ABSTRACT When using old-growth trees from semiarid, open-canopy environments, basal area increment (BAI), an absolute measure of radial growth, is sometimes used instead of the more commonly used ‘conservative techniques’ (negative exponential or linear regression with a negative slope; NegX) because narrow rings have been shown to potentially bias results. In this study we explore the relationship between radial growth of ponderosa pine from four study sites in Montana and climate (temperature, precipitation, drought severity) using unstandardized raw ring width and BAI values, and standardized values generated via Friedman Super Smoother and NegX. All sites are minimally disturbed, and our selection criteria are limited to older (interior dates pre-A.D. 1850 at breast height) trees growing in open-canopy environments free of visible disturbance such as lightning strikes. We found the strongest relationships (r > 0.60) for radial growth with July and prior-year October Palmer Drought Severity Index values. Our results show that radial growth-climate responses generally fall within a narrow range regardless of the representation of annual growth (e.g. for July temperature r-values are largely –0.3 to – 0.4) and that site conditions determine which radial-growth values (i.e. unstandardized or standardized) optimize climate-growth responses.

中文翻译：

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使用多种测量年径向生长的松树对气候生长的响应

摘要 当使用来自半干旱、开放冠层环境的老树时，基面积增量 (BAI) 是径向生长的绝对量度，有时会代替更常用的“保守技术”（负指数或线性回归）负斜率；NegX）因为窄环已被证明可能会使结果产生偏差。在这项研究中，我们使用未标准化的原始环宽和 BAI 值，以及通过 Friedman Super Smoother 和 NegX 生成的标准化值，探讨了蒙大拿州四个研究地点的黄松径向生长与气候（温度、降水、干旱严重程度）之间的关系。所有站点都受到最小程度的干扰，我们的选择标准仅限于较旧的（公元前的内部日期）1850 胸高）树木生长在开放的树冠环境中，没有雷击等可见干扰。我们发现径向增长与 7 月和去年 10 月帕尔默干旱严重程度指数值之间的关系最强 (r > 0.60)。我们的结果表明，径向生长气候响应通常落在一个狭窄的范围内，而不管年增长的表现如何（例如，7 月的温度 r 值主要是 –0.3 到 – 0.4），并且场地条件决定了哪些径向生长值（即非标准化或标准化）优化气候增长响应。