Effect Of Simulated Climate Change On Field CH₄ Fluxes And Related Microbes In The Soil

Global climate change is a global concern,and is a topic of intense international research efforts in order to combat and adapt to climate change.Methane?CH₄?is one of the most important greenhouse gases.There are many sources of CH₄,including non-biological sources such as biomass burning,volcanic activity and biological sources mediated by microbes.The major sink of CH₄ includes photochemical oxidation by the hydroxyl radical in the atmosphere and biological oxidation by methanotrophs in soil.This study used two different soils,a forest red soil with little or no human influence and an intensively managed vegetable soil.In order to simulate projected global climate change scenarios,we established several small greenhouses in the field to produce warmer and drier conditions,where the temperature inside the greenhouses was 2-5? higher than outside and soil moisture content inside the greenhouses was 5-10%?WFPS?lower than outside.At the same time,we applied urea to some of the plots and organic fertilizer to some other plots.The whole experiment was divided into two phases.At the beginning of the second phase,some of the greenhouses in the first phase were removed to determine the changes in methane emissions and related microbes during the second phase.The above studies can reveal the changes of methane emissions and related microbes in the soil under the influence of simulated global climate change scenarios and different fertilization treatments.The results are as follows:The experiment of vegetable soil showed that soil moisture was the key factor influencing methane emissions in the vegetable soil.The results showed that the simulated warmer and drier conditions in the greenhouses significantly decreased CH₄ emissions largely due to the lower soil moisture content.For the same reason,CH₄ emissions of treatments in Phase I were much lower than that in the same treatments in Phase ?.The abundance of methanotrophs showed a more significant response than methanogens to the simulated climate change scenarios,increasing under simulated drier conditions.Methanogenic community abundance remained low,except where manure was applied which provided a source of organic C that stimulated methanogen growth.Soil moisture content was a major driver for methanotroph abundance and strongly affected CH₄ emissions.The application of N source decreased CH₄ emissions probably due to stimulated methanotroph activity.Soil acidity was found to be a key factor to limit methane emissions in the red soil.Compared with the experiment of the vegetable soil,methane emissions and the abundance of methanogens and methanotrophs in the red soil were much lower than those in the vegetable soil.