The 19,500-acre Buckeye Forest in northwestern Sonoma County holds a lot of trees. More than 75 percent of the trees are redwoods, tanoaks, and Douglas firs, with the rest a combination of sugar pines, true oaks, bay laurel, and other hardwoods.
You might take a close look at a sample of those trees to count them and size them and so see how much carbon is in them. Then, you might use statistics to arrive at an estimate of carbon in the entire forest. A forester did this and came up with the figure of 1.1 million tons of carbon. You can then calculate backward from carbon stored in trees to a “carbon dioxide equivalent,” which is basically the amount of carbon dioxide the trees took out of the air, over their lifetimes, to make themselves. The Buckeye Forest trees are built out of nearly 4 million tons of carbon dioxide, or roughly what would be emitted in 6,400 airplane trips around the world.
The climate case for keeping those trees in the ground is not just the carbon dioxide they’ve taken out of the air so far, but the trees’ potential to continue taking carbon dioxide out of the air and storing it. But there is also no timber or development money in letting trees grow. Enter California’s carbon offset market. In 2013, a Virginia-based nonprofit group called Sustainable Conservation Inc. teamed with several government agencies and private foundations to buy the Buckeye Forest (then called Preservation Ranch) on the assumption that it could pay back part of the purchase price by selling offset credits to carbon polluters. Keeping those trees upright and inhaling carbon dioxide was worth about $2 million in 2015.
“Redwood prices now are at a historic high,” says Chris Kelly, the California director of The Conservation Fund, which manages the Buckeye Forest. “Everyone’s going to be out there cutting like crazy if they can. So the baseline condition is what would be likely to be the level of harvest if you were to be an economically rational landowner wanting to maximize return that was [legally] permissible and economically feasible. And everything you do that’s less extractive than that can be quantified.”
Offset critics have been skeptical of forest projects for allowing emissions in exchange for simply preserving the status quo, as opposed to actually removing additional carbon dioxide from the atmosphere. And according to a recent article by Stanford graduate student Christa Anderson and colleagues in the journal Frontiers in Ecology and the Environment, forest projects do seem to contribute more than just their baseline. “The offset program, the principal idea is that a polluter, a greenhouse gas emitter, will buy a credit and then emit that ton,” Anderson says. “Because of that arrangement it’s important to know that there’s been a ton sequestered.”
In other words it’s not just saving the trees that’s valuable, Anderson says, but helping them to grow more and so sequester more carbon. What she’s found is that a managed forest does capture and store more carbon than an unmanaged forest – which, according to offset reports, is what’s happening at the Buckeye Forest.
Instead of logging even a part of the forest immediately, The Conservation Fund has let the forest rest for five years, increasing carbon storage by an estimated six tons per acre between 2013 and 2016. Although the group hasn’t submitted plans to log yet, when it does, it will use a practice called “selection cutting” that essentially considers each tree’s harvest and standing value, ultimately creating mixed-age forests and helping preserve soil nutrients—and soil carbon—relative to logging in swaths. A stand in the Buckeye Forest could be logged, an offset data report says, when its trees reach a density of one tree per 125 square feet. Those stands would then be cut to one tree per 75 square feet. After logging, each stand would then be left alone for a minimum of 10 years. According to a calculation by TCF, under a selection cutting plan, the forest would continue to sequester carbon even with annual logging.
Although it’s not reflected in the offset law, there’s also more of importance to the conservation world than just carbon dioxide. Forest offset projects help fund intact forests, Anderson says, allowing a number of “co-benefits” to wildlife. In her paper, Anderson calls for a better reporting and accounting for co-benefits to understand what and how much they’re helping.
Buckeye offers a number of conservation co-benefits. It protects 29 miles of fish-bearing rivers and streams. The forest spills over into Mendocino County to the north, joining with two more Conservation Fund–managed parcels to create a nearly 60,000-acre solid block of trees that allows wildlife movement and migration. A conservation easement with the Sonoma County Agricultural and Open Space District means it could one day be opened to the public for hiking.
The sheer size of what the offset revenue allows is maybe the most impressive part, Kelly says. There’s an old Cal Fire tower at the entrance to the Buckeye parcel that’s been converted into a cell tower. From the top you can look west over the ocean at Sea Ranch and north over 28 miles of unbroken forest. “The image that first comes to mind is standing on that tower and looking north, how far into the distance the northern edge of our ownership is,” Kelly says. “One of the things that matters for conservation is scale. The common wisdom from conservation biologists is the bigger the better.”