Soil Affects Tropical Forest

Nutrients in the soil can strongly influence the distribution of trees in tropical forests, a new study suggests.

Tropical forests are among the most diverse plant communities on Earth, and scientists have labored for decades to identify the ecological and evolutionary processes that created and maintain them. A key question is whether all tree species are equivalent in their use of resources--water, light and nutrients--or whether each species has its own niche.

The study evaluated three sites: two lowland forests, in central Panama and eastern Ecuador, and a mountain forest in southern Colombia. The researchers plotted every tree and mapped the distribution of soil nutrients on a total of 247 acres (100 hectares) at the sites. The study included 1,400 tree species and more than 500,000 trees.

Each of the sites was very different, but at each the researchers found evidence that soil composition significantly influenced where certain tree species grew:

The finding, published this week in the Proceedings of the National Academy of Sciences, challenges the theory that at local scales tree distributions in a forest simply reflect patterns of seed dispersal, said a principal researcher on the study, James W. Dalling of University of Illinois.

---LiveScience Staff

• Amazing Images: Photos You Submit
• Image Galleries: Science All Around You
• Videos: Science and Nature in Action

Credit: Christian Ziegler