Human activities have resulted in increased nitrogen deposition and atmospheric CO2 concentrations in the biosphere, potentially causing significant changes in many ecological processes. In addition to these ongoing perturbations of the abiotic environment, human-induced losses of biodiversity are also of major concern and may interact in important ways with biogeochemical perturbations to affect ecosystem structure and function. We have evaluated the effects of these perturbations on plant biomass stoichiometric composition (C:N:P ratios) within the framework of the BioCON experimental setup (biodiversity, CO2, N) conducted at the Cedar Creek Natural History Area, Minnesota. Here we present data for five plant species: Solidago rigida, Achillea millefolium, Amorpha canescens, Lespedeza capitata, and Lupinus perennis. We found significantly higher C:N and C:P ratios under elevated CO2 treatments, but species responded idiosyncratically to the treatment. Nitrogen addition decreased C:N ratios, but this response was greater in the ambient CO2 treatments than under elevated CO2. Higher plant species diversity generally lowered both C:N and C:P ratios. Importantly, increased diversity also led to a more modest increase in the C:N ratio with elevated CO2 levels. In addition, legumes exhibited lower C:N and higher C:P and N:P ratios than non-legumes, highlighting the effect of physiological characteristics defining plant functional types. These data suggest that atmospheric CO2 levels, N availability, and plant species diversity interact to affect both aboveground and belowground processes by altering plant elemental composition.
Bibliographical noteFunding Information:
by the US National Science Foundation (IRCEB program, DEB-9977047; LTER program, DEB-0080382; Biocomplexity program; DEB-0322057) and the U.S. Department of Energy (FG02-96ER62291). Special thanks are extended to the following individuals who have helped on this project: William Fagan, John Sabo, David Lewis, Dan Hernandez, and Megan Ogdahl. The experiments conducted in this project comply with the current laws of the United States.
- Ecological stoichiometry
- Elevated CO
- Nitrogen enrichment
- Species richness