Study site
We used archived increment cores that were collected as part of a study
of forest responses to bark beetle attack during the summers of
2005-2007 on the Markagunt Plateau in southern Utah, located on the
western edge of the Colorado Plateau (see DeRose and Long 2012a, 2012b;
Table 1, Fig. 3). Prior to a D. rufipennis outbreak in the 1990s
that killed over ninety-five percent of overstory P. engelmannii(DeRose and Long 2007; DeRose et al. 2017), these forests were dominated
by P. engelmannii and Abies lasiocarpa and included
smaller components of Populus tremuloides or Pseudotsuga
menziesii (Appendix S1: Fig. S2). Our six study sites were distributed
across the plateau, ranged in elevation from 3202 to 2879 m, and ranged
in pre-outbreak P. engelmannii basal area from 91.3% to 55.5%
(Appendix S1: Table S1). Plots were located in areas representative of
the larger forest matrix where trees were killed that spanned all slopes
and aspects across the plateau.