Blazing a path for butterflies
Southern Norfolk Sand Plain prescribed burn (photo by NCC)
Not all fires are bad. In fact, fire is essential to maintaining many types of ecosystems. In nature, low intensity fires rejuvenate landscapes by returning nutrients to the soil through the burning of decaying vegetation and stimulates the germination of seeds by clearing away understory consisting of non-native and other woody plants.
For these reasons, prescribed burning is commonly used as a resource management tool to improve ecosystems where low-intensity fires no longer occur naturally. The Nature Conservancy of Canada (NCC) has used this tool on many of our properties, including in the Rice Lake Plains, and most recently in the Southern Norfolk Sand Plain (SNSP) Natural Area.
Southern Norfolk Sand Plain post prescribed burn (photo by NCC)
In 2010, NCC acquired a property in the SNSP, which likely supported native prairie ecosystems prior to being be cleared for agriculture. In 2011, NCC restored the former agricultural fields by planting a diverse mix of native species to create a matrix of tall grass and Carolinian forest habitat.
Wild lupine growing after prescribed burn (photo by NCC)
Over the years, however, the restored fields were overtaken by invasive conifer trees as a result of seed dispersal from adjacent pine plantations. With the objective of addressing this ongoing invasive issue, NCC staff completed their first prescribed burn in the SNSP on March 22, 2020.
Prescribed burns are an exact science, and before a controlled fire is lit, a detailed plan is devised that includes details like where the fire will take place, how big it will be and what the objective is.
Male mottled duskywing (photo by Jessica Linton)
Working with conservation partners Natural Resource Solutions Inc, the Ontario Butterfly Species at Risk Recovery Team, Long Point Basin Land Trust and Tallgrass Ontario, NCC burned approximately 20 hectares (approximately 49 acres) of tall grass habitat in the SNSP. This will help ensure a healthy wildflower population and reduce the number of invasive pines in the fields.
The prescribed burn is part of a multi-year habitat management project funded by the Canada Nature Fund to improve the overall condition of several restored tall grass prairie fields in the SNSP. The work will focus on prescribed burning, management of invasive pine plantations, removal of invasive species including, autumn olive, multiflora rose and rabbit’s foot clover and planting additional native wildflower seeds.
Mottled duskywing on New Jersey tea (photo by Jessica Linton)
“The conifers seeding into this prairie restoration were threatening to overtake the site, reducing the diversity and amount of native plants that support a variety of beneficial insects, birds and mammals,” says Kristen Bernard, NCC's program director for southwestern Ontario. “Fire is an effective tool for managing this issue and we look forward to getting on the site and monitoring the results.”
The areas being targeted for this work have been identified by the Ontario Species at Risk Butterfly Recovery Team as potential introduction sites for mottled duskywing. Mottled duskywing is listed as an endangered species by the Committee on the Status of Species at Risk in Ontario and requires a specific ecosystem to thrive.
New Jersey tea (photo by Jessica Linton)
“Historically, the greatest threat to mottled duskywing was habitat loss associated with clearing the land," says Jessica Linton, senior terrestrial and wetland biologist at Natural Resource Solutions Inc. "Today, isolated populations live in fragmented habitats, many of which continue to face pressures from inadequate management, pesticide use and invasive species.”
In Ontario, mottled duskywing will only deposit their eggs on two closely related plants: New Jersey tea and prairie redroot. With funding from Natural Sciences and Engineering Research Council of Canada, the stewardship actions NCC will be implementing over the next few years will increase populations of New Jersey tea, the host plant of mottled duskywing, and maintain the area as open habitat for this butterfly and other species at risk.
Mottled duskywing egg deposited on New Jersey tea (photo by Jessica Linton)
“This project has the potential to help a variety of species at risk, particularly those associated with rare oak savanna habitats," says Jessica. "The hope is that this project will have a conservation ripple effect because it will result in habitat restoration, creation and improved management but will also provide an opportunity for public outreach and education focused on a lesser known species.”
This area is quickly becoming a hub for species at risk monitoring and research. Lessons learned from this restored site will continue to inform NCC's management and contribute to the wider body of knowledge on restoration and species at risk.