Fueled by increased demand from China, log and lumber exports from the West Coast are on the rise, according to a study released this week. The value and volume of lumber exports from Washington, Oregon, Alaska and Northern California jumped by 50 percent during the third quarter of the year, compared with figures from the same period in 2012. And the value of log exports rose by 40 percent, while the volume increased by 25 percent.That’s according to the U.S. Forest Service’s Pacific Northwest Research Station.“Demand from China is the major reason for the increased lumber exports we saw in the third quarter,” said Xiaoping Zhou, a research economist who compiled the data.The report found that total U.S. lumber exports in the first nine months of 2013 increased by about 10 percent compared with the same period in 2012, while the value increased by more than 14 percent.And total U.S. log exports in the first nine months of 2013 increased by about 22 percent, compared to 2012, while the value rose by more than 28 percent.The Pacific Northwest Research Station, headquartered in Portland, has 11 laboratories and centers in Alaska, Washington, and Oregon.