Tree-ring stable isotopes are typically measured in latewood cellulose to mitigate potential carry-over effects from previous year storage pools. The isotopic composition of individual tree-ring segments is thought to include considerable intra-annual variability. This sampling strategy may be complicated by steep intra-annual isotope gradients that can rival the inter-annual variability, however. Consistent sampling of latewood material may not always be possible due to low sample availability or high prevalence of narrow rings or low amounts of latewood because of species-specific changes in ring width. Therefore, years that contain samples with higher portions of non-latewood (earlywood) material may influence the final chronology of isotopic variability. Here, we analyze the potential influence that changing earlywood and latewood components of individual tree rings can have on stable carbon and oxygen records from Quercus spp. and Pinus heldreichii chronologies. Analysis of stable isotopes in oak tree rings with varying amounts of latewood show no statistically significant differences in the range of isotopic composition, nor any major differences when considering the same calendric year. Similar results were found for the pine data, when comparing stable isotope measurements with earlywood-to-latewood ratio and maximum density. We argue that this simple approach should be applied to any long-term tree-ring stable isotope record in order to provide a better understanding of the potential biases that could arise from previously recorded intra-annual variability in the wood.

通常在晚材纤维素中测量树木年轮稳定同位素，以减轻前一年储存池的潜在残留影响。各个树木年轮片段的同位素组成被认为包括相当大的年内变化。然而，这种采样策略可能会因年内同位素梯度陡峭而变得复杂，该梯度可以与年际变化相媲美。由于样品可用性低或窄年轮普遍存在，或由于年轮宽度因物种特定的变化而导致晚材含量低，因此不一定总是能够对晚材材料进行一致的采样。因此，包含非晚材（早材）材料比例较高的样品的年份可能会影响同位素变异性的最终年代。在这里，我们分析了单个树木年轮的早材和晚材成分的变化对栎属植物稳定碳和氧记录的潜在影响。和松树年表。对晚材含量不同的橡树年轮中的稳定同位素分析表明，同位素组成范围没有统计学上的显着差异，考虑到同一历年也没有任何重大差异。当将稳定同位素测量值与早材与晚材比率以及最大密度进行比较时，松树数据也发现了类似的结果。我们认为，这种简单的方法应该应用于任何长期树木年轮稳定同位素记录，以便更好地理解先前记录的木材年内变化可能产生的潜在偏差。