What happens when your restoration vision conflicts with restoration targets?

A case against targeting a single species for restoration within urban nature preserves.

By Heather Whitehouse, Senior Ecologist

Heather Whitehouse will present her restoration work on the Lathrop Nature Preserve at the SER World Conference 2021 Home page | SER 2021

The vision for any ecosystem restoration project is to maintain and enhance the biodiversity of the ecosystem being restored. But take care. Conflict can arise if you focus on enhancing or restoring habitat for a single species. If you don’t remain flexible, your restoration may end up inadvertently threatening other species on site.  Let’s look at one example of how flexibility in a restoration plan led to better outcomes – both for at-risk species, and for clients.

An Ecological Gem

The Lathrop Nature Preserve in Southern Ontario is an ecological gem. Located within the Niagara Escarpment (a UNESCO World Heritage Site), the site contains Carolinian forest and wetland habitat which support many Species at Risk.

At the start of this project, our client and stakeholders had a key goal – improve the downstream habitat for a rare cold-water fish species. The Lathrop Nature Preserve is currently managed for conservation purposes. Historically, the property was altered by construction and the operation of a now decommissioned rail line. Today, that rail line serves as a pedestrian trail through portions of the property. Back when the rail line was first installed, it was necessary to fill several valleys on the property, which resulted in a constructed embankment. This embankment impounds groundwater seepage and overland flow within the former valley areas. The result? Two anthropogenic ponds were formed, that is, ponds that are the result of human activity. These ponds naturally overflow into a headwater tributary of a cold-water creek, and they have been identified as contributing to increased water temperatures, which may be causing negative impacts on downstream cold-water fish habitat.

Clear Targets

The approach for achieving the restoration target for the Lathrop Nature Preserve was clear: Remove the ponds and direct groundwater seepage towards the downstream cold-water creek. Historically, the ponds had been observed to contain goldfish, a non-native species, a species we did not need to worry about protecting.

At the outset of our restoration project, we conducted new baseline wildlife studies at the two ponds. In the process, we observed that the ponds provided overwintering and foraging habitat for two turtle species of concern. So, through these baseline studies, we discovered that the restoration target to improve downstream cold-water fish habitat by removing the ponds would conflict with the restoration vision of maintaining and enhancing the biodiversity of the project site. So, what next?

Today, the historic rail line at the Lathrop Nature Preserve serves as a pedestrian trail through portions of the property.

Flexibility is Key

This is when being flexible became essential. Our approach for meeting the restoration target of improving habitat for a single cold-water fish species had to change. The ponds provided warm-water habitat for two turtle species at risk. Now, instead of removing these ponds, we had to protect them.

We revised our plan. Our new restoration plan will create a headwater tributary to capture surface water drainage and groundwater seepage before it reaches the ponds. Part of the former rail line will be removed to connect this new tributary with the existing tributary downstream.  Baseline studies confirmed that the groundwater table intersects the ponds, and that they did not need to be supported by overland flow from the adjacent vegetation communities.  This new plan enables us to achieve our restoration target: Improve the downstream cold-water fish while also maintaining the project site biodiversity. Win-win!

Our restoration plan will be constructed over the next year, and the need to be flexible continues. Restoration projects need to consider the sensitivity of the site when developing and implementing a restoration plan. As the proposed headwater tributary is within existing wetland and lowland Carolinian forest, we determined the minimum tributary dimensions to reduce disturbing the footprint within this Carolinian forest and wetland habitat. Even our construction methods changed. Much of the new tributary will be hand-dug to minimize the impacts of construction on key windows for wildlife habitat, breeding, and overwintering.

Conclusion

The Lathrop Nature Preserve project is a great example of how a project’s intent to enhance biodiversity could threaten the existing biodiversity present if baseline studies are not completed.  It is essential to revisit your restoration target(s) from project conception to implementation (construction) to ensure that the project site’s existing biodiversity will be protected, and new habitats created.  Remember – flexibility is key in restoration!

To learn more about ecosystem restoration, or to discuss your own restoration needs, contact me: hwhitehouse@geiconsultants.com

 About Heather Whitehouse

 Heather is a senior ecologist and Certified Ecological Restoration Practitioner with expertise in natural heritage system design, wetland ecology, environmental impact assessment, ecological monitoring and ecosystem restoration. Heather leads GEI’s Ecological Restoration Group in Canada.