Influences of urban stormwater management ponds on wetlandscape connectivity

Abstract

Wetlands have been degraded and destroyed in many human-dominated landscapes worldwide, threatening vital ecosystem services. Landscape connectivity is critical for wetland biota, but is often reduced among remaining wetlands. With urban development, stormwater management (SWM) ponds are installed to hold runoff and associated contaminants. Unfortunately, SWM ponds do not adequately replace the ecosystem services and functions provided by a connected wetlandscape. We use a graph theory approach to analyze landscape connectivity of wetlands and stormwater management ponds in seven municipalities in southern Ontario, Canada. We analyze changes in connectivity through time, alongside potential effects of SWM pond creation on connectivity. We calculate the number of links (NL) and components (NC) at the landscape-level (i.e. connectivity within a municipality), and the probability of connection and two of its components (i.e. dPCflux and dPCconnector) at the habitat-level (i.e. contributions of individual wetlands and SWM ponds to landscape connectivity). Our results suggest that landscape connectivity has decreased with wetland loss, while SWM pond construction has improved connectivity. Wetlands appear to be more connected over the landscape, while SWM ponds might act as stepping-stones for species moving between wetlands. Our results point towards the need to protect and restore wetlands to safeguard critical ecosystem services. Stormwater ponds may not provide habitat of equivalent quality to wetlands; however, their strategic placement within urban areas could improve wetlandscape connectivity.

Keywords:

• Landscape connectivity
• wetlands
• stormwater management
• land use and land cover change
• wetland conversion
• wetland loss

Disclosure statement

The authors report there are no competing interests to declare

Data availability

Data used for this research are publicly available from the Ontario GeoHub, Scholars GeoPortal, and municipal governments. The majority of this data was provided under data sharing agreements and datasets generated or analyzed during the current study are available only from the original data provider. The following links provide repositories where the data can be found, or contact information for the department that can provide the data. https://geohub.lio.gov.on.ca/, http://geo1.scholarsportal.info/, https://open-kitchenergis.opendata.arcgis.com/, https://www.waterloo.ca/en/government/maps-and-open-data.aspx#, https://www.cambridge.ca/en/your-city/Open-Data.aspx#, https://www.vaughan.ca/maps/Pages/default.aspx, https://www.markham.ca/wps/portal/home/about/data, https://www.whitby.ca/en/discoverwhitby/explorewhitbygistools.asp?_mid_=11615, and https://www.london.ca/city-hall/open-data/Pages/default.aspx.

Additional information

Funding

This research was generously supported by the Canadian Natural Science and Engineering Research Council (NSERC), Canadian Institute of Planners (CIP) Planning Student Trust Fund through support of Dillon Consulting Limited, University of Waterloo through the President’s Office and School of Planning, and Dean and Rose Ann Mutrie in honour of Professor George Mulamoottil.