Abstract The blue intensity (BI) technique provides opportunities to obtain surrogates to tree-ring density for reconstructing summer temperatures in high-latitude regions. In this study, we compare latewood BI (LBI) and delta BI (DBI), with the conventional X-ray maximum latewood density (MXD) and tree-ring width (TRW) data using 178 living trees of black spruce (Picea mariana (Mill.) B.S.P.), one of the most dominant species of conifers in the Northern Hemisphere, from 17 sites across the eastern Canadian taiga. The regional LBI and DBI chronologies are highly correlated to that of MXD (Pearson’s r = 0.97 and 0.92, respectively), while DBI is also similar to TRW (Pearson’s r = 0.67). Both LBI and DBI exhibit stronger responses to the May–August temperatures than TRW over larger time and spatial scales. However, only DBI is comparable to MXD data from inter-annual to decadal timescales. Low-frequency components of LBI data are likely distorted by color biases even if no obvious discoloration is present, as well as by the potentially low measurement resolution, leading to an overall weaker temperature sensitivity compared to the MXD data. Resampling experiments suggest that a minimum replication of 10 trees is needed to retain ≥90% of the optimal temperature signal for MXD, LBI, and DBI data, and a minimum of 20 trees is required for TRW data.

中文翻译：

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加拿大东部针叶林活体黑云杉的蓝色强度、最大晚材密度和年轮宽度数据的温度敏感性

摘要 蓝色强度 (BI) 技术提供了获得树木年轮密度替代值以重建高纬度地区夏季温度的机会。在这项研究中，我们使用 178 棵黑云杉 (Picea mariana) 活树将晚材 BI (LBI) 和 delta BI (DBI) 与传统的 X 射线最大晚材密度 (MXD) 和树轮宽度 (TRW) 数据进行比较。 Mill.) BSP)，北半球最主要的针叶树种之一，来自加拿大东部针叶林的 17 个地点。区域 LBI 和 DBI 年表与 MXD 高度相关（分别为 Pearson 的 r = 0.97 和 0.92），而 DBI 也与 TRW 相似（Pearson 的 r = 0.67）。在更大的时间和空间尺度上，LBI 和 DBI 对 5 月至 8 月的温度表现出比 TRW 更强的响应。然而，只有 DBI 可与从年际到十年时间尺度的 MXD 数据相媲美。即使不存在明显的变色，LBI 数据的低频分量也可能因颜色偏差以及潜在的低测量分辨率而失真，从而导致与 MXD 数据相比整体温度敏感性较弱。重采样实验表明，MXD、LBI 和 DBI 数据至少需要 10 棵树的复制才能保留 ≥90% 的最佳温度信号，TRW 数据至少需要 20 棵树。