Ahern, Jack

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Professor Emeritus of Landscape Architecture
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Jack Ahern is a professor of landscape architecture and urban planning at the University of Massachusetts Amherst.  His research and teaching focuses on the application of urban landscape ecology theory in cities to provide ecosystem services and build resilience capacity. His recent publications advance theory on applied urban ecology, supported by case studies and precedents from professional practices in the US, Europe and Asia. He is currently focusing on new theories of “novel urban ecosystems” to better understand how “new nature” in contemporary cities can be understood, classified, designed and managed for beauty and ecological functions. Jack consults on native plant community establishment and management for leading design firms – integrating his horticultural, design and ecological knowledge in the cause of making memorable landscapes.  

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Now showing 1 - 5 of 5
  • Publication
    Applying landscape ecological concepts and metrics in sustainable landscape planning
    (2002-01-01) Botequilha Leitão, André; Ahern, Jack F.
    It is increasingly recognized that more sustainable approaches are needed for planning and managing landscapes worldwide. New tools are needed to effectively apply sustainable principles to planning and management. The spatial dimension of sustainability engages processes and relations between different land uses, ecosystems and biotopes at different scales, and over time. Therefore, ecological knowledge is essential when planning for sustainability. The paper briefly reviews the historical role of ecology in planning, and ecological planning and management theories and methodologies. Building on existing ecological planning methods, we have developed a conceptual framework for sustainable landscape planning applying landscape ecological concepts and exploring the multiple potential roles of landscape metrics as ecological planning tools. We argue for a common framework that applies ecological knowledge in land planning, applicable to all physical planning activities. We believe this framework represents a significant contribution to increase the acceptance and use of ecological knowledge across the horizontal sectors planning, and to enhance communication between planners, thus contributing to an increased scientific and cultural consensus for sustainable landscape planning. Numerous quantitative metrics have emerged from landscape ecology that are useful for applying landscape ecology concepts to sustainable landscape planning. These metrics are essential tools to address the spatial dimension of sustainability in a quantitatively rigorous and robust manner. This paper proposes a core (sub)set of metrics, identified through literature reviews, which are understood as the most useful and relevant for landscape planning. A two-part sustainable landscape planning perspective is proposed, integrating horizontal and vertical perspectives. We believe that this dual approach can help to structure and clarify why, where, how and which landscape ecological principles and metrics can most effectively assist planning. We include a demonstration of this approach in the Mill River Watershed, USA. We argue that proper and informed use of landscape metrics will contribute to advance landscape planning theory and practice towards the goal of sustainability.
  • Publication
    Novel Urban Ecosystems: Concepts, Definitions and a Strategy to Support Urban Sustainability and Resilience
    (2016-01-01) Ahern, Jack F.
    The 21st century is already known for unprecedented and fundamental changes and new trajectories - think climate change, global economics, migration and population growth. The world is now predominantly urban and will become increasingly so until mid-century when global population is expected to stabilize at around 70% urban. The world has entered a new geological era, the Anthropocene, in which the impacts and artifacts of humans are recognized as a geologic force. In this "Century of the City, - for the world to be sustainable and resilient, cities must be an essential part of the solution - and novel urban ecosystems will play a fundamental role. A new conception, definition, and typology of 21st century ""novel" urban nature is proposed here as the basis for a novel urban ecosystem strategy to provide essential ecosystem services to support urban sustainability and resilience. This proposed novel nature strategy is informed by landscape and urban ecology and collaborates systematically in "designed experiments" with urban landscape architecture practice. Designed experiments on novel urban ecosystem are necessary to: 1 I monitor the performance of innovative designs to provide essential ecosystem services; 2] to mitigate the inescapable ecosystem disservices; and 3) to build public understanding and support for new types and new models of novel urban ecosystems.
  • Publication
    Gloucester Marine Station: Future Development Feasibility Study
    (2010-10-01) Ahern, Jack F; Webb, Ben Eli
    The study commenced in July 2009 with historical research about the site and its context, site analysis, including the existing conditions and development regulations. This analysis included: topography, soils, vegetation, structures, utilities, easements, property deed, and city, state, and federal regulations. From this analysis an assessment of future development potentials was made based on the existing data/documents from UMass files, public records, Mass GIS data, site visits, and interviews with Gloucester, Commonwealth of Massachusetts, and other officials and stakeholders. From the assessment we identified potential future uses, building locations, and feasible alternative layouts of the site. These alternatives were summarily analyzed to support continuing discussions among committed and potential partners regarding shared space and facilities, development costs and timing of future needs.
  • Publication
    From fail-safe to safe-to-fail: sustainability and resilience in the new urban world
    (2011-04-01) Ahern, Jack F
    Abstract: The extent to which the 21st Century world will be "sustainable" depends in large part on the sustainability of cities. Early ideas on implementing sustainability focused on concepts of achieving stability, practicing effective management and the control of change and growth-- a "fail-safe" mentality. More recent thinking about change, disturbance, uncertainty, and adaptability is fundamental to the emerging science of resilience, the capacity of systems to reorganize and recover from change and disturbance without changing to other states-- in other words, systems that are "safe to fail." While the concept of resilience is intellectually intriguing, it remains largely unpracticed in contemporary urban planning and design. This essay discusses the theory of resilience as it applies to urban conditions, and offers a suite of strategies intended to build urban resilience capacity: multifunctionality, redundancy and modularization, (bio and social) diversity, multi-scale networks and connectivity, and adaptive planning and design. The strategies are discussed in the context of resilience theory and sustainability science, and are …
  • Publication
    'Learning by doing': adaptive planning as a strategy to address uncertainty in planning
    (2008-07-01) Kato, Sadahisa; Ahern, Jack f
    Adaptive management, an established method in natural resource and ecosystem management, has not been widely applied to landscape planning due to the lack of an operational method that addresses the role of uncertainty and standardized monitoring protocols and methods. A review of adaptive management literature and practices reveals several key concepts and principles for adaptive planning: (1) management actions are best understood and practiced as experiments; (2) several plans/experiments can be implemented simultaneously; (3) monitoring of management actions are key; and (4) adaptive management can be understood as 'learning by doing'. The paper identifies various uncertainties in landscape planning as the major obstacles for the adoption of an adaptive approach. To address the uncertainty in landscape planning, an adaptive planning method is proposed where monitoring plays an integral role to reduce uncertainty. The proposed method is then applied to a conceptual test in water resource planning addressing abiotic-biotic-cultural resources. To operationalize adaptive planning, it is argued that professionals, stakeholders and researchers need to function in a genuinely transdisciplinary mode where all contribute to, and benefit from, decision making and the continuous generation of new knowledge.