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Preston, United Kingdom

Lawrence A.,Japan Forestry and Forest Products Research Institute | De Vreese R.,Vrije Universiteit Brussel | Johnston M.,Myerscough College | Konijnendijk van den Bosch C.C.,Copenhagen University | Sanesi G.,University of Bari
Urban Forestry and Urban Greening | Year: 2013

Research on urban forest governance is scarce, despite the current high level of interest in urban forestry. This paper addresses one of the main reasons for this scarcity - poor understanding of what governance is, and how it can be described. We propose a systematic approach to researching urban forest governance, based on a case study framework which provides a way to describe examples clearly, and to compare them robustly. The paper briefly reviews definitions and debates around governance, before using a descriptive definition as the basis for developing a framework. It then uses five examples from across Europe, to illustrate the use of the framework for describing urban forest governance. The analysis reflects on the experience of writing and sharing case studies, to distill out the framework as a research tool, and discusses issues arising from the application of the framework and the challenges of standardisation. The paper concludes with reflections on the role of this framework in stimulating comparisons while maintaining the flexibility to contribute to individual research needs and traditions. © 2013. Source

Slater D.,Myerscough College | Ennos R.,University of Hull
Arboricultural Journal | Year: 2015

Xylem found in the stems of woody plants has contrasting strength in different planes due to its anisotropy. At the apex of the junctions of woody plant branches, sufficient wood strength is needed to prevent the arising branches splitting apart. The main aim of this research was to address an issue so far overlooked, which is the contribution of wood grain orientation and patterns at this location (the apex of such junctions) to supplying the required strength. In this study, the wood grain patterns of xylem produced at the apex of junctions of hazel (Corylus avellana L.) were investigated. The mechanical properties were determined using compression and tensile tests of excised wood samples with an Instron® Universal Testing Machine. Sample strength was contrasted with the strength of xylem produced at the side of the junctions and in the adjacent lower stems. Wood formed at the top of junctions in the hazel exhibited more tortuous wood grain patterns and had twice the radial and tangential tensile strength when compared with adjacent wood formed in the stem. It also had significantly higher radial and tangential compression strength. Density of xylem at the apex of hazel junctions was 13.4% greater than in the adjacent stem. The authors conclude that tortuous wood grain patterns supply additional strength to junctions in hazel trees. This mechanical arrangement should inform anatomical studies of junctions and may inform the design of manufactured Y-shaped components made from fibrous composite materials. © 2015 Taylor & Francis and Arboricultural Association. Source

Johnston M.,Myerscough College
Arboricultural Journal | Year: 2010

In February 2008, the Department for Communities and Local Government published its long awaited report on urban trees in England entitled Trees in Towns II. The report assesses the urban tree population in England as well as identifying the policies and practice of urban tree management by English local authorities. This paper highlights the significance of this government report for the arboricultural industry. It also stresses the report's relevance to the growing debate about the importance of green infrastructure, sustainable cities and urban climate adaptation. Lastly, it explores the potential contribution of the arboricultural industry to achieving the aims of Trees in Towns II and the promotion of green infrastructure and sustainable cities. © AB Academic Publishers 2010. Source

Slater D.,Myerscough College
Arboricultural Journal | Year: 2010

The branch attachment model set out by Alex Shigo in the Canadian Journal of Botany is 25 years old this year. Despite the model's wide use in arboricultural literature, it can be shown by simple logical argument to be erroneous. Ongoing investigations into the nature and strength of branch attachments at Myerscough College and the University of Manchester have highlighted the need for a new anatomical model for these attachments to inform research. Arguments against Shigo's model are given and a new model is offered that considers the mechanical and conducting functions of xylem and its ontogenesis. © AB Academic Publishers 2010. Source

Slater D.,Myerscough College
Arboricultural Journal | Year: 2016

The axiom of uniform stress is based on the theory that trees carry out their secondary growth in such a way that bending stresses are averaged out over the outer surfaces of the tree and the tree’s resulting aerial form avoids stress concentrations and repairs “notch stresses”. However, this can be shown, by combining a series of logical propositions, to be an errant or incomplete concept of how tree form develops, even in the limited scope of local stress levels that component parts of trees experience due to gravitational or dynamic wind loading. This paper presents an argument against the veracity of this axiom and highlights the extent of contradictory scientific work on the adaptive responses of trees to strain, their dynamic movement in the wind and the habit of some species to fail in a graduated way. It is concluded that a better model of the biomechanical behaviour of trees can be achieved through a synthesis of existing scientific models. © 2016 Taylor & Francis and Arboricultural Association Source

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