Urban forests face many challenges from development, climate change and extreme weather, invasive species and disease. These challenges become particularly pronounced when one or two tree species dominate a woodlot, and even more so when they are non-native. This very fact became apparent with the detection of pine wilt disease at Russett Park, a woodlot once dominated by the non-native Scots pine (Pinus sylvestris).
© 2023 Sarah Halonen / LEAF
LEAF staff and volunteers celebrating the achievement of their planting efforts.
Pine wilt is a dramatic disease that affects trees in the Pinus genus of coniferous trees. It is caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus. PWN is a microscopic roundworm native to North America. In native conifers, the nematode feeds harmlessly on fungi that bark and wood-boring beetles (Monochamus species) introduce into trees.
Reproduced, by permission, from Donald, P. A., W. T. Stamps, M. J. Linit, and T. C. Todd. Pine wilt disease. The Plant Health Instructor. DOI:10.1094/PHI-I-2003-0130-01. Updated 2016 by T. C. Todd. © The American Phytopathological Society.
However, when PWN infects non-native pines, it feeds within their vascular system, creating air pockets and making it impossible for the host trees to transport water freely. Just as humans cannot drink through a straw with holes in it, the tree cannot move water upward. The outcome is wilting in the upper canopy that works its way down. Death to the host tree can occur in as little as a few weeks, as witnessed in Russett Park.
© 2020 City of Oshawa
A section of Scots pine stand at Russett Park experiencing decline and mortality due to pine wilt.
After several years of monitoring and the steady removal of diseased and dead trees by the City of Oshawa, it became apparent that the overall health of the woodlot declined to the point where the area was no longer safe for public use. In addition to safety concerns, the timely removal of trees killed by pine wilt disease can eliminate breeding habitat and prevent further transmission to healthy trees. As a result, the City undertook large-scale removal of the woodlot in 2021, to be followed by intensive replanting.
© 2021 Jason Liebregts/Metroland (might still need to secure permission)
Tree removal at Russett park in late 2021.
This large-scale tree removal at Russett Park provided a unique opportunity to enhance biodiversity and resiliency. Not only does the non-native Scots pine serve as a vector for pine wilt disease, but it also tends to dominate an area by shading out native plant species, reducing overall biodiversity and habitat.
Since 2022, LEAF has partnered with the City of Oshawa to help with the restoration of Russett Park. Over 1000 native trees and shrubs, representing more than 30 different species, have been planted so far in an effort to create a more sustainable urban forest. Replacing predominantly felled species of non-native pine trees with new native trees and shrubs of diverse species suitable to the site is of utmost importance. By planting the right trees in the right place, we can build a stronger, fuller and more resilient urban forest for the future.
© 2023 Sarah Halonen / LEAF
Recent fall 2023 community planting of 500 native trees and shrubs.
Over the past two fall seasons, 200 community members from all over the GTA participated in the replanting of this woodlot. For one participant, this action proved to be especially meaningful: “I grew up playing in the woods at Russett Park, so it was very meaningful to me to help reforest the area for future generations to enjoy.”
© 2023 Sarah Halonen / LEAF
Community members from across the GTA are helping in the effort to restore Russett Park.
Thanks to the help and hard work of the community, Russett Park is being brought back to life, more diverse and stronger than ever! Stay tuned for future community tree plantings at this cherished Oshawa woodlot.
Sarah Halonen is the Stewardship Coordinator at LEAF.
Our 2023 fall planting events at Russett Park were supported by the City of Oshawa through an Oshawa Community Grant and Ontario Power Generation.
