Chapters 4 and 5: Valuing hedgerows (4) and Medicinal tree products offer therapeutic benefits and potential diversification (5)

Chapters 4 and 5: Valuing Hedgerows (by Mark Tilzey) and Medicinal tree products offer therapeutic benefits and potential diversification for small scale agroforestry and farm woodlands (by Anne Stobart, José Prieto García, Anja Vieweger, Sally Westaway and Lindsay Whistance)

The sustainability challenges that are faced today as a consequence of agriculture are exemplified in chapter 4 of the publication Medicinal AgroEcology, through the history of hedgerows in lowland British (mainly English) landscapes, their introduction and their disappearance - and with them the multiple ecosystem services they provided. It is a good example of how agrarian policies, industrial developments and market mechanisms have and continue to influence the creation and destruction of landscapes or landscape elements, for the better or the worse. It is also a plea for bringing them back, as a means of landscape, ecosystem and farm health restoration. Chapter 5 in turn is forward looking and provides interesting and inspiring examples of how the ecological value of trees and other woody perennials in farm landscapes - either as part of hedgerows, of wood pasture, or as part of agroforestry farms - can be increased by consciously bringing these back in the form of trees and shrubs with medicinal properties.?

Developments and political incentives supporting the creation or destruction of landscapes and landscape elements

In the first parts of chapter 4, the authors analyse the incentives that have led to hedgerows as functional and iconic landscape elements either being put in place or being removed in the UK in the past five to six centuries. Privatisation of formerly commonly held land goes as far back as the 16th century, which in fact marks the beginning of “capitalist agriculture”. In the centuries that followed, the main agricultural method politically promoted consisted of crop rotation on four ‘larger’ fields of around 8 hectares each, and a couple of smaller plots to facilitate livestock management. These fields were separated from one another by hedgerows to confine and protect livestock and to define boundaries. These hedgerows or hedges were either planted strips, strips of existing vegetation that remained from woodland clearance, or strips that were naturally formed by trees and shrubs that colonise on pre-existing structures, like field margins or banks, with the latter types being the most biodiverse. Their management was non-mechanical and done in a way that supported their biodiverse nature and other multifunctional benefits, which the authors define as Ecosystem Services (ES). These ES vary from supporting and regulating functions that benefit soil and ecosystem health, water management and climate regulation (carbon sequestration, purification, humidity, energy, shelter) to pollination, pest control and even human - mental - wellbeing, and from provisioning (food, fibre, fuel, biochemicals and pharmaceuticals, genetic resources) and biodiversity services to cultural services (recreation and ecotourism, cultural heritage, education, aesthetic).?

Political ecology

Their coming was mainly related to what the authors refer to as “political ecology”, based on private or parliamentary enclosure acts, driven by privatisation of land and industrial capitalism, with the need for increasing production for export markets on the one hand, and for food for the rapidly growing urban population on the other. An interesting fact here is that the loss of vast areas of permanent pasture land was compensated by the introduction of new fodder crops like turnip and clover. These formed part of the rotation model introduced by Lord (‘Turnip’) Townshend in the mid eighteenth century. The increased availability of fodder allowed for more livestock, which in turn provided for more meat, but also manure. Introduction of manure and reuse of other agricultural ‘waste’ in the hedgerows improved the quality of the land and ecosystems and led to increased productivity in a circular and self-sustaining manner.?

The consequences of the ‘metabolic rift’, agrarian capitalism and productivism

The abandonment and disappearance of numerous hedgerows was driven by what is called the ‘metabolic rift’, the shift from agriculture with nutrients that circulate back into soils, to a broken cycle with increased dependence on fossil fuels, synthetic fertilisers and other external inputs, often imported from abroad. This was the result of increasingly linear, export oriented supply chains that followed from growing international trade, and the post WW-II imposition of agrarian capitalist and political productivism inspired policies and laws. In addition, laws that protected local farmers against competition from lower cost food products from abroad were abolished. What followed was a sole focus on increased productivity and yield per hectare, which was achieved through scale in terms of larger fields and replacement of labour by machines. As a consequence, many hedgerows disappeared, and those remaining impoverished because of mechanised and more intensive, annual ‘maintenance’.?

The ecological and therapeutic potential of medicinal hedgerows and trees in farm lands

With the hedgerows in the UK - and other European countries, like the Netherlands - disappearing or their quality affected, the vast range of ES provided by the hedgerows disappeared too, including the availability of a range of medicinal plants and trees. The potential value of bringing these - woody - plants and trees back to farm lands is further described in chapter 5 of the book, which carries the title: “Medicinal tree products offer therapeutic benefits and potential diversification for small scale agroforestry and farm woodlands. An overview with indications for further studies.”

About farmer decision making on which medicinal plants to choose

From the literature researched, the authors of chapter 5 acknowledge the potential benefit of medicinal plants and trees for different purposes, whether for therapeutic, cosmetic or veterinary use, for the agroecological and environmental value these plants and trees can provide for farmers, and for the overall health, wellbeing and resilience they can bring to farms and local communities. However, the authors signal a gap in terms of research answers on medicinal plants and trees in connection with agroecological approaches that can support farmers in decision making about which species to include appropriate cultivation designs, methods for harvesting and postharvest processing to ensure the required quality. From their search, they identify existing research and outcomes, as well as research gaps, covering a set of key areas: demand and choice of species; supply and cultivation approaches; quality control; additional benefits; and approaches to research. Each of these searches confirm the potential or ascertain a need, but do not provide farmers with sufficient information and concrete tools for assessment and decision making.?

Choosing medicinal tree species

To support farmers in decision making on which medicinal tree species to plant, they see themselves confronted with different voids in terms of required information and data. Information on the use of a specific medicinal tree can be available, but commercial data about which species are traded in which volumes and against which prices is available in Europe, except for a few species specific records. The availability of scientific proof for therapeutic benefits of a certain species generally leads to a number of new health products - whether pharmaceutical or phytotherapeutic - being developed and the demand for it growing. When harvested in the wild, this generally means a threat to the wild population and an incentive for cultivation - where possible - as wild collection is generally unpredictable. This type of research can be helpful for farmers to anticipate market growth and support investment choices. Other factors that should support decision making are the value they can have for other uses, like animal health and care, as well as the intrinsic value of certain tree species in farm lands, like for instance the willow tree (Salix). In this way the authors do mention willow bark for parasite control in chickens and ruminants for instance, but not its specific intrinsic ecosystem services and other benefits, like shelter for chicken against predatory birds, the use of the twigs as mineral and protein rich feed for rabbits for instance, and the many insects and even different types of smaller plants that are hosted by the willow.?

Cultivation and harvest return

Where monoculture approaches to agriculture and productive trees often lead to monocropping plantations - like in the case of Moringa -, in smaller land sizes more and more medicinal trees are being brought into cultivation as an element within farms. Design systems can vary from alley cropping to forest gardens and silvopasture. When for medicinal purposes, organic cultivation is generally desirable, which will in turn contribute to the conservation of soil and water, as well as to biodiversity, soil improvement, reduced pollution and reduced burden on animal and human health. Methods to increase yield and facilitate harvesting, like coppicing (near to the ground cutting) and pollarding (cutting the stem from 1 or 2 metres height), sometimes combined with shredding (repeated cutting of side branches), are showing promising results. Forest floor medicinal plants can also have high value and offer good returns for farmers. Well designed agroforestry systems can even be more productive than monocropping systems and lead to better quality crops if smartly designed and combined. Trees can be grown in alleys and alternated with field crops (alley cropping), which still allows mechanised farming. Another promising design is forest gardening, a layered design analogue to food forests. The authors present the example of a UK based practitioner of herbal medicine, whose 1 hectare herb farm was replanted in sections of 1 quarter of an acre. The introduced woody plants and trees and the techniques of coppicing and pollarding proved abundant for the herbal practitioner. Additional harvests were processed into body care products and a range of health-promoting and artisanal products that were sold locally and online. Another example given is that of multipurpose hedgerows.?

Assessing quality: certification and in-field analysis with new technologies

As said, buyers of medicinal plants used for therapeutic purposes have a widespread preference for organic certification as a minimum requirement. Buyer specifications may vary, but upon receipt of the product (samples) further authentication and screening of the material for pesticides, heavy metals and other contaminants will be performed. Since the focus of the authors is on moderate climate zones and organic certification assumed, traceability is assumed not to be the main challenge. Organic certification supports traceability, but when collected from the wild, the challenge is far bigger. However, in case of products from subtropical and tropical areas, traceability is a huge challenge. Aggregation and industrial processing in large quantities is the most common system, but leads to more risks in the supply chain and to industrial waste, including chemical solvents, which is being discarded. The better approach, as stated by the authors, is the development and promotion of on-site systems, which allow for on- or close to site processing, the use of green solvents and a first on-site round of analysis. Green extraction methods exist and can provide a fully circular solution. First in-field biological and chemical analysis with portable analytical instruments (‘lab-on-a-chip’) and remote sensing devices can be other gamechangers. This will provide a first selection and prevent unnecessary transport to and analysis in central labs, which can be limited to pre-analysed materials.?

Collaboration is key

The authors end their chapter with a discussion and a conclusion on the above, which boils down to the need for information, collaboration and research to underpin promising findings and practices, whether related to market demand and requirements, the right species, cultivation design and techniques, or in- or close to field analysis and processing. Collaboration between different stakeholders in the supply chain is needed to streamline supply and demand. Collaboration in research is needed, because their findings had to be gathered from many different disciplines, varying from ethnobotany and forestry to environmental sciences, and from clinical medicine to social sciences. Funding schemes will have to support this. If thus enabled to make informed decisions, the authors conclude, the cultivation of medicinal trees by farmers with small(er) land holdings - in this case in temperate climates - has huge potential.