Advocacy for plant diversity

Canada is not adequately protecting its plants, according to a recent report by the Council of Canadian Academies. The explosion of international trade and climate change are transporting new insects and pathogens that current practices at borders and in fields and forests will not be able to contain.

Mathieu Perreault
The Press

Plant more trees

The results of the study conducted at the Morgan Arboretum are clear: forests where four species of trees coexist are less affected by insects and diseases than forests composed of only two tree species. “The productivity of the forest is better,” explains Christian Messier, a UQAM biologist who conducted this study in recent years. Mr. Messier co-signs the new report Cultivate diversity of the Council of Canadian Academies (CCA). “This is a good example of the findings of the CAC report: agricultural and forestry diversity must be increased to counter the growing threats to plants in the country. We are trying to convince the government to change the management of public forests in this direction, but for the moment, nothing is happening. We have a little more success with private forests. Mr. Messier is part of an international network that is interested in the biodiversity of plantations.

The case of maple groves

Sugar bushes are one of the targets of this movement, because they are among the forests closest to monocultures in the country. Mr. Messier published last fall in the journal Forestry progress a presentation on diversity in sugar bushes, where he compares a typical plantation, composed of 75% sugar maple and 20% red maple, to another where there is only 35% sugar and 10% red maple. In both cases, it is necessary to reduce the portion of maple trees and increase that of other species, in particular drought-resistant species. Some 45% maple is still too much.

The climate

Climate change is causing diseases and insect pest species from the south to migrate north. What about the direct effects of global warming on fields and forests? “The direct effects will mostly be felt in northern Canada,” says Messier.

Border detection

The other recommendation of the CAC report is increased border surveillance. Mr. Messier cites New Zealand as an example. “When we get off the plane, we systematically walk in bins containing liquids that kill bacteria and insects. Is it possible to do such surveillance in Canada, with its long border with the United States? “Phytosanitary surveillance at borders is much better in the United States than in Canada,” replies Mr. Messier. We must increase our surveillance at airports and ports, particularly for people and cargo coming from climates similar to ours. For example, from northern China. »

The Indigenous experience

The report was written by biologists and social scientists. “We have reserved an important place for Aboriginal communities,” said Mr. Messier. For example for monitoring forest disturbances, emerging diseases and insects. There is also ancestral knowledge. In pre-colonial forests, there was a lot of white pine and red oak, two fire-resistant species. Indigenous peoples also set fire to the forest intentionally, to remove the fuel to the ground. Much of the increase in forest fires in recent years is due to the accumulation of fuel on the ground. » The red oak is protected from fire by its deep roots and the white pine by its height, which allows both its foliage to survive certain fires and its seeds to disperse very far, taking advantage in particular of the openings created by the lights.

native species

Planting native species is generally preferable to promote biodiversity. “In addition, native species are less likely to be invasive,” says Messier. Think of the Norway maple, which is slowly invading the natural forests around our cities. Tree plantations in Canada are made up of 98% native trees, compared to only 22% of European forests, according to a study published last year by Mr. Messier in the journal Conservation Letters. Why ? “300 years ago, when Europeans were exploring the world, they had destroyed their forests and decided to introduce trees to facilitate reforestation. Also, Europe has fewer native tree species than North America. This is caused by the orientation of the high mountain ranges. They are oriented north-south in North America, which allowed rapid recolonization after the last glaciation. In Europe, the mountains blocked this recolonization. »

Accessibility and protection

To promote plant diversity and protect forests, should they be protected from human incursions? “It is certain that to democratize access to nature, we may want to develop access roads, says Mr. Messier. It all depends on the environment. In Mount Royal Park, for example, it is not a natural forest and there are many invasive species, including the Norway maple. It’s very anthropized, maybe we don’t need to preserve all the forest. But in Parc d’Oka, it’s a much more natural environment, so we can perhaps limit the access roads. At the same time, climatic and biotic pressures are so strong that even preserving natural ecosystems would not be enough with the stresses that are coming. »