A world of colour

by Fanny Petibon

Colours surround us. Everywhere in our daily life, meanings are often associated with colours. Yellow, serenity… Red, love, anger, passion… Green, hope, nature… White, peace… Could you now imagine a world in black and white?

Some animals do and interpret the world with a shades-of-grey scale. Some others can perceive some colours. More surprisingly, others perceive black when you see red.

What are colours? Why might the perception of colour differ? Which role do the colour play in ecosystem functioning? Why do their diversity is vital for the conservation of biodiversity?

Why do environmental scientists are interesting in colours?

What is light?

Colour is light. Light is made of different energies, called wavelengths. Colour is energy. Light interaction is a fascinating phenomenon: According to the material the object interacting is made of and its geometry, energy is absorbed, reflected, refracted and/or deviated. The sum of the remaining energy that reaches our eyes is the colour.  

Colours result thus from physical and chemical phenomena. There are in the Nature as much ways of creating colour as shades of colours. Thousands …

Molecules may be responsible for colours. Called chromophores, or more commonly pigments, they form a wide and diverse family of compounds including not only natural pigments responsible for the greenness of the forest, but also synthetic dyes colouring your food, your clothes, or your furniture.  

In plant, pigments ensure fundamental and vital roles: harvesting and storing energy, protecting from environmental aggressions, communicating with the external environment, …

Monitoring how pigments evolve in plants over the year help indicate health status of plants, understand how plants interact with their environment, and which strategies plants adopt in response to environmental changing such as warming.

How can we catch the colour?

Spectrometers are optical devices that enable to measure wavelengths (light energy).

On one side, scientists collect plant in the field. Back in the lab they extract from them all individual colour compounds like you would prepare tea. They eventually identify and quantify these compounds.

On the other side, remote sensing technologies offer to fly spectrometers with drones, planes and satellites to record gigabits of spectral data from the sky

In my research, I try to make this two approaches work together to better listen to what pigment can teach us on forest dynamics.

Be ready to roll up your sleeves to measure light signal, extract colours… and help scientist resolve the secret of light! Around a cup of tea and a piece of chocolate, you will also be invited in this Busker to dive into a colourful adventure investigating the ecosystem services fulfilled by colours.