Willow trees grow fast and tall, quickly replenishing timber cut for furniture and household items. However, as the willow trees support a lot of mammals, birds, and pollinators, cutting down the trees hurts wildlife. So we had to ask: How sustainable is it to buy products made out of willow wood? 

Willow wood is sustainable thanks to its carbon sequestration. Willow trees’ rapid growth allows the timber to be harvested without harming the forest. Also, black willow trees grow natively in the US, resulting in their wood having a lower transporting carbon emission than tropical hardwoods. 

In this article, we’ll walk you through the life-cycle of willow wood used for furniture and household items. Then, we evaluate its sustainability, potentials, and shortfalls. And in the end, we’ll show you tips for buying sustainable willow wood. 

Here’s How Sustainable Willow Wood Is

Willow wood is a sustainable material because of the willow trees’ carbon sequestration potential and the carbon offset value at the end of any products made with willow wood. 

“Sustainable: The ability to be maintained at a certain rate or level | Avoidance of the depletion of natural resources in order to maintain an ecological balance”

Oxford Dictionary

To better understand the sustainability of willow wood, we assess the life-cycle of willow furniture. This life-cycle assessment (LCA) is a method to evaluate the environmental impacts of each stage in a product’s life-cycle, from the making to the recycling. Over the years, companies have strategically used LCA to research and create more sustainable products. 

In this article, we’ll use the cradle-to-grave perspective of the LCA, examining the five stages of the life cycle of willow wood. Where it is relevant, we also use data from cradle-to-gate assessments. 

Overall, we can say that willow wood is sustainable. However, the actual environmental impact of a particular product, like a table or a chair, depends on many factors, especially the distance and mode of transportation. Let’s dive deeper into each stage and find out how it can be more sustainable. 

How Sustainable Is the Growing of Willow Wood

Growing willow trees for timber is sustainable thanks to the carbon sequestration potential, the rapid growth of these tree species and other possible usages of the trees beyond providing timber. 

What Type of Wood Is Willow Wood and What Does This Mean for Sustainability

Willow wood comes from fast-growing hardwood tree species of the Salix genus, the Salicaceae family. There are hundreds of willow species, of which around 90 are native to North America. Commercial-wise, black willow is the most important willow species in the US. Unless specified otherwise, data used in this article refers to black willow wood. 

Black willow is a short-live tree species. Though some trees can live to 85 years, the average black willow tree matures at 55 years. During their relatively short lifespan, black willow trees have varying growth rates.

In their native environment of lower Mississippi Valley, black willow trees are reported with average heights of 49 ft, 72ft, and 101ft after 10 years, 20 years, and 40 years respectively. That is a rapid height increase of 31 inches per year in the first 40 years. This growth rate might be slower than softwood species like redwood but much faster than many other American hardwood trees, including white oak, hard maple, or birch.

How Sustainably Does Willow Wood Grow

Willow wood’s sustainability lies in the potential for carbon sequestration, the fast replacement, and its role in reversing eroded- and fire-damaged lands. 

• Carbon Sequestration: As willow trees grow, they absorb CO₂ from the atmosphere while releasing oxygen. They act as a carbon sink during their lifespan. It means that they are taking greenhouse gasses out of the atmosphere, helping to mitigate the climate crisis. And they can store fair amounts of carbon. Black willow trees can reach 100 feet in height and 3 feet in trunk diameter.

• Fast replacement: A rapid growth rate means the forests can quickly regrow cut willow timber. In fact, the net volume of willow wood from the US forests (after harvest) is a surplus of 0.84 million m3 each year. 

Black willow accounts for only about 0.4% of all US hardwood growing stock – a small percentage compared with most other hardwoods. For example, red oak wood represents 18%, while tulipwood accounts for 7.7%. However, as the demand for willow wood is not very high, the US willow growth still exceeds harvest in most US states where these species grow natively.

• Land usage: Willow tree species can establish with ease from cutting and can tolerate flooding. Thus, they are ideal for soil stabilization in areas prone to flood and erosion, such as stream banks and islands. Besides, black willow trees have the ability to sprout from the base if damaged by fire. The seeds can be dispersed by both wind and water, an essential factor leading to black willow being a pioneer tree after a fire. 

Where Is Willow Wood Usually Grown

Willow trees are found in cold and temperate regions in the Northern Hemisphere. There are about 90 different willow species native to North America. In the US, willow trees grow throughout the eastern states, bordering Canada to the north and Mexico to the south. 

Willow trees are shade-tolerant and flood-tolerant species found in bottomland hardwood forests. They often grow densely in pure stands. Common tree associates are red maple, cottonwood and river birch. 

Even though growing willow trees for timber is generally sustainable thanks to the species’ fast growth, it is still important not to forget these trees’ significant role for wildlife and the potential disruptions caused by cutting them down. 

Willow flowers are particularly essential for pollinators because they bloom earlier, a critical time in the life cycle of many native bees. For example, pussy willows are the first to flower in spring in Connecticut. 

Because black willow trees have a lot of stems, they provide a lot of flowers in succession, keeping the nectar and pollen supply going over a long period of time. Once the flowers turn into seeds, they become food for many birds and bugs. 

Other parts of willow trees are also food sources for wildlife. Deer eat willow twigs and leaves, rodents eat the bark and buds, and yellow-bellied sapsucker feeds on the sap. 

Willow trees are also a good nesting ground for many birds. Hummingbirds, yellow warblers and other bird species line their nests with soft material from willow trees.

Hence, cutting down willow trees, especially when done illegally or unsustainably, can disrupt the forests’ wild animals, which depend on the forest for food and shelter. The only way for consumers to tackle unsustainable logging practices is to source sustainable woods. We will point you in the right direction with willow wood at the end of this article. 

In total, logging of forestry products from plantations accounts for 26% of forest loss, which is a combination of deforestation and forest degradation. However, the loss in bio-diverse forests in tropical climates is more significant (and sometimes less properly recorded) than in temperate, well-managed logging forests. 

How Sustainable Is the Manufacturing of Willow Wood

Turning willow wood into furniture has a relatively low carbon footprint because wood waste can be recycled fully as by-products or biomass pellets to offset the carbon emissions during harvesting and processing. 

The first step of manufacturing willow wood furniture involves cutting down trees and turning them into lumber in a sawmill. Electricity is needed to run sawing machines. 

The next step is to dry lumber before turning it into furniture. If a piece of lumber can be air-dried to the desired moisture content, no added energy is needed for this step. However, if a kiln is used, it requires extra energy, which could mean higher carbon emissions.

Willow wood dries rapidly, but the drying process could be tricky because moisture pockets often occur in willow logs. Dry willow timber is, however, dimensionally stable. 

The carbon footprint of the drying step for 1m³ of willow lumber, 4/4 (1 inch) thick, is 42.7 CO₂-eq, according to the life cycle assessment tool of the American Hardwood Export Council. That is 

• lower than the carbon footprint of drying, for example, white oak (98.3 kg CO₂-eq) and red oak (89.7CO₂-eq),
• similar to the carbon footprint of drying, for example, black cherry (42.7 kg CO₂-eq),
• but higher than the carbon footprint of drying, for example, ash (38.5 kg CO₂-eq), or tulipwood (25.6 kg CO₂-eq).

However, a high proportion of energy (to power sawing machines and kilns) can come from burning wood waste. At least 90% of all thermal energy used for kiln drying in the US hardwood sector is derived from biomass (instead of fossil fuels).

How Sustainable Is the Transportation of Willow Wood

Transporting is a relatively carbon-intensive stage in the life cycle of willow wood furniture due to the emissions associated with operating the hauling vehicles that take timber to sawmills and factories, then furniture to stores. 

As willow trees are distributed widely in the US, a piece of willow wood furniture would have a lower carbon footprint than that made from imported woods like mahogany, teak, or rosewood, providing they are both sold in the US. 

Calculations made by the Norwegian Forest and Landscape Institute showed that smaller wood hauling trucks emitted more CO₂ per transported cubic meters of timber: 1.25 times more than larger wood hauling trucks, 1.3 times more than sea vessels, and six times more than freight trains. Therefore, the sustainable transportation option would be rail or large trucks running on biofuel. You can check with your wood suppliers how their products are transported and opt for the more sustainable option. 

According to the life cycle assessment tool of the American Hardwood Export Council, transporting 1m³ of willow lumber, 4/4 (1 inch) thick from the forest to the kiln results in 37.9 kg CO₂-eq, and from the kiln to the customer in Western Europe 144 kg CO₂-eq. Transporting carbon footprint (in this scenario) is more than four times higher than manufacturing. 

Compared with some other American hardwoods, the growing, manufacturing, and transporting of willow wood have a carbon footprint amongst the lowest. 

For example, PE International AG assessed the environmental impacts of 19 American hardwoods through stages from cradle to gate plus transport. They found a carbon footprint of 310 kg CO₂-eq for one cubic meter of kiln-dried willow lumber, 4/4 (1 inch) thick. That is 

• lower than the carbon footprint of, for example, hard maple (394 kg CO₂-eq), ash (407 kg CO₂-eq), walnut (427 kg CO₂-eq), and white oak (559 kg CO₂-eq),
• but higher than the carbon footprint of, for example, cherry (301 kg CO₂-eq) and tulipwood (270 kg CO₂-eq).

How Sustainable Is the Usage of Willow Wood

Using willow wood furniture can be sustainable thanks to the carbon capture during the products’ long life.

Black willow wood is not rated as being durable because it is susceptible to insect attacks. However, indoor willow furniture can still last a century, providing proper care. 

When willow wood is decayed, either naturally in the forest or because of damage caused by usage at home, the carbon stored in the wood is released back to the atmosphere. Therefore, long-lasting furniture can be considered a good way of keeping carbon out of the atmosphere. If the wood is then reclaimed for making another piece of furniture, its positive carbon storage environmental impact is even higher. 

How Sustainable Is the End-of-Life of Willow Wood

The end-of-life stage for willow wood furniture is sustainable when the wood is reused or burned as bioenergy. 

There are a few scenarios for wood products – furniture and household items- at the end of their life: 

1. They can end up in landfills and don’t decompose. In this case, it keeps its role as carbon storage.
   
2. Wood products can also be upcycled and reused, extending their role as carbon storage and reducing the fossil CO₂ emitted as much as four times when comparing, for example, a recovered hardwood flooring with a new one. New wood products often travel much further to their markets, compared with recovered wood products. The latter is typically made in urban centers and sold locally, which lowers the transportation environmental burdens.
   
3. In another end-of-life scenario, products like a willow wood cabinet can be burned for biomass energy displacing coal or natural gas in generating electricity. 

With smaller household items, like a bowl or a chopping board, the offset won’t be as high as there is much less waste for burning. However, if such products are made from manufacturing wood waste as by-products, their carbon footprint is minimal. 

According to the life-cycle assessment done by the American Hardwood Export Council, the carbon emission of willow wood is negative, largely thanks to the enormous carbon uptake during the forestry stage. 

How Can You Buy Willow Wood More Sustainably

The key to sustainably buying any wood is to check on relevant environmental and original certifications. Reliable certifications for sustainable woods are: 

• Forest Stewardship Council: 

An FSC certification ensures that the willow wood comes from responsibly managed forests that provide environmental, social, and economic benefits.

• Program for Endorsement of Forest Certification: 

PEFC’s approaches to sustainable forest management are in line with protecting the forests globally and locally and making the certificate work for everyone. Getting a PEFC certification is strict enough to ensure the sustainable management of a forest is socially just, ecologically sound, and economically viable but attainable not only by big but small forest owners.

Why Is It Important to Buy More Sustainable Wood

Buying sustainable wood also means helping to prevent illegal or unsustainable logging, which harms the forests’ biosystems and accelerates climate change. 

Logging of forestry products from plantations accounts for 26% of forest loss. Cutting down trees for wood has a lesser impact on carbon storage than digging up the whole forest floor and turning it into farms or mines. However, if logging is not sustainably managed, it can badly damage wildlife.

When logging happens in tropical forests – the bio hotspots of our planet – the biodiversity loss can be much more damaging. Subtropical and tropical forests are packed with unique wildlife – endemic mammals, birds, and amphibians. The displacement of such wildlife during poorly managed logging would be a major contributor to global biodiversity loss. 

Sustainable management of forests also means that trees are cut down for timber only when they are mature. These trees will then be able to regrow and eventually replace the loss of canopy, absorb carbon from the atmosphere and reduce the effect of climate change. 

Final Thoughts

You can buy furniture made from willow wood as long as the material comes from sustainably managed forests. And, to make it even more sustainable, use any willow wood furniture for as long as you can, upcycle the material to extend its usage, and arrange for it to be recycled fully.

Stay impactful,

Sources

• Science Direct: Life-cycle assessment (LCA)
• MIT SMR: Strategic Sustainability Uses of Life-Cycle Analysis
• European Environment Agency: cradle-to-grave
• Science Direct: Cradle-to-Gate Assessment
• Britannica: willow plant
• Forest Service: Black Willow
• Impactful Ninja: How Sustainable Is Redwood? Here Are the Facts
• Impactful Ninja: How Sustainable Is White Oak Wood? Here Are the Facts
• Impactful Ninja: How Sustainable Is Maple Wood? Here Are the Facts
• Impactful Ninja: How Sustainable Is Birch Wood? Here Are the Facts
• THE WOOD DATABASE: BLACK WILLOW
• American Export Hardwood Council: Willow
• Forest Service: SPECIES: Salix nigra
• KAREN BUSSOLIN: Why Willows for Wildlife?
• Impactful Ninja: How Sustainable Is Black Cherry Wood? Here Are the Facts
• Impactful Ninja: How Sustainable Is Ash Wood? Here Are the Facts
• Impactful Ninja: How Sustainable Is Tulipwood? Here Are the Facts
• American Export Hardwood Council: American Hardwood’s Life Cycle Assessment Tool
• Impactful Ninja: What Is the Carbon Footprint of Biomass Energy? A Life-Cycle Assessment
• Impactful Ninja: How Sustainable Is Mahogany Wood? Here Are the Facts
• Impactful Ninja: How Sustainable Is Teak Wood? Here Are the Facts
• Impactful Ninja: How Sustainable Is Rosewood? Here Are the Facts
• Science Norway: Larger logging trucks give less CO₂ emissions
• PE INTERNATIONAL AG: Life Cycle Assessment of Rough-sawn Kiln-dried Hardwood Lumber
• Los Angeles Times: Notes on Willow Furniture: TREASURE HUNTING: Willow Furniture
• Research Gate: Life cycle primary energy and carbon analysis of recovering softwood 
• Forest Stewardship Council
• Program for Endorsement of Forest Certification
• Our World in Data: Epidemic Mammal Species