PORTLAND — Maine forestry officials are looking for a few big trees.

The Maine Forest Service is taking nominations through Dec. 31 for its 2011-2012 Maine Register of Big Trees, which lists the largest known specimens of each tree type in the state. The forest service has been compiling the register since 1968.

The current edition has 159 trees, representing 149 tree species. But at least four of those trees have died, including the giant elm in Yarmouth nicknamed “Herbie” that was cut down this year after being decimated by Dutch elm disease.

Candidates are measured by state foresters and given a score based on height, circumference and average crown spread.

People can visit http://projectcanopy.maine.gov for more information about the program and how to nominate a tree.