Supervisor: Jochen Jaeger
Supervisor: Jochen Jaeger
ProjectMeasuring landscape connectivity: On the importance of within-patch connectivity. & An adaptive plan for prioritizing road sections for fencing to reduce animal mortality.
A number of metrics only measure between-patch connectivity, i.e. the connectivity between different habitat patches, which can produce misleading results. This work demonstrates that the inclusion of within-patch connectivity is important for accurate results. The behavior of two metrics is compared: the Connectance Index (CONNECT), which measures only between-patch connectivity, and the effective mesh size (meff), which includes both within-patch and between-patch connectivity. The connectivity values of both metrics were calculated on a set of simulated landscapes. Twenty cities were then added to these landscapes to calculate the resulting changes in connectivity. When using CONNECT, counter-intuitive results occurred due to not including within-patch connectivity, such as scenarios where connectivity increased with increasing habitat loss and fragmentation. These counter-intuitive results were resolved when using meff. For example, landscapes with low habitat amount may be particularly sensitive to urban development, but this is not reflected by CONNECT. Applying misleading results from met- rics like CONNECT can have detrimental effects on natural ecosystems, because reductions in within- patch connectivity by human activities are neglected. Therefore, this paper provides evidence for the crucial need to consider the balance between within-patch connectivity and between-patch connectivity when calculating the connectivity of landscapes. 2nd project: We devised an adaptive fence-implementation plan to prioritize road sections for fencing. In this framework, areas along roads of high, moderate, and low levels of animal mortality (respectively, roadkill hotspots, warmspots, and coldspots) are identified at multiple scales (i.e., in circles of different diameters [200–2000 m] in which mortality frequency is measured). Fence deployment is based on the relationship between the amount of fencing being added to the road, starting with the strongest roadkill hotspots, and potential reduction in road mortality (displayed in mortality-reduction graphs). We applied our approach to empirical and simulated spatial patterns of wildlife–vehicle collisions. The scale used for analysis affected the number and spatial extent of roadkill hot-, warm-, and coldspots. At fine scales (e.g., 200 m), more hotspots were identified than at coarse scales (e.g., 2000 m), but combined the fine-scale hotspots covered less road and less fencing was needed to reduce road mortality. However, many short fences may be less effective in practice due to a fence-end effect (i.e., animals moving around the fence more easily), resulting in a trade-off between few long and many short fences, which we call the FLOMS (few-long-or-many-short) fences trade-off. Thresholds in the mortality-reduction graphs occurred for some roadkill patterns, but not for others. Thresholds may be useful to consider when determining road-mitigation targets. The existence of thresholds at multiple scales and the FLOMS trade-off have important implications for biodiversity conservation.
Keywordslandscape connectivity, road mortality, within-patch connectivity, FLOMS: Few long or many short fences?
Publications1- Measuring landscape connectivity: On the importance of within-patch connectivity
Spanowicz, Ariel G., Jochen A. G. Jaeger
2019 Landscape Ecology
2- An adaptive plan for prioritizing road sections for fencing to reduce animal mortality
Spanowicz, Ariel G., Fernanda Zimmermann Teixeira, Jochen A. G. Jaeger
2020 Conservation Biology
3- Road mortality locations of small and medium-sized mammals along a partly-fenced highway in Quebec, Canada, 2012–2015
Plante, Judith, Katrina Bélanger-Smith, Ariel G. Spanowicz, Anthony P. Clevenger, Jochen A.G. Jaeger
2018 Data in Brief
4- Clôtures et passages fauniques pour les petits et moyens mammifères le long de la route 175 au Québec : quelle est leur efficacité ?
Jaeger, Jochen A. G., Ariel G. Spanowicz, Jeff Bowman, Anthony P. Clevenger
2018 Le Naturaliste canadien