July 11^th 2024

Over the past 20 years, the white-tailed deer population in southern Quebec has skyrocketed. According to data obtained in the winter of 2018, there are 2-3 times more deer on Mont Saint-Hilaire than it can naturally sustain. As a direct effect, the understory vegetation of its forests has diminished rapidly.

What's the understory?

The understory provides moisture and nutrients to other plants and trees as well as food and shelter for many animal species. In addition, the understory is necessary for taking over the tree canopy as older trees die, making it an essential component of any healthy, sustained forest ecosystem. Thus, its protection is paramount.

How can we keep track of the decline?

In 2006, the Gault Nature Reserve took a proactive step to document the diminishing understory by initiating a long-term monitoring project using small exclosures around the mountain. These exclosures focus on the growth of white trillium, a key indicator species of deer grazing. Replicas of these circular exclosures can be seen in the trails linking the Lac Hertel picnic area with the Welcome Centre.

While these small circular exclosures have been incredibly valuable as monitoring tools, the sustained high density of deer calls for new tools in our arsenals: much larger exclosures designed with regeneration in mind.

Combining monitoring efforts with more widespread protection

The first large exclosure, erected last fall in partnership with Connexion Nature is on the purple trail next to the meadow. This latest addition allows us to protect and monitor a larger area of roughly 625 m², thereby encompassing a higher diversity of species of trees and plants than was previously possible.

These past few weeks, our Field Operations Assistants have started monitoring the regeneration of native species and locating potential seed banks in the soil. A seed bank, in this context, is an area on or in the soil where plants store reservoirs of seeds for new generations of plant growth in the future.

These data are a first step towards creating healthy populations of vegetation to be propagated across the mountain, thereby restoring a vibrant, healthy understory. We will build more of these exclosures in the coming months and years. The data and resources gathered from these exclosures will be invaluable in understanding and fostering a healthy future for Mont Saint-Hilaire's forests.

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