'Nitrogen fixing' trees could help tropical forests bounce back, research suggests

Driving up steep hills in Panama's sweltering heat, dodging mosquitoes while hauling nitrogen fertilizer to experimental forest plots, researchers have discovered something remarkable: a simple nutrient boost can nearly double the growth of young tropical trees recovering from deforestation.

The Smithsonian study tracked forests across the Panama Canal watershed for four years, finding that nitrogen fertilizer increased tree biomass by 95% in areas that had been cattle pastures just a year earlier. Even decade-old recovering forests showed a 48% growth boost.

"You're driving up and down these steep hills to get to the field site," researcher Batterman explained. "And it's super beautiful. You can see the Panama Canal in the distance, with the big ships driving through."

The findings highlight how tropical soils remain nutrient-depleted decades after deforestation. Rather than suggesting widespread fertilization, scientists propose planting more nitrogen-fixing trees that naturally convert atmospheric nitrogen into soil nutrients.

These recovering forests represent the largest component of the global carbon sink, absorbing about 2.5 pentagrams of carbon annually.