Pando’s Pulse: Vital Signs Signal Course Correction at World-Renowned Aspen Forest

Upland aspen ( Populus spp. ) forests contribute significantly to biodiversity in their circumboreal role as keystone species. As aspen ecosystems flourish or diminish, myriad dependent species follow suit. The 43-hectare Pando aspen ( Populus tremuloides Michx.) clone in Utah, USA, is thought to be the largest living organism on earth, but is faltering due to chronic herbivory. Long-term resilience in aspen communities, including Pando, rests on successful recruitment of vegetative suckers that are nutritiously desirable to browsing ungulates. Here, I evaluate aspen reproduction alongside numerous vital indicators of Pando’s status in the first trend assessment of this embattled iconic forest. I measured 64 plots using 19 indicators to determine current conditions. Findings show that the genetically uniform Pando is “breaking up” because of herbivory and fencing. Initial successes within fenced zones are tempered by nearly half of Pando that remains unprotected from chronic wild and domestic herbivory. I propose a strategy of process-based stewardship informed by adaptive monitoring to restore this famed ‘one-tree forest.’ Lessons from Pando include linkages to struggling, often species rich, aspen systems facing similar challenges globally.