Aug. 20 (UPI) -- New research suggests the same deforestation that precipitated the collapse of the Mayan civilization led to the decimation of Central America's carbon reserves.
Analysis of the region's long-term carbon cycle showed damages caused by ancient deforestation continued to undermine soil health for centuries, even after trees returned.
Previous research has detailed the dramatic deforestation carried out by the Mayans some 4,000 years ago. But the latest study, published Monday in the journal Nature Geoscience, is one of the first to look at the effect of ancient deforestation on carbon reserves.
Soil remains Earth's largest carbon reserve. The planet's soil holds twice the amount of carbon currently found in Earth's atmosphere.
Previous studies have detailed changes in soil health across small timescales. The latest research looked at the long-term impacts of deforestation on soil health and the ability of soil to store carbon.
"When you go to this area today, much of it looks like dense, old-growth rainforest," Peter Douglas, McGill University geochemist, said in a news release. "But when you look at soil carbon storage, it seems the ecosystem was fundamentally changed and never returned to its original state."
Douglas and his colleagues analyzed a variety of sediment core samples collected from lake bottoms in southern Mexico and Guatemala. The researchers used radiocarbon dating to measure the age of plant waxes in the soil.
Because plant wax molecules easily attach to minerals, they typically remain the soil for long periods of time. Scientists compared the age of plant wax molecules to the age of plan fossils found in the same layers of sediment.
The radiocarbon analysis showed the age difference between fossils and plant waxes shrank in the wake of Mayan deforestation. The change suggests carbon began moving in and out of the soil at an accelerated rate. As more and more trees were cleared to make way for Mayan farms and cities, carbon storage became less stable.
"This offers another reason -- adding to a long list -- to protect the remaining areas of old-growth tropical forests in the world," Douglas said. "It could also have implications for how we design things like carbon offsets, which often involve reforestation but don't fully account for the long-term storage of carbon."
The new study is one of several that have shown ancient civilization had great impact on ecological and climate systems than scientists previously thought.
Douglas hopes to use his method of radiocarbon dating plant waxes to study the impacts of climate change on carbon cycles in Canada's permafrost regions.