Measuring success in natural areas
Savanna on the Pelee Island Alvar, Ontario (Photo by NCC)
The Nature Conservancy of Canada (NCC) owns globally significant alvar habitat on Pelee Island, in the Western Lake Erie Islands Natural Area. This is the most southerly land mass in Canada, and supports many species and plant communities at the extreme northern edge of their natural distribution.
Alvars are characterized by shallow or no soil, and large patches of exposed bedrock. Extremes of temperature and moisture are frequent, and only a few specialized (and often rare) plants like nodding onion and cliff conobea are able to survive here. Over time changes in land use practices and the introduction of invasive species throughout the natural area have resulted in smaller alvar habitats with fewer specialized alvar plants.
Managing such habitats in the face of invasive species and other threats is a huge responsibility. There are few other examples of the same habitats to learn from.
NCC used an adaptive management approach, testing several different methods on an experimental scale to identify the most successful restoration approach.
After two years of monitoring the response of rare alvar species and invasive species to different restoration methods (across 30 alvar plots), NCC conservation biologists are now confident that they can successfully restore the natural area’s alvar habitats and species.
Although the method of carefully applying a dilute solution of herbicide was effective at removing invasive plants, this did not lead to the removal of the turf “mat” on the bedrock. This method will however be used where the soil is deeper and we simply need to replace invasive plants with native plants.
The winning restoration method (the physical removal of invasive grass turf, and exposure of underlying bedrock) will enable NCC to re-establish alvar species within just one growing season.
Having invested up front and at a small scale in measuring the success of different restoration methods, NCC can now proceed with confidence that our actions throughout the natural area will be both efficient and effective.
Moving forward, southwestern Ontario stewardship staff will continue to monitor any changes in plant communities in response to our treatments. As we become more confident and increase the area treated, our monitoring will become less intense and less frequent. However, our experimental plots will remain available for external researchers to make use of if they wish, to address future ecological questions.