Western Red Cedar (Thuja plicata) is an iconic evergreen tree of the west coast. It’s beauty has made it a popular ornamental, and it can now be found growing in gardens, parks and yards all over the world. This time of the year a vast number of cedar and other evergreen branches are cut to make holiday decorations. While I definitely prefer this type of decoration to a disposable, non-biodegradable plastic one, it is still important to think about our impact on nature. When thinking about harvesting cedar boughs the impact on the tree must be considered.
Any injury to a tree leaves a tree at risk for infection from fungi, viruses, insects and other pathogens. Cedar is able to continue to grow despite rotting in another area (1). The capacity of trees to wall off dead or sick tissue varies, but is affected by the size and nature of the wound. Ripped bark and jagged edges make it more difficult for trees to heal (2). The amount of biomass removed must also be considered. If a tree loses too many branches it will be weakened and more prone to illness. An estimated maximum of 20% in a given year is suggested.
Habitat loss is another major issue. Global Forest Watch said that Canada had the highest rate of disturbance of virgin forest in the world in 2013 (including forest fires) (3). Similar concerns are being voiced with regards to Alberta’s tar sands (4). Natural Resources Canada countered by saying Canada has one of the lowest rates of deforestation in the world (5). To me it is apparent that a debate is being waged based on slick statistical application and semantics. What gets lost is an appeal for real change, not only in forestry practices (which include reduced tree diversity and heavy herbicide application), but to change our own consumption driven lifestyles. Suzanne Simard’s TED talk is a great place to start learning about forests in Canada.
Other issues include increasing cedar dieback, which many attribute to climate change and reduced available water for trees (6). A recognition of the importance of cedar for Coastal First Nations should also be acknowledged. It is important to consider the need of our First Peoples to reclaim their traditional practices; guaranteeing access may include reducing consumption and resource use.
Cedar is a magical tree, and her healing properties are apparent to most who walk under her boughs. There is a protective energy, that must be reciprocated. She protects us and we in turn must protect her.
Popular use of cedar in Western Herbal Medicine centers primarily around the use of Thuja occidentalis, Northern White Cedar. Northern White Cedar is popularly used as an antiviral and antitumour medicine. Western Red Cedar is also strongly antimicrobial and has been traditionally used to support the lungs and immune system.
Both types of cedar contain the infamous thujone. Thujone is now discredited as the source of artistic madness caused by absinthe consumption in turn of the century bohemian Europe. Toxicity of thujone has not been adequately established in humans. Recommended safe dosage is between 3-7mg per day (7), in context, 1g of fresh cedar contains approximately 10.5 mg of thujone (my own calculation based on 8, 9). However, a single cup of sage (Salvia officinalis) tea (2g) has been shown to have between 3.66mg and 58.81mg thujone (10).
Other safety concerns I have heard expressed with regards to cedar are around allergy. Allergies that have been documented include hay fever (rhinitis) caused by cedar pollen, occupational asthma due to saw dust exposure (plicatic acid is implicated), contact dermatitis (skin inflammation) in wood saunas, and a single case of seizure in a homeopathic remedy given to an infant (11).
Western Red Cedar – Thuja plicata
Family: Cupressaceae
Lifecycle: Perennial, evergreen tree
Key features:
- Scale-like needles, needles are flattened on branches, white waxy markings are found on the leaf underside, aromatic
- Reddish bark
Parts used: Needles and branches (anytime)
Harvesting considerations:
- Avoid harvesting more than 20% of the biomass of a single tree
- Avoid creating large wounds that may become infected, practice proper pruning
- Harvest fallen branches after a wind storm
How to prepare:
- Use branch tips to make a tea (1 tbsp per litre water), simmer for 15-20 minutes
- Make a syrup from a concentrated decoction (boiled tea), or infuse directly in honey (5% fresh cedar branch tips in honey for a teaspoon dose in the “safe range”)
- Avoid during pregnancy and lactation and in children under 2 years of age
References:
1) Culturally Modified Trees, Millenia Research Limited: http://millennia-research.com/services/culturally-modified-cedar-trees-cmt/
2) Tree Wounds, Wayne Clatterbuck: https://extension.tennessee.edu/publications/Documents/SP683.pdf
3) Canada Largest Contributor to Deforestation Worldwide: Study, Huffington Post: https://www.huffingtonpost.ca/2014/09/05/canada-deforestation-worst-in-world_n_5773142.html
4) Some of Alberta’s Forests Shrinking Faster than Amazon rain forest: report, Bob Weber: https://globalnews.ca/news/4010811/alberta-ecosystems-disappearing-nature/
5) Deforestation in Canada: Key myths and facts, Natural Resources Canada: https://www.nrcan.gc.ca/forests/fire-insects-disturbances/deforestation/13419
6) Western Redcedar Dieback: Possible Links to Climate Change and Implications for Forest Managment on Vancouver Island, B.C., Tanya Marie Seebacher, 2003: http://web.forestry.ubc.ca/ecomodels/team/thesis/Seebacher%202007%20thesis.pdf
7) Thujone and thujone-containing herbal medicinal and botanical products: toxicological assessment, Pelkonen et al., 2013: https://www.ncbi.nlm.nih.gov/pubmed/23201408
8) Population variation in the leaf oil terpene composition of western red cedar, Thuja plicata, von Rudolff and Lapp, 1978: http://www.nrcresearchpress.com/doi/pdf/10.1139/b79-061
9) Chemosystematic value of the essential oil composition of Thuja species cultivated in Poland-antimicrobial activity, Tsiri et al., 2009: https://www.ncbi.nlm.nih.gov/pubmed/19935470
10) Determination of Α– and Β-Thujone in Wormwood and Sage Infusions of Greek Flora and Estimation of their Average Toxicity, Sotiropoulou et al., 2016: http://www.foodandnutritionjournal.org/vol04nospl-issue-conf-october-2016/determination-of-%CE%B1-and-%CE%B2-thujone-in-wormwood-and-sage-infusions-of-greek-flora-and-estimation-of-their-average-toxicity/
11) Allergen of the Month: Western Red Cedar, Richard Weber, 2015: https://www.annallergy.org/article/S1081-1206(15)00487-1/fulltext