Health and climate related ecosystem services provided by street trees in the urban environment

Published onlineJournal ArticleUrban tree planting initiatives are being actively promoted as a planning tool to enable urban areas to adapt to and mitigate against climate change, enhance urban sustainability and improve human health and well-being. However, opportunities for creating new areas of green space within cities are often limited and tree planting initiatives may be constrained to kerbside locations. At this scale, the net impact of trees on human health and the local environment is less clear, and generalised approaches for evaluating their impact are not well developed.In this review, we use an urban ecosystems services framework to evaluate the direct, and locally-generated, ecosystems services and disservices provided by street trees. We focus our review on the services of major importance to human health and well-being which include 'climate regulation', 'air quality regulation' and 'aesthetics and cultural services'. These are themes that are commonly used to justify new street tree or street tree retention initiatives. We argue that current scientific understanding of the impact of street trees on human health and the urban environment has been limited by predominantly regional-scale reductionist approaches which consider vegetation generally and/or single out individual services or impacts without considering the wider synergistic impacts of street trees on urban ecosystems. This can lead planners and policymakers towards decision making based on single parameter optimisation strategies which may be problematic when a single intervention offers different outcomes and has multiple effects and potential trade-offs in different places.We suggest that a holistic approach is required to evaluate the services and disservices provided by street trees at different scales. We provide information to guide decision makers and planners in their attempts to evaluate the value of vegetation in their local setting. We show that by ensuring that the specific aim of the intervention, the scale of the desired biophysical effect and an awareness of a range of impacts guide the choice of i) tree species, ii) location and iii) density of tree placement, street trees can be an important tool for urban planners and designers in developing resilient and resourceful cities in an era of climatic change

Opinion: Why Protect Nature? Rethinking Values and the Environment

A cornerstone of environmental policy is the debate over protecting nature for humans’ sake (instrumental values) or for nature’s (intrinsic values) (1). We propose that focusing only on instrumental or intrinsic values may fail to resonate with views on personal and collective well-being, or “what is right,” with regard to nature and the environment. Without complementary attention to other ways that value is expressed and realized by people, such a focus may inadvertently promote worldviews at odds with fair and desirable futures. It is time to engage seriously with a third class of values, one with diverse roots and current expressions: relational values. By doing so, we reframe the discussion about environmental protection, and open the door to new, potentially more productive policy approaches

Clumpy galaxies in CANDELS. II. Physical properties of UV-bright clumps at 0.5 ≤ z < 3

Studying giant star-forming clumps in distant galaxies is important to understand galaxy formation and evolution. At present, however, observers and theorists have not reached a consensus on whether the observed "clumps" in distant galaxies are the same phenomenon that is seen in simulations. In this paper, as a step to establish a benchmark of direct comparisons between observations and theories, we publish a sample of clumps constructed to represent the commonly observed "clumps" in the literature. This sample contains 3193 clumps detected from 1270 galaxies at $0.5\leqslant z\lt 3.0$. The clumps are detected from rest-frame UV images, as described in our previous paper. Their physical properties (e.g., rest-frame color, stellar mass (M*), star formation rate (SFR), age, and dust extinction) are measured by fitting the spectral energy distribution (SED) to synthetic stellar population models. We carefully test the procedures of measuring clump properties, especially the method of subtracting background fluxes from the diffuse component of galaxies. With our fiducial background subtraction, we find a radial clump U − V color variation, where clumps close to galactic centers are redder than those in outskirts. The slope of the color gradient (clump color as a function of their galactocentric distance scaled by the semimajor axis of galaxies) changes with redshift and M* of the host galaxies: at a fixed M*, the slope becomes steeper toward low redshift, and at a fixed redshift, it becomes slightly steeper with M*. Based on our SED fitting, this observed color gradient can be explained by a combination of a negative age gradient, a negative E(B − V) gradient, and a positive specific SFR gradient of the clumps. We also find that the color gradients of clumps are steeper than those of intra-clump regions. Correspondingly, the radial gradients of the derived physical properties of clumps are different from those of the diffuse component or intra-clump regions

Filling the void : struggles over implementing freshwater policy in Aotearoa New Zealand

This dissertation analyzes how the implementation of environmental policy is shaped by struggles over interpretation. Policy implementation is not a linear or mechanistic process, but is influenced by the subjective interpretation of policy concepts and how those relate to implementation practices. At the same time, however, not all interpretations are equal, and some are more influential than others. While there may be an initial ‘institutional void’ in which many interpretations are considered legitimate, political actors will attempt to structure this void by narrowing down the range of acceptable policy interpretations. The following chapters investigate how actors attempt to structure the institutional void of policy implementation. Chapter 2 situates the meaning of freshwater policy within historical debates about freshwater and its connection to colonial, biophysical, economic, and regulatory problems. Chapters 3-5 explore how three sets of actors engage in interpretive channelization by crafting and circulating their preferred interpretations of policy concepts in the implementation process. The state uses a diverse menu of regulatory and non-regulatory mechanisms to require and guide local authorities to implement policy in a certain way. Local governments face unique circumstances and must narrate the policy requirements into alignment with the interests of local organizations. Non-state experts such as intermediaries can augment local government interpretations by providing research and technical advice, but can also engage antagonistically by challenging interpretations in court or by using spatial inter-referencing to weaken the power of specific interpretations. By treating the implementation of policy as amenable to political struggle, a clearer political diagnosis of opportunities and constraints can be conducted. Within each of the channelizing processes described here, both constraint and opportunity exist: even a neoliberal government must respond to public aspirations for water; politicians influence but cannot completely control bureaucrats within the state apparatus; local governments experience progressive as well as conservative contextual forces; and expert intermediaries can be champions of decolonization and not just advocates of cost-minimization. While the contours of opportunity and constraint will be unique for each policy context, it is crucial to attend to both together if we want to realize environmental justice in practice.Arts, Faculty ofGeography, Department ofGraduat

Getting the measure of nature: the inconspicuous geopolitics of environmental measurement

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Making sense of environmental values: a typology of concepts

Debates about environmental values and valuation are perplexing, in part because these terms are used in vastly different ways in a variety of contexts. For some, quantifying human and ecological values is promoted as a useful technical exercise that can support decision-making. Others spurn environmental valuation, equating it with reducing ethics to numbers or "putting a price tag on nature." We make sense of these complexities by distilling four fundamental concepts of value (and valuation) from across the literature. These four concepts - value as a magnitude of preference, value as contribution to a goal, values as individual priorities, and values as relations - entail fundamentally different approaches to environmental valuation. Two notions of values (as magnitudes of preference or contributions to a goal) are often operationalized in technical tools, including monetary valuation, in which experts tightly structure (and thus limit) citizen participation in decision-making. This kind of valuation, while useful in some contexts, can mask important societal choices as technical judgments. The concept of values as priorities provides a way of describing individuals' priorities and considering how these priorities differ across a wider population. Finally, the concept of values as relations is generally used to foster deliberative forms of civic participation, but this tends to leave unresolved the final translation of civic meanings for decision-makers. We argue that all forms of valuation - even those that are technical tools - constitute technologies of participation, and that values practitioners should consider themselves more as reflexive facilitators than objective experts who represent the public interest. We thus encourage debate about environmental values to pivot away from theoretical gridlock and toward a concern with citizen empowerment and environmental democracy

Reading the landscape : integrating the theory and practice of geomorphology to develop place-based understandings of river systems

Assertions of a naughty world' (Kennedy, 1979) point to the importance of place-based knowledge in informing landscape interpretations and management applications. Building upon conceptual and theoretical insights into the geomorphic character, behaviour and evolution of rivers, this paper outlines an approach to the practice of fluvial geomorphology: reading the landscape'. This scaffolded framework of field-based interpretations explicitly recognizes the contingent nature of biophysical interactions within any given landscape. A bottom-up, constructivist approach is applied to identify landforms, assess their morphodynamics, and interpret the interaction and evolution of these features at reach and catchment scales. Reading the landscape is framed as an open-ended and generic set of questions that inform process-form interpretations of river landscapes. Rather than relying unduly on conceptual or theoretical representations of landscapes that suggest how the world should' ideally look and behave, appropriately contextualized, place-based understandings can be used to detect where local differences matter, thereby addressing concerns for the transferability of insights between locations and the representativeness of sample or reference sites. The approach provides a basis for scientifically informed management efforts that respect and work with the inherent diversity and dynamics of any given river system.21 page(s