Effects of post-windthrow management interventions on understory plant communities in aspen-dominated boreal forests
Forest Ecology and Management
Understory plants are critical to diversity and ecosystem function in boreal forests. Significant advances have been made in understanding understory vegetation dynamics following fire and clearcutting but the effect of stand-replacing windthrow on understory plant abundance, diversity, and composition, especially when followed by management interventions such as salvage logging and forest renewal, is poorly understood. We examined herbaceous and woody understory plant communities in aspen stands in the first 5 years following stand-replacing windthrow and subsequent salvage logging and forest renewal operations. Five windthrow–renewal options were included: windthrow (W), windthrow–salvage (WS), windthrow–salvage–windrow (planting) (WSW), and windthrow–salvage–windrow (planting)–herbicide application (WSWH). The understory vegetation in these treatment plots was compared with that in a typical clearcut (C) (without post-harvest management interventions). The windthrow created understory communities that generally had higher Shannon diversity index and species evenness values, but lower percent cover than those in the C; species richness, however, did not differ between W and C treatments. Low intensity salvage logging (WS) in winter did not affect understory plant species cover, richness, Shannon diversity index, or evenness values compared to those in non-salvage logged areas (W). Community composition, however, differed due to increases in some herbaceous species, shrubs, and deciduous trees and damage to advanced growth conifers during the salvage logging operation. Similar treatment effects were also found for WSW. The herbicide application after planting (WSWH) significantly reduced woody cover and increased herbaceous plant species richness. Our results demonstrated that post-windthrow management interventions influenced understory community composition, with the effects of herbicide application being strongest. The changes in understory composition have significant implications to long-term stand structure and composition. We expect increasing abundance of conifers from advanced growth in the W treatment areas to planted trees in the WSW and WSWH treatment areas and of deciduous trees from WS and WSW to C treatment areas.
Schafer, A., R. Man, H. Y. Chen, and P. Lu. 2014. Effects of post-windthrow management interventions on understory plant communities in aspen-dominated boreal forests. Forest Ecology and Management 323:39-46.