Urban ecological connectivity as a planning tool for different animal species

Abstract

The application of ecological theory to urban planning is becoming more important as land managers focus on increasing urban biodiversity as a way to improve human welfare. City authorities must decide not only what types of biodiversity-focused infrastructure should be prioritized, but also where new resources should be positioned and existing resources protected or enhanced. Careful spatial planning can contribute to the successful return and conservation of urban nature by maximizing the contribution of green infrastructure to landscape connectivity. By using ecological connectivity theory as a planning tool, governments can quantify the effect of different interventions on the ease with which wildlife can move across the landscape. Here we outline an approach to a) quantify ecological connectivity for different urban wildlife species and b) use this to test different urban planning scenarios using QGIS. We demonstrate four extensions to the work by Deslaurier et al. (2018) and Spanowicz & Jaeger (2019) which improve the application of this method as a planning tool for local government: - A step-by-step method for calculating effective mesh size using the open-source software QGIS. - Conversion of the effective mesh size value to a 'probability of connectedness' (for easier interpretation by local government and comparisons between planning scenarios). - Guidance for measuring species-specific connectivity, including how to decide what spatial information should be included and which types of species might be most responsive to connectivity planning. - Advice for using the method to measure the outcome of different urban planning scenarios on ecological connectivity.

Quantifying taxon-specific habitat connectivity requirements of urban wildlife using structured expert judgement

“…We selected seven taxon groups for which to quantify the landscape-scale habitat connectivity requirements of fauna within urban Canberra. We decided to use a taxon group approach which considers species that have relative ecological similarities and share broad dispersal abilities and habitat requirements (as opposed to an individual species approach) (e.g., Kirk et al 2018). We included seven taxon groups to best capture the breadth of ecosystem associations, habitat needs, and movement abilities of most fauna in urban Canberra, particularly ACT threatened species.…”

“…To be informative for such measures, metrics that define taxon-specific habitat connectivity need to be both ecologically meaningful and translate into spatial data layers that are location-specific and readily available (Kirk et al 2023). We selected 30 metrics to represent landscape-scale, functional habitat connectivity for our seven taxon groups (Table 2) that were ecologically important (Doerr et al 2010; and had the potential to provide the spatial data inputs to underpin robust measures of functional connectivity (Kirk et al 2018;. They included metrics that represented (1) ideal habitat requirements (n = 8), (2) habitat constraints (n = 13), (3) barriers to movement (n = 6), and (4) movement thresholds (n = 3).…”

“…The first two principles of BSUD intend, among other things, to direct more strategic design and placement of connected wildlife habitat in urban landscapes (Garrard et al 2018). However, Kirk et al (2018) identified two key factors that currently limit the capacity of urban design to achieve habitat connectivity outcomes: (1) the assumption that connected habitat defined by structural elements (e.g., patch dimensions, vegetation composition, and spatial continuity) provides appropriately for target wildlife in the absence of defining functional constraints (e.g., physical, physiological, or behavioural barriers to successful use, movement, or dispersal), and (2) a lack of empirical information to describe taxon-specific ideal habitat requirements and constraints at the relevant spatial scale to inform evidence-based urban design for target wildlife.…”

“…The 'City Biodiversity Index' -a Convention on Biological Diversity endorsed tool to monitor urban biodiversity -measures ecological connectivity as the relationship between the total area of habitat available and the degree to which it is functionally (dis)connected, either by distance (e.g., small birds will be unable to disperse where distance between tree cover exceeds their movement capacity (Tremblay and St. Clair 2009)) or by physical or behavioural barriers to movement (Chan et al 2014;Deslauriers et al 2017;Kirk et al 2018Kirk et al , 2023. While recent studies have highlighted the value of using this approach for spatially mapping and measuring habitat connectivity in BSUD (e.g., Kirk et al 2018Kirk et al , 2021, the input data often remains coarse in terms of what constitutes habitat (e.g., presence of trees only without consideration of preferred spacing and composition), and taxonspecific movement thresholds and movement barriers (Kirk et al 2023). Applying BSUD to achieve ecological connectivity outcomes requires a greater taxon-specific understanding of what constitutes functional connected habitat to underpin these connectivity maps, models, and measures.…”

Connectivity at home: A data-driven connectivity modeling framework for home range movements in heterogeneous landscapes

“…Connectivity does, however, also affect daily movements in home ranges (Koen et al, 2014; LaPoint et al, 2013; Zeller et al, 2016) and their size, formation, and shape (Bevanda et al, 2015; Sutherland et al, 2015; Walter et al, 2009). In very heterogeneous landscapes like cities, connectivity is crucial for a species’ access to resources distributed across patches (Kirk et al, 2018), thereby influencing home range establishment and species distributions. Moreover, territories in such areas are relatively small compared to a vertebrate’s home range and their size corresponds more to one or few sub-populations than a metapopulation (Beninde et al, 2016; Braaker et al, 2017).…”