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© Lora Denis
Located on Pelee Island, Ontario Nature’s Stone Road Alvar Nature Reserve is part of a larger complex of conservation lands that are also owned by the Essex Region Conservation Authority and the Nature Conservancy of Canada. Its unique habitats support a diverse array of rare flora and fauna, such as Downy Wood Mint and Blue Ash.
Alvars are among some of the most species-rich terrestrial communities. Of Ontario Nature’s 42-hectare Stone Road Alvar property, 9 hectares are classified as grassland alvar habitat. The species found within alvar habitats are adapted to withstand disturbances such as extreme heat, flooding, and drought. The persistence of disturbances are necessary to maintain these unique ecosystems and promote the growth of native alvar species.
In the fall of 2019, Ontario Nature conducted the first low-intensity prescribed burn in nearly two decades at Stone Road Alvar, with the purpose of restoring and maintaining alvar habitat for rare and at-risk species, including snakes, plants and invertebrates.
The main goal of the low-intensity burn was to help reduce the encroachment of woody shrubs, such as Prickly Ash and Staghorn Sumac, into these open areas. To understand the impact of the burn, a variety of species were monitored, including the snakes that are found on Stone Road Alvar, which rely heavily on grassland alvars with very low canopy cover and minimal shade.
Ontario Nature’s conservation science team and researchers examined the number of snakes observed before (2018, 2019) and after (2020) the study area was burned. Preliminary findings suggest that the burn did not significantly impact snake abundance, although there was an overall decrease in snake observations in the area (both at the burn and control sites). Like many scientific research projects, preliminary results from one year of post-burn monitoring are not enough to determine the effectiveness of the prescribed burn as a management tool. There are multiple confounding factors that have likely contributed to the result, such as climate variations and anthropogenic influences. Continued monitoring is needed to determine the driving factors behind the observed decrease in snake numbers.
Our team also evaluated the change in microhabitat thermal quality before and after the burn to understand whether prescribed burning is an effective method for maintaining alvar habitat for at-risk snake species.
Why is thermal quality an important factor to look at? When environmental temperatures do not equate to their preferred body temperature, snakes must spend energy to thermoregulate through finding suitable habitats and adjusting behaviors. This takes time away from performing necessary activities, such as foraging and mating. Hence, habitats with temperatures closer to the species’ preferred body temperatures are desirable and of high thermal quality.
Preliminary results from this research show that the prescribed burn increased the thermal quality of the species’ habitats to a certain extent, however it was not statistically significant.
While the results to date show that the low-intensity prescribed burn did not significantly impact snake abundance and habitat thermal quality, we will continue to monitor snake populations to help answer this question. Data on prey availability (e.g., small mammal abundance) will also be collected. This ongoing research will bring us closer to understanding snake responses to the prescribed burn by eliminating the current confounding variables.
To improve future restoration efforts in alvar habitats, we will also continue to monitor microhabitat thermal quality, specifically in areas that were altered by the burn. Additionally, we will evaluate changes in vegetation structure to determine the effects of the burn on habitat availability.
Later this year, we are also hoping to host in-person outreach events at Stone Road Alvar. While this will depend on COVID-19 restrictions, please visit our events calendar for further updates.
To learn more about our work on Pelee Island, watch our research webinar here:
Helen McCrea Peacock Foundation