Tropical forest soils capture carbon under elevated nitrogen deposition

by Chinese Academy of Sciences

In a new study, Dr. Lu Xiankai and his colleagues from the South China Botanical Garden (SCBG) of the Chinese Academy of Sciences (CAS) found that tropical forests can capture carbon dioxide (CO2) into soils and thus reduce emitted CO2. But how exactly do tropical forest soils capture atmospheric CO2?

Current knowledge of forest soil carbon sequestration mainly focuses on temperate and boreal forests, where most ecosystems are nitrogen-limited, and an increase in nitrogen supply can enhance net primary productivity (NPP) and subsequent soil carbon sequestration.

Traditionally, many scientists thought that nitrogen-rich tropical forests are unlikely to increase belowground soil carbon storage under greater nitrogen supply due to a lack of stimulation of NPP. However, this assumption has not been fully verified under field conditions, and belowground ecosystems have always been neglected by scientists.

Dr. Lu and his colleagues initiated more than a decade of continuous nitrogen addition experiments in a nitrogen-rich tropical forest ecosystem and quantitatively demonstrated that excessive nitrogen deposition significantly increased soil carbon storage by 7-21%.

According to the researchers, soil carbon sequestration efficiency was estimated to be 9 kg of carbon per unit of added nitrogen, which is comparable to temperate forest ecosystems. Interestingly, soil nitrogen retention was significantly and positively correlated with carbon sequestration.

> Source: PHYS.ORG