Trees fail to sequester carbon

Surprising many, planting trees may not reduce airborne carbon.

Duke FACE FacilityTo detect if trees deposited carbon in the soil, several projects enriched the air over forest canopy by spraying pure CO2 through laser drilled holes in tubing mounted on telescopic poles.

Duke University has been pumping extra CO2 over trees for ten years and found that forests may not absorb enough carbon to make a difference to global warming. “Elevated CO2 could significantly increase the production of foliage, but this would lead to only a very small increase in ecosystem carbon storage.”

In some areas, plant growth increased from 10-40 percent, but in most areas carbon was not moved from the air back to earth, the target of carbon reduction and sequestration efforts.

Carbon storage seems to occur only in the most robust and nutrient rich soils where biological activity is the most vigorous. Without paying attention to water and soils, conventional tree planting may not help reduce global warming. On average or marginal land, trees merely return the carbon dioxide to the air. Carbon will only be absorbed in a forest floor with a healthy and complex system of water, minerals, fungi and bacteria.

Oddly, invigorating soil with charcoal may produce healthy soil and thus absorb more CO2. As BioPact says, “When biochar is added to soils, they become impressively fertile because they prevent nutrients from getting washed away by rain and erosion.” I think the explanation for biochar benefits will go beyond erosion and soil mechanics. Carbon provides more than structure at the microscopic level and may interact with water and minerals as well as becoming a lattice for fungi.

Bioenergy.list is keeping abreast of soil’s ability to store carbon and the increasing attention given to charcoal as a zero-carbon biofuel.

The University of Hawaii energy program found that charcoal is a zero-carbon fuel and “the sustainable fuel replacement for coal”.

“Coal combustion is the most important contributor to climate change.

“Coal combustion adds about 220 lb of CO2 to the atmosphere for every million BTU of energy that it delivers; whereas crude oil adds 170 lb per million BTU, gasoline adds 161 lb per million BTU, and natural gas adds 130 lb of CO2 to the atmosphere per million BTU of delivered energy.

“On the other hand, the combustion of charcoal – sustainably produced from renewable biomass – adds no CO2 to the atmosphere! Thus, the replacement of coal by charcoal is among the most important steps we can take to ameliorate climate change.”