Altering rainfall amount and pattern affects above- and belowground productivity differently among three US grassland types
Results/Conclusions: ANPP was significantly increased by water addition in the shortgrass steppe and tallgrass prairie while only in the shortgrass steppe did precipitation pattern matter – the FL treatment increased productivity relative to ambient plots, but the MS treatment did not. Similarly, BNPP responses to rainfall amount also occurred in both shortgrass steppe and tallgrass prairie. Here, the MS treatment increased BNPP only in the shortgrass steppe whereas the FL treatment increased production only in tallgrass prairie relative to ambient. Total productivity (ANPP + BNPP) responded to precipitation amount in both shortgrass steppe and tallgrass prairie, with neither pattern of addition having an effect on total productivity. In contrast to these two C4 dominated grasslands, the C3 dominated northern mixed grass prairie did not respond to precipitation amount or pattern in either year. This suggests that the cooler northern mixed grass prairie may rely more on non-growing season precipitation inputs and thus that there is substantial variability in central US grassland sensitivity to forecast changes in precipitation regimes.