Theoretical Perspectives of the Baltimore Ecosystem Study: Conceptual Evolution in a Social-Ecological Research Project

Conceptualizing the human drivers of low tree diversity in planted urban landscapes

Despite the abundance of tree diversity in the natural world, and generally high tree species richness in urban areas, urban forests continue to be dominated by a limited number of species. As socio-ecological systems, urban forests are shaped by historical and current management efforts and decision-making across a wide range of human actors. Drawing on past research, we offer a conceptual framework for describing the complex interactions among tree producers and consumers as trees are selected, grown, specified, and planted in private and public urban areas. We illustrate how multiple layers of selection criteria filter down the entirety of potential local tree diversity to a handful of commonly used and accepted tree species. We detail the actors and decision-makers who impact tree composition and diversity across several land types. Finally, we identify research, education, and outreach needs as they relate to creating more diverse and resilient urban forest ecosystems.

Dynamic and Heterogeneity of Urban Heat Island: A Theoretical Framework in the Context of Urban Ecology

The dynamic and heterogeneity of the urban heat island (UHI) is the result of the interactions between biotic, physical, social, and built components. Urban ecology as a transdisciplinary science can provide a context to understand the complex social–biophysical issues such as the thermal environment in cities. This study aimed at developing a theoretical framework to elucidate the interactions between the social–biophysical patterns and processes mediating UHI. To do it, we conducted a theoretical review to delineate UHI complexity using the concept of dynamic heterogeneity of pattern, process, and function in UHI phenomenon. Furthermore, a hypothetical heterogeneity spiral (i.e., driver-outcome spiral) related to the UHI was conceived as a model template. The adopted theoretical framework can provide a holistic vision of the UHI, contributing to a better understanding of UHI’s spatial variations in long-term studies. Through the developed framework, we can devise appropriate methodological approaches (i.e., statistic-based techniques) to develop prediction models of UHI’s spatial heterogeneity.

Detecting patterns of vertebrate biodiversity across the multidimensional urban landscape

Explicit characterisation of the complexity of urban landscapes is critical for understanding patterns of biodiversity and for detecting the underlying social and ecological processes that shape them. Urban environments exhibit variable heterogeneity and connectivity, influenced by different historical contingencies, that affect community assembly across scales. The multidimensional nature of urban disturbance and co-occurrence of multiple stressors can cause synergistic effects leading to nonlinear responses in populations and communities. Yet, current research design of urban ecology and evolutionary studies typically relies on simple representation of the parameter space that can be observed. Sampling approaches apply simple urban gradients such as linear transects in space or comparisons of urban sites across the urban mosaic accounting for a few variables. This rarely considers multiple dimensions and scales of biodiversity, and proves to be inadequate to explain observed patterns. We apply a multidimensional approach that integrates distinctive social, ecological and built characteristics of urban landscapes, representing variations along dimensions of heterogeneity, connectivity and historical contingency. Measuring species richness and beta diversity across 100 US metropolitan areas at the city and 1-km scales, we show that distinctive signatures of urban biodiversity can result from interactions between socioecological heterogeneity and connectivity, mediated by historical contingency.

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

Urban forested natural areas are an important component of the forest and tree canopy in northeastern United States urban areas. Although similar to native forests in surrounding regions in structure, composition, and function, these natural areas are threatened by multiple, co-occurring biological and climate stressors that are exacerbated by the urban environment. Furthermore, forests in cities often lack application of formal silvicultural approaches reliant upon evidence-based applied ecological sciences. These include both urban- and climate-adapted silvicultural techniques to increase the resilience and sustainability of native forests in cities. With this in mind, we convened a group of urban forest practitioners and researchers from along a latitudinal gradient in the northeastern United States to participate in a workshop focused on co-developing long-term, replicated ecological studies that will underlie the basis for potential silvicultural applications to urban forests. In this article we review the process and outcomes of the workshop, including an assessment of forest vulnerability, and adaptive capacity across the region, as well as shared management goals and objectives. We discuss the social and ecological challenges of managing urban oak-dominated mixed hardwood forests relative to non-urban forests and identify potential examples of urban- and climate-adapted silviculture strategies created by practitioners and researchers. In doing so, we highlight the challenges and need for basic and long-term applied ecological research relevant to silvicultural applications in cities.

Coproduction of place and knowledge for ecology with the city

Ecology with the city is a transdisciplinary pursuit, combining the work of researchers, policy makers, managers, and residents to advance equity and sustainability. This undertaking may be facilitated by understanding the parallels in two kinds of coproduction. First, is how urban systems themselves are places that are jointly constituted or coproduced by biophysical and social processes. Second, is how sustainable planning and policies also join human concerns with biophysical structures and processes. Seeking connections between coproduction of place and the coproduction of knowledge may help improve how urban ecology engages with diverse communities and urban interests in service of sustainability.