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Issues Of The Environment: How 'Green' Is Your Christmas Tree?

Dec 19, 2018

Dr. Bert Cregg, professor of horticulture at Michigan State University
Credit Michigan State University, College of Agriculture and Natural Resources / msu.edu

Finding the right Christmas tree for your home is always a big part of the holiday season.  But which type of tree is better for the environment--real or artificial?  In this week's "Issues of the Environment," WEMU's David Fair tries to settle this debate with Michigan State University horticulture professor Dr. Bert Cregg.

Overview

  • Christmas trees are big business in Michigan.  According to the Michigan Christmas Tree Association, Michigan is the third largest producer of Christmas trees.  There are approximately 2 million trees sold in Michigan, and for each tree cut, three are planted.  Michigan generates $27 million from trees and $1.5 million from garlands and boughs.
  • What type of Christmas tree you choose plays a very small role in your overall carbon footprint, but pondering the best choice is an excellent exercise in what to consider when making environmentally responsible choices as a consumer.
  • 45% of Christmas trees purchased in 2017 were artificial, and the share is growing. Are fake trees bad for the environment?  Are real trees a better choice?  According to Dr. Bert Cregg's analysis, “Which option “wins” in terms of carbon footprint depends entirely on assumptions about how long consumers would keep an artificial tree versus how far they would drive each year to purchase a real tree.” (see analysis below for details.)  The takeaway is that for real trees, the fuel use associated with driving to cut down a tree is only somewhat offset by the carbon sequestered by the tree and its roots.  For synthetic trees, which are mostly imported from China, transport is a factor.
  • The Michigan Christmas Tree Association reports that because trees take nearly a decade to be ready for harvest, there are fewer live trees available this season than in the past, mostly due to the Great Recession, and there will be more trees in the coming decade.
  • Dr. Cregg, Professor of Horticulture and Forestry - Michigan State University, employs a method called life cycle assessment to develop a “cradle to grave” accounting of inputs and outputs required to produce, use and dispose of Christmas trees.  He is considered Michigan’s preeminent Christmas tree and tree farm expert.

How to Determine if your Christmas Tree Choice is Environmentally Responsible

Environmentally conscious consumers often ask me whether a real Christmas tree or an artificial one is the more sustainable choice.  As a horticulture and forestry researcher, I know this question is also a concern for the Christmas tree industry, which is wary of losing market share to artificial trees.  And they have good reason: Of the 48.5 million Christmas trees Americans purchased in 2017, 45 percent were artificial, and that share is growing.

Many factors can influence this choice, but the bottom line is that both real and artificial Christmas trees have negligible environmental impacts.  Which option “wins” in terms of carbon footprint depends entirely on assumptions about how long consumers would keep an artificial tree versus how far they would drive each year to purchase a real tree.

Many consumers believe real Christmas trees are harvested from wild forest stands and that this process contributes to deforestation.  In fact, the vast majority of Christmas trees are grown on farms for that express purpose.

To estimate the total impact of something like a Christmas tree, researchers use a method called life cycle assessment to develop a “cradle to grave” accounting of inputs and outputs required to produce, use and dispose of it.

Natural Trees

For natural Christmas trees, this covers everything from planting seedlings to harvesting the trees and disposing of them, including equipment use, fertilizer and pesticide applications, and water consumption for irrigation.  Life cycle assessments often will also estimate a system’s carbon footprint.  Fuel use is the biggest source of greenhouse gas emissions in Christmas tree production.  Using 1 gallon of gas or diesel to power a tractor or delivery truck releases 20 to 22 pounds (9 to 10 kilograms) of carbon dioxide into the atmosphere.

On the positive side, Christmas trees absorb and store carbon from the atmosphere as they grow, which helps to offset emissions from operations.  Carbon represents about 50 percent of the dry weight of the wood in a tree at harvest.  According to recent estimates, Christmas tree-sized conifers store roughly 20 pounds of carbon dioxide in their above-ground tissue and likely store similar amounts below ground in their roots.  However, using 1 gallon of gasoline produces about the same amount of carbon dioxide, so if a family drives 10 miles each way to get their real tree, they likely have already offset the carbon sequestered by the tree.  Buying a tree closer to home or at a tree lot along your daily commute can reduce or eliminate this impact.

And natural trees have other impacts.  In 2009, Scientific American specifically called out the Christmas tree industry for greenwashing, because growers’ press releases touted carbon uptake from Christmas tree plantations while ignoring pesticide use and carbon dioxide emissions from plantation management, harvesting and shipping.

Is Synthetic Better?

Artificial trees have a different set of impacts.  Although many people think shipping trees from factories in China takes a lot of energy, ocean shipping is actually very efficient.  The largest energy use in artificial trees is in manufacturing.

Producing the polyvinyl chloride and metals that are used to make artificial trees generates greenhouse gas emissions and other pollutants.  China is working to reduce pollution from its chemical industry, but this may drive up the prices of those materials and the goods made from them.

Moreover, to consider sustainability from a broader perspective, production of real Christmas trees supports local communities and economies in the United States, whereas purchasing artificial trees principally supports manufacturers in China.

Going Head to Head

Recently, the American Christmas Tree Association, which represents artificial tree manufacturers, commissioned a life cycle assessment comparing real and artificial Christmas trees.  The analysis considered environmental aspects of sustainability, but did not examine social or economic impacts.

The report concluded that the environmental ‘break-even’ point between a real Christmas tree and an artificial tree was 4.7 years.  In other words, consumers would need to keep artificial trees for five years to offset the environmental impact of purchasing a real tree each year.

One major shortcoming of this analysis was that it ignored the contribution of tree roots – which farmers typically leave in the ground after harvest – to soil carbon storage.  This omission could have a significant impact on the break-even analysis, given that increasing soil organic matter by just one percent can sequester 11,600 pounds of carbon per acre.

Reuse or Recycle your Tree

Consumers can’t affect how farmers grow their live trees or how manufacturers produce artificial versions, but they can control what happens after Christmas to the trees they purchase.  For artificial trees, that means reusing them as many times as possible.  For natural trees, it means recycling them.  This is essential to optimize the carbon footprint of a real tree.  Grinding used Christmas trees and using them for mulch returns organic matter to the soil, and can contribute to building soil carbon.  Many public works departments across the United States routinely collect and chip used Christmas trees after the holidays.  If local tree recycling is not available, trees can be chipped and added to compost piles.  They also can be placed in backyards or ponds to provide bird or fish habitat.

In contrast, if a used tree is tossed into a bonfire, all of its carbon content is immediately returned to the air as carbon dioxide.  This also applies to culled trees on tree farms.  And if used trees are placed in landfills, their carbon content will ultimately return to atmosphere as methane because of the way materials buried in landfills break down.  Methane is a greenhouse gas 21 times more potent than carbon dioxide over a century, so this is the most environmentally harmful way to dispose of a used tree.

All kinds of factors influence choices about Christmas trees, from fresh trees’ scent to family traditions, travel plans and the desire to support farmers or buy locally.  Regardless of your choice, the key to relieving environmental angst is planning to reuse or recycle your tree.  Then you can focus on gifts to put under it.

Christmas Trees are Big Business in Michigan

Michigan is third in the nation for harvesting Christmas trees, with 27,000 commercial acres of growing Christmas trees.  There are approximately 2 million trees sold in Michigan, and for each tree cut, three are planted.  Michigan generates $27 million from trees and $1.5 million from garlands and boughs.  “There’s a whole market to all those products, also,” said Amy Start, executive director for the Michigan Christmas Tree Association.  Her organization has 120 members currently, which primarily grow Christmas trees.  These include nurseries, farms and wholesalers.  Over the past 10 years, numbers have declined.  She said younger people aren’t getting into farming, and the recession forced a lot of farms out of the business. “It breaks my heart,” she said.

2018 Tree Shortage

This means that there are fewer trees to buy and to choose from this season. “We’re seeing that effect now, seeing a tightening of a market nationwide,” she said.  “It’s not tremendous, but there are fewer Christmas tree growers than there used to be,” said David Petts, owner of Branching Out Nursery and Landscaping in Fenton Township.  There were fewer trees planted around the time of the Great Recession, which can take eight to 10 years to grow.  “For the next few years there are going to be fewer trees than you’re used to,” he said.

This just means that growers like Petts will have fewer options to offer buyers.  They may have to compromise on their purchase.  He said that in the past, excess trees were sometimes sold to non-profit organizations for their fundraiser.  Petts hasn’t had excess for a while, so he hasn’t been able to sell anything wholesale.  In a few years, there will be more excess, and more choices for consumers.  He thinks any shortage will be at its worst this year.  Other nurseries have closed, and he’s absorbing those clients, leading to more sales and fewer trees.

Despite this, prices haven’t really increased.  He said the exception is Frasier firs, which are available in fewer numbers, have increased in demand, and take much longer to grow.  These trees grow at the rate of about 8 inches per year.  For comparison, a Scotch pine or Norway spruce will grow a couple feet per year. Most recent numbers point to $27 million to $30 million in economic activity generated by Christmas tree farms per year in Michigan.  These are the price of goods as produced by the farms, or “farm gate value.”

How to Choose a Tree

Petts said the white fir is growing in popularity and is starting to replace the blue spruce in popularity. Overall, the Frasier fir is still king.  Petts said there’s no average order size or tree. It depends on the space, and the needs of the consumer.  Some trees have weaker boughs that can’t handle a lot of ceramic ornaments.  “Just understand how you decorate,” Petts said.

A white pine, for example, will last until spring but can’t handle heavy ornaments.  Firs and spruce trees can better handle heavier ornaments, he said.  Someone with a smaller home will seek a tree appropriate for the space.  Some people want a 3-foot tree while others want a 16-foot tree.

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— David Fair is the WEMU News Director and host of Morning Edition on WEMU.  You can contact David at 734.487.3363, on twitter @DavidFairWEMU, or email him at dfair@emich.edu