For a century after John Howard willed his property to the City of Toronto as parkland, High Park held a secret that only centuries-old oak trees knew.
Not until 1976 did researchers determine that a third of the park consisted of a rare patch of black oak savannah, an ecosystem that thrives on sandy soil, marked by oak trees sparsely spread out over grassland, and which benefits from occasional grass fires. From an estimated 2 million hectares (ha) of prairie grasses and oak savannah once found across southern Ontario, just over 2,000 ha remain, 44 of which are found in the park.
The open nature of the oak savannah cursed it. In many places, since it required minimal clearing, it was ideal for farming or developing urban settlements. In High Park, beautification efforts such as frequent mowing and the introduction of exotic plant species threatened the savannah’s long-term survival. Alarm bells raised by a survey of the park’s ecosystem in the early 1990s reversed these practises. Lawnmowers, which clipped the grasses up to six times a year, were given a rest, while three plots were identified as prime spots for controlled burns. If you spot one of these periodic fires, don’t panic — think of it as a restorative spa treatment for the savannah.
By Jamie Bradburn