1. 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.
2. 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).
3. 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.
4. 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.

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.

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".