Forests Are Rapidly Changing: Global Study Warns of Biodiversity Loss

Our forests are losing vital tree diversity as fast-growing species replace slow-growing ones. Discover why this makes ecosystems vulnerable and threatens carbon storage.

Forests around the world are changing at a concerning rate. Trees are essential for life on Earth, as they take in and store carbon dioxide, help control the climate, support a variety of wildlife including animals, fungi and insects, prevent soil from being washed away, manage water flow, and provide people with materials, food and protection from the heat.

Despite their critical role, forests are becoming more similar and less varied. A major global study published in Nature Plants looked at over 31,000 tree species from around the world. The researchers discovered that many forests are losing their diversity and becoming less stable, which makes them more at risk from future environmental changes.

Fast-Growing Trees vs Slow-Growing Trees

One of the key trends is the increase in fast-growing tree species. These trees grow quickly and spread easily, but slower-growing species with more specific features are facing a decline or even extinction. This trend is especially worrying in tropical and subtropical areas, where many unique tree species are found only in small regions. When these rare native trees disappear, the spaces they leave in the ecosystem are seldom filled by other tree species.

Slow-growing trees are especially important for the stability of forests. They often have thick wood, dense leaves and long lifespans. These features help forests store carbon for a long time and make them more able to handle environmental stress. However, if climate change and deforestation continue, forests may start to favour faster-growing species that have lighter wood and leaves. Examples include trees from genera like Acacia, Eucalyptus, Populus and Pinus. Although these trees grow rapidly, they are generally more vulnerable to drought, storms, pests and diseases, making forests less effective at storing carbon over time.

Building Healthier Ecosystems

The study also points out the spread of naturalised species, which are trees that have been introduced from other parts of the world and now grow in the wild. These species often grow quickly and are able to thrive in disturbed environments. However, they do not fully replace the ecological functions of native trees and may compete with them for sunlight, water and nutrients.

Tropical areas are likely to experience the biggest losses, as many slow-growing species there have very limited ranges. These changes are mostly driven by human activities such as climate change, logging, intensive forestry and global trade.

The researchers suggest that forest management needs to change. Protecting and planting more slow-growing and rare tree species could help restore diversity, enhance resilience, and support healthier ecosystems in the long term.