Irrigation and fertilization as tools to boost growth stability of stone pine (Pinus pinea L.) plantations

Abstract

Pinus pinea is a Mediterranean species that has been found to grow and develop vigorously in Chile. This species is resistant to drought; however, it has been found to be sensitive to increasing aridity. A few studies have reported the effects of irrigation and fertilization on growth, but no detailed studies have considered the effects of both management techniques to improve growth stability. In this work, daily stem diameter variations (SDVs) in stone pine were monitored for a whole growth year using digital dendrometers in a 31-year-old plantation in Chile. Four management practices were assessed as tools to boost growth: fertilization, irrigation, their combination, and control. Daily growth series showed a marked synchronicity among trees of different management schemes. The combined treatment (fertilization and irrigation) resulted in a 25% longer growing period and greater growth than the control. During the fastest stem growth period, daily diameter increments were, on average, 0.06 mm for fertilized and irrigated trees, and 0.02 mm for control trees. Significant correlations between the standardized SDVs and series of climate variables were found, showing that untreated trees had the highest sensitivity to extreme temperature, rainfall, and potential evapotranspiration. Variability in daily stem diameter growth of fertilized and irrigated trees was correlated only to minimum temperature. The results highlight the importance of fertilization and irrigation in stone pine plantations to enhance diameter growth and reduce variability due to the sensitivity to environmental conditions.