A Northern California wildfire is burning in a vast swath of land where trees are protected in exchange for so-called carbon credits. The Shelly Fire, which ignited July 3 in Siskiyou County, has spread across thousands of acres of land owned by the Portland-based Ecotrust Forest Management, or EFM. The investment firm protects the trees on its land, rather than clear-cut logging them as some neighboring landowners do. Storing carbon on the land in the form of trees allows the company to sell carbon credits intended to offset the harmful climate effects of other activities. …The Shelly Fire has burned across about 11,000 acres of EFM’s 18,000-acre carbon storage project in Siskiyou County. This raises questions about the viability of carbon storage projects in areas prone to high-severity fire. Much of EFM’s carbon offset plot …was covered with extremely overstocked, unhealthy forests — conditions that can result in high-severity fire that decimates trees.