Assessing patterns of oak regeneration and C storage in relation to restoration-focused management, historical land use, and potential trade-offs

Abstract

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.

Conceptualizing social-ecological drivers of change in urban forest patches

“…Others have examined patterns of change in forest patch size, shape, and number (Zipperer et al 2012), and have emphasized the importance of the urban landscape matrix to native and non-native species dispersal (Lopez et al 2018). Recent city or metropolitan region-wide approaches have yielded new insights such as indicating that land cover, land use histories, and pre-urban vegetation have lasting effects on ecosystem structure and function (e.g., Fahey et al 2012;Carter et al 2015;Fahey and Casali 2017).…”

“…Woods" of The Morton Arboretum in the suburban part of the Chicago metropolitan region and the relevant factors for assessing the socioecological system of urban forest patch propagule dynamics. For additional detail on the site and region see Fahey et al (2012), Carter et al (2015), and Fahey and Casali (2017) and between individual components. For example, the multilevel governance network component is comprised of many actors, relationships, and scales.…”

Distribution of forest ecosystems over two centuries in a highly urbanized landscape

“…The high canopy cover of these areas is a positive in some respects (such as providing shade for humans and other animals; Nowak et al, 2013), but is also likely a factor in the consistent lack of oak regeneration evident in the region (Carter et al, 2015;Fahey et al, 2014;Lorimer, 1993).…”

Testing the effect of restoration‐focused silviculture on oak regeneration and groundlayer plant communities in urban–exurban oak woodlands

“…Declines in oak regeneration will have cascading consequences for the future of these ecosystems and the foundational oak species which drive structure and function in the system (Dey 2014). Even in many presently oak‐dominated ecosystems, oak seedlings occur at relatively low densities and oak saplings and understory trees are exceedingly rare (Abrams 1992; Carter et al 2015; Dey & Kabrick 2015). Oak regeneration failures have been attributed to poor initial establishment and slow juvenile growth (Lorimer 1993; Brose & Rebbeck 2016) as well as a lack of seedling and sapling recruitment into the canopy in dense forest stands (Povak et al 2008).…”