World's Tallest Trees Rely On Limited Seasonal Temperature Variations
January 8, 2014

World’s Tallest Trees Rely On Limited Seasonal Temperature Variations

Lee Rannals for - Your Universe Online

A new study published in New Phytologist suggests that temperature could be a growing tree’s best friend.

Height is a competitive benefit when it comes to trees, because the taller the tree, the more exposed its leaves are to the sun. As a tree rises above its neighbor to reach more sunlight, it is taking its canopy past the shade that other trees create.

Taller trees are able to place leaves at higher light levels while suppressing their competitors. Height can also allow for wind-dispersed pollen and fruits to travel farther. Ecological scientists know that the bigger the tree, the more carbon it is able to store, which is an important area of research.

The latest study looked into the role that temperature plays in helping to drive tree growth. The study could help scientists forecast how forests will adapt to climate change. A researcher from the University of Helsinki studied the temperature-driven physiological model of tree height to help explain the thermal climates in which the tallest of the tall tree species grow.

"It is amazing how little we know about the causes of global tree size variation even though not knowing current variation makes predicting climate change caused changes difficult or impossible," Markku Larjavaara, from the Department of Forest Sciences at the University of Helsinki, said in a statement. "If trees will get bigger in the future they will store more carbon than they do now and would therefore mitigate climate change."

According to the study’s findings, the world’s nine tallest tree species were found to grow in climate with an unusually small seasonal temperature variation. Larjavaara found that this slight variation accounted for only 2.1 percent of global land area.

The scientist discovered that the tallest of trees had a distance from the equator that ranged from 2,400 miles to 3,100 miles, and an altitude above sea level that ranged from 164-feet to a little over a mile high. The team said that the distance between the most distant localities ranged from 1,600 miles in Australia to 869 miles in North America.

“The location of the tallest trees close to the sea has been associated with high precipitation or common fog, but the role of the ocean is likely to be more important in keeping temperatures closer to the optimum for large trees,” Larjavaara, lead author of the paper, wrote in the journal.

The team said that nearly all of the tall trees studied lived less than 60 miles from the ocean shore and usually in a downwind direction.

“Most of these grew within a few dozen kilometers from the shore, in a zone influenced by sea breeze, characterized by cooler daytime temperatures conditions during hot spells inland, allowing these coastal trees to avoid energetically expensive warming of woody tissues in heat waves,” the researcher concluded.