Get reliable science

Poa pratensis is ubiquitous in native prairie remnants of the Midwest and eastern Great Plains.   At Nine-Mile Prairie in eastern Nebraska, the high frequency of Poa in native prairie quadrats has changed little from 1928 to 2012. Extensive studies at the Cedar Creek Long Term Ecological Research site in east-central Minnesota examined Poa along with more than 30 other grasses and forbs.  Measurements included above- and belowground physiological and morphological traits, as well as soil mineral nitrogen (N) depletion and net nitrogen mineralization.  Relative to dominant C4 grasses, Poa has high tissue N concentrations, high tissue turnover and decomposition rates, and the potential to accelerate soil N cycling.  However, when placed with other grasses and forbs on a multivariate axis representing nitrogen use, Poa takes an intermediate position.  Poa responds well to N enrichment, yet persists better than most “high N” forage grasses under infertile conditions. Simulations for Cedar Creek and Nine-Mile Prairie with the ecosystem model CENTURY suggest that the impact of Poa on soil carbon and nitrogen pools is relatively neutral.  This contrasts with invasive C3 grasses (e.g. Bromus inermis or Agropyron repens) that decrease soil C and N in the long-term, or tall C4 grasses that increase them.