Abstract Coarse woody debris (CWD; i.e. downed limbs and boles) serves numerous ecosystem functions, which vary according to the degree of decay. CWD decay is often described using five categories based on readily observed physical characteristics ranging from freshly fallen (Class I) to advanced decay with little structural integrity (Class V). Though useful in categorizing downed wood in a forest, these categories do not necessarily provide information about time since death or the decay process. Dendrochronology can be used to assign death dates to CWD and begin to provide a temporal description of the decay process. We used standard dendrochronological techniques to determine the death dates of 94 CWD samples from five common hardwood taxa in southern Indiana. Across taxa, the time since death of Class I (1.4 ± 1.7 years; mean ± SD; least decayed class) was significantly shorter than Class II (5.2 ± 3.6 years), which was shorter than the more decayed classes (Class III: 11.5 ± 4.9, and Class IV: 11.2 ± 5.6 years). Within this general trend, time since death within a decay class varied greatly among taxa. Combining dendrochronology techniques with visual decay characteristics can improve our understanding of CWD's role and provide a more precise timeline for biomass and nutrient turnover within forested systems.

中文翻译：

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确定中央硬木地区（美国印第安纳州）多种树种的粗木屑的死亡日期

摘要 粗木屑（CWD；即倒下的树枝和木茎）具有多种生态系统功能，其功能因腐烂程度而异。CWD 衰减通常使用五个类别来描述，这些分类基于容易观察到的物理特征，范围从刚掉落的（I 级）到结构完整性很少的高级衰减（V 级）。虽然对森林中倒下的木材进行分类很有用，但这些类别不一定提供关于死亡或腐烂过程的时间信息。树木年代学可用于为 CWD 分配死亡日期，并开始提供衰变过程的时间描述。我们使用标准的树木年代学技术来确定来自印第安纳州南部五个常见硬木分类群的 94 个 CWD 样本的死亡日期。在整个分类群中，I 类死亡后的时间（1.4 ± 1.7 年；平均值 ± SD；最少腐烂的等级）明显短于 II 类（5.2±3.6 年），后者比腐烂程度更高的等级（III 类：11.5±4.9 年，IV 类：11.2±5.6 年）短。在这个总体趋势中，一个衰变类中的死亡时间在不同分类群之间差异很大。将树木年代学技术与视觉衰减特征相结合，可以提高我们对 CWD 作用的理解，并为森林系统内的生物量和养分周转提供更精确的时间表。