Why are maple syrup yields shrinking?

Scientists in Nova Scotia are investigating why maple syrup tree taps are yielding less sap than decades ago and whether climate change is one of the culprits.

The maple syrup industry in the province has grown over the decades and there are currently more than 350,000 trees tapped in Nova Scotia. While there's more maple syrup being produced, an average tap is yielding about a quarter less syrup than in the 1970s.

Producers have plenty of theories about why, but are looking for solid evidence.

Raj Lada, a professor in the Faculty of Agriculture at Dalhousie University's Agricultural Campus in Truro, is hoping he will be able to provide those answers.

"Is it due to biological issues associated with the tree? Or is it with the environment the climate change related aspect?" he said.

"That's the major issue, basically, we're currently working on."

The extraction of maple sap, which is turned into syrup, can be affected by fluctuations in temperature.

The study will analyze historic detailed weather and yield data. If climate change is the culprit, Lada hopes his research will help producers better deal with the challenges.

For instance, science may be able to give producers an optimum day to begin tapping, generating better yields over the season, which usually lasts for several weeks during the late winter and spring.

Lada is also taking a look at whether other aspects are at play, such as the size of the canopy and the strength of tree roots.

There are other theories, too. Keith Crowe has been working in the maple syrup industry for 62 years.

He suspects part of the problem may be trees that have been tapped for too long.

"I think subsequent tapping is slightly detrimental to the tree," Crowe said.

"I don't think it's ever as productive as it is in the initial stages in spite of the growth that might happen in the meantime."