Microbial CO production, CH dynamics and nitrogen in a wetland soil (New York State, USA) associated with three plant species (Typha, Lythrum, Phalaris)

摘要

Plants 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 -Typha sp.; purple loosestrife -Lythrum salicaria L.; reed canarygrass -Phalaris arundinacea L.) co-mingled. We also established an experimental plot with plant shoot removal. The Phalaris area 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 CO (0.10 vs. 0.21-0.46 omol kgp# sp#) and CH (0.040 vs. 0.054-0.079 nmol kgp# sp#). Nitrogen cycling was dominated by net nitrification, with similar rates (17.2-18.9 mg kgp# 14 daysp#) 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 CO and CH. The three plant species had similar amounts of root growth (ca 290 g mpo yearp#). Fungal biomass was similar in soils with root in-growth versus root exclusion, regardless of dominant plant species. Rates of soil CO production did not differ with root in-growth versus root exclusion, and added glucose increased CO production rates by only 35%. Root in-growth did lead to greater rates of CH production; albeit, addition of glucose had much greater effect on CH production (1.24 nmol kgp# sp#) compared with controls without added glucose (0.058 nmol kgp# sp#). 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.