Responses Of Mycorrhizal Fungi Characteristics To Continuous Cropping And Elevation In Chinese Fir Forests

Cunninghamia lanceolata?Chinese fir?is one of the most important plantaton tree species in China.However,the decline of the productivity of Chinese fir plantation has been the consensus in recent years.Therefore,how to enhance the productivity of Chinese fir and ensure the high yield of Chinese fir plantation has become an important problem to be solved urgently.AMF provides an important way to solve the problem of Chinese fir productivity.As a mycorrhizal fungi symbiotic with the host plant,AMF can help the host plant absorb more substances needed for their growth and development,promote the growth of the host plant and improve the yield.This paper selects three Chinese fir continuous planting forest?first generation forest,second generation forest,third generation forest?in Castanopsis kawakamii Nature Reserve,Sanming City,Fujian Province,three altitudes of Chinese fir forest?1400 m,800 m,200am?in Wuyi Mountain National Nature Reserve and fir forest?200bm?in Ancaoxia,Wangtai Town,Nanping City as research objection.To explore Chinese fir continuous cropping and the changes of soil environmental factors and their effects on AMF in Chinese fir at different altitudes,and attempts to find out the key factors influence the growth and development of AMF in Chinese fir forest.Then provide a theoretical basis for how to promote the growth of AMF to improve the productivity of Chinese fir.The results show that:1.Soil fertility of Chinese fir was not significantly degraded after continuous cropping.The structure of AMF in continuous cropping did not change consistently in the Chinese fir forests of each continuous cropping algebra,and there was no significant change of glomalin in the Chinese fir forests of the three continuous cropping algebra.Compared with soil microbial and enzyme activities,soil physical and chemical properties have a greater impact on AMF,among which MBC and DOC are the main factors leading to the change of AMF.2.In addition to the infection rate,the other index structures?spore,glomalin and mycelium density?of AMF in Chinese fir forests at different elevations increased with altitude.Compared with Chinese fir continuous plantation,soil physical and chemical properties also had a more obvious effect on AMF.In addition,the soil environmental factors affecting AMF in Chinese fir forests at different elevations were more complex.SOC,moisture content,DOC,TN,MBC,NO₃^--N and pH all affect AMF to some extent.3.By comparing the control variables of"different tree ages at the same altitude"and"different elevations at the same tree age"in the 200b m plot of the Ancaoxia and the three elevation gradients of Wuyi Mountain,it was found that the age of the tree has little effect on the growth of AMF,and the difference in altitude was the main cause of AMF change.4.The changes between the internal mechanisms of AMF are not consistent,in which the infection rate was negatively correlated with other AMF structures in both continuous cropping and altitude studies,while changes among the latter were consistent.Overall,the main factors influencing the AMF change of Chinese fir were the contents of MBC,DOC and SOC in the soil.The results indicated that the soil volatile carbon and organic carbon were the key factors to regulate AMF in Chinese fir forest.Therefore,to some extent,improving the effectiveness of soil active carbon and the mutually beneficial relationship between AMF and soil microorganisms is the most important way to improve the productivity of Chinese fir plantation...