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.

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)

Each row is an individual tree. 

Column names and definitions (See Corona et al. 2022 for more information): 

Site: KDD or KPE

Species: WS = White spruce; BF = Balsam fir

Dead0_Alive1_2019: This indicates whether in July 2019 the tree was completely defoliated (no needles; classified as 'dead') or had green needles (classified as 'alive'). Note that trees had been monitored up to 2021, and no tree classified as 'dead' regained needles.

DBH_cm: Diameter at breast height, measured in centimetres.

CrownClass: We adapted crown classes from DeYoung and Sutton (2016) as an assessment of tree height relative to other trees in the stand, based on access to sunlight. Open grown (OP) trees either grew separated from other trees or had a crown that substantially surpassed (in height) the trees that surrounded it. Dominant (DO) were trees that were able to intercept more sunlight from the top and sides of the tree for most of the day than surrounding trees. Codominant (CO) trees were similar in height to surrounding trees and intercepted sunlight via the top of the crown for most of the day. Intermediate (IN) trees gather little sunlight through small gaps within the canopies of CO and DO trees in their respective populations. Overtopped (OV) were subcanopy trees that had little to no direct sunlight.