Chronic Harvesting Threatens Tropical Tree in Africa

Harvesting trees may affect them more than we realized. Scientists have discovered that chronic harvesting of a tropical tree can alter the tree's reproduction and drastically curtail fruit and seed yields over its lifetime. The findings could have major implications for communities that rely on this tree over their daily lives.

The tropical tree is known as Khaya senegalensis, commonly referred to as African mahogany. Located in many habitats in Western Africa, it can be found from forests to savanna woodland. This tree, though, is considered to be a vulnerable species due to a combination of drought and logging. It's usually harvested for its leaves to feed cattle and for its bark, which is used medicinally to treat everything from stomachaches to malaria fevers.

"For indigenous people who are harvesting these plants, knowing how long a particular species is going to persist or how soon it is going to reproduce is valuable information for planning and management, especially for plants for which fruits are harvested," said Orou Gaoeue, the lead author of the study, in a news release.

Unfortunately, it seems that this tree may be in a bit of trouble. In this latest study, researchers analyzed harvesting effects on the tree in both try and moist conditions in Benin. In the end, the scientists found that plant harvesting affects life history in different ways depending on climactic conditions. For example, in the moist region chronic harvest delayed reproduction and the trees lived longer. In the dry region, in contrast, chronic harvesting hastened reproduction and shortened a tree's lifespan.

 "As we consider how globa warming may affect human livelihood and the resources we use, it is important to understand and account for the ways in which variation in climate and human behavior can change the traits or productivity of harvested wild plants," said Gaoeue. "Here we found that if you fail to account for that variability, even in harvesters' behavior, you may underestimate the effect of harvesting on population life history traits."

The findings are published in the Journal of Ecology.