Climate change has the potential to not only rewrite shorelines, alter your morning cup of coffee, and damage the world's chocolate industry, but it could also limit the size of wild Norway spruces, which provide some of the world's most iconic Christmas trees.
As climate change brings smaller snowpacks to the boreal forests that ring the northern hemisphere, trees such as the Norway spruce could suffer limited growth, according to new research published in the journal Forest Ecology and Management.
The snowpack acts as a blanket for tree roots during the cold winter, and removing that can affect shoot growth the next spring. The research adds to a body of work that is trying to understand how forests will be affected by changing climates.
The Finnish ecologists spent two seasons studying a stand of 47-year-old spruce trees. They had a control group of trees that they did not alter, another group that they shoveled snow from, and a third group that they shoveled the snow from and then insulated to delay soil thawing in spring, which is a possibility if the climate continues to warm.
For the trees that had the snow removed and the area was insulated, bud burst was delayed by two weeks for one season but not for as long the following season, which was warmer. The researchers attribute the difference to the fact that there are many factors that affect when trees bud, and air temperature is one of the most important.
It would seem as though the potential warmer air from climate change would offset the benefits of a thick snowpack, but the research suggests that may not be the case. The combination of reduced water uptake due to delayed thawing means the trees had reduced energy available from the process of photosynthesis, and less energy translated for budding and shoot growth.
It was not just water availability that matters in the soil, the researchers found, but damaged root function in the cold soil that led to the limited uptake of water. If conditions like this persisted year-over-year, the trees could grow slower.
"This study really shows us that temperature changes, while important in these boreal forest, are not the only thing that is significantly affecting tree growth," said Clint Springer, associate professor of biology at Saint Joseph's University.
Hawaii and Arizona both grow more Christmas trees than Wyoming.
He added that because the authors did not directly measure photosynthesis or water uptake, their findings lack data that could be added by future studies. "This is an interesting first look at this issue and should definitely be examined further," Springer said.
Although wild trees, such as the Norway spruce that was cut for this year's Rockefeller Center Christmas tree, could have delayed growth, there is some hope for the larger lot of trees that are destined for living rooms every December.
The vast majority of Christmas trees come from farms, not the wild. Oregon is the largest producer of Christmas trees in the United States, with more than six million trees harvested annually. Farms should be able to adapt somewhat to changing climates, according to Nick Houtman, an assistant director for research communications at Oregon State University.
Christmas trees are generally grown in five to seven year rotations, so farmers could adjust somewhat for short-term variation in temperature or precipitation, such as switching to a different species of tree.
Trees are grown in nearly every US state and are not necessarily clustered in the northern states. American Christmas tree farms are in ecosystems that are different than the deep snow falls and soil thawing dynamics of boreal forests. Hawaii and Arizona both grow more Christmas trees than Wyoming, according to data from the National Christmas Tree Association.
Although some tree species used for Christmas may be affected by climate change, buying a real Christmas tree is actually one way to lower your carbon footprint during the consumption-focused holiday season when compared with getting a fake tree.
A seven-foot-tall natural tree has a 60 percent smaller footprint compared to a seven-foot artificial one that's used for six years, according to Clint Springer, assistant professor of biology at Saint Joseph's University in Philadelphia.
Real Christmas trees are also renewable, while fake trees are usually made from petroleum-based products. Springer recommends people look for locally grown trees by farmers who continually replant, which benefits the environment and supports local agriculture. Additionally, if a tree is spared being draped in tinsel, it can also be recycled, either into woodchips or even hardwood if it's large enough.
As for the 85-foot Norway spruce that sits ensconced in blinking lights at Rockefeller Center this season, it will find a second home as lumber for Habitat for Humanity.
Follow Katherine Tweed on Twitter: @katherinetweed