The Dynamics Of Microbial Community During The Decomposition Of Litter Mixed Eucalyptus Grandis With Alnus Formosana

Litter decomposition is the most important process in material cycling. Microorganism is the main decomposer during litter decomposition. It is assumed that the mixed littler decomposition could show higher decomposition rate compared with the decomposition of signal species because of the increase of microbial diversity. However, the previous results were confused, and the relative process was unclear. Therefore, Eucalyptus grandis plantation was selected for its rapid development and large area. Litterbag method was used to study the microbial biomass and bacterial community during leaf-litter decomposition mixed Eucalyptus grandis and Alnus formosana with different mixed proportion (10:0(Ⅰ),7:3(Ⅱ),5:5(Ⅲ),3:7(Ⅳ) and 0:10(Ⅴ)). The results could be expected to provide scientific data for the construction of Eucalyptus grandis plantation. The results are followed:There were significantly variations in Microbial biomass carbon (MBC) and nitrogen (MBN) during the decomposition of mixed little with different mixed proportions. Three Mixed (Ⅱ,Ⅲ,Ⅳ) microbial biomass carbon (MBC) and nitrogen (MBN) significantly higher than two single (Ⅰ,Ⅴ). Microbial biomass carbon (MBC) and nitrogen (MBN) ofⅡisⅠ2.3 times andⅤ1.8 times. Therefore, different proportional mixed Eucalyptus grandis with Alnus formosana had significant effects on the activity of microorganism. Microbial biomass carbon (MBC) and nitrogen (MBN) is the largest from August to October. However, different proportional mixed Eucalyptus grandis with Alnus formosana had fewer effects on MBP.Significant change in DGGE bands of bacteria were observed in five treatments.Ⅱis significantly higher thanⅠandⅤ. It is I 1.4 times andⅤ1.5 times. This result indicated that different proportional mixed Eucalyptus grandis with Alnus formosana had effects on bacterial amount. Shannon-Wiener index (H), evenness (EH), Simpson dominance index (C) also have a similar trend. Compared withⅠand V, Bacteria Wiener index and Shannon-bacteria evenness (EH) index ofⅢincreased significantly, while Simpson dominance index showed down.Differences of bacteria community composition were also observed in five treatments (varied from 7% to 80%). There is a considerable difference exists from three hybrid treatment to two single treatments. This shows that different litter mixed-mode has a significant effect on the community structure.Generally, litter different mixed treatment has an important influence on litter microbial biomass and bacterial community structure. Different mixed Eucalyptus grandis with Alnus formosana changed litter materials preparation, ventilation properties, moisture content, temperature change rate, affect litter microbial biomass and bacterial community structure. Accordingly, the changes of mixed Eucalyptus grandis with Alnus formosana could be beneficial to understanding the processes of Eucalyptus grandis artificially mixed forests. These results indicate that different mixed Eucalyptus grandis with Alnus formosana can increase the microbial community diversity, improve their litter decomposition process. The results suggested that the litter mixed Eucalyptus grandis with Alnus formosana could improve the microbial biomass and microbial activity during litter decomposition. According to the results from litter decomposition, the plantation mixed Eucalyptus grandis with Alnus formosana could be the potential reasonable modification.