The loss of biodiversity worldwide has prompted close investigation of the link between biodiversity and ecosystem services. However, few studies have explored this relationship outside of a controlled experiment. We examined the negative relationship between methane emission and diversity found in a previous study to see how applicable the experimental findings were to natural wetlands. The objective of this research was to investigate the link between plant community (composition and diversity) and key functions such as above- and belowground productivity and the ecosystem exchange of carbon dioxide and methane. Four wetland sites in central Ohio were divided into two communities represented by either a clonal dominant or non-clonal functional group. A minimum of 15 plots (0.25 m²) were selected to represent the plant diversity gradient from lowest to highest in each community including reference plots without vegetation. The Shannon diversity index, H’, was used as a measure of diversity. Gas samples were collected over a 15 minute period using a static chamber method and analyzed for methane and carbon dioxide concentrations with a gas chromatograph. We took above- and belowground biomass samples (0-10 cm and 10-30 cm depths) following gas sampling.

Results/Conclusions

Aboveground biomass was significantly higher in the clonal community (F_{4, 115} = 21.96, P < 0.001). In contrast, belowground biomass at both depths was significantly higher in the non-clonal community (F_{4, 115} = 6.14, P < 0.001 and F_{4, 113} = 20.24, P < 0.001). As for the effects of diversity, there was a negative relationship between aboveground biomass and H’ (F_{1, 118} = 28.55, P < 0.001). There was no relationship between belowground biomass and H’. Methane emission was significantly higher in the clonal community (F_{4, 118} = 6.36, P < 0.001). However, diversity showed no effect on methane emission. No effects of community composition or diversity on the ecosystem exchange of carbon dioxide were found either. As expected methane emission was positively correlated with water depth (F_{1, 121} = 43.14, P < 0.001), whereas it was negatively correlated with belowground biomass (F_{1, 121} = 15.45, P < 0.001). Differences in carbon cycling were found between the plant communities, except for carbon dioxide, indicating that plant community does matter in terms of carbon cycling in a non-experimental setting. Diversity didn't show as strong of an effect; however it may determine patterns of aboveground biomass in wetlands, especially in highly productive clonal dominant communities.