Can plants stimulate soil microbes and their own nutrient supply? Evidence from a grazing tolerant grass

E. W. Hamilton, D. A. Frank

Research output: Contribution to journalArticlepeer-review

433 Scopus citations


The primary source of mineral nutrients for plants is the decomposition of organic matter by soil microbes. Plants are traditionally viewed as largely passive participants in the decomposition process, incapable of directly affecting rates of decomposition significantly and primarily assimilating nutrients unused by the microbial pool. We performed a 13C pulse-chase experiment on a common grazing tolerant grass, Poa pratensis L., of Yellowstone National Park, to follow carbon flow into the soil rhizosphere and microbial biomass and the associated effects on soil N availability and plant N dynamics. Grazing promoted root exudation of carbon, which was quickly assimilated into a burgeoning microbial population in the rhizosphere of clipped plants. Moreover, these facilitating effects of defoliation on rhizospheric processes positively fed back on soil inorganic N pools, plant N uptake, leaf N content, and photosynthesis. Such findings are the first evidence, to our knowledge, that suggest (1) plants are capable of promoting rhizospheric microbial populations to facilitate uptake of a limiting soil resource and (2) that there is a general positive feedback mechanism by which herbivory promotes plant regrowth as well as energy and nutrient flows in grazed landscapes.

Original languageEnglish (US)
Pages (from-to)2397-2402
Number of pages6
Issue number9
StatePublished - Jan 1 2001
Externally publishedYes


  • Grassland
  • Grazing
  • Herbivory
  • Microbe
  • Nitrogen
  • Poa pratensis
  • Yellowstone National Park

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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