When did the first forests on Earth appear?

Although plants first appeared on land about 470 million years ago, trees and forests did not appear until nearly 390 million years ago. During that time, plants slowly evolved the genetic precursors needed to make trees, and later they became superior to other plants, says paleontologist Chris Berry at the University of California. Cardiff University, England, shared with Live Science on July 2.

Millions of years after the first plants appeared on land, new forests began to form.

In 2019, Berry and colleagues presented research on the oldest forest ever recorded in the journal Current Biology. The forest discovered in Cairo, New York, reveals that the characteristics of trees and forests appeared much earlier than scientists had previously thought, which was in the early Devonian period, about 385 years ago. million years.

The Cairo Forest holds fossilized root systems of ancient trees, indicating where they once grew. "We don't see tree fossils, but we do see maps of the exact locations of those trees. So we can learn about the ecology of the forest," Berry said.

This fossil "map" features Archaeopteris - an ancient group of plants with large woody roots and leafy branches, like modern trees, according to a Binghamton University report. Before that, the earliest evidence for Archaeopteris led scientists to think that this group of plants did not appear 20 million years later.

The development of these primitive forests depends on the process of evolutionary precursors. "I think the key factor is evolution, the anatomical development that allowed the tree to branch out more complex," Berry said. Plants, he said, have evolved a "gene toolkit" to be able to create structures like the trees we have today.

For example, early branching systems developed just before the Devonian, during the Silurian (443.8 - 419.2 million years ago), while the first root systems appeared in the early Devonian, as reported by the Brooklyn Botanical Garden. The characteristics of the tree then give great advantages, especially the ability to rise up to absorb sunlight.

However, some environmental changes may have helped at least one important feature of the tree to form. Megaphylls, the common leaves of today with characteristic branching veins, grew much larger than their ancestors, thereby absorbing more sunlight. They first appeared about 390 million years ago, but 30 million years later, in the late Devonian period, did they become common.

This delay occurs because the high CO2 concentration causes the Earth to overheat with its large megaphyll leaves. They absorb too much sunlight and become excessively hot. However, CO2 levels during the Devonian period dropped rapidly, greatly benefiting the megaphyll. The earth cools, while large megaphyll leaves can retrofit more holes called stomata to absorb more CO2. The leaves may then have helped spur the growth of forests.