Files
Abstract
Understory plants can take up water lifted by trees, but the effects of hydraulic lift on these plants remain unknown. The objective of this study was to determine how hydraulic lift affects the physiology and growth of understory plants in longleaf pine sandhills. We measured soil moisture, and compared water potentials, gas exchange, and growth across four understory species in root exclusion and control plots. We did not find evidence of hydraulic lift during an unusually wet year. Soil moisture, physiological measurements, and growth either did not differ between treatments, or were greater in root exclusion plots, against expectations. Competition for water may therefore dominate overstory - understory interactions during wetter periods. Physiological parameters were correlated with soil moisture, suggesting that water does indeed limit plant functioning and productivity in these systems. The four species differed in their water usage over the growing season.