Matching Items (2)
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- All Subjects: Saltcedar
- Creators: Miller, William H.
Description
In riparian ecosystems, reptiles and amphibians are good indicators of environmental conditions. Herpetofauna have been linked to specific microhabitat characteristics, microclimates, and water resources in riparian forests. My objective was to relate herpetofauna abundance to changes in riparian habitat along the Virgin River caused by the Tamarix biological control agent, Diorhabda carinulata, and riparian restoration.
During 2013 and 2014, vegetation and herpetofauna were monitored at 21 riparian locations along the Virgin River via trapping and visual encounter surveys. Study sites were divided into four stand types based on density and percent cover of dominant trees (Tamarix, Prosopis, Populus, and Salix) and presence of restoration activities: Tam, Tam-Pros, Tam-Pop/Sal, and Restored Tam-Pop/Sal. Restoration activities consisted of mechanical removal of non-native trees, transplanting native trees, and introduction of water flow. All sites were affected by biological control. I predicted that herpetofauna abundance would vary between stand types and that herpetofauna abundance would be greatest in Restored Tam-Pop/Sal sites due to increased habitat openness and variation following restoration efforts.
Results from trapping indicated that Restored Tam-Pop/Sal sites had three times more total lizard and eight times more Sceloporus uniformis captures than other stand types. Anaxyrus woodhousii abundance was greatest in Tam-Pop/Sal and Restored Tam-Pop/Sal sites. Visual encounter surveys indicated that herpetofauna abundance was greatest in the Restored Tam-Pop/Sal site compared to the adjacent Unrestored Tam-Pop/Sal site. Habitat variables were reduced to six components using a principle component analysis and significant differences were detected among stand types. Restored Tam-Pop/Sal sites were most similar to Tam-Pop/Sal sites. S. uniformis were positively associated with large woody debris and high densities of Populus, Salix, and large diameter Prosopis.
Restored Tam-Pop/Sal sites likely supported higher abundances of herpetofauna, as these areas exhibited greater habitat heterogeneity. Restoration activities created a mosaic habitat by reducing canopy cover and increasing native tree density and surface water. Natural resource managers should consider implementing additional restoration efforts following biological control when attempting to restore riparian areas dominated by Tamarix and other non-native trees.
During 2013 and 2014, vegetation and herpetofauna were monitored at 21 riparian locations along the Virgin River via trapping and visual encounter surveys. Study sites were divided into four stand types based on density and percent cover of dominant trees (Tamarix, Prosopis, Populus, and Salix) and presence of restoration activities: Tam, Tam-Pros, Tam-Pop/Sal, and Restored Tam-Pop/Sal. Restoration activities consisted of mechanical removal of non-native trees, transplanting native trees, and introduction of water flow. All sites were affected by biological control. I predicted that herpetofauna abundance would vary between stand types and that herpetofauna abundance would be greatest in Restored Tam-Pop/Sal sites due to increased habitat openness and variation following restoration efforts.
Results from trapping indicated that Restored Tam-Pop/Sal sites had three times more total lizard and eight times more Sceloporus uniformis captures than other stand types. Anaxyrus woodhousii abundance was greatest in Tam-Pop/Sal and Restored Tam-Pop/Sal sites. Visual encounter surveys indicated that herpetofauna abundance was greatest in the Restored Tam-Pop/Sal site compared to the adjacent Unrestored Tam-Pop/Sal site. Habitat variables were reduced to six components using a principle component analysis and significant differences were detected among stand types. Restored Tam-Pop/Sal sites were most similar to Tam-Pop/Sal sites. S. uniformis were positively associated with large woody debris and high densities of Populus, Salix, and large diameter Prosopis.
Restored Tam-Pop/Sal sites likely supported higher abundances of herpetofauna, as these areas exhibited greater habitat heterogeneity. Restoration activities created a mosaic habitat by reducing canopy cover and increasing native tree density and surface water. Natural resource managers should consider implementing additional restoration efforts following biological control when attempting to restore riparian areas dominated by Tamarix and other non-native trees.
ContributorsMosher, Kent (Author) / Bateman, Heather L (Thesis advisor) / Stromberg, Juliet C. (Committee member) / Miller, William H. (Committee member) / Arizona State University (Publisher)
Created2014
Description
Non-native saltcedar (Tamarix spp.) has invaded many riparian communities and is the third most abundant tree in Southwestern riparian areas. I evaluated lizard populations and microhabitat selection during 2009 and 2010 along the Virgin River in Nevada and Arizona to determine the impact of saltcedar. Along the riparian corridor, I observed common side-blotched lizards (Uta stansburiana) within two vegetation types: monotypic non-native saltcedar stands or mixed stands of cottonwood (Populus fremontii), willow (Salix spp.), mesquite (Prosopis spp.) and saltcedar. I predicted that population parameters such as body condition, adult to hatchling ratio, abundance, and persistence would vary among vegetation types. Also, I predicted the presence of saltcedar influences how lizards utilize available habitat. Lizard population parameters were obtained from a mark-recapture study in which I captured 233 individual lizards. I examined habitat selection and habitat availability using visual encounter surveys (VES) for lizards and recorded 11 microhabitat variables where 16 lizards were found. I found no significant difference in population parameters between mixed and non-native saltcedar communities. However, population parameters were negatively correlated with canopy cover. I found that lizards selected habitat with low understory and canopy cover regardless of vegetation type. My results indicate that lizards utilize similar structural characteristics in both mixed and non-native vegetation. Understanding impacts of saltcedar on native fauna is important for managers who are tasked with control and management of this non-native species.
ContributorsNielsen, Danny (Author) / Bateman, Heather L. (Thesis advisor) / Miller, William H. (Committee member) / Sullivan, Brian K. (Committee member) / Arizona State University (Publisher)
Created2011