Fontainebleau, France \u2013 The once-majestic oak tree is all but dead: battered by repeated heat waves, it has shut down vital functions to conserve water and is slowly dying in a French forest.<\/p>\n
It is one of countless trees across Europe\u2019s forests adopting drastic \u2014 and often fatal \u2014 strategies to survive worsening heat and drought linked to climate change.<\/p>\n
As France endures a record-breaking early season heat wave, scientists warn that many of Europe\u2019s forests are already bearing the scars of years of rising temperatures and intense drought.<\/p>\n
Like humans cooling themselves through sweat, trees regulate temperature through transpiration, drawing water from the soil and releasing it as vapor through tiny pores in their leaves.<\/p>\n
As temperatures rise, water loss from leaves and soils accelerates, forcing trees into dire straits to conserve moisture.<\/p>\n
Manuel Nicolas, from France\u2019s National Forestry Office, has studied this phenomenon across the country\u2019s public forests for decades.<\/p>\n
All trees are \u201csuffering\u201d but their response to heat stress varies depending on species and location, said Nicolas, who heads the national forest ecosystem monitoring program.<\/p>\n
Some trees reduce water loss by rapidly closing their stomata \u2014 microscopic pores on leaves or needles that regulate gas exchange and water vapor release.<\/p>\n
Closing the stomata conserves water but slows or even halts photosynthesis, the process that converts sunlight, carbon dioxide and water into sugars needed for growth and survival.<\/p>\n
Over time, the tree can effectively starve.<\/p>\n
Another strategy favored particularly by trees with deep root systems is to draw water from the soil and keep their stomata open as long as possible, said Nicolas.<\/p>\n
\u201cBut the risk this time is dying of thirst,\u201d he said in Fontainebleau, a vast forest roughly 60 kilometers south of Paris.<\/p>\n
\u201cA tree is a column of water\u201d that can absorb up to 200 liters per day, Nicolas said, transporting moisture from the ground to the canopy. But this system can become overwhelmed from heat or drought, and break down entirely.<\/p>\n
\u201cAir bubbles enter the vessels and prevent the sap from circulating to the tips of the branches. This is called gas embolism,\u201d said Nicolas.<\/p>\n
\u201cAnd when the embolism affects too many vessels, the entire tree dies from dehydration.\u201d<\/p>\n
Scientists say that as heat waves and droughts become more frequent, trees are increasingly being pushed to these limits.<\/p>\n
In France, home to some of Europe\u2019s most diverse forests, government figures show tree mortality has doubled over the past decade.<\/p>\n
Projections suggest that around 30% of tree species could be at risk of decline by 2050.<\/p>\n
Experts say that forests are being forced to quickly adapt to climatic changes that normally unfold over millennia.<\/p>\n
The world has warmed by around 1.4 degrees Celsius since the pre-industrial era mostly because of the burning of fossil fuels for energy.<\/p>\n
But scientists say the current period is likely the hottest the Earth has experienced in 125,000 years.<\/p>\n
The impact on trees is visible to the naked eye in Fontainebleau, where some giants have shed their branches and leaves in a hopeless bid to cling on.<\/p>\n
Among them is oak number 37 \u2014 still standing, but limbless and ragged, its fate sealed.<\/p>\n
Nicolas and his team have been tagging and observing trees on this plot for 34 years and know its time is near.<\/p>\n
But others nearby remain tall and healthy for reasons scientists are still deciphering.<\/p>\n
An intense heatwave in 2018 scorched a cluster of pines in Fontainebleau but other conifers in the woodland thrived for reasons that are still not well understood.<\/p>\n
Some trees, such as Mediterranean species, can be more resilient against heat, Nicolas said.<\/p>\n
They are better suited to drought conditions because they \u201climit water loss through transpiration with small, leathery leaves covered in hairs or an impermeable cuticle, as in the holm oak,\u201d he said.<\/p>\n
Understanding \u201cwhich species will be suitable 100 years from now\u201d will be crucial to safeguarding forests from the heat to come, Nicolas said.<\/p>\n
\u201cAgainst heat waves, there\u2019s not much we can do. But we can try to help the forest adapt,\u201d Nicolas said.<\/p>\n","protected":false},"excerpt":{"rendered":"Fontainebleau, France \u2013 The once-majestic oak tree is all but dead: battered by repeated heat waves, it has…\n","protected":false},"author":2,"featured_media":31582,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[15766,3668,14926,8,33],"class_list":["post-31581","post","type-post","status-publish","format-standard","has-post-thumbnail","category-japan","tag-forests","tag-france","tag-heat-waves","tag-japan","tag-nihon"],"_links":{"self":[{"href":"https:\/\/www.europesays.com\/japan\/wp-json\/wp\/v2\/posts\/31581","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/japan\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/japan\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/japan\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/japan\/wp-json\/wp\/v2\/comments?post=31581"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/japan\/wp-json\/wp\/v2\/posts\/31581\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/japan\/wp-json\/wp\/v2\/media\/31582"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/japan\/wp-json\/wp\/v2\/media?parent=31581"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/japan\/wp-json\/wp\/v2\/categories?post=31581"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/japan\/wp-json\/wp\/v2\/tags?post=31581"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}