Grounds manager wants to teach us about trees’ value

Sometime around 1745, about a century before Hamilton was incorporated as a city and more than 140 years before McMaster University was established, an acorn sprouted.

Today, that sprout is a massive, spreading white oak tree, a sentinel along the eastern edge of McMaster’s campus at King and Forsyth, where a curious little sign hangs from a rope around its huge trunk.

The sign tells us that oak tree, which has quietly been providing shade, sequestering carbon dioxide and soaking up wastewater for the better part of three centuries, has contributed more than $100,000 worth of benefits to the community that grew up around it.

“People’s heads turn when they start to understand all the ways these trees benefit society,” said McMaster’s grounds manager Barb Rabicki, who hung that sign and others like it around campus to teach the public about the true value that trees provide.

“I believe that education, which is why McMaster is here, is holistic,” she said. “We have students in classrooms. The outdoors is also an important classroom, and it’s a very important learning environment.”

There’s another sign tied to the trunk of the London plane tree that lords over the arts quadrangle, a relative child at just 90 years old, but already having contributed benefits estimated at $26,730.

A sugar maple between the arts quad and the David Braley Athletic Centre is estimated to be 114 years old and to have contributed $31,122.

Near the McMaster Museum of Art, there is a grove of slippery elm trees, each rated at about $32,000 in terms of contributions.

“People tend to marginalize the importance of our environment, and when you assign dollar values to it, they tend to take note,” Rabicki said.

She tabulated the trees’ contributions using a formula developed by the U.S. Department of Agriculture’s Centre for Urban Forest Research. The formula considers the size, species and location of trees.

(An online calculator is available at Hamilton and Burlington are in the northeast zone.)

David Galbraith, head of science for the Royal Botanical Gardens, said Rabicki’s project is important because it calls the attention of a price-obsessed society to the value of what grows.

“I think there is a tendency to view spaces in our area, whether we’re in a city or in a rural space, as something that should be serving a human purpose,” he said. “The ecological productivity of a tree or a wetland or any one of these green spaces often doesn’t come to people’s obvious attention.”

Trees are being recognized ever more as living artifacts, he said, with public bodies treating, protecting and celebrating their urban forests as collections, along the same lines as valuable paintings or books.

Both the University of Western Ontario and Queen’s University have formally designated their campus tree collections.

McMaster’s tree collection — or arboretum — should be considered as a living museum, Galbraith said, given its social, environmental, health, historical and educational value.

“There’s good reason to look at those trees as a real collection,” he said. “They can be understood as a group of entities — a collection — that has a real value in and of itself.”

Not including the natural forests along the northern and western borders of McMaster’s property, the developed part of the 120-hectare (300-acre) campus is home to some 5,000 trees.

The university works to preserve mature trees, Rabicki said, and when one has to be taken down for construction, it is replaced by two new ones.

Rabicki, who completed an inventory of McMaster’s trees five years ago, is working to raise the awareness of trees’ value in partnership with the RBG, which once owned much of the property McMaster now occupies.

The gardens is helping with archival research, expert advice and identification tags.

Rabicki is in the final stages of preparing a pamphlet, expected to be available soon, which will guide students and members of the public through McMaster’s tree collection. It will include GPS points and facts about the university’s urban forest.

About 8 per cent of McMaster’s trees, for example, are ash, and subject to predation by the invasive emerald ash borer.

Even the lowly Norway maple, once planted deliberately but now scorned as an invasive tree, gets a sympathetic mention from Rabicki, who offers this reminder: even the Norway makes shade and oxygen.

Wade Hemsworth

Republished from The Hamilton Spectator June 3, 2010

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