Barnyardgrass (Echinochloa crusgalli) emergence and growth in a changing climate in great plains wetlands

Projected twenty first century increases in temperature and precipitation intensity in the U.S. Great Plains may alter playa wetland hydroperiods. Our objective was to identify favorable germination conditions for a common moist-soil grass, Barnyardgrass (Echinochloa crusgalli L.), by evaluating emergence and growth response to various environmental conditions specific to the Northern (Nebraska) and Southern (Texas) range of playas. We used a temperature-controlled growth chamber experiment to evaluate emergence and growth response of Barnyardgrass to three main effects: (i) weekly temperatures representing historical and future conditions under a moderate emissions scenario, (ii) dry, moist, and saturated soil moisture conditions, and (iii) various seed bank densities. In Nebraska samples, projected future temperatures reduced emergence percentage by up to 20%, but increased emergence percentage by up to 15% for Texas samples. For Nebraska samples, plants were 9.6 cm taller under field capacity moisture compared to saturated moisture. Texas plant height was driven by temperature, where historical conditions produced plants that were 13 cm shorter than future warm conditions. These effects may be exacerbated in natural settings over time and when inter-specific competition exists; thus, temperature, soil moisture, and seed bank densities may be important considerations when planning for playa management in future climate conditions.