Dead trees around the world are shocking scientists

September 3, 2023 7:38 AM

Forests once deemed resilient are suffering surprising die-offs. To predict the fate of the world’s woods in the face of climate change, researchers need to understand how trees die.
posted by Etrigan (15 comments total)

I spend a lot of time in the California forests. I can’t really look at them anymore without seeing the stress on the trees. I wonder what they looked like when they were thriving. Whether the visible difference was great or small. Decline is hard to live with.
posted by q*ben at 8:33 AM on September 3, 2023 [5 favorites]

As I read this I received a note that my Virginia county is now under a drought watch. The article made me look hard at the leaves on trees around me, watching for unseasonal yellow and orange.
posted by doctornemo at 8:42 AM on September 3, 2023 [2 favorites]

In my work I study (among other things) how academia can respond to the climate crisis. One aspect of this is the research enterprise, and the linked article is a good example. Thank you for sharing it.
posted by doctornemo at 8:43 AM on September 3, 2023 [3 favorites]

This year Austin lost hundreds of trees across the city in a climate event we called "arborgedden."
posted by tofu_crouton at 8:55 AM on September 3, 2023 [3 favorites]

I was lucky enough to see Spirit Lake before the eruption wiped it all away.

2020's Creek Fire above Fresno consumed about 2X a footprint of forested land.

I'd last been up there in 2018, and finally went back up in late July to see how the recovery was going. I'd also had my eye on home listings over the years and I remember being shocked to see how the ongoing drought was slowly killing off the Sierra forestland at 3000+' (no water -> no defensive sap -> bark beetles can dig into the trees) . . . prior to the fire I kinda got the impression that the smart money was beginning to retreat from owning these wonderful mountain properties since the dying forest was turning into a ticking time bomb.

Sad how such a thin and unstable cover of vibrant greenery makes so much esthetic difference, and how it's not probably coming back.
posted by Heywood Mogroot III at 9:14 AM on September 3, 2023 [2 favorites]

Were the places we live (and farm) forested with the same species when the atmosphere was last at 550 eCO2? Were they even forests at all? We've put so much stock into slow and gradual change because slow linear systems were easier for us to model.

Look at the crop yeild vs temperatrue and its a slow rise, a round peak, the start of a slow decline past the optimum, and then it crashes to 0 because the plant dies. the past 10,000 years of conditions have not prepared forests and other holocene ecosystems for the conditions that haven't existed in what? 125,000 years? 2,000,000 years? headed to 6 million years?

That's why its a mass extinction. Its a cascade.
posted by AnchoriteOfPalgrave at 9:27 AM on September 3, 2023 [8 favorites]

Thank you for this post. It is heartbreaking to witness the longer pest seasons and shorter sap seasons here in New England. The point in the article that describes tree drought defense as basically shutting off the carbon intake via respiration, then shutting down carbon use (making wood) even when taking in carbon just to shunt it into the ground, is not one to read in a fragile mood. When the earths surface ceases to be a carbon sink to manage it is game over. (counting the oceans it is even harder to contemplate.)

I am back in the White Mountain National Forest this weekend after a year away, and I don’t know how to process the fact that all of this could just fail.

There is work to identify the new natives - trees native to the mid-Atlantic that might need to be planted up here now to prepare for the next thirty years. I will be looking at them with a new set of criteria after reading this.
posted by drowsy at 9:41 AM on September 3, 2023 [4 favorites]

Thanks for posting this. It is just so heart-breaking, and also terrifying. We are dealing with a scale of destruction that is almost incomprehensible.
posted by mumimor at 10:05 AM on September 3, 2023 [3 favorites]

There are sections of forest near where I am in Montana where 80% of the trees have been killed by bark beetles. The beetles have always been around, but normally they were kept in check by cold winters that the beetles couldn’t survive. As the climate warms, the winters become milder and the beetles march on in even larger populations.
posted by CheeseDigestsAll at 10:30 AM on September 3, 2023 [6 favorites]

I spend 4+ weeks a year camping on public land all over California. Every year, several of my spots burn. It's incredible how fast the forests are disappearing.

I keep detailed GPS records of every place I've been, every spot I've camped. Here's a screenshot of all my GPS notes overlaid on a yellow and orange patchwork of recent wildfires, and red icons for current, active fires. Most have burned.

Get out and enjoy California forests now. Right now! If you wait 5 or 10 years, there will be a lot less.
posted by ryanrs at 10:44 AM on September 3, 2023 [4 favorites]

Interesting study, but doesn't go further than 'warming', and glances off elevated carbon dioxide - eCO2, but good to see 'carbon dioxide is fertiliser' myth attacked. A long-term oil industry / evangelical churches project.

I study eCO2 effects (in both plant systems, & engineering - eCO2 accelerates concrete breakdown) to make my planting schemes more robust as eCO2 is now directly affecting planting growth, irrespective of temperature change/increase.

There are a lot of papers (finally) being published like this:

Declining tree growth rates despite increasing water-use efficiency under elevated CO2 reveals a possible global overestimation of CO2 fertilization effect [pdf Cell journal]

Plants have an optimum CO2 'healthy condition level' - where they are nutritious for us, if allergic those effects are lower, and useful in our landscapes - from home gardens to regions.

But CO2 above a certain level (probably 280ppm) increasingly changes all this. These effects are little studied as several prominent researchers have been threatened, lost tenure / employment, found it very hard to publish.

Increasing flammability - known for some grasses:
Blank White & Ziska 2006 Combustion properties of Bromus tectorum L.: influence of ecotype and growth under four CO2 concentrations [pdf J Wildland Fire .au] Trump had Ziska removed from the USDA.

Negative effects on invertebrates, including many pest insects:
Jactel et al Responses of forest insect pests to climate change: not so simple [pdf sciencedirect]

eCO2 also makes many plants a lot more water efficient - Leiprand 2006 Global effects of doubled atmospheric CO2 content on evapotranspiration, soil moisture and runoff under potential natural vegetation [pdf tandfonline]. Sounds great but not as soils are adapted to a given precipitation regime and so you get; increased runoff, wetter soil - >disease, >methane loss, changes in invertebrates and soil fungi and non-wet-tolerant trees dieing.

I'm trying to get a research paper together on this as this wet effect will affect all soil, even gentle slopes (where I think I'm seeing it first as it should not happen.
posted by unearthed at 10:48 AM on September 3, 2023 [15 favorites]

Reminder, if existing forests are struggling, it will be even harder for those instant-forest mass tree-planting projects to succeed. Reforestation and afforestation are still important work, don't stop doing them, just don't count on those offsets to uh, offset anything.
posted by AnchoriteOfPalgrave at 11:26 AM on September 3, 2023 [6 favorites]

Inside the Michigan lab where scientists raise killer bugs to save trees.
posted by clavdivs at 6:21 PM on September 3, 2023 [2 favorites]

Slightly tangential perhaps, but lately my main feeling about work is resentment that I'm spending my day in front of a computer when I want to be out enjoying the last few years of the natural world as I have known it. I'll be trapped inside soon enough.
posted by HotToddy at 7:13 PM on September 3, 2023 [5 favorites]

We don't seem to be talking about moving forests north via planting. Where I live (Calgary, AB), we've already moved to the next warmer cultivation zone over the last few years. We should probably be thinking about bringing appropriate species north, so that 20 years from now maybe we'll have some diversity to go forward with.
posted by sneebler at 7:13 PM on September 3, 2023 [5 favorites]