To counteract the effects of herbivores and pathogens, conifers have developed a sophisticated resin-based defensive system. Since defences are costly, trees must continuously accommodate defensive investment throughout plastic responses to environmental stimuli. However, the extent of such responses can differ at the intra-specific level (i.e. genetic variation in plasticity). Here we examined whether and to what extent year-to-year climate fluctuations, an important source of environmental heterogeneity during the trees' life, drive plasticity in defensive allocation of a widespread pine species. Specifically, we quantified interannual variation in resin duct production along a 31-year-period in 174 Pinus pinaster trees of nine range-wide populations grown in two common gardens in Central Spain. We aimed to explore (i) patterns of interannual variation (i.e., temporal plasticity) in resin duct production among populations and sites, (ii) whether such patterns are linked to plastic responses to interannual variation in climate conditions (i.e., climatic plasticity), and (iii) whether plastic responses to climate differ among populations (i.e., genetic variation in plasticity) and sites. We found large interannual plasticity in resin duct production (22.8 % of total variance), with temporal patterns differing among sites and populations. Climate conditions during the early growth period significantly affected the annual differentiation of resin ducts. Particularly, April precipitation had a positive overall effect on resin duct production. Inversely, warmer conditions in April had a negative effect but only in certain populations, which demonstrates genetic variation in climate sensitivity of resin duct formation. Despite significant effects of certain climate variables on annual resin duct production, climate only accounted for a small proportion of the total interannual variation (up to 3.8 % of interannual variation explained by climate factors). This suggests that alternative factors such as trade-offs with growth and temporal variation in biotic and non-climatic abiotic conditions likely contribute to explain interannual fluctuations in defensive investment.

为了抵消草食动物和病原体的影响，针叶树已经开发了一种基于树脂的高级防御系统。由于防御成本高昂，树木必须在对环境刺激的整个塑料反应中不断适应防御性投资。但是，这种反应的程度在种内水平上可能不同（即可塑性的遗传变异）。在这里，我们研究了树木生命过程中环境异质性的重要来源，逐年的气候波动是否以及在何种程度上驱动了广泛分布的松树物种的防御性分配的可塑性。具体而言，我们对174个Pinus pinaster沿31年的树脂导管生产的年际变化进行了量化在西班牙中部的两个常见花园中种植了九种范围广泛的种群的树木。我们旨在探讨（i）种群和地点之间树脂导管生产的年际变化模式（即时间可塑性），（ii）这种模式是否与对气候条件的年际变化的塑料响应（即气候可塑性）相关联， （iii）人口（即可塑性的遗传变异）和地点之间对气候的塑性响应是否不同。我们发现树脂导管生产中具有较大的年际可塑性（占总方差的22.8％），时间点在地点和种群之间存在差异。生长初期的气候条件显着影响了树脂导管的年度分化。特别是，四月份的降水对树脂管的生产产生了积极的总体影响。相反，4月份的暖化条件有负面影响，但仅对某些人群有负面影响，这表明遗传对树脂导管形成气候敏感性的变异。尽管某些气候变量对树脂导管的年产量有显着影响，但气候仅占总年际变化的一小部分（由气候因素解释，高达年际变化的3.8％）。这表明生物和非气候非生物条件的增长和时间变化之间的权衡取舍等替代因素可能有助于解释防御性投资的年际波动。尽管某些气候变量对树脂导管的年产量有显着影响，但气候仅占总年际变化的一小部分（由气候因素解释，高达年际变化的3.8％）。这表明生物和非气候非生物条件的增长和时间变化之间的权衡取舍等替代因素可能有助于解释防御性投资的年际波动。尽管某些气候变量对树脂导管的年产量有显着影响，但气候仅占总年际变化的一小部分（由气候因素解释，高达年际变化的3.8％）。这表明，生物和非气候非生物环境中的增长与时间变化以及权衡取舍等其他因素可能有助于解释防御性投资的年际波动。