Daniel Auerbach
Jonathan M. Friedman
Gregor T. Auble
Patrick B. Shafroth
Michael Merigliano
Michael L. Scott
N. Leroy Poff
Ryan McShane
2015
<p><span>Management of riparian plant invasions across the landscape requires understanding the combined influence of climate, hydrology, geologic constraints and patterns of introduction. We measured abundance of nine riparian woody taxa at 456 stream gages across the western USA. We constructed conditional inference recursive binary partitioning models to discriminate the influence of eleven environmental variables on plant occurrence and abundance, focusing on the two most abundant non-native taxa, </span><i>Tamarix</i><span> spp. and </span><i>Elaeagnus angustifolia</i><span>, and their native competitor </span><i>Populus deltoides</i><span>. River reaches in this study were distributed along a composite gradient from cooler, wetter higher-elevation reaches with higher stream power and earlier snowmelt flood peaks to warmer, drier lower-elevation reaches with lower power and later peaks. Plant distributions were strongly related to climate, hydrologic and geomorphic factors, and introduction history. The strongest associations were with temperature and then precipitation. Among hydrologic and geomorphic variables, stream power, peak flow timing and 10-yr flood magnitude had stronger associations than did peak flow predictability, low-flow magnitude, mean annual flow and channel confinement. Nearby intentional planting of </span><i>Elaeagnus</i><span> was the best predictor of its occurrence, but planting of </span><i>Tamarix</i><span> was rare. Higher temperatures were associated with greater abundance of </span><i>Tamarix</i><span> relative to </span><i>P. deltoides</i><span>, and greater abundance of </span><i>P. deltoides</i><span> relative to</span><i>Elaeagnus. Populus deltoides</i><span> abundance was more strongly related to peak flow timing than was that of </span><i>Elaeagnus</i><span> or </span><i>Tamarix</i><span>. Higher stream power and larger 10-yr floods were associated with greater abundance of </span><i>P. deltoides</i><span> and </span><i>Tamarix</i><span> relative to </span><i>Elaeagnus</i><span>. Therefore, increases in temperature could increase abundance of </span><i>Tamarix</i><span> and decrease that of </span><i>Elaeagnus</i><span> relative to </span><i>P. deltoides</i><span>, changes in peak flow timing caused by climate change or dam operations could increase abundance of both invasive taxa, and dam-induced reductions in flood peaks could increase abundance of </span><i>Elaeagnus</i><span> relative to </span><i>Tamarix</i><span> and </span><i>P. deltoides</i><span>.</span></p>
application/pdf
10.1111/ecog.01285
en
Wiley-Blackwell Publishing, Inc.
Distribution of invasive and native riparian woody plants across the western USA in relation to climate, river flow, floodplain geometry and patterns of introduction
article