Rapid Soil Moisture Recharge to Depth by Roots in a Stand of Artemisia Tridentata

Abstract

The temporal patterns of soil water potential in a stand of Artemisia tridentata in central Utah, USA, were monitored during the summer, which included small periodic rainfall events, and over the winter, when most of the soil recharge occurs in this environment. The pattern of recharge, when compared to an area cleared of aboveground vegetation, strongly indicated that the downward movement of water to 1.5 m was primarily conducted via roots by the process known as hydraulic redistribution. Rainwater was moved rapidly downward shortly after the rain event and continued over a period of a few days. For rainwater reaching a 0.3–1.5 m depth, the portion redistributed by roots was estimated to range from 100% for small rainfall events (<8 mm) to 74% for a 36‐mm event. Simulations with a model of soil water movement that compared situations with and without hydraulic redistribution by roots, indicated that during the fall–spring recharge period, 67% of all water moved downward below 0.1 m was via roots, while 87% of the water moved below 0.3 m was via roots. These results indicate that rapid downward movement of rainwater by roots can be a significant mechanism of soil water recharge to depth in arid and semiarid ecosystems. Corresponding Editor: F. C. Meinzer

Root functioning modifies seasonal climate

“…However, the amount of deep roots in those regions would be very small because we followed the observed root distribution so that this effect would be minimal. For the HR run, we assumed that upward HR during the dry season brings water to only within 4 cm of the surface, because many superficially shallow (0-5 cm deep) roots die in very dry soils (29,30). Water drawn up by upward HR is therefore not available for soil evaporation in the HR run; however, soil water coming directly from rain will be continuously evaporated.…”

Fine root distribution and persistence under field conditions of three co‐occurring Great Basin species of different life form

“…3). Artemisia continues to extract water during the summer and can draw soil moisture potentials down to −5 MPa (DeLucia & Heckathorn, 1989;Ryel et al, 2003) whereas Bromus is apparently unable to withdraw moisture below c. −1 MPa and then rapidly senesces when this threshold is reached in the upper soil layers in the late spring (Klemmedson & Smith, 1964;Rice et al, 1992). In turn, the fine roots of these three species experienced different water potentials during the late spring and summer, which may have a bearing on their residence times.…”

Progress and challenges in using stable isotopes to trace plant carbon and water relations across scales

“…Good examples are utilization of different water sources and redistribution (Caldwell et al, 1998;Ryel et al, 2003), which can in turn be linked to community composition , niche partitioning and spatial and temporal variations in plant distributions (e.g. Dawson et al, 2002;Snyder and Williams, 2000;Stratton et al, 2000;Drake and Franks, 2003;Rose et al, 2003;Grams and Matyssek, 2010).…”