainly extracted from Pinus pinaster and to a lesser extent from Pinus pinea, the two most widespread pine species in the country. The resin tapping season coincides with the growing season, from spring to autumn. Thus, growth and resin production may compete for carbon, although their response to environmental conditions can differ. This study investigates how the daily growth and biweekly resin production of P. pinaster and P. pinea in a mixed stand respond to environment over the 2021 growing season. During the resin tapping period, growth of both species showed a positive correlation with temperature, soil moisture, air relative humidity and radiation. Resin yield of both species showed a positive relation with soil temperature, and a negative relation with growth, suggesting a trade-off between growth and resin yield. Our results indicate that both growth and resin yield increase with temperature, with growth being more sensitive to soil moisture and relative humidity. Under a scenario of rising temperatures and precipitation reduction, both functions (growth and resin yield) are expected to be affected positively. However, resin production depends on carbon assimilation and allocation, both of which are reduced or altered during periods of extreme drought. This can lead to increasing competition for carbon allocation between growth, storage and resin yield, making resin yield responses to climate change scenarios uncertain.