The Study On Spruce Forest Decline Mechanism In Low-lying Land In Eastern Mountain Area In Heilongjiang Province

This thesis is one part of Grand Project of National natural Science Foundation Association named " Study on mutual affection mechanism between eastern China terrestrial agricultural ecosystem and global climate change" which was directed by professor Zhou Xiaofeng . By the traditional ecological investigation methods, we systematically researched spruce forest decline mechanism in low-lying land in eastern mountain area in Heilongjiang province with ecological and biological specific character of spruce forest, habitat of spruce, influenced by disease and insect, and affected by global climate change. The results as follows:The firstly, the spruce has been grown decline for about 40 years, and the reason is only climate change factor. The spruce forest is progressive population in Tahe, Wuyiling, Tangwanghe and Hongxing forestry bureau, however, which is decline population in Wuying and Bailing forestry bureau. The age structure of died spruce is widely, from 108 to 220. The age structure rule out death possibility of overmature forest, further demonstrate that the death of spruce is caused by the external disturbance.The secondly, there are no closely relationship between soil PH and spruce death. In addition, we can draw a conclusion that the soil in this site is not acid. However, the low exchangeable caution of cation is one of the reason about spruce death. There are no clearly difference of nutrient content of spruce organs in different growth condition about death tree, close to the death tree and healthy tree. There are no closely relationship between nutrient content and growth condition of spruce, which further show that there are no relationship about spruce growth condition and absorb of nutrient element. There are plenty of microorganisms in every plot, especially in the spruce plot, the number of bacterium is more clearly than the other plot. In the meanwhile, the number of bacterium in ara of spruce death are more than those in area of growth normal, and there are no closely relationship between the variation of number of actinomyces and spruce death.The thirdly, there are no relationship between spruce death and endangering of nematodes, and disease is not directly reason of causing spruce growth decline. The ectomycorrhizal of spruce show decline tendency, and the decline of ectomycorrhizal of spruce is one of the reason of forest decline in low-lying land, but the decline of ectomycorrhizal of spruce is complicated process, the decline reason is need further more research work.The fourth, the annual mean temperature increases as 0.25℃/10a in Heilongjiang province Chinain recent hundred years, and the precipitation shows fluctuation change, the cycle is 11 a. In the Liangshui Nature Reserve: the air temperature increases clearly in recent 30 years, there are noobviously difference about the precipitation in recent 30 years, which keeps the tendency steadily. The annual mean temperature, annual mean lowest temperature and annual mean highest temperature increases clearly, and the variation of precipitation changes obviously, which decreases 50mm in recent 30 years, it shows that this area changes drier and drier. The annual mean temperature increases clearly very much, the precipitation is stable, and it exists enlarger tendency slightly.The fifth, the direct reason-predisposing factors of spruce forest decline in low-lying land in eastern mountain area in Heilongjiang province is global climate change, the increased temperature causes northern movement of south boundary of permafrost in Daxinganling and Xiaoxinganling mountain area. However, the original south boundary of permafrost in dialing district in Yichun city is all melting now. For the melting permafrost in dialing, the climate exists dry spring, summer and autumn is too wet. So, the climatic change in this area is the direct reason causing spruce decline, which is predisposing factors.With the obvious decreasing growth of spruce forest in low-lying land, which can cause the disease and insect invading the tree, so, it can fu...