Two new papers on Novel ecosystems and Biodiversity Sensitive Urban Design

I think one of the great challenges for modern conservation is finding ways of getting good outcomes for biodiversity in environments that would traditionally be considered to be human-dominated. Think, for example, about the urban or agricultural landscapes that make up the vast majority of land cover in many countries. And then imagine if we could achieve benefits for biodiversity at that scale. It’s an exciting prospect.

But achieving biodiversity gains in human environments usually requires trade-offs between the different objectives and requirements of people and nature. And without good frameworks in place, these trade-offs can be challenging. Two recent papers by myself and colleagues in ICON Science attempt to help decision makers navigate these trade-offs in urban environments.

Biodiversity Sensitive Urban Design in Conservation Letters

Urban development is one of the biggest drivers of biodiversity loss around the world.  But there are many compelling reasons to protect and enhance biodiversity in cities. First, cities and their surrounds are home to many of our threatened species, making them important places for conservation in their own right. Second, having nature in cities provides an extraordinary range of benefits to people, including important livability and human health and well-being benefits. And third, cities present an unparalleled opportunity to reconnect people with nature, because of the huge human populations that live in them.

Despite this, the way we plan for, design and build cities is still incredibly harmful for biodiversity. Standard approaches to biodiversity conservation in cities protect only the highest quality areas – everything else is cleared and compensated for through an off-site offset – and they do not address the significant threats associated with the surrounding urban matrix. This leads to 3 undesirable outcomes: 1) Nature, and the benefits it provides, are located far from the places where people live and work; 2) High-quality biodiversity remnants are enclosed within hostile urban environments, and end up degrading over time; and 3) Because of 1 and 2, the disconnection between people and nature is exacerbated, which perpetuates a negative feedback loop in which residents’ attitudes towards nature decline and biodiversity loss worsens.

Fortunately, some of the negative impacts of urbanization can be mitigated by improvements to urban design. But in the absence of a practical framework for incorporating existing urban ecological knowledge into urban design and development, planners and developers have little guidance about which design elements to implement, or how to balance biodiversity with other objectives.

The biodiversity impacts of urbanization can be mitigated by sensitive urban design. (A): Residential development across the road from a protected native grassland remnant in northern Melbourne, Australia. This residential property is devoid of vegetation (save for the lawn on the nature strip), providing little habitat or resources for native species that live in the grassland across the road. Compare this to image (B) (also in Melbourne), where the nature strip has been planted with a variety of native species, including trees, shrubs and grasses. The structural diversity creates a mosaic of habitat for a range of species. (C): The roof and walls of the Jerusalem Bird Observatory have been designed to provide habitat for birds and bats. (D): The biodiverse roof at The University of Melbourne provides a diverse range of habitats, including hollow logs, grassland, and an ephemeral stream. Photo credits. A, B: Georgia Garrard; C: Architecture–WEINSTEIN VAADIA ARCHITECTS, Photography–Amir Balaban; D: Nick Williams.

This paper outlines a biodiversity sensitive urban design (BSUD) framework for incorporating ecological knowledge into urban design and decision making. We think BSUD makes three important advances in the field of urban conservation planning. First, it seeks to achieve onsite biodiversity gains, which will be necessary for reversing biodiversity decline, and further, is important for reconnecting urban residents with nature and exposing them to the benefits it provides.

Second, by seeking to achieve biodiversity benefits in any development, BSUD rises above the dominant land sparing/sharing debate which can be difficult to apply in practice because development patterns typically lie somewhere between sparing and sharing. And third, because it explicitly links urban design to measurable biodiversity outcomes, BSUD provides a flexible framework for developers and planners to make transparent trade-offs between biodiversity and other socioeconomic objectives.

Grappling with the social dimensions of novel ecosystems in Frontiers in Ecology and the Environment

Since the introduction of the novel ecosystem concept more than a decade ago, debate has raged about whether it is a good thing. Critics fear that the recognition of these ecosystems as having crossed a threshold beyond which restoration to a ‘natural’ state is impossible is the beginning of a slippery slope towards devaluing conservation and restoration. On the flip side, proponents argue that the novel ecosystem concept adds conservation value to human-modified ecosystems that might otherwise be dismissed or overlooked.

Regardless of where you sit in this debate, it is clear that for many ecosystems, particularly in urban environments, restoration to an historical, ‘natural’ benchmark is impossible – either because it is ecologically impossible, or infeasible because of time, money or knowledge limitations. ICON Science PhD student Anna Backstrom was interested to know when, and under what conditions, novel ecosystems could be considered an appropriate management benchmark for modified landscapes.

Resolving this is only possible by acknowledging and trading-off between multiple values, which may be environmental, social or economic.  For example, a reserve or green space in an urban area may be valued for its capacity to provide habitat for a native species, as well as for recreation and water filtering.

In the US, Tamarisk (Tamarix sp., above) has transformed large riparian areas to monotypic stands that hold limited habitat value for small mammals, amphibians, and reptiles but are used extensively by the endangered southwestern willow flycatcher (below). Decisions about whether this invasive plant should be eradicated, controlled, or protected are contentious and inevitably involve ecological and social values about the relative importance of the broader riparian system compared to the flycatcher. Photos: Tamarisk, C. Shock; Flycatcher, S Howell.


In her paper, Anna proposes a values-based decision approach for determining appropriate management of modified ecosystems and argues that it is only within this ecological decision-making context that there is a defined role for the novel ecosystem concept. Using this approach, novel ecosystems are assessed not as “right” or “wrong”, but by the extent to which they meet desired ecological, social, and economic objectives.

Find our papers:

Garrard GE, Williams NSW, Mata L, Thomas J & Bekessy SA (2017) Biodiversity sensitive urban design. Conservation Letters. doi:10.1111/conl.12411

Backstrom AC, Garrard GE, Hobbs RJ & Bekessy SA (2018) Grapping with the social dimensions of novel ecosystems. Frontiers in Ecology and the Environment. doi:10.1002/fee.1769

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