Tropical forest carbon sequestration accelerated by nitrogen

Area of Science:

• Ecology
• Forestry
• Biogeochemistry

Background:

• Understanding forest carbon sequestration is vital for managing the global carbon cycle.
• Evidence is lacking on nutrient limitation in tropical forests during recovery from land use change.
• Tropical forest recovery rates and carbon sinks may be influenced by nutrient availability.

Purpose of the Study:

• To investigate nutrient limitation in tropical forests during secondary succession.
• To determine how nitrogen and phosphorus affect aboveground biomass accumulation in recovering forests.
• To assess the impact of nutrient addition on forest recovery rates across a successional gradient.

Main Methods:

• Experimental nutrient manipulation (nitrogen and phosphorus addition) was conducted.
• The study spanned a secondary succession gradient in a recovering Central American landscape.
• Aboveground biomass accumulation was measured in response to nutrient addition across different forest ages.

Main Results:

• Nutrient limitation shifted from strong nitrogen limitation in young forests to no limitation in older forests.
• Nitrogen addition significantly increased aboveground biomass by 95% in recently abandoned pastures and 48% in 10-year-old forests.
• No phosphorus limitation was observed at any successional stage, and nitrogen had no effect on older forests.

Conclusions:

• Nitrogen availability is a critical limiting factor for carbon sequestration in young, recovering tropical forests.
• Older secondary and mature tropical forests do not appear to be nutrient-limited.
• Global nitrogen limitation in young tropical forests could hinder annual carbon sequestration by up to 0.69 Gt CO2.