Agroforestry / July 15, 2019

Carbon Farming, Coconuts, Carpentry—An Agricultural Primer

Shifts in agricultural management represent some of the best opportunities to capture carbon and store it for the long term. “Land use change and forestry is responsible for about 25% of all greenhouse emissions” and according to the Carbon Cycle Institute, “Land management is the second largest contributor to carbon dioxide emissions on planet earth.” But, the institute also reminds, “Agriculture is the one sector that has the ability to transform from a net emitter of CO2 to a net sequesterer of CO2 — there is no other human managed realm with this potential.”

When a plant photosynthesizes, it captures carbon dioxide from the air and secures it in its leaves, trunk, roots, and the surrounding soil. Carbon farming—which seeks to maximize the ability of agriculture to capture and store carbon through increased production of biomass, compost, silvoculture, agroforestry, and a host of other regenerative techniques, can turn agricultural spaces into much-needed carbon sinks.

Carbon Farming, Coconuts, Carpentry—An Agricultural Primer

Forestry (of all kinds) is Key
You may have noticed the headlines this past week, that a study published in Science on July 4 found planting 1 trillion trees in open spaces around the world may hold the ability to capture 25% of the atmosphere’s CO2. The great potential of forests lies in their long lives. As soon as a plant is no longer actively growing, it begins to release CO2 back into the atmosphere as it decomposes. The size and long-lived nature of trees means they can capture more carbon and hold it for longer than other plants.

Enduring forests are preferred for this work, but all trees can be carbon sinks. Plantation coconut trees still live for an average of 60-80 years and Dr. S. Naresh Kumar, Senior Scientist of Plant Physiology at CPCRI in Kasaragod, India rates the annual carbon sequestration potential of coconut plantations at between 8 and 32 t CO2/ha, making them a viable option for carbon farming.

Young Forests Sequester More Carbon
What has become more apparent recently is young trees actually sequester more carbon than old trees. Researchers at the UK’s Birmingham Institute of Forest Research (BIFoR) found that old-growth forests sequester 950 million-1.11 billion metric tons of carbon annually. In contrast, forests growing for 140 years or less outperformed, storing 1.17-1.66 billion metric tons of carbon each year—1.5 times more on the high end.

There are a variety of explanations for this, but the simplest is new trees are usually growing in open spaces. Less competition means more available sunlight, more photosynthesis, and thus higher rates of growth and carbon sequestration.

Wood Products Extend Carbon Storage
Ultimately forests are something of a layover point for carbon. Remember, as soon as that tree begins to burn or decompose it releases the carbon it once stored. This makes the tree’s afterlife a matter of supreme importance. Thankfully, wood products extend a tree’s ability to store carbon. This is a major mental block that must be overcome in regards to the purpose and use of wood products. Using alternative products to “save trees” or “protect the environment” is really working against the goal. Most alternative products are made from plastics or other non-renewable resources that are net emitters rather than sequesterers of carbon. In contrast, wood products extend the carbon-sequestering potential of every tree, so the higher quality and longer lasting they are, the better (see: wood, teak).

Once the life of a wood product has reached its terminus, there are still carbon-capturing options to be explored. If the wood decomposes, carbon is released to the atmosphere. However, allowing the wood to decompose belowground via hugelkultur is an effective carbon farming technique to secure much of that carbon within the soil. Also, a team of researchers point out in the Forest Products Journal, “end-of-life (i.e., after first product use) scenarios for old wood products can result in large cumulative energy savings and fossil CO2 emission reductions when discarded wood is used to displace coal or natural gas in producing electric power. In fact, for the base case end-of-life scenario developed by Bergman et al. (2013a), these energy savings would offset 53 and 75 percent of biomass energy consumed to make new softwood framing lumber and new hardwood flooring, respectively.”

Even though burning wood releases carbon, recycling wood products for fuel squeezes extra value out of the product and offsets the more negative impact of dirtier fuel sources.

The Honorable Harvest
As we put the pieces of this puzzle together, we continue to learn that stewardship and commerce need not be at odds. Conservation does not require a hands-off approach to the natural world—setting aside as much land as possible for parks and wilderness areas (though those spaces are certainly sacred and needed). The reality is meeting our needs in a responsible manner can be the most effective way to facilitate the health of the natural systems that sustain us. New agroforestry plantings capture carbon at the highest rates, and when they are harvested for use in commercial wood products and then responsibly replanted, carbon farming potential is maximized.

In many ways, the responsible management of carbon farming is more challenging than hands-off versions of conservation, as it requires we examine every step of our processes to determine if our actions are destructive or regenerative. But on the upside, it’s a reminder that humanity has a rightful place in the holistic systems of the natural world. We can harvest and produce in a manner that encourages ecological and human flourishing. It isn’t easy, but it’s always worth the effort.