FOR more than a century, provincial tree planting has cut flood risks in Ontario. Rivers have surged over their banks this spring, flooding hundreds of homes, businesses and cottages. The Ottawa, Muskoka, French and Mattagami rivers (and many others) have flooded — and the risk now extends to lakes as well.

“Forecast high winds . . . will pose additional flood hazards along the shorelines of Lake Erie and Lake Ontario due to high water, wind-driven storm surge and damages due to erosive wave action,” read a late-May warning from the province’s flood forecasting system. Fourteen Ontario Conservation Authorities had issued flood warnings before the end of May.

In the 1920s and 1930s, flooding was commonplace in Ontario. Edmund Zavitz, chief forester of Ontario a century ago, traced the problem to deforestation. Settlers had cleared most of southern and eastern Ontario, leaving a bare-bones forest cover of about nine per cent. The Thames and Ganaraska watersheds were down to about four per cent forest cover. The indiscriminate clearing had stripped away some of the key features that absorb rainfall surges, such as swamps and wetlands along creeks. Deserts spread. Sand dunes engulfed orchards and roads. There was nothing to soak up the rain and flash floods multiplied.

Zavitz offered a simple solution; plant trees, he said.

Tree roots hold back riverbanks and prevent erosion. Trees act as sponges, soaking up rainwater; the trees release water into the atmosphere through what’s called transpiration. This is a benefit of adequate forest cover. And the United States Geological Survey estimates that a large oak tree transpires more than 150,000 litres of water every year. Water that a tree soaks up and that evaporates from tree leaves stays out of the sewer system, saving money on new pipes.

In 1908, Ontario opened the St. John Forest Station and Nursery; the same year, the province opened the St. Williams nursery, near Lake Erie, to grow tree seedlings. A network of provincial nurseries grew. In 1911, a Conservative government passed the County Reforestation Act. In the 1930s, Conservative governments supported municipal reforestation efforts including the Inglis Falls Municipal Forest just south of Owen Sound as well as widespread reforestation in, for example, Simcoe County and Northumberland County.

In the 1940s and 1950s, planting in the Larose Forest in eastern Ontario rose to one million trees per year. Thanks to provincial cash, the forest cover of southern Ontario tripled from 9.7 per cent in 1943 to 25.5 per cent in 1963. In 1968, John Robarts, Progressive Conservative premier of Ontario, planted the province’s one-billionth tree — a sugar maple grown in a government nursery. And the planting continued.

In 2008, the Government of Ontario launched the 50 Million Tree Program to increase forest cover in the province. The program, administered by Forests Ontario, a not-for-profit tree planting and forest education charity, has so far succeeded in planting more than 28 million trees.

Government support through the 50 Million Tree Program has kept down the price of trees, encouraging private landowners to turn fields into forests. These afforestation programs benefit us all, because they reduce the risk of floods and erosion.

Forests Ontario maintains a wide network of experienced professionals. In every region, soils and climate conditions differ. The program also ensures that planters choose seedlings grown from seeds collected in the same seed zone. In this way, the 50 Million Tree Program makes sure that the right tree goes in the right spot — and gets the care it needs.

In its April budget, the government of Premier Doug Ford cut the funding for Ontario’s 50 Million Tree Program. The Ford government may think enough trees have been planted, but an ever-growing number of Ontarians disagree.

More than 87,000 people have signed a petition on the website, “Rescind the order to cancel the 50 Million Tree Program!”

The cancellation has also inspired new donors and new memberships for Forests Ontario. The website allows donors to list their gift as “in memoriam;” one donor dedicated their contribution as “in memoriam for our planet.”

We can only hope that our leaders are listening. The $4.7 million annual cost of the 50 Million Tree Program is a small price to pay to mitigate the flooding that threatens the homes of many people in Ontario.

Rob Keen is a registered professional forester and chief executive officer for Forests Ontario.

(Originally published June 5, 2019)

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