DOI: 10.5061/dryad.7sqv9s4sh
title: Data from: Rocky Mountain forests are poised to recover following bark beetle outbreaks, but with altered composition

description: Amplified by warming temperatures and drought, recent outbreaks of native
 bark beetles (Curculionidae: Scolytinae) have caused extensive tree
 mortality throughout Europe and North America. Despite their ubiquitous
 nature and important effects on ecosystems, forest recovery following such
 disturbances is poorly understood, particularly across regions with
 varying abiotic conditions and outbreak effects. To better understand
 post-outbreak recovery across a topographically complex region, we
 synthesized data from 16 field studies spanning subalpine forests in the
 Southern Rocky Mountains, USA. From 1997 to 2019, these forests were
 heavily affected by outbreaks of three native bark beetle species
 (Dendroctonus ponderosae, Dendroctonus rufipennis, and Dryocoetes
 confusus). We compared pre- and post-outbreak forest conditions and
 developed region-wide predictive maps of post-outbreak (1) live basal
 areas, (2) juvenile densities, and (3) height growth rates for the most
 abundant tree species – aspen (Populus tremuloides), Engelmann spruce
 (Picea engelmannii), lodgepole pine (Pinus contorta), and subalpine fir
 (Abies lasiocarpa). Beetle-caused tree mortality reduced the average
 diameter of live trees by 28.4% (5.6 cm), and species dominance was
 altered on 27.8% of field plots with shifts away from pine and spruce.
 However, most plots (82.1%) are likely to recover towards pre-outbreak
 tree densities without any additional regeneration. Region-wide maps
 indicated that fir and aspen, non-host species for bark beetle species
 with the most severe effects (i.e., Dendroctonus spp.), will benefit from
 outbreaks through greater post-outbreak basal areas and higher juvenile
 densities. After accounting for individual size, height growth rates for
 all conifer species were more rapid in sites with low winter precipitation
 and high outbreak severity. Synthesis: In subalpine forests of the US
 Rocky Mountains, recent outbreaks of three bark beetle species have driven
 reductions in tree sizes and shifts in species composition. While eventual
 recovery of the pre-outbreak forest structure is likely in most places,
 shifts in species composition may persist for decades. Still, forest
 communities following bark beetle outbreaks are widely variable due to
 differences in pre-outbreak conditions, outbreak severity, and abiotic
 gradients. This regional variability has critical implications for
 ecosystem services and susceptibility to future disturbances.
description: This archive includes field data (969 field plots) and spatial
 data (regionwide predictive maps) describing subalpine forest stand
 structure and composition following bark beetle outbreaks throughout the
 Southern Rocky Mountains Ecoregion (EPA Level III Ecoregion #21) in
 Colorado, New Mexico, and Wyoming, USA. See
 "README.md" for information about datasets and their
 collection.
description: We place no restrictions on the use of these data. We encourage
 researchers interested in using these data to reach out to the original
 collectors of each dataset - contact information is provided in
 "README.md".