{"id":11492,"date":"2026-05-11T20:34:13","date_gmt":"2026-05-11T20:34:13","guid":{"rendered":"https:\/\/diverseproject.uqo.ca\/?p=11492"},"modified":"2026-05-27T13:13:30","modified_gmt":"2026-05-27T13:13:30","slug":"canadas-forests-are-running-out-of-breathing-room","status":"publish","type":"post","link":"https:\/\/diverseproject.uqo.ca\/fr\/2026\/05\/11\/canadas-forests-are-running-out-of-breathing-room\/","title":{"rendered":"Les for\u00eats canadiennes sont \u00e0 cours de r\u00e9pit\u00a0"},"content":{"rendered":"

By Morgane Dendoncker, Christian Messier, Manuel Esperon-Rodriguez & Olivier Villemaire-C\u00f4t\u00e9<\/em> Published in Climate Change Ecology (2026), with the contribution of Madeleine Gauthier for communication<\/em><\/p>\n\n\n\n

\u00c0 mesure que les temp\u00e9ratures augmentent et que les r\u00e9gimes pr\u00e9cipitations changent, les arbres qui poussent sur nos 2,3 millions de km\u00b2 de for\u00eats canadiennes g\u00e9r\u00e9es sont confront\u00e9s \u00e0 des conditions climatiques qui d\u00e9passent celles auxquelles ils se sont adapt\u00e9s au fil du temps. Notre nouvelle \u00e9tude, publi\u00e9e dans Climate Change Ecology<\/em>, offers a subcontinental-scale diagnosis of this stress, which can help the forest industry think about the vulnerabilities of the forests they manage. <\/p>\n\n\n\n

Are Canadian trees stressed right now?<\/strong> <\/p>\n\n\n\n

Most tools used to assess how forests will respond to climate change rely on species distribution models (SDMs) which are statistical approaches that predict where a species might live based on where it currently lives. These are useful, but they have a blind spot: they can’t tell you whether a species living in a given location today is already at its climate physiological limit. <\/p>\n\n\n\n

We took a different approach. Instead of asking ”where” species might live, we asked ”how much more change” the trees already in place can tolerate before they run into trouble. To do this, we used climate safety margins (CSMs) which are a measure of the gap between the climate a species is currently experiencing and its realized physiological tolerance limits. <\/p>\n\n\n\n

Voyez cela comme votre zone de confort au travail. Chacun dispose d\u2019une marge dans laquelle il est performant, suffisamment \u00e0 l\u2019aise pour se concentrer et suffisamment r\u00e9silient pour faire face \u00e0 une mauvaise journ\u00e9e. Si l\u2019on pousse quelqu\u2019un de mani\u00e8re chronique au-del\u00e0 de cette limite, son bien-\u00eatre diminue, sa productivit\u00e9 baisse, le stress s\u2019accumule et il en faut de moins en moins pour le faire basculer. C'est la m\u00eame chose pour les arbres ! <\/p>\n\n\n\n

Ce que nous avons constat\u00e9 : un passage d'un stress li\u00e9 au froid a un stress li\u00e9 \u00e0 la chaleur<\/strong> <\/p>\n\n\n\n

Nous avons analys\u00e9 313 esp\u00e8ces d'arbres nord-am\u00e9ricaines pr\u00e9sentes dans les for\u00eats am\u00e9nag\u00e9es du Canada. Pour cela, nous avons utilis\u00e9 l'ensemble des donn\u00e9es disponibles sur la r\u00e9partition de ces esp\u00e8ces dans cette r\u00e9gion en combinant les donn\u00e9es de l'inventaire forestier national du Canada, des parcelles d'\u00e9chantillonnage provinciales, de l'inventaire forestier des \u00c9tats-Unis et de GBIF.\u00a0Dans nos analyses, nous nous sommes concentr\u00e9s sur cinq variables climatiques : la temp\u00e9rature annuelle moyenne, la temp\u00e9rature minimale du mois le plus froid, la temp\u00e9rature maximale du mois le plus chaud, les pr\u00e9cipitations annuelles et les pr\u00e9cipitations mensuelles moyennes du trimestre le plus sec, afin de rendre compte \u00e0 la fois des conditions thermiques et hydriques qui d\u00e9terminent les endroits o\u00f9 les arbres peuvent survivre et cro\u00eetre. <\/p>\n\n\n\n

\n

Les r\u00e9sultats montrent clairement un syst\u00e8me en pleine transition.<\/p>\n<\/blockquote>\n\n\n\n

Today, an important climatic factor for most Canadian tree species is cold: specifically, the minimum temperature of the coldest month. Given the geography of the Canada, nearly all species are living in the cold edge of their distribution somewhere in the country, particularly in the far north and at high elevations. This is expected; cold winters define range boundaries. <\/p>\n\n\n\n

By the end of the century, that pattern flips. Under intermediate and high emission scenarios, warming winters reduce cold stress,\u00a0but rising summer temperatures become the new threat. By 2071\u20132100, up to\u00a097% of Canadian tree species\u00a0are projected to exceed their tolerance for summer heat (maximum temperature of the warmest month) in at least one part of their range. Forests\u00a0aren’t\u00a0just gaining climatically suitable space at their cold northern\u00a0margins;\u00a0they’re\u00a0simultaneously losing it at their hot southern ones.<\/p>\n\n\n\n

Cette transition \u00ab du froid vers la chaleur \u00bb n\u2019est pas propre au Canada ; des tendances similaires ont \u00e9t\u00e9 observ\u00e9es dans les for\u00eats europ\u00e9ennes et asiatiques. Mais pour les forestiers canadiens, les implications sont bien r\u00e9elles : les esp\u00e8ces plant\u00e9es il y a 30 ans pour un climat bor\u00e9al froid ne seront peut-\u00eatre plus le bon choix pour les 30 prochaines ann\u00e9es.<\/p>\n\n\n\n

Le casse-t\u00eate de la migration assist\u00e9e et le goulot d'\u00e9tranglement du froid<\/strong><\/p>\n\n\n\n

One response to this challenge is assisted migration, which entails moving species or seed sources from warmer regions into areas where the future climate will suit them better. It’s a strategy gaining traction in forest management circles, but our results reveal a critical and underappreciated obstacle. <\/p>\n\n\n\n

Using climate analogues (places in Canada or the U.S. where today’s climate resembles what a target region will look like in the future), we identified a pool of candidate species that could theoretically grow under future climate conditions. On average, about 30 to 35 such candidate species exist for a given location (from Table 2). <\/p>\n\n\n\n

But here’s the catch: to establish, those candidates have to be in their comfort zone and survive today’s climate first, as seedlings and saplings, before they can match future conditions. And for many of them, the current cold winters in their target region represent a hard barrier, what we call the climate bottleneck. For now, and in the next decades, winter cold temperatures eliminate most candidates. This bottleneck is most severe in northern Manitoba, Saskatchewan, Ontario, and southwestern Qu\u00e9bec. <\/p>\n\n\n\n

\n

The upshot: after filtering for species that are safe under both baseline and future climates, only 4 to 13 species per location remain viable candidates for forest diversification, depending on emission scenario and how conservatively you define a species’ climate tolerance.<\/p>\n<\/blockquote>\n\n\n\n

Quelles sont les implications pour la gestion foresti\u00e8re ?<\/strong><\/p>\n\n\n\n

Nos r\u00e9sultats ne sont pas alarmants, mais ils appellent \u00e0 la rigueur. Voici quelques conseils pratiques : <\/p>\n\n\n\n

Negative safety margins are a warning, not a death sentence. A species operating slightly outside its comfort zone may still grow, but it might be less vigorous and more susceptible to secondary stressors like pests or drought-induced dieback. <\/p>\n\n\n\n

Not all regions face the same risk. Southwestern Ontario, Nova Scotia, and New Brunswick consistently emerge as areas where suitable species, both native and candidate migrants, are most available. Central and western Canada, particularly Alberta and British Columbia, face larger “no-analogue” climate zones where even climate analogue-based planning is limited. <\/p>\n\n\n\n

Assisted migration is promising but not a silver bullet. The climate bottleneck means introduction timing matters enormously. Species that will thrive in 2070 may not survive a harsh winter in 2030. Practitioners should consider microsite selection, shelter planting, and phased introduction strategies to bridge that gap.<\/p>\n\n\n\n

Pour la suite<\/strong> <\/p>\n\n\n\n

Cette \u00e9tude fournit un outil de projection \u00e0 grande \u00e9chelle, servant de premier filtre pour identifier les esp\u00e8ces qui m\u00e9ritent une attention particuli\u00e8re et les r\u00e9gions o\u00f9 la situation est la plus urgente.\u00a0\u00c0 l'\u00e9chelle locale, les \u00e9valuations de vuln\u00e9rabilit\u00e9 devraient \u00eatre raffin\u00e9es en tenant compte de facteurs tels que la topographie, les caract\u00e9ristiques du sol, les diff\u00e9rences g\u00e9n\u00e9tiques, l'origine des semences et les pratiques de gestion foresti\u00e8re. Ces facteurs peuvent contribuer \u00e0 prot\u00e9ger les esp\u00e8ces qui se trouvent \u00e0 la limite de leur aire de confort climatique et influencer des r\u00e9sultats qui ne sont pas pleinement refl\u00e9t\u00e9s dans les analyses \u00e0 l'\u00e9chelle continentale. <\/p>\n\n\n\n

En tant que cadre permettant de d\u00e9terminer les priorit\u00e9s en mati\u00e8re d'intervention et de s\u00e9lectionner les esp\u00e8ces \u00e0 prendre en compte, les marges de s\u00e9curit\u00e9 climatique offrent un atout que la plupart des outils existants ne poss\u00e8dent pas : une mesure du risque physiologique, fond\u00e9e sur la r\u00e9partition g\u00e9ographique des arbres \u00e0 travers le monde. <\/p>\n\n\n\n

The full paper is available open-access in Climate Change Ecology: <\/em>doi.org\/10.1016\/j.ecochg.2026.100114<\/em><\/a> <\/p>\n\n\n\n

<\/p>","protected":false},"excerpt":{"rendered":"

By Morgane Dendoncker, Christian Messier, Manuel Esperon-Rodriguez & Olivier Villemaire-C\u00f4t\u00e9 Published in Climate Change Ecology (2026), with the contribution of Madeleine Gauthier for communication As temperatures climb and precipitation patterns shift, the trees growing across our 2.3 million km\u00b2 of managed forest are increasingly pushed beyond the climatic conditions they evolved to handle. Our new study, published in Climate […]<\/p>\n","protected":false},"author":6,"featured_media":11398,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","footnotes":"","_links_to":"","_links_to_target":""},"categories":[101],"tags":[],"class_list":["post-11492","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"_links":{"self":[{"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/posts\/11492","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/comments?post=11492"}],"version-history":[{"count":4,"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/posts\/11492\/revisions"}],"predecessor-version":[{"id":11503,"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/posts\/11492\/revisions\/11503"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/media\/11398"}],"wp:attachment":[{"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/media?parent=11492"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/categories?post=11492"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/diverseproject.uqo.ca\/fr\/wp-json\/wp\/v2\/tags?post=11492"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}