Relationships between ammonia-oxidizing communities, soil methane uptake and nitrous oxide fluxes in a subtropical plantation soil with nitrogen enrichment

Abstract

a b s t r a c tAmmonia-oxidizers play an essential role in nitrogen (N) transformation and nitrous oxide (N 2 O) emission in forest soils. It remains unclear if ammonia-oxidizers affect interaction between methane (CH 4 ) uptake and N 2 O emission. Our specific goal was to test the impacts of changes in ammoniaoxidizing communities elicited by N enrichment on soil CH 4 uptake and N 2 O emission. Based on a field experiment, two-forms (NH 4 Cl and NaNO 3 ) and two levels (40 and 120 kg N ha À1 yr À1 ) of N were applied in the subtropical plantation forest of southern China. Soil CH 4 and N 2 O fluxes, the abundance and structure of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities were measured using static chamber-gas chromatography, quantitative PCR (qPCR), and terminalrestriction fragment length polymorphism (T-RFLP). Nitrogen addition tended to inhibit soil CH 4 uptake, but significantly promoted soil N 2 O emission; moreover, these impacts were more significant with NH 4 þ À N than with NO 3 À À N addition. NH 4 Cl addition significantly changed ammonia-oxidizer abundance with an increase in AOA and a decrease in AOB. Nitrogen additions significantly decreased the relative abundance of 329 bp and 421 bp of archaeal amoA gene. Negative relationships occurred between soil CH 4 uptake and AOA abundance and between soil CH 4 uptake and AOA/AOB ratio; however, a positive relationship was found between soil N 2 O emission and AOA abundance. These results indicate that a shift in abundance and composition of ammonia-oxidizing communities is closely linked to changes in soil CH 4 uptake and N 2 O emission under N enrichment. Furthermore, AOA communities play a contrasting role from AOB communities for regulating the fluctuation between soil CH 4 and N 2 O fluxes.

Short-term effect of Eucalyptus plantations on soil microbial communities and soil-atmosphere methane and nitrous oxide exchange

“…The higher archaeal amoA gene copy number compared to bacterial amoA could be linked to the acidic soil pH (<4.5 in all treatments) 43 . This phenomenon has been widely observed in previous soil studies, and may be explained by the fact that NH 3 content is reduced at lower pH and ammonia-oxidizing Archaea have a higher affinity for NH 3 than ammonia-oxidizing bacteria 18 .…”

“…The absence of a correlation between levels of functional genes and gas fluxes is surprising because correlations between the nosZ , archaeal amoA , and bacterial amoA genes and N 2 O fluxes have previously been described in forest systems 16 – 18 . The quantification results for pmoA may explain CH 4 fluxes, as this gene has been shown to be positively correlated to CH 4 emissions from soil 17 .…”

“…Soil microbial processes are particularly impacted by land use practices, which can deregulate nutrient cycles and thereby increase or reduce GHG emissions 15 , 16 . Some studies have revealed a correlation between the abundance and/or expression of functional genes involved in N and C cycles and GHG fluxes in forest soils 16 – 18 . However, until now, no study has focused on the link between a microbial community and the GHG fluxes in the soil of Eucalyptus plantations.…”

Impacts of Nitrogen Addition on Nitrous Oxide Emission: Model-Data Comparison

“…However, these impacts were not reproduced by all of the six models except for the DELM and NOE 195 models. Previous study showed that the impacts of NH4 + addition on N2O emissions are, to some extent, larger compared with NO3 -addition (Wang et al, 2016). This is probably due to two primary reasons.…”

Differential Responses and Controls of Soil CO2 and N2O Fluxes to Experimental Warming and Nitrogen Fertilization in a Subalpine Coniferous Spruce (Picea asperata Mast.) Plantation Forest

“…Furthermore, soil microorganisms can be affected by multiply factors such as climate, soil physical, and chemical properties, and substrate quantity and quality [20,21]. Several studies reported that soil microbial community structure and diversity are strongly impacted by warming and N fertilization, and play an important role on controlling soil CO 2 and N 2 O fluxes [17,22,23]. However, convincing data about the direct link of soil GHG fluxes and soil microbial characteristics under warming and N fertilization are still scarce.…”