Earlier spring and earlier onset of growth, as a consequence of climate change, may expose trees and crops to increased risk of exposure to frost damage. In this study, we compare the frequency of frost rings in three regions [Porcupine Provincial Forest (PPF; north-latitude); Duck Mountain Provincial Forest (DMPF; mid-latitude) and Riding Mountain National Park (RMNP, south-latitude)] located in the Boreal Plains of interior North America. In each of PPF and DMPF, twenty upland black spruce [Picea mariana (Mill.) BSP] trees were sampled using stem analysis and others were sampled at breast height or below. In RMNP, multiple coniferous tree species were sampled at breast height or below to allow comparison among species. Results from stem analysis indicated that frost rings were more frequent in DMPF than PPF (north of DMPF). Frost rings identified up to a height of 16 m and were formed predominantly in the early cambial age zone. As a general pattern, frost rings recorded in PPF occurred more abundantly in years with warm April temperatures and this association was less prevalent in DMPF. Frost rings were formed following extreme frost events in late May - early June and frost-ring years corresponded to years with cooler June temperatures. A significant positive association was found between frost-ring frequency and the El Niño Southern Oscillation. In the absence of an early spring, black spruce trees were less affected by frost damages. Stem analysis provided a better record of spring frosts than solely sampling at breast height or below. The multi-species approach used in RMNP revealed many years with synchronous frost rings among species. The development of a large network of frost-ring chronologies from tree species of various age classes and/or from stem analysis will help with assessing the impact of late spring frosts on forest dynamics and to document large-scale climate anomalies in areas with low climate data coverage and/or prior to instrumental records.

由于气候变化，春季初春和生长较早开始可能使树木和农作物遭受霜冻危害的风险增加。在这项研究中，我们比较了三个地区[豪猪省森林（PPF;北纬）; 位于北美内陆的北方平原的鸭山省立森林（DMPF；中纬度）和骑马山国家公园（RMNP，南纬度）。在PPF和DMPF中，有二十个山地黑云杉[ Picea mariana（密西根州）[BSP]树木使用茎分析进行采样，而其他树木则在乳房高度以下进行采样。在RMNP中，从胸高或以下取样了多个针叶树种，以进行种间比较。茎分析的结果表明，DMPF中的霜环比PPF（DMPF的北部）更频繁。鉴定出的霜冻环最高达16 m，主要形成于冈比亚早期年龄带。作为一般模式，PPF中记录的霜冻环在4月温暖的年份中发生的次数较多，而这种关联在DMPF中不那么普遍。在五月下旬至六月初的极端霜冻事件后形成了霜冻环，霜冻环的年份对应于六月温度较低的年份。在霜环频率和厄尔尼诺南方涛动之间发现显着的正相关。在没有早春的情况下，黑云杉的树木受霜害的影响较小。与仅在乳房高度或更低的高度进行采样相比，干分析提供了更好的春季霜冻记录。RMNP中使用的多物种方法揭示了许多年，物种间出现了同步霜冻环。由不同年龄类别的树种和/或茎分析建立的大型霜环年表网络将有助于评估晚春霜冻对森林动态的影响，并记录低气候地区的大规模气候异常。数据覆盖范围和/或在工具记录之前。与仅在乳房高度或更低的高度进行采样相比，干分析提供了更好的春季霜冻记录。RMNP中使用的多物种方法揭示了许多年，物种之间出现了同步霜冻环。由不同年龄类别的树种和/或茎分析建立的大型霜环年表网络将有助于评估晚春霜冻对森林动态的影响，并记录低气候地区的大规模气候异常。数据覆盖范围和/或在工具记录之前。与仅在乳房高度或更低的高度进行采样相比，干分析提供了更好的春季霜冻记录。RMNP中使用的多物种方法揭示了许多年，物种间出现了同步霜冻环。由不同年龄类别的树种和/或茎分析建立的大型霜环年表网络将有助于评估晚春霜冻对森林动态的影响，并记录低气候地区的大规模气候异常。数据覆盖范围和/或在工具记录之前。