It’s not very often that you hear jaws drop when a scientific paper is being presented. But that was the case earlier this year, when Trent University grad student Shelby Conquer shared the results of her work with sugar maples.

Shelby has been studying how spreading wood ash in the forest affects the flow of sap in maple trees. And after just one season, the results were astonishing.

“In terms of average sap volume, there was twice as much sap produced from trees in the ash plots as compared to the control plots,” she said.

Even better, when she compared the level of sugar in the sap, there was no difference at all between the trees that had been exposed to wood ash and those that hadn’t.

“We’re not seeing the dilution of sugar content despite the increased amount sap being produced,” she said.

What that means is that trees that had wood ash spread at their base were producing twice as much sap – and potentially twice as much maple syrup – as those that hadn’t.

Shelby presented her results to a gathering of the Friends of the Muskoka Watershed (FMW), a non-profit organization that is behind the AshMuskoka project.

Hundreds of volunteers across Muskoka have been saving and donating the ash from their fireplaces and wood stoves, which FMW volunteers and staff then sifted, weighed, and spread in calibrated amounts in test projects at Camp Big Canoe in Bracebridge and three maple sugar bushes in Muskoka.

Trent University and several other universities have been involved in the research side of the project.

The project was launched several years ago, in response to low calcium levels in Muskoka’s lakes and forest soils. Decades of acid rain had flushed much of the naturally occurring calcium (among other minerals) from the soil and waterways. While acid rain was halted many years ago, it will take decades – or possibly centuries – for the ecosystem to recover on its own.

Fireplace wood ash is widely available and rich in calcium. And so the researchers wondered if it could be used to replenish the lakes and forests – not just in Muskoka but throughout central Ontario.

The research focused on sugar maples, because they are especially susceptible to malnutrition when faced with a dearth of calcium.

“Basically, sugar maples need a higher amount of calcium than other trees to remain healthy,” says Shelby.

Spreading wood ash allows the soil to soak up the nutrients – which include calcium, potassium and more – which is then fed to the trees through their roots.

At Camp Big Canoe, they established eight, 40-by-40 metre plots in 2020; four were treated with a six-tonne per hectare dose of wood ash and four were kept as control plots.

In 2021, they returned to establish four more plots, which were treated with a two-tonne per hectare dose.

“This is to help us establish whether or not we can see the same benefits with a lower dose and therefore spread the ash a little bit farther,” says Shelby, noting those results would be available after samples are taken later in 2022.

Eventually, the FMW hopes to see a residential wood ash recycling program established which will spread ash on a watershed-wide scale.

In terms of recent results, Shelby says they are promising, however there is always the caveat: “it’s still very early to tell.”

Potassium a factor As anyone who has ever tapped a tree knows, sap production can vary dramatically from year to year. Shelby notes that factors involved include tree health, soil fertility and water availability.

“However, having the plots in the same area means all the trees will be impacted by the environment in the same way … allowing for research results to be more accurate,” she says.

The initial research focused on calcium, but researchers note that potassium – which is also found in the wood ash – also has a key role to play. “It appears that large increases in potassium are stimulating the production of sap,” says Shelby. “Potassium increases pressure in the tree which allows for more uptake of water, and that is likely leading to the increased sap production.”

Fellow Trent grad student Batool Syeda, who also presented findings to the FMW gathering, found that there was a significant increase in potassium in the tree foliage where ash was applied – as well as an overall increase in calcium.

Similar results were found at the three maple producers, where samples were taken from full a range of trees, from full-grown down to saplings.

Some research suggests that potassium helps with carbon dioxide assimilation, while it is well documented that it helps with photosynthesis and promotes overall tree health.

“We can see the ash is having an impact,” says Batool, while noting it’s still early and the full impact won’t be known for a few more years. “Until we see the full increase in a few years at the mineral layer (well below the top soil) plus the results in the actual trees at that time, we need to take these results with a grain of salt.”

Helping maple producersBrooklands Farm is one of the sugar maple producers taking part in the AshMuskoka research. Ken and Katya Riley and their sons are the fifth and sixth generations of the family to own the farm, which has long produced maple syrup among other fresh foods.

They happily provided a few trees for research because they know this is a concern for both producers and the public at large. Over the past 30 years, Ken has done his own research along with fellow Muskoka maple producers. When they started testing soil samples, they found a dramatic and concerning calcium shortage.

“This is something we need to work on and correct,” says Ken. “In Muskoka, one of the main constraints in our soil is acid, and it has to be corrected with calcium.”

To combat the problem, over the years they have spread powdered lime, which contains high amounts of calcium. “I’ve been an advocate for lime in agricultural soils for a long time,” he says. “It makes a huge difference, we know, to add a few tonnes of lime.”

While Ken loves the idea of the AshMuskoka project, he says it may be best to do it in conjunction with spreading dry agricultural lime to help increase the calcium content, noting it depends on the size of the property and sugar bush.

“We have a 100-acre bush. We would have to burn an awful lot of wood to cover our whole bush,” he says. “However, ash is nice because it does provide other nutrients as well. Potassium is a big one that is also limited. I’ve been testing soils for 30 years or more and potassium is a big limitation as well: we have to routinely put on potassium and phosphorus on our soils.”

Kens says they regularly put wood ash into their compost and then use a manure spreader to mix it up and put it back on the fields.

This is one way to help promote and increase the health of sugar maples – and other trees – throughout Muskoka. Whether you are a maple producer or a concerned landowner who cares about healthy trees, there is a lot you can do.

One way is to get involved with the next component of the AshMuskoka project as a Citizen Scientist, spreading ash on your own property and recording the results (details are at FOTMW.org/citizen-science). Another is just saving and spreading your own residential wood ash on your property.

Either way, you’ll be helping to add calcium, potassium, and other nutrients into the trees’ diet. And, if it’s a sugar maple, getting rewarded with plenty of sweet, golden syrup.

More than just syrup
Adding calcium to the forests has the potential to do more than just make more maple syrup.

Studies are just getting started now, but there are indications that every part of the forest is nutrient deprived, and has been for a long time. “It’s like the trees are asleep, and spreading wood ash helps them to wake up,” says Dr. Norman Yan, past chair of the Friends of the Muskoka Watershed.

• In addition, calcium that is added to the soil will make its way into the lakes, which are also known to be deficient in calcium.

• Among the potential benefits of wood ash that are being researched are:

• Increasing the amount of water trees absorb and transpire (pump back into the atmosphere), potentially mitigating the risk of spring flooding.

• Increasing the growth rate of all trees (not just maples), enhancing the ability of our forests to capture and store carbon and combat climate change.

• Enhancing terrestrial species other than trees, including fungi, insects, smaller plants and amphibians, as well as birds.

• Supporting aquatic species that are known to be calcium-dependent, such as crayfish and daphnia (tiny aquatic creatures that play a vital role in cleaning lake water and feeding on algae).

ARTICLE BY CHRIS OCCHIUZZI | PHOTOGRAPHY BY ANDREW FEARMAN