12 Steenberg et al: A Social-Ecological Analysis of Urban Tree Vulnerability impervious surfaces (e.g., commercial land uses), have higher rates of tree mortality and urban forest decline (Nowak et al. 2004; Lu et al. 2010). Cities are also characterized by high rates of commercial trade and shipping that can expose urban trees and forests to invasive insects and pathogens (Laćan and McBride 2008; Vander Vecht and Conway 2015), such as the emerald ash borer (Agrilus planipennis; EAB), Asian longhorned beetle (Anoplophora gla- bripennis; ALB), and butternut canker (Sirococcus clavigignenti-juglandacearum). These stressors and disturbances can be interactive and cumulative, and their ultimate effect on individual trees and urban for- est ecosystems is dependent on tree condition, spe- cies, age, and overall species and structural diversity. The influences of the human population and socio- economic variability on urban forest structure and function are complex, dynamic, and uncertain. There are a number of social stressors, ranging from vandal- ism and poor management practices, affecting indi- vidual trees (Lu et al. 2010; Jack-Scott et al. 2013; Koeser et al. 2013), to citywide issues of urban forest policy and governance affecting the maintenance of the entire urban forest resource (Conway and Urbani 2007). Furthermore, there is a growing body of research that has investigated the influence of the socioeconomic characteristics of residents and their association with urban forest condition as well as the spatial distribution of city trees and their provision of benefits (Grove et al. 2006; Jack-Scott et al. 2013; Shakeel and Conway 2014; Moskell et al. 2016). This research points to strong positive relationships between resident affluence and urban tree cover, where higher levels of resident income, education, and homeownership are spatially associated with urban tree cover. Moreover, several studies highlight direct relationships of these resident socioeconomic attributes with participation in urban forest steward- ship activities (Conway et al. 2011; Greene et al. 2011). Research investigating the rates and causes of tree mortality and declines in urban forest structure and function is an important resource for urban forest practitioners. The disciplines of ecology, urban plan- ning, and geography continue to explore the dynam- ics of urban forests and their relationship with human populations. However, there is a considerable knowl- edge gap on the combined effects of these stressors and their interaction with urban forest structure. ©2019 International Society of Arboriculture Moreover, there are comparatively few empirical field studies investigating the effects of socioeco- nomic variability on urban forest ecosystem decline. Vulnerability science can offer a useful theoretical framework for addressing these gaps and for bridging the potential contributions of different disciplines that investigate urban forests and their benefits (Steenberg et al. 2017a). Vulnerability science in social-ecological systems is a useful approach for exploring issues of sustainability and environmental change in both the- oretical and applied research (Turner et al. 2003; Füssel 2010). Examples of applied vulnerability research have ranged from agricultural systems and regional land-use change to arctic systems and climate change (Turner et al. 2003; Adger 2006). It was used in the recent development of an urban forest vulnerability framework (Steenberg et al. 2017a), where vulnera- bility is defined as the likelihood of decline in urban forest ecosystem service supply in response to stress, and is comprised of exposure, sensitivity, and adaptive capacity. Exposure refers to the magnitude, frequency, dura- tion, and spatial extent of stressors and disturbances that affect a system (Burton et al. 1993; Adger 2006). These are the external causes of tree decline and mor- tality associated with the urban environment. Sensi- tivity is the relative level of response by a system to stressors or disturbances, and is determined by intrin- sic characteristics of the system itself (Turner et al. 2003). Urban forest sensitivity is the internal struc- ture of urban tree species assemblages, such as spe- cies, size/age, condition, and diversity. Adaptive capacity is the capacity for a system to shift or alter its state to reduce its vulnerability or accommodate a greater range in its ability to function while stressed (Adger 2006; Füssel 2010). For urban forests, this refers to associated human populations and their behaviors regarding urban forest stewardship, as well as the environmental capacity for increasing and maintaining tree cover. By shifting research focus away from external agents of stress and disturbance only (i.e., impacts-only research), vulnerability analysis may allow for a more comprehensive and integrative mechanism for assessing urban forest structure, func- tion, and change. The purpose of this study is to explore the pro- cesses of urban forest vulnerability for trees in the public right of way in a residential neighborhood. Specifically, a conceptual framework of urban forest
January 2019
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
