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Based on the study methods of forest decline, surveys and analysis were carried out on soil chemistiy, soil fertility, soil microorganisms, nutrient contents of spruce organs, forest diseases and insect pests, ectomycorrhizas of spruce, etc. The results show that the death of spruce in Liangshui Nature Reserve is mainly caused by global warming, which resulted in the solution and disappearing of permanent frozen layer of soil.. As a result,, high level swamp on the forestland was developed, which led to the lack of oxygen in root zone and the hindering of root respiration, especially resulted in the declining of the ectomycorrhizas of spruce. Consequently, the vitality of spruce was decreased, which caused the server damages to spruce from Monochamus urussow and Ips t~iqographets, leading to the death of spruce.
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