Biology graduate student William Van Hemessen is spending his summer hunting in the wilds of southern Ontario, on the lookout for macrofungi.
Perhaps the most recognizable form of fungi to humans, macrofungi, such as mushrooms, toadstools and puffballs are distinguishable by their visible fruiting bodies.
“Many macrofungi have a critical role in global nutrient cycles and therefore have an important role in the vegetation health in virtually all habitat types,” said Van Hemessen, a master’s student in biology who has been tasked with scouring Ontario’s slice of the Carolinian Zone.
The Carolinian Zone, which includes the region within 150 kilometres of the Lake Erie shoreline, is the most southerly biome in Canada. By many metrics, it is the most biodiverse region in Canada.
“We know these areas are special within Canada as having the highest biodiversity in birds, vascular plants and amphibians,” said biology professor Greg Thorn, who is supervising Van Hemessen’s work. “We presume the same may be true of fungi, but we don’t know.”
Macrofungi are immensely diverse, but for all their importance to an ecosystem, little is known about the types that can be found in southern Ontario.
According to Van Hemessen, the estimates of the global diversity of macrofungi range from 500,000 to several million species.
“We know very little about their diversity, biogeography and conservation status compared to most other organisms. Since biodiversity loss is ongoing and accelerating around the world, we need to be documenting macrofungi at the regional scale,” he said.
The mushroom hunter
Throughout the summer months, Van Hemessen will be conducting an inventory of the macrofungi of Norfolk County, Brant County, Six Nations of the Grand River and the Waterloo Region.
Growing up in London, Ont., Van Hemessen completed a bachelor’s degree in environmental studies in 2011. From there he began working in the environmental consulting industry as a botanist until he felt the urge to return to higher education.
“I started looking for opportunities to do a master’s degree and serendipitously found out about professor Thorn’s Carolinian project,” said Van Hemessen.
Thorn says it was an application he was happy to accept.
“I had known Will for several years as one of the top field botanists in Ontario. I knew he had an interest in fungi, so I was delighted when he suggested working with me on an inventory of fungi in this part of the Carolinian Zone. He is an expert on plant diversity in this region, including the ecology and distribution of rare plants,” said Thorn.
It’s this expertise that made Van Hemessen the ideal “hunter.”
Finding new species
Van Hemessen is relying on his intimate knowledge of the area in order to document the region’s macrofungi.
He will be visiting natural areas aiming to achieve comprehensive coverage geographically and across different habitat types.
“My surveys aren’t structured in the sense that I’m not mapping out transects of sampling plots,” said Van Hemessen. “I use an ad hoc approach to focus on the most interesting and productive microhabitats within each natural area.”
He notes his approach is unorthodox, but with a decade’s experience as a botanist and vegetation ecologist, he has crossed paths with macrofungi several times and knows where to look.
“Based on early observations, it seems we may find many species of fungi that had not been previously known to occur here, as well as some species that may be completely unknown,” said Thorn.
Van Hemessen is intrigued by the process of uncovering something new, but his true passion is in protecting what he knows is a crucial part of our ecosystem.
“We need to understand how macrofungi tie into local and global ecology and whether there are rare species that need protection.” He noted that while the Carolinian Zone is one of the most biodiverse, it is also one of the smallest biomes in Canada and is densely populated by humans. “Documenting macrofungi here can help us identify whether the conservation status of a species is of concern and if they would benefit from legal protection,” he said.
From the ground up macrofungi are playing a critical role in supporting the complex biome that is the Carolinian Zone. With the knowledge that macrofungi play impact nutrient cycles and vegetation health, it makes Van Hemessen’s work vital because as Thorn says, “you cannot conserve what you are not aware of.”