Abstract Detail

Recent Topics Posters

Giddens, Jon [1], McCarthy, Heather [2].

Where does the water come from?  A tree's perspective on water sourcing using Eastern redcedar (Cupressaceae: Juniperus virginiana) across Oklahoma’s precipitation gradient.

Evapotranspiration (ET) is the largest component in the water budget in semiarid regions, accounting for ~90% of the total ecosystem water flux and playing a key role in understanding the effects of other hydrological components, such as streamflow and aquifer recharge (Villegas et al. 2010).  ET rates have been shown to be highly impacted in areas of woody encroachment as grasslands are converted to woodlands (Huxman et al. 2005).  Understanding the impacts ET, and the movement of water in plants and soil specifically, is crucial to understanding the full impact of woody encroachment by Juniperus virginiana (ERC) on the water budget.  In this study, I use stable oxygen and hydrogen isotopes to determine the primary water source for ERC individuals across a precipitation gradient in Oklahoma to examine differences in rooting strategies under different, naturally occurring water stress conditions.  I hypothesized that individuals located in the western site (DC WMA) would utilize a deeper rooting strategy, thus reflecting more ground water as a primary water source for individuals relative to individuals located in the central (KAEFS) and southeastern Oklahoma sites (BR WMA).  12 individuals located in three transects per site were sampled.  Additionally, for each site I sampled and analyzed the isotopic ratios of ẟ D and ẟ¹⁸O present in stem, soil, precipitation, surface, and ground water sources in order to distinguish the isotopic signatures in each.  Although each site was sampled once per season, only the data for the summer and winter samples have been fully processed and are presented here.  Contrary to my hypothesis, the summer samples from DC WMA indicate a shallow soil water source in almost all sampled individuals; while individuals sampled at KAEFS and the BR WMA seem to reflect water being withdrawn from deeper soils, with few individuals utilizing ground water and possibly surface water.  However, the results from the winter samples indicate a higher dependence on deeper soil water and ground water sources in all sites suggesting that total soil water availability may be the major determining factor for plant water sourcing.  These data suggest that with decreasing soil water availability in a semi-arid ecosystem, ERC individuals utilize a deeper rooting strategy to continue to thrive and expand while putting more pressures on the water budget, especially aquifer and stream water recharge.

1 - University of Oklahoma, Department of Microbiology and Plant Biology, 770 Van Vleet Oval, #144, Norman, OK, 73019, USA
2 - University of Oklahoma, Department of Microbiology and Plant Biology, 770 Van Vleet Oval, Norman, OK, 73019, USA

Keywords:
Juniperus
Isotopes
Oklahoma
water relations
Groundwater
Eastern redcedar.

Presentation Type: Recent Topics Poster
Session: P, Recent Topics Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM
Number: PRT030
Abstract ID:1223
Candidate for Awards:None