It’s that time of year again, where conifers across the globe are chopped down and taken into people’s homes or workplaces in celebration of Christmas. According to the IUFRO (International Organizations of Forest Organizations), over 80 million trees are consumed annually across the globe for Christmas. Though this number pales in comparison to industrial logging for timber, it nonetheless garners significance in the scientific community.
To start at the beginning, why do we even have what is today often called the Christmas tree, or also a holiday tree? The tradition appears to have begun in an entirely secular manner. The quality of retaining needles year-round, which gives evergreens their names, was often used as a symbol of eternal life by the ancient Egyptian, Chinese, and Hebrew. Evergreen boughs celebrated winter and the fact that spring would once again return. [1, 2, 3]
The first decorated full tree is said to have originated in Germany, though some sources point to the first tree being in Riga, Latvia in 1510 [1, 2, 3, 4] or potentially as early as 1441 in nearby Estonia [5]. These were often decorated with apples, or other fruits and edible goods. The tradition spread, acquiring its religious affiliation, becoming common in Germany in the 17th century, expanding throughout Europe and reaching North America sometime in the 18th and 19th century.
Along with this social history of our decorated conifer also comes it evolutionary history. From chopping down a fir tree in your yard to selecting today’s picture-perfect pine, a lot has happened. Fortuitously, the Huffington Post came out last week with an article on research of conifer genomes. Not only is this sort of research being put to use by the timber industry, but additionally for many holiday celebrations.
Most Christmas trees sold commercially today are Scotch pine, Douglas fir, Fraser fir, Balsam fir, and white pine. These trees, grown in farms, take on average 6 to 8 years to reach maturity [4]. There are many research groups and labs working internationally on genetic improvement of trees, from North Carolina, Washington, New Mexico, and Pennsylvania, to Denmark. Though it was surprising to me at first, when you think of all of the study and work that goes into other domesticated crops or ornamental species, this is not out of the ordinary.
The IUFRO has a division on Christmas trees working on nearly all aspects of tree and greenery production: genetics, nutrition, propagation, disease, pests, weeds, production techniques, quality after harvest, and marketing. These all clearly make sense: healthy trees are a necessity, and post-harvest quality, such as needle retention after cutting, is something anyone would want. No needle cleanup from your tree?
A professor at Washington State University, Dr. Gary Chastagner, has been working on just that. Because the advent of genetic techniques and resources for conifers is quite new though, past work has been done by selective breeding for seedlings or mature trees with desirable phenotypes. Many genetically variable trees are grown up and selected for specific qualities they possess. In the case of Christmas trees, this ranges from not only needle retention, but also including rapid growth, shorter needles, good branch structure, pleasant scent, dark green color, disease and pest resistance, and low flammability.
The forestry industry operates this way as well, though often selecting for different traits, and has been successful at producing better trees in terms of wood density, straight growth, and high growth rates. Projects, including those mentioned by Malcom Ritter in the HuffPo article, such as working to uncover the Norway spruce genome, the loblolly and other pine genomes, and others looking to find SNPs conferring local adaptation in pine and spruce, are now working to truly understand the genetic basis of useful traits in order to inform tree breeding and reforestation. Dr. Chastagner now aims to do the same, and identify the perfect Christmas tree by simply looking at its genotype.
This leaves us again with great examples of the progress advancing genetic techniques are allowing for in the field of molecular ecology. Perhaps in the future, we may never have to worry about having a Christmas tree like this again (if you’d like, you can skip from 0:50 to 5:30) … or maybe for some of us, those are the ones we actually want?