Advancing management of urban forested natural areas: toward an urban silviculture?

Abstract

Cities worldwide are engaging in large-scale greening projects motivated by the wide range of documented ecological, economic, and social benefits of urban forests. Urban forested natural areas are a critical component of the total urban forest but are often overlooked and typically lack formal management frameworks. One approach to addressing this deficiency may be to borrow from traditional ecological management frameworks and practices (that is, silviculture). Although urban forested natural areas share similarities with rural forests, the impacts of urbanization on forest stand dynamics may require modification of these methods and in some cases development of novel silvicultural guidelines. We present an urban silviculture framework through which we synthesize emerging research and identify challenges and opportunities for advancing goal setting, assessments, and on-theground management strategies. Adapting silvicultural practices to cities can improve the long-term sustainability of urban forests and establish management approaches that address future conditions in forests across the urban-rural continuum.

Climate Adaptive Silviculture for the City: Practitioners and Researchers Co-create a Framework for Studying Urban Oak-Dominated Mixed Hardwood Forests

“…Such areas are especially valuable in cities because of the local ecosystem services they provide, such as access to high quality recreational greenspace for residents. However, even "good woods" in urban areas typically have limited natural regeneration of native tree species, high pressures of herbivory from deer, and high pollutant loading all resulting in a dissimilarity between the mature canopy and seedling composition (e.g., Pregitzer et al, 2019b;Piana et al, 2021b). As a result, today's "good woods" are vulnerable to future disturbance, such as windthrow and pests, and may become tomorrow's invaded forest gaps.…”

“…These long-term experiments have informed forest management practice and environmental policy for decades. Inspired in part by the experimental forests, a growing body of work examining specific dynamics of forests in urban settings provides the basis for urban silviculture (Schuler and Forrest, 2008;Pregitzer et al, 2019a;Sonti et al, 2019;Piana et al, 2021b;Zukswert et al, 2021). Also, at a broader scale, frameworks are being developed for adapting urban forests to climate change (e.g., Brandt et al, 2016) and efforts are emerging in other cities that test silvicultural strategies to adapt to a changing climate (e.g., Hammes et al, 2020;Pastick et al, 2021).…”

“…Specifically, Urban Forested Natural Areas (UFNA's) are of particular importance for cities in forested biomes. The socio-ecological contexts of these urban greenspace types have only recently been defined (e.g., Pregitzer et al, 2019a;Johnson et al, 2020;Piana et al, 2021a) and can be similar to non-urban native forests in composition, structure, and function (e.g., Pregitzer et al, 2019b;Piana et al, 2021b).…”

“…For example, not all traditional silvicultural practices may be practical or possible in UFNA's (e.g., prescribed burn, harvesting, use of herbicides, limited deer control options) given the social-ecological context, including policy, law, and/or public perception of these greenspaces. However, the primary issue is that though many of the same problems in urban natural areas are faced in non-urban areas (e.g., climate change, invasive pests and plants, deer herbivory, aging canopy, and pollutants), they are under greater interacting extremes from these stressors because of much greater fragmentation, higher chronic levels of disturbance, and the ever-present urban heat island effect (e.g., Hellmann et al, 2010;IPCC, 2019;Johnson et al, 2020;Trammell et al, 2020;Piana et al, 2021b). Urban Forested Natural Areas currently face more extreme conditions (Gill et al, 2007;Kirshen et al, 2008) that our more rural forests might experience in the future (Carreiro and Tripler, 2005).…”

Diverging conditions of current and potential future urban forest patches

“…A source of this confusion is likely due to the fact that urban forests—similar to their rural counterparts—may represent a range of forest types and conditions. For example, whereas studies in rural forests are typically stratified by age, past land use, forest type, and so on, urban forests are more often examined as a single “urban” forest type (Piana et al, 2021). Yet, urban forested natural areas, like their rural counterparts, represent a range of conditions, land‐use histories, and sizes making city‐scale studies with stratified sampling designs critical to understanding this variation (see Pregitzer et al, 2019).…”