Grassland vegetation changes and nocturnal global warming

Global minimum temperatures (T-MIN) are increasing faster than maximum temp eratures, but the ecological consequences of this are Largely unexplored. L ong-term data sets from the shortgrass steppe were used to identify correla tions between T-MIN and several vegetation variables. This ecosystem is pot entially sensitive to increases in T-MIN. Most notably, increased spring T- MIN was correlated with decreased net primary production by the dominant C- 4 grass (Bouteloua gracilis) and with increased abundance and production by exotic and native C-3 forbs. Reductions in B. gracilis may make this syste m more vulnerable to invasion by exotic species and less tolerant of drough t and grazing.