Samples for this study were collected from a 31-year old P.
koraiensis provenance experiment located at the Maoershan Experimental
Farm, Heilongjiang province, China. The area has a continental
monsoon climate; it is cold and dry in winter but warm
and humid in summer. In total, 10 provenances were included in
the experiment which was established in 1983 using 2-year old
seedlings. The experiment was established as a randomized complete
block design of 5 blocks and 100-trees plots, planted with a
2–row layout with 50 trees per row. The experiment was thinned
in 2003 by removing one of the rows per plot.