Urban biodiversity in an era of climate change: Towards an optimised landscape pattern in support of indigenous wildlife species in urban New Zealand

Abstract

Biodiversity is the basis of life on the planet Earth. Without biodiversity, ecosystems and the life within them will not thrive. Nevertheless, biodiversity currently grapples with unprecedented challenges attributed to climate change and anthropogenic development, mostly in urban landscapes. While less than 3% of the world’s land surface is covered by urban settlements, biodiversity conservation in urban landscapes is vital because historically most cities have been established at ecosystem junctions where a variety of wildlife species co-exist and interact with abiotic resources to support ecosystem health, and therefore ecosystem services which are essential to human wellbeing, and indeed survival.

To support biodiversity and ensure ecosystem services in these human-occupied ecosystem junctions, developing and advancing accurate and reliable knowledge to enable the informed arrangement of ecological patterns and processes in space and time should perhaps be one of the principal tenets of landscape architecture in the twenty-first century. One way this can be fulfilled is through the spatial design of land cover patterns based upon what wildlife require to survive in such a changing and unpredictable atmosphere. Thus, there is an urgent need for undertaking research to inform landscape architecture researchers and practitioners who engage in a wide range of planned interventions in urban landscapes, including decision making on site selection and the allocation of land for human activities or nature preservation, long-term land use planning in its broad sense, urban forestry, landscape restoration, geo-design practices, etc.

In this research, Wellington New Zealand is chosen as the study area. Ecologically fragmented and rapidly growing, the city has been established and continues to expand at one of the most valuable ecosystem junctions in the Southern Hemisphere. As one of the world’s most important biodiversity hotspots, New Zealand is experiencing widespread biodiversity loss in its urban landscapes. Unique but fragile, New Zealand indigenous fauna face a wide range of impacts imposed by climate change including ecosystem degradation and habitat loss, biological invasions by some exotic plants, an increased rate of predation by introduced mammals that is exacerbated by rising temperatures, the spread of diseases by introduced species, phenological changes, and food scarcity particularly during winter.

In response to these threats, this research drills down into the role of spatial patterning of patches of vegetation in order to safeguard indigenous fauna against climate change in urban New Zealand where possible. The aim is to examine opportunities for biodiversity conservation through spatial planning and design based upon the habitat requirements of urban fauna as a determinant factor for shaping and characterising urban landscapes. This is conducted to contribute to an informed spatial design of land cover patterns in relation to ecological processes in order to enhance human-wildlife co-existence in urban landscapes and to support the continuation of a wide range of ecosystem services in a climate that continues to change.

A novel methodology employed in this research involves (1) a questionnaire-centred survey of international scholars, (2) semi-structured interviews with New Zealand subject-matter experts, and (3) a GIS-based spatial analysis of Wellington New Zealand using a rich collection of spatial datasets. Arc Map v. 10.4.1, FRAGSTATS v.4.2, and a core set of 15 landscape metrics have been used to quantify and measure the current composition and configuration of land cover classes distributed in Wellington with regards to the spatial ecology of six keystone species endemic to New Zealand.

Results provide an array of land-based information applicable in landscape architecture research and practice. According to this research, the study area has suffered from widespread land cover change and habitat loss over the last two centuries. Although a large proportion of the urban landscape is still covered by different types of green space, in most, if not all, cases, the spatial composition and configuration of patches of vegetation do not meet the minimum habitat requirements that will allow urban fauna to respond effectively to the current threats attributed to climate change.

To avoid further biodiversity loss and ensure the natural regeneration of indigenous ecosystems in the region over time, this research suggests that the allocation of land for human activities and/or biodiversity conservation in urban New Zealand should be informed by an in-depth knowledge of the spatial ecology of keystone species, such as kererū and tūī. Based upon this key concept, it is informed interventions in the composition and configuration of land cover classes that are likely to contribute most effectively to safeguarding wildlife species from the local impacts of climate change in urban New Zealand, not necessarily conventional development of green spaces or increasing the percentage of green space per capita without careful strategic consideration of the location and nature of that green space. The nature and level of these interventions should be determined with particular regard to the floristic nature of each land cover class as well as ecological interactions between the land cover classes and urban fauna in space and time. These findings are discussed, depicted, and illustrated in detail and reveal, for the first time, an integrated picture of current capacities and bottlenecks for biodiversity conservation through spatial planning in the context of climate change in urban New Zealand.

The research ends with ten spatially-explicit recommendations for landscape architecture and land use planning practitioners in urban New Zealand, proposing practical solutions for achieving optimised landscape pattern compositions and configurations for safeguarding urban fauna against the impacts of climate change where possible. The research also opens up six specific areas of inquiry for future research in New Zealand and other regions with similar issues and challenges, worldwide.

While the research places particular emphasis on urban New Zealand, lessons learned can contribute to the body of landscape architecture knowledge on a global scale, and show that landscape architects have a critical role in maintaining and increasing the well-being of people in cities through focusing on the health of urban biodiversity.