The sustainability of wild-harvested medicinal plants is under threat

Did you know that most medicinal and aromatic plants in our everyday food and cosmetic products are wild-harvested? Local communities worldwide rely on the trade of these plants for their livelihood. But wild plants are under threat by global trade and climate change.

The vast majority of plants in our everyday food and cosmetic products are wild-harvested. Wild-harvested medicinal and aromatic plants are of crucial importance to our health and wellbeing. Each of these wild plants is unique in terms of its habitat, uses, and the socioeconomic conditions of the local harvesters. They are also unique in terms of their vulnerability to climate change and other pressure from human activity. The threats to the sustainability of these plants are neither well researched, nor widely known. I want to shed a light on the challenges that these wild plant populations are facing, and on the opportunities available for ensuring their survival.

Global medicinal plant use

It is widely recognised that in many regions of the world, people rely on traditional plant-based medicines for their primary healthcare. For an estimated 70 to 95% of people in most less economically developed countries the primary materia medica is composed of plant-based medicines. For example, in many rural communities in Africa, parts of Asia, and Central and South America. In these countries it is easy and affordable to access medicinal plants and knowledge of their traditional uses. At the same time, western medicines may not be readily available, which increases dependency on plant-based medicines.

In some of the more economically developed countries, the use of traditional medicine is just as significant; between 70% and 90% of the populations in Canada, France, Germany, and Italy have used traditional medicine in some form. And the use of medicinal and aromatic plants by people in wealthier countries is increasing. As a result of population growth, but also due to increased pressure on health systems, and the growing popularity of natural and environmentally friendly products.

In addition to human uses of medicinal plants, there are many accounts of animals that ingest plants solely for the purpose of self-medication. For example, chimpanzees in the wild self-medicate to treat parasite infections, and similar behaviour has been observed in bonobos in Congo. Elephants in Laos have also been observed to self-medicate for a variety of health disorders. When medicinal plant populations decline or even disappear, this will affect the ability of both human and animal populations to treat diseases and live a healthy life.

Wild harvested medicinal plants in global trade

Medicinal and aromatic plants are not only used in primary healthcare, but also as dietary supplements, in cosmetic products, and as flavouring agents in everyday food products and in homewares. Almost 30.000 species of these so-called Medicinal and Aromatic Plants are used for medicinal purposes, and an estimated 4000-6000 species are traded internationally. The global import value of plant material for medicinal purposes was over US$3 billion in 2015 and has shown a threefold growth between 1999 and 2015 alone.

The vast majority of these medicinal and aromatic plants, an estimated 60 to 90%, are wild harvested. Their unique growing conditions and profit rates make cultivation often not feasible. Often it is marginalised communities depend on wild harvesting as a significant source of income. Wild harvested medicinal and aromatic plants are also more in demand with consumers than cultivated ones. This is because the medicinal action of wild plants tends to be stronger than those of cultivated plants, as a result of higher stress factors experienced in natural ecosystems.

As demand grows, higher volumes are needed, and pressure on wild plant populations is increasing. For the vast majority of plant species, the conservation status is unknown, which means they are not on the radar for standards and guidelines for protection. We do know that nearly 600 plant species have gone extinct in the past 250 years. And we know that of the meager 7% of medicinal and aromatic plant species that have been recorded so far, one in five in the wild are threatened with extinction. Examples of common wild-harvested medicinal and aromatic plants susceptible to either over-harvesting or unfair trading practices are; Goldenseal (Hydrastis canadensis), used as herbal medicine, Candelilla (Euphorbia antisyphilitica) a wax used in cosmetic products, and liquorice (Glycyrrhiza spp.) often used in herbal medicine, cosmetics, and food.

It is worth noting that the growing trade in essential oils plays a role in this growth in demand as well. The demand for essential oils is mostly due to the food and cosmetics industries. With an estimated 10% annual growth rate, the trade in essential oils is expected to reach US$ 14–15 billion in 2025. Essential oils can be distilled from cultivated as well as wild-harvested medicinal and aromatic plants. Some of those wild-harvested plants are now listed as critically endangered, such as agarwood (Aquilaria rostrata; A. malaccensis), costus (Saussurea costus), and spikenard (Nardostachys jatamansi). Various Boswellia species, which provide the resin for the popular Frankincense essential oil, are also threatened by over-harvesting and ecosystem degradation. The Airmid Institute regularly updates a list of threatened and near-threatened essential and carrier oil-bearing plants.

Why are these plants under threat?

The growing worldwide demand for medicinal plants is one of the multiple threats to wild medicinal and aromatic plant populations. In addition, habitat destruction, habitat fragmentation, and climate change are factors that are endangering plant populations worldwide. Other known threats are invasive species, exotic pathogens, and increased herbivory due to the extermination of large predators. Major food crops and plant-based commodities are generally cultivated in agricultural settings, with sufficient knowledge and practices for sustainable crop management. However, each wild medicinal and aromatic plant has its own unique habitat, cultural and health factors, pressure from human activity, and suitable management strategies.

An example of a wild-harvested plant under threat is the medicinal plant American Ginseng (Panax quinquefolius L.) in Appalachia, eastern North America. American Ginseng is highly valued and used as a treatment for conditions such as fatigue, hypertension, and upper respiratory infections. The plant is in high demand on the Chinese market. At the same time the income of local harvesters is 40% lower than the US average. The high demand in combination with the financial needs of the harvesters has led to illegal harvesting. In combination with herbivory by deer this pressure has resulted in reduced size of the American Ginseng population and of the plant itself.

Wild-harvested plants and climate change

The effects of climate change on wild plant species are subject to both complexity and uncertainty. Changes that have been identified so far include reduced populations due to temperature changes and extreme weather events, increased pests, phenological changes, such as time of flowering, and changes in the phytochemistry of medicinal plants. Climate change effects, therefore, are likely to reduce the consistent availability but also the medicinal value of these plants. Understanding these developments is crucial since these are plants that people depend on economically.

Temperature changes and extreme weather events

The plant species most vulnerable to climate change are those in the fast-changing polar and alpine regions. As temperatures increase, plant species move up to find cooler climates. This leads to competition for space as well as resources. When there is nowhere to move to in the highest regions, plant species can face extinction. However, it has also been observed that plant species spread to distant summits, take advantage of steep inclines correlated with steep temperature changes, or move from south to north facing slopes.

Extreme weather events such as floods and droughts are also having an impact on plant populations. A wild medicinal aromatic plant in Arctic areas of Europe, Asia, and North America that is significantly affected by climate change is Rhodiola (Rhodiola rosea L.). The roots of Rhodiola are used for preparations that are considered an adaptogenic and can treat altitude sickness and boost energy, among many other uses. Wild populations of Rhodiola are suffering due to competition from invasive species, and rising sea levels which erode the plant’s habitat.

Phenological changes

Plant species can respond to changes in climate and weather patterns through unpredictable changes in their seasonal activities, such as flowering times. These changes are referred to as phenological changes and can threaten the survival of a plant species. For example, if an early spring is followed by a late frost, frost-sensitive plants can be severely impacted.

Additionally, there is the risk of ‘phenological mismatch’, such as disturbance of relationships with pollinators, or plants unexpectedly competing over resources with other plants. As a result of unpredictable phenological changes, some local harvesters can no longer forecast and plan harvest times. For example, the harvest time for Schisandra berries has radically changed over the last decade.

Phytochemistry changes

Climate change is also causing unpredictable changes in phytochemical content, because of plant responses to temperature change. Other stress factors include temperature, light exposure, soil moisture, but also animal grazing and competition between plants. Generally, plants produce higher concentrations of secondary metabolites as a response to stresses. It is these secondary metabolites that are responsible for the medicinal action of the plant. Phytochemical changes observed so far have been inconsistent and therefore hard to predict. This is concerning because of their changing medicinal value in various health systems, leading to either insufficient or too much intake of the active constituents.

Can sustainable wild harvesting be a solution?

As a result of increased pressure on wild-harvested plant populations, the cultivation of medicinal and aromatic plant species is being considered. However, many medicinal and aromatic plants are difficult to cultivate, since the growth and reproduction requirements of most species are unique and often unknown. Small farmers struggle to make high prior investments and land for cultivation of non-food crops is often limited in communities who harvest wild plants. Transitioning from wild harvesting to forest cultivation proved not profitable for 6 out of 8 forest plant species investigated in eastern North America. As mentioned, cultivated plants also often do not offer the medicinal efficacy as wild grown plants, therefore not supporting the case for cultivation.

At the same time, a number of benefits of wild harvesting have been identified. Wild harvesting prevents habitats to be converted into agricultural lands. Maintaining the tradition of wild harvesting also helps preserve traditional ecological knowledge, sense of place, and local culture. And it requires no prior financial investment by the wild harvesters.Sustainable wild harvesting has been identified as more viable then cultivation. To reach the dual goals of wild plant conservation and improvement of local livelihoods, sustainable wild harvesting must be promoted. To achieve this, it is essential that knowledge about the unique growing conditions and habitats of each plant species is acquired. Clarifying land use rights is also important, as well as appropriate legislation and policy. It has already been highlighted that local communities are often the best stewards of the land.

Convention on International Trade of Endangered Species

On a national and international government level, medicinal and aromatic plants have been added to the Convention on International Trade of Endangered Species (CITES). CITES, also known as the Washington Convention, is a governmental licensing system that helps prevent the extinction of selected species since 1975. It does that by controlling international trade in endangered plants and animals. CITES protects more than 37,000 species of animals and plants, of which approximately 300 are medicinal and aromatic plant species.

An example is Agarwood (Aquilaria malaccensis), a wild-harvested aromatic tree in high demand due to its resinous wood, which is critically endangered. Quota are placed on its export from Indonesia and Malaysia, and export for commercial purposes has been banned from India and the Philipines. Not only do these agreements help control trade, but producers and consumers alike can also ask for CITES certification to ensure that they do not purchase medicinal and aromatic plants from critically endangered populations. Producers can verify the origin of plant materials in their supply chain, and consumers can hold producers responsible for plant ingredients in their products.

What is needed?

Producers and consumer choices impact the production process of plant-based medicine and other consumer products. The good news is that consumers are increasingly preferring ethical and environmentally friendly products. For example, US consumers have been buying more locally sourced products in the last year and millennial consumers prefer companies with a positive impact on society and the environment. With more education and transparency, it is likely that consumers will choose certified products that support wild plant populations, managed sustainably, and traded fairly.

However, knowledge about wild-harvested medicinal and aromatic plant populations and their use in herbal medicine, supplements, food, and cosmetics, is lacking. And without clear labeling and certification, consumers will be hampered in their ability to choose. Certification schemes can be effective both in educating producers and consumers and offering product certification. But overall, many labels do not provide a means to verify sustainable wild harvesting. This could be related to the unique context and sustainable management requirements of each plant species. The complexity and length of the supply chains can be a barrier. One certification system aimed at ensuring sustainable harvest and trade of wild medicinal and aromatic plants is FairWild. In 2018 there were over 20 different plant species certified, sourced from wild collection operations in ten different countries.

What we can we do as consumers?

Wild harvested medicinal and aromatic plant populations are essential to human health and wellbeing, and to global ecosystem health. Their unique habitats, growing conditions, and socio-economic context prevent a generalised solution for sustainable management and cultivation. We need more research to understand these individual cases, and the promotion of sustainable wild harvesting with local communities is essential. Intergovernmental trade agreements need to be developed, and producers and consumers need a better understanding of the problem.

Where can you start?

• Check out the Wild Dozen by Fairwild, 12 potentially problematic wild plants that you can find in everyday products, such as cosmetic products, food supplements and herbal products.
• Do some research into the producer you are buying from frequently, do they make visible efforts to ensure a sustainable supply chain with fair working environments?
• When you see that product ingredients are from threatened plants, ask questions, and request information on CITES certification.
• Buy herbal products and food supplements that are certified, for example by FairWild. If you are not sure what labels mean, certified organic is always a good choice.