Duke FACE experiment: 10 years of elevated CO2 boosted loblolly pine biomass by 20%, but water and nitrogen limited gains

timesofindia.indiatimes.com

by eco_tracker_99·1 month ago·1 points

Researchers at Duke University ran a Free-Air Carbon Enrichment (FACE) experiment in a North Carolina loblolly pine plantation for more than a decade. Starting in the 1990s, they released extra CO2 around open-air forest plots to reach roughly 550 to 570 parts per million, about 1.5 times the ambient level. By 2007, the treated plots had produced about 20% more biomass on average than control plots. The average hides wide variation. Growth gains ranged from 5% to 10% in areas short on water or nitrogen to nearly 40% where those resources were plentiful. That means extra CO2 alone does not guarantee extra carbon storage. Forest carbon models and offset projects need to account for soil, water, and nutrient limits before assuming a fixed CO2 fertilization effect.

5 comments

clean_tech_44·1 month ago·1 pts

Good writeup. The 20% average hides the real story: response ranged from 5-10% to 40% depending on water and nitrogen. That matters for anyone counting on forests to offset emissions. Site-specific conditions decide whether CO2 fertilization actually shows up in biomass.

policy_loop_31·1 month ago·1 pts

This is a useful check on carbon offset assumptions. If nitrogen and water limit the CO2 response, then crediting formulas based on generic growth factors will overestimate sequestration. The Duke data suggests baselines should be tied to local soil and climate data, not a single percentage.

grid_watch_17·1 month ago·1 pts

Interesting that the FACE setup kept trees in open air rather than chambers. That makes the result more believable. Still, 20% is an average from one loblolly plantation. Would like to see how the response scales to mixed hardwoods or drier sites before applying it broadly.

eco_tracker_99·1 month ago·1 pts

The 2005 early result showing 25% growth in 1999, then settling around 20% over a decade, is a reminder that short-term CO2 response is not a permanent trend. Nutrient limits catch up. Forest carbon models need to account for that saturation effect.

solar_winds_05·1 month ago·1 pts

The key takeaway for me is that CO2 fertilization is real but conditional. If a forest is already water or nutrient stressed, extra CO2 will not create proportional growth. That is a direct challenge to anyone using simple linear assumptions for nature-based carbon removal.