tailieunhanh - Báo cáo lâm nghiệp: "The results of manipulated experiments with inoculation of Ips typographus (L., 1758) to spruce trees under various levels"

Tuyển tập những bài báo cáo nghiên cứu khoa học hay nhất được đăng trên tạp chí JOURNAL OF FOREST SCIENCE đề tài: The results of manipulated experiments with inoculation of Ips typographus (L., 1758) to spruce trees under various levels. | JOURNAL OF FOREST SCIENCE 53 2007 Special Issue 25-30 The results of manipulated experiments with inoculation of Ips typographus L. 1758 to spruce trees under various levels of water stress M. Turcáni O. Nakládal Faculty of Forestry and Wood Sciences Czech University of Life Sciences Prague Prague Czech Republic ABSTRACT Manipulated experiments with males of Ips typographus L. 1758 were conducted in spruce stands in north-western Slovakia. Some of trees were stressed by a lack of water caused by preparation of roofs under canopy. Inoculation experiments with bark beetles were conducted on such trees. According to results the differences in attack rates between differently positioned trees on slope were not statistically significant P for bottom and middle and P for bottom and top and P for middle and top trees t-test . Also the differences in attacks rate and the speed of entry holes preparation between more stressed and less-stressed trees were not statistically significant P t-test . Thus the results of inoculation confirmed that low level of water stress does not lead necessarily to higher attack rate and neither faster speed of entry holes preparation. The obtained results are discussed. Keywords Ips typographus spruce water stress manipulated inoculation experiments Natural tree composition has been dramatically changed across Europe. Today distributional ranges of several tree species are mainly determined by former management practices rather than by natural factors Ellenberg 1986 . As a result of social and economy development there appeared vast regions of non-native monocultures suffering from problems in forest health. In many of these regions the forest decline has recently been subject of concern Blank et al. 1988 Fuhrer 1990 Kandler Innes 1995 . Large area of such stands along with compound of biotic and abiotic stressors air pollution degradation and compaction of soil nutrients exhaustion increased activity of pests and .