Why do leaves change colour in Autumn? Science made simple

Why Do Leaves Change Colour in Autumn? Science Made Simple (image: Canva)

Autumn is a time when trees in temperate regions produce an amazing display of red, orange and yellow foliage. But why does this happen?

The Role of Chlorophyll

The green hue of the leaves during spring and summer is due to chlorophyll, a pigment that captures sunlight and transforms it into energy through photosynthesis. With the help of chlorophyll, a tree can produce sugars from carbon dioxide and water, which is critical to its growth.

Shorter Days and Cooler Temperatures

During autumn, trees in the forest prepare for low temperatures and shorter days. Reduced sunlight and cooler conditions slow chlorophyll production, causing the green colour to fade and revealing other pigments in the leaf.

Carotenoids and Anthocyanins

Carotenoids are always present in leaves, producing yellow and orange colours. Anthocyanins, formed in response to bright light and sugar accumulation, give red and purple tones. The combination of these pigments creates the stunning palette characteristic of autumn foliage.

Energy Conservation and Survival

Shedding leaves helps trees conserve energy and water during the harsh winter months. By breaking down chlorophyll and reabsorbing nutrients, trees prepare for new growth in spring, ensuring their survival year after year.

A Seasonal Spectacle

The changing colours of leaves are not simply a beautiful phenomenon but evidence of nature’s complex survival mechanisms. This annual transformation reminds us of the remarkable interplay between sunlight, temperature and plant biology.