CHICAGO (AP) — Christmas tree breeder Jim Rockis knows what it looks like when one dies long before it reaches a buyer.
Rockis cultivates the trees in West Virginia and Pennsylvania, where he and other growers often grow their iconic evergreens outside their preferred habitat in the mountains. But that may mean planting in soil that's warm and wet — places where a nasty fungal disease called Phytophthora root rot can spread, which sucks moisture from plants and turns the needles a burnt orange color. Makes it crisp.
"After a while, it gets to its core," Rockis said. "They just dry up."
Christmas tree growers and breeders have long been preparing for future warmer weather that will also change soil conditions. People buying trees may not notice any difference in availability this year and probably not in the next two years; The average Christmas tree takes eight to 10 years to reach marketable size.
But this means that the trees being grown now are tomorrow's favorite holiday traditions for millions of families.
“You have to start thinking about how you're going to approach this,” Rockis said.
That's why researchers like Washington State University professor Gary Chastagner, "Dr." Said. 'Christmas Tree' For its decades of work on cedar and other festive species, it is working with breeders like Rockis to see whether species in other parts of the world – for example, Turkish cedar – are at risk from climate change. Are better adapted to the situations that arise.
Over the past two years, a fungal disease outbreak killed surprisingly large numbers of evergreen plants in Washington and Oregon. Chastagner is concerned that changing soil temperature and moisture may "change the frequency at which we will see some Phytophthora that are more adapted to warmer soil conditions." Some may attack trees more aggressively, he said.
Chastagner and his team are doing more sampling work to understand the causes of these outbreaks and whether they represent a pattern that could spread in the future.
But some scientists say there hasn't been enough research on rising 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 promote the many pests and diseases that can attack them, such as insects and fungi. Changes in forests and farms can't happen overnight, said Burt Craig, a professor of horticulture and forestry at Michigan State University. But with a warming climate over time, "some trees may become more difficult to grow," he said.
Soil changes also impact soil carbon storage, a climate change solution The US has already invested a lot of money and effort into research. Researchers say warmer soil temperatures reduce its long-term carbon storage capacity, partly because underground microbial life is affected.
“The activity of these microbes generally increases with temperature, so storing carbon there is less stable,” said Almudena García-Garcia, one of the authors of Nature Climate Change and a postdoctoral scientist at the Helmholtz Center for Environmental Research – UFZ in Leipzig. he said. Germany.
Melissa Widalm, associate director and regional climatologist at Purdue University's Midwestern Regional Climate Center, said that although getting more information about how changing soils will affect crops and carbon is important, scientists sometimes struggle to get enough data. One has to struggle for it. Because soil temperature is measured differently from air temperature, records do not go back very far, making it difficult to discern long-term trends.
Widlam, who was not involved in the Nature Climate Change research, said she would like more studies to take place in other places, such as North America, and that the results are fascinating because they combined physical observations in the ground with satellite data and computer simulations. Have added. "This paper does a good job of quantifying soil temperature-moisture relationships that scientists know about but are difficult to measure," he said.
Garcia-Garcia said his team plans to study changes in soil temperatures in more locations in the future, if possible. "All sources of information indicate that this is happening," he said. “We are always studying extreme events from measurements in the air. But what is happening beneath our feet?”
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