Newly published research shows that tropical forests can regenerate twice as fast after deforestation when their soil has enough nitrogen. The study shows that what happens below the bottom plays a serious role in how quickly the forest returns after the land is cleared.
Scientists led by the University of Leeds have launched the biggest and longest experiment ever designed to look at how nutrients shape forest regrowth. Work focused on tropical areas previously cleared for activities similar to logging and agriculture.
Tracking forest regrowth over many years
The researchers chosen 76 forest plots in Central America and monitored them for 20 years. Each site varies in age and size, allowing the team to follow how trees grow and die as forests get better over time.
To test the role of nutrients, plots received different treatments. Some got nitrogen fertilizer, others phosphorus fertilizer, some received each nutrients, and a few were untreated. This approach allowed scientists to directly compare how forests responded to different soil conditions.
Nitrogen has emerged as a key driver
The results show that soil nutrients strongly influence how quickly tropical forests regenerate. During the primary 10 years of recovery, forests with adequate nitrogen lost at twice the speed resulting from its deficiency. Phosphorus alone didn't produce the identical effect.
The study involved researchers from the University of Glasgow, the Smithsonian's Tropical Research Institute, Yale University, Princeton University, Cornell University, the National University of Singapore, and the Cary Institute of Ecosystem Studies. The findings were published within the journal Jan. 13.
Climate and Implications of Deforestation
Lead writer Wenguang Tang, who carried out the research while completing a PhD on the University of Leeds, said: “Our study is interesting because it shows that we can promote the capture and storage of greenhouse gases through deforestation by managing the nutrients available to trees.”
Although nitrogen fertilizer was utilized in the experiment, the researchers don't recommend fertilizing forests. Widespread use of fertilizers can result in harmful uncomfortable side effects, including the discharge of nitrous oxide, a potent greenhouse gas.
Instead, the team suggests practical alternatives. Forest managers can plant trees from the leguminous (bean) family, which naturally add nitrogen to the soil. Another option is reforestation in areas that have already got enough nitrogen resulting from the results of air pollution.
Why rapid regrowth matters for the climate
Tropical forests are among the many world's most significant carbon sinks. They help slow climate change by removing carbon from the atmosphere and storing it in trees, a process often known as carbon sequestration.
Researchers estimate that if nitrogen shortages affect young tropical forests worldwide, about 0.69 billion tons of carbon dioxide may very well be lost annually. This amount is similar to two years of carbon dioxide and greenhouse gas emissions within the UK
Policy relevance after COP 30
The study was released a couple of weeks after the tip of COP 30 in Brazil, where the Tropical Forest Forever Facility (TFFF) Fund was announced. The initiative goals to assist tropical forest countries protect existing forests and restore those which have been damaged.
Principal investigator Dr Sarah Buttleman, an associate professor on the Leeds School of Geography, said: “Our empirical findings have implications for a way we understand and manage tropical forests for natural climate solutions.
“Avoiding deforestation of mature tropical forests should always be a priority, but our findings about the effects of nutrients on carbon sequestration are important as policymakers evaluate where and how to restore forests to maximize carbon sequestration.”