Wild rocks and wildflowers.
Manitoulin gold (Hymenoxys acaulis) on Manitoulin Island. This is a rare plant largely restricted to alvars along Lake Huron.
Dr. Andy Fyon photo
The Parry Sound Nature Club meeting on April 18 was very well attended this month with about 50 people coming out to hear our guest speaker, Dr. Andy Fyon.
Dr. Fyon is the director of the Ontario Geological Survey with the Ministry of Northern Development, Mines and Forestry. A geological engineer by training, he is also very interested in wildflowers, and he maintains a website www.ontariowildflower.com, which is worth the time to check out! His presentation to the Nature Club was a melding of his two passions demonstrating how they are closely intertwined – like a marriage of rocks and plants.
Andy started off his talk with an overview of the geology and geological history of Ontario, especially the triangular area from Manitoulin Island to Sudbury and down to Parry Sound. Ontario is a patchwork of different types of rocks, and the history leading to the formation of these rocks and landforms varies also. Approximately 1.5 billion years ago, the rocks of the Parry Sound area were buried 25 – 30 km beneath a tall mountain range. Over the next half a billion years or so, volcanic islands started to form in the ocean just to the south (about where New York State is now) because the rocks of the northern plates of the earth’s surface were being pushed under the southern plates. As they were forced deep into the earth, they melted and were pushed up as volcanic islands. The islands gradually squished together and formed new rocks, as pressure and high temperature "cooked" them, changing their structure. These volcanic islands were then pushed northwards until they hit shield rock, resulting in a patchwork of rock types because of the melding and mixing of southern rocks on top of northern rocks. The mountain range above Parry Sound eventually eroded away (just imagine 30 km deep rocks eroding away!)
Almost 600 million years ago, fault lines running in an East-West orientation appeared (picture the French/Mattawa/Ottawa rivers) and were related to the early formation of the Atlantic Ocean. About 450 million years ago, a warm, shallow ocean covered the area from Manitoulin Island south. This ocean deposited layers of hard, resistant rock layers as well as softer, easily eroded layers. These layers are visible at many sites on Manitoulin Island, like Bridal Veil Falls. More recently – 110,000 to 10,000 years ago – the advance and retreat of the glaciers left the present landscape exposed.
Armed with some knowledge of the geological history of an area, one can predict the types of plants that will grow there. Thus, the geological processes and history of an area create the landscape, which provides varying habitats, which determine plant communities thriving in those habitats. From here, Andy went on to describe some of those habitats and the adaptations of plants to survive in them.
When you look at the landscape on a small scale, we actually have a lot of ‘micro-desert’ around us in the form of open rock areas. There is little or no water, poor nutrient availability, great solar intensity and variation in temperatures. Plants trying to establish themselves in this type of habitat have developed adaptations such as deep roots to reach through cracks to find soil and water, leaves that are slender and reflective to minimize water loss and reflect excess sun (for example, Pearly Everlasting), or small and thick leaves similar to succulents to hold water (for example, Sedum). Plants that grow in sand deserts have evolved to deal with sand dunes that are always shifting. Immobile plants like trees would either get buried or have their roots exposed, so some plants have developed long surface root systems that allow new plants to spring up from nodes on the roots, and thus they can move with the shifting sands.
An alvar is an area of rock, usually limestone or dolomite, which has little soil and is high in bicarbonate so it is very alkaline. It is a harsh, inhospitable environment that is very hot and dry in the summer, but may often be flooded in spring. The Bruce Peninsula and Manitoulin Island have great examples of alvars. Fossils found in the rocks in these areas contain corals, indicating that in their geological history, they were formed by sediments in a warm ocean environment. These alvars are inhabited by “calciphile” plant species that thrive in the bicarbonate-rich environment. There are also examples of plants that appear to be “out of place” in this area – plants like prairie wildflowers and coastal maritime plants. Geological history provides one possible explanation. As the glaciers retreated, ocean waters flowing in from the east and west carriedplants (or their seeds) from grasslands to the west and maritime plants from the east.
Bogs are isolated, acidic and nutrient-poor areas characterized by sphagnum moss, sedges, heaths and carnivorous plants. These areas may have been formed from chunks of glacier ice broken off and left behind as the main glaciers retreated. When these chunks melted, they formed isolated pockets of water that are not based on water flowing in or out via a river or stream. Some plants have adapted to this type of nutrient-poor habitat by finding other sources of food – they have become carnivorous! Pitcher plants, Bladderwort and Sundew are examples of plants with various strategies to capture and digest insects to obtain required nutrients.
Andy’s presentation demonstrated how two very different disciplines can be very intertwined. His knowledge of the geology of Ontario has led to a better understanding of his hobby of wildflowers, and the enthusiasm and passion he has for each area of study is very evident, and contagious! Many members had questions and comments for Andy, and I’m sure everyone came away with a better understanding and appreciation for the rocks that we see every day and how they influence everything “from the ground up.” ?The next meeting for the Nature Club will be on Wednesday, May 16, at 7 p.m. at the West Parry Sound District Museum. Everett Hanna will tell us about his research into the migratory behaviour of Sandhill Cranes. He is a PhD candidate at the University of Western Ontario and is conducting radio telemetry to determine the current range of the eastern population of Sandhill Cranes. All are welcome (non-members $3), and remember to bring your own mug for coffee and tea!