Short-Term Vegetation Response Following Mechanical Control of Saltcedar (Tamarixspp.) on the Virgin River, Nevada, USA

Abstract

Tamarisk (a.k.a. saltcedar, Tamarix spp.) is an invasive plant species that occurs throughout western riparian and wetland ecosystems. It is implicated in alterations of ecosystem structure and function and is the subject of many local control projects, including removal using heavy equipment. We evaluated short-term vegetation responses to mechanical Tamarix spp. removal at sites ranging from 2 to 5 yr post-treatment along the Virgin River in Nevada, USA. Treatments resulted in lower density and cover (but not eradication) of Tamarix spp., increased cover of the native shrub Pluchea sericia (arrow weed), decreased density and cover of all woody species combined, increased density of both native annual forbs and the nonnative annual Salsola tragus (prickly Russian-thistle), and lower density of nonnative annual grasses. The treated plots had lower mean woody species richness, but greater herbaceous species richness and diversity. Among herbaceous species, native taxa increased in richness whereas nonnative species increased in both species richness and diversity. Thus, efforts to remove Tamarix spp. at the Virgin River reduced vegetative cover contributing to fuel loads and probability of fire, and resulted in positive effects for native plant diversity, with mixed effects on other nonnative species. However, absolute abundances of native species and species diversity were very low, suggesting that targets of restoring vegetation to pre-invasion conditions were not met. Longer evaluation periods are needed to adequately evaluate how short-term post-treatment patterns translate to long-term patterns of plant community dynamics.

Vegetation response to invasive Tamarix control in southwestern U.S. rivers: a collaborative study including 416 sites

“…, Ostoja et al. ). In better situations, native vegetation, usually not strictly riparian as the local hydrology is frequently not restored, may establish (Reynolds and Cooper ).…”

“…, Ostoja et al. ). Most studies of vegetation recovery have been at the stream reach scale, or when done regionally, poorly replicated in space and time.…”

“…, Reynolds and Cooper , Ostoja et al. ). These approaches have used burning, mechanical removal with heavy machinery, aerial application of herbicide, and a popular technique consisting of cutting the tree with hand or chain saws followed by herbicide application to the stump (cut‐stump method).…”

Selection for genetics‐based architecture traits in a native cottonwood negatively affects invasive tamarisk in a restoration field trial

“…Restoration efforts in the Southwest include replacing tamarisk with cottonwood (Shafroth et al 2008;Bangert et al 2013), but removal and restoration costs are expensive (Zavaleta 2000) and tamarisk is known to resprout from broken stems and roots (Brotherson & Field 1987), potentially compromising restoration projects (Ostoja et al 2014). Cottonwood and box elder (Acer negundo) seedlings have been shown to overtop tamarisk seedlings in field trials (Sher et al 2002;Sher & Marshall 2003;DeWine & Cooper 2008).…”

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

“…In addition, changes in stream hydrology that led to saltcedar domination may no longer support native vegetation (Stromberg et al ). In these situations, saltcedar or other non‐native plants may recolonize restored areas (Shafroth et al ; Hultine et al ; Ostoja et al ). Even worse, large‐scale removal of saltcedar may reduce the only habitat available for riparian wildlife species (Hultine et al ; Paxton et al ).…”