a b s t r a c tRestoration of composition, structure, and function in oak dominated ecosystems is the focus of management in temperate forests around the world. Land managers focused on oak ecosystem restoration are challenged by the legacy effects of complex land-use histories, urbanization, climate change, and potential stakeholder response to management. Trade-offs may exist between managing forests for climate mitigation (e.g., maximizing C storage or sequestration) and promoting shade-intolerant species historically associated with frequent or high-severity disturbances. This study assessed the potentially conflicting goals of sustained live biomass accrual and increased oak regeneration in the East Woods Natural Area at The Morton Arboretum in Lisle, IL, USA. We evaluated how biomass trends and oak regeneration were related to management regimes, land-use history, current stand structure and composition, and topoedaphic factors. Our results indicated no significant trade-off between sustained live biomass accrual and oak regeneration. Live biomass was increasing across the landscape (biomass increment averaged 18,186 kg ha À1 yr À1 ) and was not strongly related to differences in management or land-use history. Oak regeneration was rare, especially beyond the seedling stage ($226 seedlings and 9 saplings ha À1 ) and was also not strongly related to recent management. Our results indicate that even 20+ years of annual prescribed burning combined with understory thinning has failed to produce the open canopy conditions and high light availability that are necessary for successful oak recruitment. The absence of any trade-offs between biomass accrual and oak regeneration may, therefore, be largely related to the ineffectiveness of current management for promoting oak regeneration. More intensive management utilizing canopy manipulations could produce greater trade-offs, but is likely necessary to establish and release oak regeneration.

Public gardens can help prevent detrimental effects of plant invasions by collecting and sharing data on taxa spreading from cultivation early in the invasion process, thereby acting as sentinels of plant invasion. Existing initiatives have called for public gardens to adopt measures preventing plant invasion, but it is unclear what actions individual gardens are implementing, as there is no formal mechanism for communicating their progress. This study used internal lists of escaping taxa from seven public gardens in the Midwestern United States and Canada to demonstrate how public gardens can collectively contribute data that is critical to assessing potential invasiveness. It also reveals methodological differences in how gardens develop their lists of escaping plants, leading to recommendations for standardization. Data pooled across gardens yielded 769 species spreading from cultivation at one or more gardens. Eight woody species were listed by all gardens despite not consistently being recognized as invasive by states and provinces containing the gardens; some species recorded by multiple gardens did not appear on any invasive lists. While it may be premature to call taxa escaping from cultivation at a few public gardens “invasive” or even “potentially invasive”, these plants should be monitored and evaluated with this information shared to facilitate stronger conclusions about risk. Thus, public gardens have a unique expertise in assisting invasive plant efforts as sentinels, particularly if challenges related to methodological inconsistencies and data sharing are suitably addressed, which is herein recommended through the adoption of a set of standardized guidelines.

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In the absence of periodic disturbance, primarily fire, many oak-dominated woodlands in the Eastern and Midwestern United States are transitioning to sugar maple (Acer saccharum) dominated communities. This experiment was conducted to determine the effects of forest overstory and/or understory removals on enrichment plantings of white oak (Quercus alba) and American hazelnut (Corylus americana). The combination of prescribed forest canopy openings and understory tree removal significantly increased mean twig elongation, an indicator of overall growth and vigor, of white oak as compared to control trees. A similar pattern was seen in the hazelnut, with the two treatments that included a group selection opening offering a significant growth advantage over the treatment which only included understory clearing. Group selection openings in this study were small (250 m2) compared to previously recommended canopy openings of 1,000 m2 or more, suggesting that oak and hazelnut regeneration may be enhanced without the dramatic visual impact of more intense silvicultural practices of clearcutting and shelterwood and when using large planting stock (> 1.5 m in height or 2.5 cm caliper for oak and 3-4 year old containerized hazelnut). As such, successful oak and hazelnut establishment and growth may be possible in intensively managed, frequently visited forest preserves where maintaining site aesthetics is a high priority.