Differential defoliation and mortality of white spruce and balsam fir by Eastern spruce budworm

White spruce (Picea glauca) and Balsam fir (Abies balsamea) tree mortality data and tree characteristics recorded in July 2019 following an Eastern spruce budworm outbreak detected at two sites in northern Wisconsin, USA in 2014. These data were collected at the individual tree level, and include tree status, tree diameter at breast height (cm) and canopy class.

Methods
Dataset collection: Fieldwork was conducted in July 2019. We assessed the characteristics of a total of 113 individual white spruce and balsam fir trees across the two sites to determine if they were related to individual-level tree mortality (KDD: n = 34 white spruce, n = 26 balsam fir; KPE: n = 26 white spruce, n = 27 balsam fir). For each tree, we recorded its species, status (alive or dead), measured its diameter at breast height (DBH; with a minimum DBH cutoff for inclusion being 10 cm), and its crown class. We adapted crown classes (DeYoung and Sutton 2016) as an assessment of tree height relative to other trees in the stand, based on access to sunlight.

Dataset processing: Two trees were omitted from the analysed dataset because they had been cut down so canopy class data were not available. 

(see Corona et al 2022 for more information)

本数据集涵盖美国威斯康星州北部两处2014年监测到东部云杉芽虫暴发后，于2019年7月记录的白云杉（Picea glauca）与香脂冷杉（Abies balsamea）的树木死亡数据及树木特征。该数据集以单株林木为采集单元，包含树木存活状态、胸径（diameter at breast height, DBH，单位：厘米）及冠层等级（canopy class）信息。

方法

数据集采集：野外调查于2019年7月开展。我们对两处样地内共计113株白云杉与香脂冷杉的特征进行了评估，以分析其与单株树木死亡率的关联（KDD样地：白云杉34株、香脂冷杉26株；KPE样地：白云杉26株、香脂冷杉27株）。针对每株树木，我们记录了其物种、存活状态（存活或死亡），测量了胸径（DBH，纳入分析的最小胸径阈值为10厘米）及冠层等级。本研究参考DeYoung与Sutton（2016）的冠层等级划分标准进行调整，用于评估林木相对于林分内其他个体的树高及光照获取能力。

数据集处理：由于有2株树木已被砍伐，无法获取冠层等级数据，因此从分析数据集中将其剔除。

更多详细信息可参考Corona等人2022年的相关研究。