Experiments conducted in wet-meadows in northeastern Alberta, Canada, tested hypotheses about species response to environmental changes expected during global warming. We hypothesized that (i) a lower water table would decrease abundance of the dominant mesophytic species (Calamagrostis canadensis) and increase abundance of xerophytic plant species; (ii) increased fire severity would increase the magnitude of change in species abundance; and (iii) Eurasian xerophytic species would increase in abundance more than native xerophytic species after treatment. Additional experiments test hypotheses that (i) the dominant species would show lower emergence and xerophytic species would show greater emergence at high than at low temperature, and (ii) that Eurasian xerophytic species would show greater emergence than native xerophytic species at high temperature. Experiments suggest that during climate change Calamagrostis Canadensis, the native graminoid species currently dominating boreal wet-meadows, would decrease abundance because of: (i) reduced growth (18 cm shorter, p>0.05, n=5 for all comparisons) caused by lower water tables; (ii) reduced regrowth (11 cm shorter), and 73% lower density after severe fire; and (iii) 30% lower seedling emergence from warmer soils. In contrast, Eurasian xerophytic weedy dicotyledons would increase abundance because of: (i) 500% higher density and cover caused by lower water table; (ii) 80% higher density and 10-20% higher cover after fire; and (iii) 300% higher seedling emergence from warmer soils. Eurasian dicotyledon density was 30-80% higher and cover was 240-320% higher than that of native dicotyledons after similar treatments. Observations suggest that Eurasian weeds will become more abundant during climate change because they are already widespread and often occupy drier parts of disturbed areas in the north; have widely dispersed propagules; show vigorous and rapid growth; and persist in areas long after the disturbance. It is hypothesized that flooding will become less frequent in boreal wet-meadows because of predicted reductions in stream flow and lake water levels. Fire is hypothesized to become more frequent, intense, and severe, and thus replace flooding as the major force affecting vegetation dynamics. We hypothesize that during climate change Eurasian weedy species will dominate boreal wet-meadows for 20 years or more after severe fires.