Data from: Trade-offs between growth rate, tree size and lifespan of mountain pine (Pinus montana) in the Swiss National Park

A within-species trade-off between growth rates and lifespan has been observed across different taxa of trees, however, there is some uncertainty whether this trade-off also applies to shade-intolerant tree species. The main objective of this study was to investigate the relationships between radial growth, tree size and lifespan of shade-intolerant mountain pines. For 200 dead standing mountain pines (Pinus montana) located along gradients of aspect, slope steepness and elevation in the Swiss National Park, radial annual growth rates and lifespan were reconstructed. While early growth (i.e. mean tree-ring width over the first 50 years) correlated positively with diameter at the time of tree death, a negative correlation resulted with lifespan, i.e. rapidly growing mountain pines face a trade-off between reaching a large diameter at the cost of early tree death. Slowly growing mountain pines may reach a large diameter and a long lifespan, but risk to die young at a small size. Early growth was not correlated with temperature or precipitation over the growing period. Variability in lifespan was further contingent on aspect, slope steepness and elevation. The shade-intolerant mountain pines follow diverging growth trajectories that are imposed by extrinsic environmental influences. The resulting trade-offs between growth rate, tree size and lifespan advance our understanding of tree population dynamics, which may ultimately improve projections of forest dynamics under changing environmental conditions.

目前已在多个树木类群中观测到物种内生长速率与寿命间的权衡关系，但该权衡是否同样适用于不耐荫树种（shade-intolerant tree species），仍存在一定不确定性。本研究的核心目标为探究不耐荫山地松的径向生长（radial growth）、树木体量与寿命之间的关联。研究针对瑞士国家公园内沿坡向、坡度与海拔梯度分布的200株枯立山地松（Pinus montana），重建了其年径向生长速率与寿命。结果显示：幼龄期生长（即树木前50年的平均年轮宽度（tree-ring width））与树木死亡时的直径呈正相关，却与寿命呈负相关——换言之，生长较快的山地松会面临以早夭为代价换取大直径的权衡关系；而生长缓慢的山地松虽可获得较大体量与较长寿命，却存在体型较小时便过早死亡的风险。生长期内的幼龄期生长与气温、降水量并无关联。寿命的变异程度还进一步受坡向、坡度与海拔的调控。不耐荫的山地松会呈现出由外界环境因素塑造的差异化生长轨迹。本次研究揭示的生长速率、树木体量与寿命间的权衡关系，深化了我们对树木种群动态的认知，最终或可提升环境变化背景下森林动态预测的准确性。