Spatial Distribution Pattern of Pine Trees Killed by Pine Wilt Disease in a Sparsely Growing, Young Pine Stand

Koichi Sone,Kunihiko Hata,Toshiyuki Matsuo,Keisuke Ohkubo

doi:10.5539/jps.v2n1p36

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.

Highlights

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
In 2009 and 2010, pine trees of various sizes were killed (140-659 cm in height, 0.9-11.5 cm in diameter at breast height (DBH)), and the incidence of pine wilt disease (PWD) did not seem to increase with the size of pine trees (Figure 2)
These results suggest that PWD was probably the only mortality factor of pine trees on the study plot during the study period, 2008-2011

Summary

Introduction

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. The spatial distribution pattern of killed trees in a pine stand is considered to be determined by the distribution of pine trees killed the previous year and the dispersal pattern of the JPS beetles.

Results

Conclusion