Grassland species root response to drought: consequences for soil carbon and nitrogen availability

• Published in: Plant and soil 2016-12, Vol.409 (1/2), p.297-312
• Main Authors: de Vries, Franciska T., Brown, Caley, Stevens, Carly J.
• Format: Article
• Language: English
• Subjects: Aboveground biomass; Bioavailability; Biomass; Biomedical and Life Sciences; Carbon content; Climate change; Dissolved organic carbon; Drought; Droughts; Ecology; Environmental aspects; Grassland soils; Grasslands; Life Sciences; Nitrogen content; Observations; Phenotypic traits; Plant biology; Plant Physiology; Plant roots; Plant Sciences; Plant tissues; Plant-soil relationships; Plants; Regular Article; Root biomass; Roots; Soil microorganisms; Soil plant interactions; Soil resources; Soil Science & Conservation; Soils; Stress response
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-016-2964-4

Background and Aims Root traits are increasingly used to predict how plants modify soil processes. Here, we assessed how drought-induced changes in root systems of four common grassland species affected C and N availability in soil. We hypothesized that drought would promote resource-conservative root traits such as high root tissue density (RTD) and low specific root length (SRL), and that these changes would result in higher soil N availability through decreased root N uptake, but lower C availability through reduced root exudation. Methods We subjected individual plants to drought under controlled conditions, and compared the response of their root biomass, root traits, and soil C and N availability, to control individuals. Results Drought affected most root traits through reducing root biomass. Only SRL and RTD displayed plasticity; drought reduced SRL, and increased RTD in small plants but decreased RTD in larger plants. Reduced root biomass and a shift towards more resource-conservative root traits increased soil inorganic N availability but did not directly affect soil C availability. Conclusions These findings identify mechanisms through which drought-induced changes in root systems affect soil C and N availability, and contribute to our understanding of how root traits modify soil processes in a changing world.