AHERN, Jack F. (2016): Novel Urban Ecosystems Concepts, Definitions

Selim Abdel CASTRO SALGADO, M. Arq. //Doctorado en Arquitectura y Urbanismo

Ficha de lectura

AHERN, Jack F. (2016): Novel Urban Ecosystems Concepts, Definitions and a Strategy To Support Urban Sustainability and Resilience

Abstract

(…) 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.

Introduction

The world is undeniable in new and uncharted territory, the Era of the Anthropocene –in which the impacts and artifacts of humans have become global in scale, and comparable to the geological forces that defined prior eras. In this context, the conventional wisdom that separates and opposes “nature” and “cities” is no longer accurate and certainly not productive to meet current and future challenges.

We know that the future will demand new conceptions, new paradigms and new structures for urban nature –including its appearance, its spatial dimensions, its functions and complexity, and ultimately its reflection on human values and aspirations. The new global urban demography will cause humanity to rethink its most fundamental concepts and conceptions of nature (…) Romantic notions of “the balance of nature” are no longer realistic, appropriate or even useful. The term “novel urban ecosystems” is increasingly engaged to represent the totality of urban nature and to inform and guide planning, design and management of cities to meet human needs in the Anthropocene.

A typology of novel urban ecosystems

Novel ecosystems, known in ecology as emerging ecosystems, are new combinations of species that arise through human action, environmental change and the introduction of species from other regions.

(…) novel urban ecosystems have “no-analog” and are increasingly the subject of research to understand their origins, ecological trajectories and opportunities for developing new management goals and approaches.

“Living organisms and their non living environment are inseparably interrelated and interact each other. Any unit that includes all of the organisms in a given area interacting with the environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles within the system is an ecological system or ecosystem”

This seminal definition focuses on biotic-abiotic interactions as the essence of ecology (…) landscape ecology subsequently extended Odum’s ecosystem concept to the landscape scale with a focus on landscape pattern and its effect(s) on landscape process(es) in human dominated landscapes. Urban ecology extends the spatial and functional perspectives of ecosystem and landscape ecology to cities –with a fundamental interest in the application of ecological theory and knowledge to address human-dominated landscapes, including urban landscapes and regions.

The Millenium Ecosystem Assessment defined four categories of ecosystem services that collectively represent the entirety of what humans need and receive from nature: Supporting, Provisioning, Regulating and Cultural services.

(…)

Ecosystem services and ecosystem disservices are those functions structures and aspects of culture that can be either beneficial or detrimental for human well-being.

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Here, I offer a “working” definition of novel urban ecosystems as: Ecosystems that persist or arise in cities, resulting from –and structured by- intentional or indirect human management actions (including inaction/ abandonment); with unique species composition and structure influenced by biotic introductions and invasions; and that provides a suite of ecosystem services/disservices resulting from interactions of the biota with the altered abiotic urban environment.

This definition can be expanded to outline a typology of novel urban ecosystems that include four types: Remnant/ Restored, Abandoned/ Ruderal, Horticultural/ Formal, and Green Infrastructure-related. This typology is based on the level and type of urban biodiversity and species composition, and the extent of human intervention and management.

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Relict NUEs provide a memory of the pre-urban ecosystem, and may serve as reference ecosystems to monitor response to climate and other changes and to serve as models for ecological restoration.

Nature in cities, and biodiversity in particular, will play an essential role in providing the ecosystem services that every city relies on to be sustainable and resilient. In addition to making our cities smarter and more efficient in multiple ways, we need to employ biodiversity to assist this unprecedented challenge.

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(…) Here is an interesting example of urban ecology where biodiversity has “learned” to process waste materials that are not found in nature, but that exist in most cities. The challenge for NUEs it to better understand such urban biodiversity and the ecosystem services that it can deliver.

NUEs need to be understood at multiple scales –from the microscopic to the metro-region. At broader scales connectivity is important because many ecosystem services depend on corridors to form networks that operate at broader scales (…) when connectivity is diminished, the functions that operate at broad scales are compromised.

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The imperative to employ innovative practices, and also to design for a particular place presents a dilemma to designers. What kind(s) of site-specific research are needed to adapt innovations from other locations to a local application?

(…) An answer to this dilemma is the concept of adaptive design, also known as learning-by-doing, design experiments and research-by-design. Under these concepts designs can be developed as experiments, testing the best available knowledge in fine-scale pilot projects where the risk of failure is understood and accepted, as is the possibility to succeed, and to innovate. Adaptive designs are understood to be hypotheses rather than proven solutions. Adaptive designs, of course, should be conceived responsibly with the best available knowledge, but with uncertainty specifically acknowledged.

Referencia

Ahern, J. (2016). Novel Urban Ecosystems: Concepts, Definitions and a Strategy To Support Urban Sustainability and Resilience. Landscape Architecture & Regional Planning Series 66, 10–21.