Effects Of Forest Management Measures On Soil Fertility And Microbial Communities Of Mixed Eucalyptus ×Parashorea Chinensis Plantations

In recent years,Eucalyptus has become the fastest growing and most planted tree species in south of China.As a short-cycle industrial plantation,eucalyptus plantations have made great contributions to China's timber production and strategic reserves.However,with the promotion of large-scale planting of eucalyptus,the ecological environment of eucalyptus plantations has attracted widespread attention from all walks of life,In particular,the issue of biodiversity security and the quality of water and fertilizer in forest lands has caused fierce disputes,it has become a hot topic in academia.we set up two different forest land cleaning modes(non-burning and controlled burning)and five pattern included control(CK),compound fertilizer application(H),compound fertilizer and charcoal application(HC),compound fertilizer and nitrogen application(HN),compound fertilizer and green fertilizer(HGF)in Eucalyptus×Parashorea chinensis Wang Hsie plantation.My study uses conventional methods and PLFA technology Aim to study the effects of different fertilization methods and different forest land cleaning modes.The conclusions are as follow:(1)In the forest land cleaning modes of non-burning,the contents of soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP),and total potassium(TK)were significantly higher than the forest of controlled burning.The contents of SOC decreased by 15.7%,6.8%,and 23.8%in the soil layers of 0?10cm,10?20cm,and 20?40cm.The contents of TN decreased by 19.4%and 9.2%in the soil layers of 0?10cm and 10?20cm.The contents of TP and TK in soil has also declined due to controlled burning.(2)Both of non-burning and controlled burning,the different fertilization measures have no significant effect on the soil fertility in soil layers of 20?60cm.The HC and HN treatments significantly increase the content of SOC,TN,AP,TK and AK.The HC treatment significantly increased the TP content,but the HN treatment significantly decreased soil TP content,in the soil of 0?10cm and 10?20cm has decreased 13.6%and 8.5%at controlled burning,4.9%and 19.4%at non-burning.In addition to reducing soil TP content,HGF treatment increased other soil fertility indicators.(3)Controlled burning significantly reduced the total PLFAs contents of soil microorganisms(13.0%),the species richness,diversity index and evenness index decreased by4.9%,9.8%and 0.4%.The contents of soil bacteria,G+ bacteria and G-bacteria decreased by 11.2%,23.8%,and 24.9%.Both of non-burning and controlled burning,the order of microbial species richness under different fertilization treatments was HC>H>HN>HGF>CK.In the five fertilization treatments,both HC and HGF treatments significantly increased the total PLFAs content of microorganisms;The HC treatment significantly increased the contents of soil bacteria and actinomycetes,and the bacteria/fungus and G+/G-were also significantly increased;The HN treatment significantly decreased the contents of soil fungi and G-bacteria,and significantly increased soil bacteria/fungi and G+/G-;The HGF treatment significantly increased the soil bacteria contents and also increased soil fungi and actinomycetes contents.(4)RDA analysis showed that the bacterial groups and actinomycetes were positively correlated with SOC in the soil,while the fungal groups were negatively correlated with soil TN.PCA analysis shows that,both of non-burning and controlled burning,the structure of soil microbial community under H treatment and CK treatment is similar,The structure of soil microbial communities under HC and HGF treatments is similar,the soil microbial structure of HN is different from the treatments of H,CK,HC,and HGF.