Emergence and establishment of Agropyron desertorum (Fisch.) (Crested Wheatgrass) seedlings in a sandhills prairie of central Saskatchewan

Agropyron desertorum (Fisch.) (crested wheatgrass), a non-native, perennial bunchgrass is invasive in native prairie on the Northern Great Plains. The objectives of this study were to: (1) determine the effects of manipulating precipitation and seedbeds on seedling emergence and establishment, and (2) determine safe sites for seedling emergence and establishment of Agropyron desertorum in a sandhills prairie of central Saskatchewan. Compared to the 60 seedlings m(-2) emerging in the control, irrigation had no effect on seedling emergence (80 seedlings m(-2)), but fewer seedlings (15 m(-2)) (P=0.01) emerged in the reduced precipitation treatment. Seedling emergence and establishment varied among seedbeds (P<0.01) with seedling densities about an order of magnitude greater in the tillage treatment than in the control, seedbeds to which 60 kg ha(-1) of nitrogen was added, and seedbeds where clubmoss (Selaginella densa Rydb.) was removed. The density of Agropyron desertorum seedlings emerging was positively correlated with soil water in all seedbeds. More Agropyron desertorum seedlings emerged and established (P<0.05) in bare soil than expected while the number of seedlings emerging and establishing in live clubmoss, dead clubmoss, or under litter was less than the expected. Agropyron desertorum can emerge and establish over a wide range of soil water in all of the seedbeds examined in this study, but disturbed sites with bare, exposed mineral soil are most likely to be invaded by the grass.