Southern pine plantations absorb carbon from the atmosphere, but how much depends on water and nutrients
Southern pine forests provide many ecosystem services, including absorbing pollutants such as atmospheric carbon dioxide. As a result, these managed forests are primarily a carbon ‘sink’, helping efforts to curb climate warming caused by rising greenhouse gas emissions. However, research suggests that the strength of these forest benefits relies on water and nutrient availability.
Managed loblolly pine plantations are important to the economy of the southern U.S., while providing ecosystem services including clean water, carbon sequestration, and wildlife habitat. USDA Forest Service scientists and partners have been conducting a series of experiments to understand how forest productivity and carbon sequestration respond to precipitation and nutrient changes. The scientists measured ecosystem productivity in two ways—plant biomass accumulation (net primary production, NPP) and net ecosystem carbon gain (NEP).
These measures show that soil carbon loss responds differently to fertilization and drought than NPP does alone. A moderate increase in NPP but a decrease in soil carbon loss resulted in a significant increase in overall carbon gain in the study’s fertilization and drought treatments. On the other hand, the drought benefit for carbon sequestration was nearly twofold without fertilization but disappeared with fertilization.
Future climate change that affects water availability is likely to affect the capacity of planted forests to sequester carbon. Findings also suggest that global models may need to be modified to reflect the combined effects of fertilization and nutrient conditions on forest carbon balances. This research provides new knowledge to guide adaptive forest management for multiple purposes, including timber production and mitigating greenhouse gas emissions over time.
