Elevated atmospheric CO2 impact on carbon and nitrogen transformations and microbial community in replicated wetland

Abstract

Abstract Background Elevated atmospheric CO2 has direct and indirect influences on ecosystem processes. The impact of elevated atmospheric CO2 concentration on carbon and nitrogen transformations, together with the microbial community, was evaluated with water hyacinth (Eichhornia crassipes) in an open-top chamber replicated wetland. The responses of nitrogen and carbon pools in water and wetland soil, and microbial community abundance were studied under ambient CO2 and elevated CO2 (ambient + 200 μL L−1). Results Total biomass for the whole plant under elevated CO2 increased by an average of 8% (p = 0.022). Wetlands, with water hyacinth, showed a significant increase in total carbon and total organic carbon in water by 7% (p = 0.001) and 21% (p = 0.001), respectively, under elevated CO2 compared to that of ambient CO2. Increase in dissolved carbon in water correlates with the presence of wetland plants since the water hyacinth can directly exchange CO2 from the atmosphere to water by the upper epidermis of leaves. Also, the enrichment CO2 showed an increase in total carbon and total organic carbon concentration in wetland soil by 3% (p = 0.344) and 6% (p = 0.008), respectively. The total nitrogen content in water increased by 26% (p = 0.0001), while total nitrogen in wetland soil pool under CO2 enrichment decreased by 9% (p = 0.011) due to increased soil microbial community abundance, extracted by phospholipid fatty acids, which was 25% larger in amount than that of the ambient treatment. Conclusion The study revealed that the elevated CO2 would affect the carbon and nitrogen transformations in wetland plant, water, and soil pool and increase soil microbial community abundance.