Grassland Vegetation Changes and Nocturnal Global Warming

Global minimum temperatures ( T MIN ) are increasing faster than maximum temperatures, but the ecological consequences of this are largely unexplored. Long-term data sets from the shortgrass steppe were used to identify correlations between T MIN and several vegetation variables. This ecosystem is potentially 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 system more vulnerable to invasion by exotic species and less tolerant of drought and grazing.