Influence of silvicultural practices in northern hardwood forests on a long-lived perennial herb, Trillium cernuum L

• Published in: Forest ecology and management 2023-10, Vol.545, p.121282, Article 121282
• Main Authors: Webster, Christopher R., Burton, Julia I., Dickinson, Yvette L.
• Format: Article
• Language: English
• Subjects: Deer herbivory; Herbaceous layer; Scarification; Shelterwood; Single-tree selection
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/j.foreco.2023.121282

•Trillium cernuum was resilient to silvicultural treatments.•Scarification achieved in our study left most plants undisturbed.•Directly monitoring populations may be necessary to quantify treatment effects. Contemporary and predicted declines in tree species diversity and forest resilience have prompted renewed interest in even-aged systems and/or site preparation to overcome bottlenecks to tree recruitment or facilitate range expansion of future-adapted species. The impact of this intensification on the herbaceous layer in forests traditionally managed with uneven-aged systems, however, is unclear, especially for uncommon dispersal limited species with heterogenous distributions. We leveraged a large-scale experiment (the Northern Hardwood Silvicultural Experiment to Enhance Diversity) to investigate the response of Trillium cernuum L., a somewhat uncommon and heterogeneously distributed non-clonal herb in our study system, to a gradient of canopy removal and soil disturbance. We monitored 16 small populations from 2015 (the year prior to treatment) to 2019 (3-years post treatment). Our results suggest that initial population size and stage structure were inextricably coupled with T. cernuum response. Independent of treatment, T. cernuum abundance and flowering generally increased over time commensurate with initial population size. Moreover, our study highlights the confounding effect of deer herbivory, which increased significantly following treatment. Collectively, our findings suggest that T. cernuum populations were resilient to canopy disturbance associated with single-tree selection and shelterwood harvests and the levels of scarification applied as part of our study. Higher levels of site impact or other site preparation methods such as herbicides will likely have greater impacts and warrant further investigation. Our results also suggest that directly monitoring populations of interest may be necessary to quantify treatment effects for uncommon and/or heterogenous species that are missed with common plot-based sampling designs or of conservation concern.