Abstract
Urbanisation is one of the greatest threats to biodiversity worldwide. Biodiversity is essential for the functioning of ecosystem services that sustain plant, animal, and human life. Biodiversity loss due to urbanisation impedes the movement of species across landscapes, impacting overall ecological connectivity. In addition to anticipated future development, the introduction of the National Policy Statement on Urban Development and Medium Density Residential Standards will see greater density development in New Zealand’s biggest cities. Higher density provisions were introduced to address New Zealand’s housing crisis, by removing some of the restrictive rules on housing density and design. The National Policy Statement on Urban Development has failed to make provision for ecological connectivity. Consequently, this research seeks to contribute to the wider biodiversity restoration, protection, and enhancement efforts in New Zealand and support the visions and implementation of Te Mana o te Taiao – Aotearoa New Zealand Biodiversity Strategy 2020 and its implementation in medium density housing developments. The overall aim of this research was to assess the ecological connectivity within Hobsonville Point and the Tāmaki redevelopment and with the wider environment, with a view to improving the ecological connectivity of medium density housing development across New Zealand. The two case study sites from Auckland, Hobsonville Point and Tāmaki, were chosen to address this aim. Being two of New Zealand’s largest housing developments, the findings from this research can inform medium density development more widely. This research established an inventory of green space at both sites to provide the basis on which ecological connectivity was measured and potential corridors and areas for connectivity enhancement were identified. This research assessed the extent of ecological connectivity within Hobsonville Point and the Tāmaki redevelopment in Auckland and their wider environment. Three scales were chosen to carry out this analysis, the block scale, the development scale, and the wider surrounds scale. The analysis was based on the natal dispersal distance or maximum dispersal distance of four indigenous bird species, the Kererū, Tūi, Grey Warbler, and Silvereye. This analysis was done with a view to exploring ways in which ecological connectivity could be enhanced in medium density developments across New Zealand. The results of the connectivity analysis found that green space is fragmented at the block scale, by houses, fences, and other impervious surfaces. At the development and wider surrounds scales, there is a lack of connectivity between larger green spaces, emphasising the need for more green space and greening strategies such as corridors, indigenous vegetation planting, and green infrastructure within medium density developments. The research found that assessing ecological connectivity is species-specific as the results suggest that the natal dispersal distance and maximum dispersal distance of bird species may influence the extent of ecological connectivity. There is a need for future research on species-specific movement characteristics and habitat requirements, and the impact that barriers, habitat quality, habitat size, and habitat maturity may have on the extent of ecological connectivity. International ecological connectivity best practice was reviewed to establish an assessment matrix that was used to evaluate New Zealand policy and planning documents. A review of relevant New Zealand policy and planning documents found that there is a lack of statutory provision for ecological connectivity in medium density developments. This research proposes the following recommendations: pursuing future ecological connectivity research; setting goals and targets at the national level; establishing design guidelines and specifications; requiring developers to produce a ‘biodiversity and ecological connectivity enhancement strategy’; integrating ecological corridors in development design; integrating greening strategies within development design; developing green spaces as habitats; and ensuring collaborative approaches to enhance ecological connectivity.