Illustration: Wikimedia CC
The Norway maple (“Acer platanoides”). Illustration from History of the forest trees of north America”, by François André Michaux.
Since always, they serve to build as much as dream… In this summer series, The Duty attempts to identify what wood they are made out of trees that surround us. Today : the invasive Norway maple.
The diversity does not seem to miss in the urban forest of Montreal and the accounts seem to be good. There are 322 species of tree in the inventory official of the city, while Quebec has a fifty natives.
By contrast, almost all of these species each account for less than 1 % of the batch. A handful of trees, always the same, dominate the forest metropolitan, according to data collected by the researchers of the Centre for forest research, UQAM over the last few months : the ash trees (14 %), which is now in danger of disappearing, the little leaf linden (8 %) and two varieties of maple, the Norway (Acer platanoides) and silver (Acer saccharinum), with in each case 17 % of the seats champions.
Diversity is therefore also lacking in the urban forest of Montreal. The accounts are definitely not good.
All the major cities of the northern hemisphere are found elsewhere in the same homogeneity that is green with a handful of genres in the over-representation.
“Everywhere, usually with four or five species, it is the turn of 50 % of the forest to a city : it is true in Quebec, New York, Philadelphia, like in Montreal,” said the biology professor Alain Paquette, of montreal. In addition, in the eastern part of North America, we meet always the same trees, the Norway maple, the silver maple, the ash of Pennsylvania. It is bad for the resilience. This is bad for diversity. In biology as in finance, it is not necessary to put all its eggs in the same basket to reduce the risk. “
Of the pandemic
The very real danger strikes regularly. As pointed out in this summer series, on trees, around four billion chestnut trees in America are gone at the beginning of the Twentieth century. The destruction of the elm disease arrived in Europe there was a half-century then led to the planting mass of ash, now attacked in their turn by the borer came from Asia.
Maple and especially sugar maple (Acer saccharum), emblematic tree of the country, may well go sooner or later. Professor Christian Messier, of UQO, other specialist forests, mentions the threat created by the terrible asian long-horned beetle. This beetle, which attacks hardwood trees has been detected for the first time in the suburbs of Toronto at the beginning of the century. Mr. Messier speaks squarely to a crisis, pandemic, latent, for tree preferred, provider of the fabulous syrup (see box).
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“This insect love maple,” he said. We managed to control it until now, but this is my fear for the next 30 to 40 years. With climate change, the long-horned beetle may proliferate and we’re going to lose the maple, as we lost the American chestnut. “
In fact, the three species most represented in our cities problems. The ash tree is dying, it is well-known. The silver maple, beautiful, native more, is enormous and therefore it is not suitable everywhere. The Norway maple, considered to be a species relatively invasive, can’t even be planted on mount Royal.
“We cannot do without because it is a champion of urban conditions and that this is one of the few to resist in the pits of the city centre, note the professor Paquette. There are too many and the next insect that might attack it will put us seriously in trouble. “
The specialist adds that the Norway maple invades all the imaginary symbolic than land. “The people who designed the stamps, currency, national symbols were in this case more lovely and have represented anywhere,” said the connoisseur. He noted that the canadian television Fund uses a samara which is not that of the sugar maple. For the maple leaf, the difference remains very elusive to the naked eye, then he will forgive the confusion when it is.
It is to participate actively in the search for solutions for tree replacement that the project IDENT-a City pushed to 2015 in the borough of Ahuntsic-Cartierville, at the edge of the river. The experimental planting of montreal provides a concrete example of the functional diversity. It includes 48 trees of 27 species.
Available in double spiral allows you to better contemplate the specimens, including helping citizens make a choice for their gardens. It is a catalogue, open to the sky. “The species are all adapted to the city and the new city, with smaller lots,” said the professor Paquette, met on-site. It has cultivars with small or medium development. “
The network IDENT (Internationial Diversity Experiment Network with Trees), co-led by profs Paquette and Messier, is conducting similar experiments on the benefits of biodiversity with 27 experiments involving more than a million trees on all the continents. The arboretum’s inaugural series has been implanted in Sainte-Anne-de-Bellevue. That of Montreal is the first of the series in urban areas.
There are three maple trees planted by the scholars of the wood in this batch, three out of the ten maple trees known in Canada : he said of Pennsylvania, also known as wood-barré syndrome, or moose ; the red maple, a garden variety relatively narrow ; and then the maple Freeman, the hybrid between red and silver. A maple-à-Giguère (Acer negundo) has pushed itself into the spiral, as he knows how to take advantage of the slightest flaw in the concrete of the cities.
The nature fits everywhere. But is this really the case ? Our forests, urban or not, are generally appointed by the human. They are nature cultivated.
In any case, there is very little wood pre-colonial in the south of Quebec, where sugar maple was dominant in the past. The oldest individuals of the ecological reserve of the Boisé-des-Muir, near Huntingdon, have a few centuries. There is a stand of sugar maples, beech, and hemlock. It is forbidden to visit it, except for the search.
Professor Christian Messier does not stop experimenting with new forests ” in the fields “, as they say in his world, for better control of the settings. He has recently planted 14 000 trees of six species mixing distributions on a regular or random on a hectare of land a farmer from the Outaouais region. It checks in particular the effects of the drought.
“The great question of my research,” said the teacher, is : what are the benefits of having forests diverse in species. There are all kinds. With our findings, we would like to convince the world to do more planting in monoculture. Approximately 95 % of the plantations on the planet are in a monoculture, which is not natural and increases the risk of destruction. “
It is also recommended to diversify the “functional traits” (such as tolerance to drought, or to salt, or in the shade) of species planted in the city as in the countryside to maximize their chances of survival. The City of Montreal has adopted this approach.
“The forest engineers and architects of landscapes love the monocultures,” he said. They speak of the beauty in the uniformity, here as everywhere in the world. Me, I’m trying to convince them of the beauty in the complexity. Nature knows it. We should learn it. “
Maple sugar sweetheart
Professor Christian Messier, of UQO, a specialist of forests, admits to a passion immoderate for the sugar maple tree, his tree favorite since always. “I picked up some of the maple water with my uncle when I was young. Later, my father bought his land to timber, as they say. I now have my own sugar shack. “
It is a notch about 200 maple trees. “It is the symbol by excellence of nature in Quebec and it is a bountiful tree,” he said. It provides a natural environment is extremely diverse, especially in spring, when he gives water and therefore the syrup, according to me the best sugar in the world. It provides shade and cools all summer. In the fall, it gives extraordinary colors ranging from yellow to dark red. I walked around everywhere in the world and I never found our forest colorful. And then, its wood is very dense beautiful it’s hot, providing a very pleasant smell and is used in cabinet making. “
His colleague Alain Paquette arrived at the scholarly of the forest by the same through the work of the wood. “I often joke that I was interested in first, to dead trees,” said the professor, UQAM, who studied social work before turning to biology and ecology. “At home, we did everything ourselves, including our furniture,” adds he, pointing to a cherry late and a black walnut in a park north of Montreal, where appropriate, the interview, ” the wood the more beautiful it was in this corner of America for cabinet work “.