by CHICAGO (AP) – Christmas tree breeder Jim Rockis knows what it’s like when one dies long before it can reach a buyer.
Rockis farms trees in West Virginia and Pennsylvania, where he and other producers grow their iconic evergreens outside of their preferred habitat higher in the mountains. But that can mean planting in soil that’s warmer and wetter – places where a nasty fungal disease called Phytophthora root rot can take hold, sucking moisture from the young trees and turning needles brittle to burnt orange .
“After a while, it just boils down to it,” Rockis said. “They just disappeared.”
Christmas tree growers and breeders have long prepared for warmer weather that will also change soil conditions. People buying trees may not have noticed any difference in availability this year and may not even in the next couple; it takes an average of eight to 10 years for a Christmas tree to reach marketable size.
But that means the trees being grown now are tomorrow’s holiday traditions for millions of families.
“You have to start thinking about how you’re going to adapt to this,” Rockis said.
That’s why researchers like Washington State University professor Gary Chastagner called “Dr. Christmas Tree” for many years working on fir and other festive species, they are working with breeders like Rockis to see if species from other parts of the world – for example, Turkish fir – are better suited to the conditions which are being operated by climate change.
In the past two years, a surprisingly high number of evergreens have died from fungal disease outbreaks in Washington and Oregon. Chastagner is concerned that the frequency with which we see Phytophthora which is better suited to warmer soil conditions may change due to the change in temperature and soil moisture. Some may attack more aggressive trees, he said.
Chastagner and his team are doing more sampling work to understand the causes of these outbreaks and whether they indicate a pattern that may expand in the future.
But some scientists say there is not enough research on warming soil temperatures that could affect Christmas trees and many other crops, especially trees.
A European study this year in the journal Nature Climate Change found that soil heat extremes are increasing faster than air heat extremes, which could affect the health of grasslands, forests and some agricultural areas.
The same weather conditions that can stress trees also favor many pests and diseases that can attack them, such as insects and fungi. The changes in forests and farmland may not happen overnight, said Bert Cregg, a professor of horticulture and forestry at Michigan State University. But with time and a warming climate, “some trees may become more difficult to grow,” he said.
Changes in soils also have implications for soil carbon storage, a solution to climate change that the US has already put a lot of money and effort into researching. Warmer soil temperatures reduce its long-term carbon storage capacity, in part because microscopic life underground is affected, the researchers say.
“The activity of these microbes tends to increase with temperature, so it is less stable to store carbon there,” said Almudena Garcia-Garcia, one of the authors of Nature Climate Change and a postdoctoral scientist at the Helmholtz Center for Environmental Research. – UFZ in Leipzig, Germany.
While it’s critical to get more information about how changing soils will affect both crops and carbon, scientists sometimes struggle to get enough data, said Melissa Widhalm, associate director and regional climatologist at the Regional Climate Center Purdue University’s Midwest. Since soil temperature is measured differently than air temperature, the records do not go back very far, making it difficult to understand long-term trends.
Widhalm, who was not involved in Nature Climate Change research, said she wanted more studies like in other places like North America, and that the results are very strong because they combined physical observations on the ground with satellite data and computer simulations. “This paper did a nice job of quantifying temperature-soil-moisture relationships that scientists know exist but are difficult to measure,” she said.
Garcia-Garcia said her team plans to study soil temperature changes more in the future, in more places if they can. “All the sources of information point to this happening,” she said. “We are always studying extreme events from measurements in the air. But what is happening beneath our feet?”
___
Read more about AP’s climate coverage at http://www.apnews.com/climate-and-environment
___
Follow Melina Walling on X: @MelinaWalling.
___
Associated Press climate and environmental coverage is supported by several private foundations. See more about the AP climate initiative here. The AP is solely responsible for all matters.
