Abstract

We studied the spatial distribution pattern of surviving Japanese black pine trees and those killed by pine wilt disease in 2008 and 2009 in a sparsely growing, young stand on a lava field in Sakurajima, Kagoshima Prefecture, southern Japan. Pine trees were distributed aggregately and formed loose colonies occupying an area of 16 - 25 m2. Pine trees killed by pine wilt disease in 2008 and 2009 also occurred in loose colonies of 16-25 m2 in area. However, the spatial distribution pattern of pine trees killed in 2009 was exclusive to that in 2008, and killed trees in 2009 occurred in colonies of pine trees where no killed pine trees occurred in 2008. Asymptomatic carrier trees might not have any significant impacts on the spatial pattern of killed trees. This spreading of pine wilt disease might have been caused by the active flight of the Japanese pine sawyer beetles and rapid invasion of the pinewood nematodes into sound trees just after the beetles emerged.

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