title: Rhizosphere stoichiometry: are C : N : P ratios of plants, soils, and enzymes conserved at the plant species-level?
abstract: As a consequence of the tight linkages among soils, plants and microbes inhabiting the rhizosphere, we hypothesized that soil nutrient and microbial stoichiometry would differ among plant species and be correlated within plant rhizospheres. We assessed plant tissue carbon (C) : nitrogen (N) : phosphorus (P) ratios for eight species representing four different plant functional groups in a semiarid grassland during near-peak biomass. Using intact plant species-specific rhizospheres, we examined soil C : N : P, microbial biomass C : N, and soil enzyme C : N : P nutrient acquisition activities. We found that few of the plant species' rhizospheres demonstrated distinct stoichiometric properties from other plant species and unvegetated soil. Plant tissue nutrient ratios and components of below-ground rhizosphere stoichiometry predominantly differed between the C4 plant species Buchloe dactyloides and the legume Astragalus laxmannii. The rhizospheres under the C4 grass B. dactyloides exhibited relatively higher microbial C and lower soil N, indicative of distinct soil organic matter (SOM) decomposition and nutrient mineralization activities. Assessing the ecological stoichiometry among plant species' rhizospheres is a high-resolution tool useful for linking plant community composition to below-ground soil microbial and nutrient characteristics. By identifying how rhizospheres differ among plant species, we can better assess how plant-microbial interactions associated with ecosystem-level processes may be influenced by plant community shifts.
authors.affiliation: Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80524-1499, USA.
authors.forename: Colin
authors.initials: C
authors.lastname: Bell
authors.affiliation: Department of Agriculture and Environment, University of Sydney, NSW, 2006, Australia.|Department of Botany and Program in Ecology, University of Wyoming, Laramie, WY, 82071-3165, USA.
authors.forename: Yolima
authors.initials: Y
authors.lastname: Carrillo
authors.affiliation: Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80524-1499, USA.
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Boot
authors.affiliation: Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80524-1499, USA.
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Rocca
authors.affiliation: Department of Botany and Program in Ecology, University of Wyoming, Laramie, WY, 82071-3165, USA.
authors.forename: Elise
authors.initials: E
authors.lastname: Pendall
authors.affiliation: Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80524-1499, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Wallenstein
mesh_terms: D018533:Biomass; D002244:Carbon / Q000032:analysis / Q000378:metabolism*; D006706:Homeostasis; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism*; D006109:Poaceae / Q000201:enzymology / Q000378:metabolism / Q000382:microbiology; D058441:Rhizosphere; D012988:Soil Microbiology; D013045:Species Specificity
chemical_list: D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen
keywords: ecological stoichiometry; extracellular enzymes; microbial biomass; plant species; rhizosphere; semiarid grassland; soil nutrients