Dear Silvie: When Is the Right Time to Thin Red Pine?

Forests Ontario's forestry experts, known collectively as Silvie, answer your forestry questions. Please send questions to info@forestsontario.ca

Dear Silvie,
I have a red pine woodlot planted 25 years ago. Is it time to thin it?
–Gunter and Elsa Vierich, Madoc

Dear Gunter and Elsa,

If you closed your eyes and imagined forest, wetlands, and meadows in place of major cities, roads, and agricultural spaces, you’d be picturing what Ontario looked like in the 1700s. Much of southern Ontario was described as “forests” into the early 1800s. However, as settlers started their new lives in Ontario, they began using these once plentiful resources; by the 1860s, there was almost no forest left in southern Ontario.

Over many decades, influential advocates for large scale replanting spurred various government funding programs. In 1966 the Woodlands Improvement Act provided landowners with support for tree planting and stand improvement for existing woodlands. Over the next 30 years, Ontario saw more than 213 million seedlings planted on over 137,000 hectares, including Red Pine, White Pine and White Spruce. Fast-forward to present day, and landowners across the province still require support with forest management activities, such as thinning.

When a plantation is established, the expectation is for those trees to be managed over time to help convert the plantation into a mixed diverse forest. Managing a plantation involves having a forestry professional and/or a certified tree marker assess the woodlot to determine the health and density of the stand as well as what trees to leave and which to remove, if needed. When managing a plantation, foresters call the removal of specific trees thinning.

Tim Gray, retired forestry technician with the Ministry of Natural Resources and Forestry, says Red Pine thrives on light. “If you want your Red Pine to grow strong and healthy, free of disease and pests, thinning the plantation is necessary,” explained Gray. Non-thinned and neglected plantations are more prone to storm damage and stunted growth.

More than one thinning must take place for the plantation to transition into what is considered a natural forest. A forestry professional can create a forest management plan which guides thinning operations over the long term. The initial thinning opens space for tree growth and the second thinning removes trees that are unhealthy or poorly formed to improve spacing and provide more growing room for the remaining trees that have the best future potential. As a result, logs thinned later will be larger and more valuable.

Thinning also helps natural regeneration. Removing some pines brings light into the forest. Shade-tolerant tree species, such as maple and oak, then can take root, often through seeds or acorns brought in by wildlife or on the wind. Thinning thus encourages transformation of a pine stand into a diverse mixed forest, welcoming to a wide range of wildlife and creating forest paths for recreation. The Red Pine that remain have space to grow to into valuable timber.

If you are considering thinning or would like more information on forest management, please contact Forests Ontario and we can connect you with a local forestry professional in your area.

Yours, Silvie

Photo: Red Pine Plantation in the forest of Gunter and Elsa Vierich in Madoc Township, planted in 1995.