An international team of researchers from the UK, Denmark and Spain together with Associate Professor Daniel Kissling of the University of Amsterdam shed new light on why and how people use palms in South America. The study shows that people are very selective when using plants for their basic needs, but less so for other needs. The results are published in Nature Plants.
About 400,000 species of plants are found in the world. Humans use approximately 10-15% of them to cover basic needs such as food, medicine and shelter, as well as other needs such as recreation, art, and craft. Certain plant traits, such as taste and scent, can affect how humans perceive plants. For example, if fruits taste sweet we like them, and if plant leaves have a mint-like scent we will use them as herbs or tea. However, plants come in all shapes and sizes and possess several traits that affect whether we like them. For most plants it remains unclear which traits determine preferences by humans.
The researchers investigated how people use palms in South America. Palms are very important for local livelihoods in several parts of the world, including South America. A total of 2,200 locals from over sixty communities were interviewed about how they use palms. Additionally, data on biological traits of palms were collected, including plant size (leaves, fruits, stems) and distributional range size. ‘A key finding was that people tend to use large, widespread palm species compared to small, narrow-ranged ones,’ says lead author Rodrigo Cámara-Leret from the Royal Botanic Gardens, Kew. ‘For example, people prefer larger palms for food, potentially because they need palms that produce large quantities of food.’
Another key finding of the study was that the link with biological traits was strongest the more basic the human need is that the plant covers. For instance, palms used for basic physiological and safety needs (e.g. food, medicine, shelter) have a strong link to plant size (the bigger, the better) and distributional range size (the more the merrier). On the other hand, palm use for psychological and self-actualisation needs (e.g. rituals, jewellery) was less dependent on biological traits of palms. In other words, people are very selective when it comes to plants used to cover basic needs, but less so when it comes to using plants for needs with no physiological underpinnings.
The study was made possible because the researchers had started to collect trait data from various sources such as books, herbaria, scientific articles and reliable online sources. ‘Over the last few years, we have compiled lots of data on fruit sizes, plant height, leave sizes, etc. for the more than 2500 species of palms in the world’, says Daniel Kissling, co-author of the study. ‘Only by mining this information from published literature and herbaria we are able to make it digitally available. ‘ Using such big trait datasets combined with environmental and ecological information is the focus of Kissling’s research team. ‘Ultimately we want to understand the distribution of life on Earth, and how it is shaped by humans and the physical environment, so that we can predict the future of biodiversity and human well-being.’
Cámara-Leret, R., Faurby, S., Macía, M.J., Balslev, H., Göldel, B., Svenning, J.-C., Kissling, W.D., Rønsted, N. & Saslis-Lagoudakis, C.H.: Fundamental species traits explain the provisioning services of New World palms. Nature Plants DOI 10.1038/nplants.2016.220