Environment

Trees are Getting Shorter and Younger

The world’s collective forests have become shorter and younger overall in the past 50 years, according to a study published in the journal Science on Friday. This means that forests have less capacity to remove carbon from the atmosphere and are less hospitable to the many species that rely on them for shelter.

The team of researchers reviewed more than 160 previous studies, analysed satellite imagery, and created models to examine how forests changed between 1900 and 2015. They found that over that 115-year period, the world has lost 14 per cent of its forests to tree harvesting alone. That includes 30 per cent of old growth forests, which are home to trees more than 140 years old and are generally tall and biodiverse.

In different places, this loss is happening at different rates and for different reasons. While wildfires are driving forest loss in Australia and Mongolia. California has seen massive wildfires and beetle infestations. And logging in the Amazon rainforest is increasing. There are some rare exceptions. Tree mortality in parts of the Pacific Northwest, for instance, is decreasing.

But though the changes vary regionally, the impact will be felt globally. Eighty per cent of Earth’s terrestrial land-based plant and animal species live in forests. Old growth forests tend to be highly biodiverse and are home to more endangered species. They also store massive amounts of carbon dioxide.

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