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Invasive sequence and ecological niche of main insect borers of <Emphasis Type="Italic">Larix gmelinii</Emphasis> forest in Aershan,Inner Mongolia |
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| Authors: | Fei Yuan You-qing Luo Juan Shi Kari Keliövaara Guo-xin Qi Xiang-jun Li Yong-shi Han Chao Chen |
| Institution: | 1. Key Laboratory for Silviculture and Conservation of Ministry of Education,Beijing Forestry University,Beijing 100083,P.R.China 2. Department of Applied Biology,University of Helsinki,FIN-00014,Finland 3. Forest Diseases and Insect Pests Control and Quarantine Station in Aershan,Inner Mongolia,Aershan 137801,P.R.China |
| Abstract: | After the outbreak of Dendrolimus superans Buret in 2002, many insect borers quickly invaded larch (Larix gmelinii Rupr.) forests in the Aershan of Inner Mongolia. Methods involved included setting sample plots, collecting adults in iron traps and measuring areas of galleries to study the invasive sequence, their ecological niche and the extent of the different effects by the main insect borers to their hosts. The results showed that the damage of D. superans weakened L. gmelinii, first Ips subelongatus Motschulsky invaded, followed by Acanthocinus carinulatus Gebler, Monochamus urussovi Fisher and M. sutor L. After the outbreak of D. superans, the average density of longhorn beetles per L. gmelinii tree increased. The ecological niche of Ips subelongatus stretches almost from the base to the top of the trunk. The number of insects in older stands of L. gmelinii is larger than those in middle aged stands. They do not damage healthy trees of L. gmelinii. The ecological niche of A. carinulatus is higher in dead L. gmelinii trees than in weak ones. The degree of damage is directly proportional with age and depth of bark. M. urussovi mainly damages trunks below 4 m in weak trees; in dead trees they can do damage up to 6 m in height. M. sutor mainly damages trunks below 5 m in weak L.gmelinii trees; in dead trees they cause damage up to 7 m. Again, the degree of damage is directly proportional with age. None of the three species of longhorn beetles damage healthy L. gmelinii and younger trees. Among the main insect borers, the degree of damage caused by L subelongatus is more serious than that of other insects. |
| Keywords: | Dendrolimus superans invasive sequence insect borer ecological niche damage degree |
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