Understory plant species composition 30–50 years after clearcutting in southeastern Wyoming coniferous forests

Abstract

To evaluate the long-term effects of clearcutting and slash treatment on understory plant species composition in Rocky Mountain coniferous forests, we collected comparable data from 30- to 50-year-old post-harvest stands and adjacent mature (>100-year-old) stands that originated after wildfire. In general, plant species richness was higher in the post-harvest stands than in adjacent mature stands, due in large part to the presence of species that benefit from disturbance. Species composition in post-harvest and mature stands was more similar in montane forests (2710–2805 m elevation) than in subalpine forests (2800–3164 m elevation), suggesting greater resilience of montane understories. Composition in post-harvest and mature stands was least similar when slash was piled and burned, and most similar when slash was lopped and scattered. Eighty-seven percent of the post-harvest stands had at least one exotic species, but total cover of exotic plant species in all post-harvest stands was ≤1%. Exotic species were largely absent from mature forests. Our results suggest that understory species of low-elevation montane forests recover more quickly from disturbance than do those of subalpine forests, with slash treatment and species life history traits strongly influencing this recovery.