Forester: Consistent chilly weather benefits trees

Farm Forum

Although many people in Aberdeen miss the warm temperatures of last year, the consistent cold should result in much healthier trees than last year, Aaron Kiesz said.

“The trees, for the most part, will be in better shape coming out of this winter than last winter,” said Kiesz, city forester of the Aberdeen’s Parks, Recreation and Forestry Department.

A tree is able to withstand extremely cold temperatures or hot temperatures, he said. What trees can’t handle well is dramatic changes in temperatures in a short period of time, which is what happened during the winter of 2011-2012, Kiesz said.

Kiesz said he saw trees growing leaves as early as January in 2012 during an unusual heat wave, Kiesz said. Trees near homes were the most likely to grow leaves early, because the roots absorbed the ambient heat from the house in addition to the sunlight.

Highs of 49 or above were recorded six times between Jan. 1 and Jan. 10 in 2012, said Ken Gillespie, meteorologist with the National Weather Service in Aberdeen. On Jan. 5, 2012, the high reached 63, which was the highest temperature ever recorded during January in South Dakota, he said.

Trees that blossomed too early in the winter experienced health problems once freezing temperatures returned, Kiesz said.

“Trees were leafing out in January, but when the cold front hit in February, those trees got hit hard,” he said. “We saw a lot of declining and thinning on those trees.”

Temperatures as low as 13 below zero were recorded in February 2012, Gillespie said.

When the temperatures remain consistently cold, as they have this year, the trees can remain dormant until later in the spring, when it should warm up, Kiesz said.

The snow on the ground is also good for the trees, since the snow insulates the ground, which protects tree roots from excessive freezing or thawing, Kiesz said.

The fact that the snow is melting slowly is also good for trees because that means more moisture will be absorbed into the ground, he said.

During the 2011-12 winter, Aberdeen had 17.5 inches of snow accumulation, according to the South Dakota Office of Climatology. Aberdeen has received 40.7 inches of snow so far this season, Gillespie said.

Still, not all trees are doing well this year, Kiesz said. Many trees, especially evergreens, are having trouble because of a lack of moisture, but the melting snow might alleviate that problem, he said.

Kiesz said his only concern is a sudden drop of temperatures in April. It should be a very healthy year for trees as long as a major cold front doesn’t hit, he said.