Research of methane metabolic microbial community in soils of slash pine plantation and Masson pine plantation

Methane is the second most abundant greenhouse gas in the atmosphere.Methane metabolic microbial community in soil affect the production and oxidation of methane.Land use type significantly influence methane release from soil and methane metabolic microorganisms.China has the biggest plantation area in the world.In central and Southern China,Masson pine(Pinus massoniana) and slash pine(Pinus elliottii) plantations account for 59% of the forested areas.What effect of plantation,especially the introduced slash pine plantation,on methane metabolic microbial community deserves much concern.While little has been researched about effects of forest type on methane metabolism community in soil.Molecular technique is a good way to reveal the community of methane metabolic microorganisms.Functional gene microarray is quantitative and it can link structure to function of soil microbial community.Thus it is a good way to reveal the soil microbial community involved in methane metabolism.Using the third generation functional gene microarray(GeoChip 3.0),this research studied structure of methane metabolic soil microbial community in Masson pine and slash pine plantations in red soil.For each type of forest plantation,we randomly selected 5 plots on independent stands in Yanshan District and Lingui County located in Guilin city in Guangxi Province,Southern China.In each plot,three subsamples within the area of 10 m × 10 m were randomly chosen.For each subsample,five 0 to 10 cm depth soil cores were extracted using a 3.5 cm diameter auger and were composite into one subsample. The results showed that,(1) there was no significant difference among forest types in the normalized signal intensity or diversity of either the whole methane metabolic microbial community,methanogenus or methanotrophs. (2) there was significant difference in methane metabolized microbial community(P=0.007). Forest type explained 34.9% variation of soil methane metabolic microbial community. (3) there was significant difference in methanogenus(microorganisms include pmoA genes) community(P=0.015),forest type explained 45.5% variation of methanogenus community in soil.The dominant species of methanogenus differed between forest types.The dominant species of methanogenus in the slash pine plantations was Methanocorpusculum labreanum Z.While the dominant species in the Masson pine plantations also included uncultured methanogenic archaeon and Methanosarcina mazei Gol in addition to Methanocorpusculum labreanum Z. (4) There was also a strong trend that Masson pine plantation and slash pine plantation differed in methanotrophs(microorganisms include pmoA genes)(P=0.068). Among methanotrophs,4 genes from uncultured bacteria were only found in the slash pine plantation,which could not be found in the Masson pine plantation. (5) The signal intensity or gene number of mcrA genes family was positively correlated with soil bulk density,and negatively correlated with soil clay content.The signal intensity or Shannon-Wiener diversity of pmoA genes family was positively correlated with content of total carbon,total phosphorus and available nitrogen content in soil. Thus,compared with the native Masson plantations,the introduced slash pine plantations had significantly changed the original methane metabolism community structure.