The effects of riparian restoration following saltcedar (Tamarix spp.) biocontrol on habitat and herpetofauna along a desert stream

Abstract

Amphibians and reptiles (herpetofauna) have been linked to specific microhabitat characteristics, microclimates, and water resources in riparian forests. Our objective was to relate variation in herpetofauna abundance to changes in habitat caused by a beetle used for Tamarix biocontrol (Diorhabda carinulata; Coleoptera: Chrysomelidae) and riparian restoration. During 2013 and 2014, we measured vegetation and monitored herpetofauna via trapping and visual encounter surveys (VES) at locations affected by biocontrol along the Virgin River in the Mojave Desert of the southwestern United States. Twenty‐one sites were divided into four riparian stand types based on density and percent cover of dominant trees (Tamarix, Prosopis, Populus, and Salix) and presence or absence of restoration. Restoration activities consisted of mechanically removing non‐native trees, transplanting native trees, and restoring hydrologic flows. Restored sites had three times more total lizard and eight times more yellow‐backed spiny lizard (Sceloporus uniformis) captures than other stand types. Woodhouse's toad (Anaxyrus woodhousii) captures were greatest in unrestored and restored Tam‐Pop/Sal sites. Results from VES indicated that herpetofauna abundance was greatest in the restored Tam‐Pop/Sal site compared with the adjacent unrestored Tam‐Pop/Sal site. Tam sites were characterized by having high Tamarix cover, percent canopy cover, and shade. Restored Tam‐Pop/Sal sites were most similar in habitat to Tam‐Pop/Sal sites. Two species of herpetofauna (spiny lizard and toad) were found to prefer habitat components characteristic of restored Tam‐Pop/Sal sites. Restored sites likely supported higher abundances of these species because restoration activities reduced canopy cover, increased native tree density, and restored surface water.

Northern tamarisk beetle (Diorhabda carinulata) and tamarisk (Tamarix spp.) interactions in the Colorado River basin

“…On the Lower Virgin River habitat structure was altered by defoliation in monotypic tamarisk stands. Amount of bare ground increased from 9–10% during predefoliation (Bateman & Ostoja ), to 23% during postdefoliation conditions (Mosher & Bateman ). Canopy cover was reduced from 82% predefoliation to 72% postdefoliation.…”

“…Sites on the Lower, Middle, and Upper Dolores River, the Colorado River near Moab, the San Juan River, and tributary streams have been monitored through annual summer field surveys since 2008 (van Riper unpublished data; Jamison et al ; Nagler et al ). Sites on the Virgin River have been monitored since 2009 (Bateman et al ; Bateman & Ostoja ; Nagler et al ; Mosher & Bateman ). Other sites have been surveyed from 2007–2015 by the Tamarisk Coalition and reported in presence‐absence maps (Tamarisk Coalition ).…”

“…The study area stretched for about 50 km. Beetles were monitored in pitfall traps associated with a large research effort to monitor herpetofauna, habitat, and ground arthropods (Bateman et al ; Mosher & Bateman ). Pitfall traps were 19‐L buckets installed at ground level.…”

Influence of seasonality and gestation on habitat selection by northern Mexican gartersnakes (Thamnophis eques megalops)

“…We measured habitat where we found gartersnakes through tracking and visual observations. Fourth-order habitat measurements included vegetative, environmental, and hydrologic characteristics ( Table 1 ) recorded at each snake point, in a 1-m-diameter plot, and along four 2.5-m transects sensu [ 10 , 39 , 55 , 56 ] ( Fig 2 ). At each snake point, we measured aspect and slope, water depth, distance to water, and canopy cover (>1m in height).…”

Threats to aquatic taxa in an arid landscape: Knowledge gaps and areas of understanding for amphibians of the American Southwest

“…Bullfrogs are well‐known invaders in the region and have been established for decades (Clarkson & DeVos, 1986), and their role as predators (Jennings & Hayes, 1994; Moyle, 1973), disease vectors (Schlaepfer, Sredl, Rosen, & Ryan, 2007), and competitors with local fauna (Bradford, Jaeger, & Shanahan, 2005) are recognized. Although bullfrogs dominated studies considering introduced species, other invasive taxa were also reported in the literature, including fish (Hossack et al, 2017; Maret et al, 2006; Reaser, 2001; Schalk, Montaña, Kralman, & Leavitt, 2018), crayfish (Witte, Sredl, Kane, & Hungerford, 2008), and plants (Mosher & Bateman, 2016; Tazik & Martin, 2002).…”