# Tropical forest carbon sequestration accelerated by nitrogen

## TL;DR

Tropical forests recover faster when nitrogen is added, especially in young forests, which could impact global carbon sequestration.

## Contribution

The study reveals a shift in nutrient limitation during tropical forest recovery, showing nitrogen's critical role in early stages.

## Key findings

- Nitrogen addition boosts biomass in young forests by up to 95%.
- Older forests show no nitrogen or phosphorus limitation.
- Global CO2 sequestration could be reduced by 0.69 Gt annually if nitrogen limits young forests.

## Abstract

Understanding forest carbon sequestration is crucial for predicting and managing the carbon cycle, yet we lack evidence for whether, when and how the carbon sink in tropical forests recovering from land use change is nutrient limited. Here we show how the tropical forest recovery rate responds to experimental nutrient manipulation over a secondary succession gradient in a naturally recovering Central American landscape. Nutrient limitation of aboveground biomass accumulation shifts from strong nitrogen limitation in young forests to no evidence of nitrogen or phosphorus limitation in older secondary or mature forests. Nitrogen addition increases aboveground biomass accumulation by 95% in recently abandoned pasture and 48% in 10-year-old forests. Conversely, we observe no influence of nitrogen on older forests and no evidence of phosphorus limitation at any stage. If our findings of nitrogen limitation extend to young tropical forests globally, nitrogen could prevent the sequestration of 0.69 (0.47-0.84) Gt CO2 each year.

Tropical forests regulate Earth’s carbon cycle, but what governs carbon sequestration following land use remains unclear. Here Tang et al find a shift from strong nitrogen limitation to no nutrient limitation over tropical forest secondary succession.