Microbial CO2production, CH4dynamics and nitrogen in a wetland soil (New York State, USA) associated with three plant species (Typha,Lythrum,Phalaris)

Abstract

SummaryPlants furnish soil with organic carbon (OC) compounds that fuel soil microorganisms, but whether individual plant species – or plants with unique traits – do so uniquely is uncertain. We evaluated soil microbial processes within a wetland in which areas dominated by a distinct plant species (cattail –Typhasp.; purple loosestrife –Lythrum salicariaL.; reed canarygrass –Phalaris arundinaceaL.) co‐mingled. We also established an experimental plot with plant shoot removal. ThePhalarisarea had more acidic soil pH (7.08 vs. 7.27–7.57), greater amount of soil organic matter (19.0% vs. 9.0–11.5%), and the slowest production rates of CO2(0.10 vs. 0.21–0.46 μmol kg−1 s−1) and CH4(0.040 vs. 0.054–0.079 nmol kg−1 s−1). Nitrogen cycling was dominated by net nitrification, with similar rates (17.2–18.9 mg kg−114 days−1) among the four sampling areas. In the second part of the study, we emplaced soil cores that either allowed root in‐growth or excluded roots to evaluate how roots directly affect soil CO2and CH4. The three plant species had similar amounts of root growth (ca 290 g m−2 year−1). Fungal biomass was similar in soils with root in‐growth versus root exclusion, regardless of dominant plant species. Rates of soil CO2production did not differ with root in‐growth versus root exclusion, and added glucose increased CO2production rates by only 35%. Root in‐growth did lead to greater rates of CH4production; albeit, addition of glucose had much greater effect on CH4production (1.24 nmol kg−1 s−1) compared with controls without added glucose (0.058 nmol kg−1 s−1). Our data revealed relatively few subtle differences in soil characteristics and processes associated with different plant species; albeit, roots had little effect, even inhibiting some microbial processes. This research highlights the need for both field and experimental studies in long‐established monocultures of plant species to understand the role of plant biodiversity in soil function.