A foreign company that has been replanting thousands of hectares of farmland with trees in British Columbia in order to claim carbon credits has been told the practice is not sustainable and is damaging local economies.

In a letter, the Regional District of Bulkley-Nechako (RDBN) told the British-based multinational Reckitt Benckiser Inc. (RB) that its conversion of some 2,000 hectares of farmland into forest is troubling.

“There are concerns that the tree planting on agricultural lands in the RDBN may have a negative impact on the region’s economy, as centrally located and productive agricultural land is taken out of production in the long term,” Bill Miller, chair of the board, wrote last fall. “There are also concerns that the continued planting of trees on centrally located and productive agricultural lands is not sustainable, and will not result in a net reduction of greenhouse-gas emissions.”

In an interview Tuesday, Mr. Miller said the letter was sent after the company bought 500 hectares in 2013, adding to 1,460 hectares already assembled between 2006 and 2010. He said the latest purchase is to be planted this year, but the land acquired earlier is already covered with aspen.

“At the start they were sort of out on the marginal areas picking up land, because of course it’s cheaper … and it wasn’t of too big a concern, but as it progressed what’s happening is now they are getting in and buying really prime agricultural land,” Mr. Miller said.

He said taking that land out of cultivation through a process that’s known as afforestation is shortsighted and counterproductive.

A report by the RDBN’s director of planning says the RB afforestation program, which runs under the names “Trees for Change” or “RB Trees,” has positive goals but is misguided. “It promotes the clearing and development of new agricultural lands … [and] this clearing activity also serves to increase greenhouse gas production,” the document states.

The company did not respond to requests for comment. But in an Oct. 27 letter to the RDBN, Victoria Wood, RB’s global head of sustainability, defends the practice.

“The RB Trees afforestation project was initiated in British Columbia in 2006 to sequester carbon on private land for the purpose of offsetting greenhouse gas emissions,” she wrote. “The project is aligned to the Intergovernmental Panel on Climate Change’s (IPCC) Good Practice Guidance (GPG) … which places restrictions on the land we can use for our project.”

Ms. Wood says RB’s approach is “to target land that is marginally productive, such as rough pasture, pasture, hay land and abandoned farms or farms that have been on the real estate market for an extended period of time.” She writes that the company’s contribution to the local economy “has been substantial, due to the range of goods and services we procure.”

RB representatives and members of the RDBN are planning to meet in June to discuss the issue.

Doug Hatfield, a businessman who is trying to assemble land for hay production, complained that RB has been buying up some of the best land. He said he was recently outbid for 500 hectares, “and I have heard they have just put an offer on another 2,100 hectares.”

Warren Wilson, a rancher in the Prince George area, said he’s seen some good cattle ranches become carbon offset forests. “It breaks my heart [to see ranch land replanted in trees] and it doesn’t make any sense at all,” he said.

B.C. Agriculture Minister Norm Letnick has said the government is watching the trend but isn’t alarmed because so far only about 1,500 hectares, a relatively small amount of land, has been afforested.

But Lana Popham, the NDP agriculture critic, said the government doesn’t have a good handle on the problem.

“I have been hearing from people from Prince George right through to the Caribou and the numbers are bigger than that,” she said. “So I don’t think the minister has enough people on the ground to figure out exactly how much land we’re talking about.”