Not far from the editorial office of Ecological Restoration and in view of the iconic Las Vegas Strip casino corridor, the 1,174-ha Clark County Wetlands Park on the eastern edge of Las Vegas, Nevada, is among my favorite local preserves to visit. I enjoy this preserve both because of its unique wetland biota in the otherwise arid Mojave Desert and the interesting considerations related to ecological restoration a visit there invokes.
The preserve was established in the early 2000s with the goals of fulfilling watershed functions for the Las Vegas municipal water system, providing habitat for native plants and fauna, and offering recreation and educational opportunities including for local school groups. For the watershed functions, the preserve is bisected by the Las Vegas Wash that carries treated wastewater and runoff leaving Las Vegas 15 km to Lake Mead. Lake Mead, in turn, provides water to Las Vegas and 25 million people in the American Southwest. Created and enhanced wetlands in and around the preserve and along the wash are intended to improve water quality before flow enters Lake Mead (Figure 1).
Of many questions and considerations related to restoration the park setting invokes, I describe three here: reference conditions and the continuum of restoration-related activities, challenges with conserving native genetics during ongoing biological invasions, and incorporating wildlife that could both aid and hinder restoration management goals.
Reference conditions for biotic communities are linked to environmental habitat settings, and an interesting aspect of the park is that habitat conditions in it are now suitable for biota not thought to have occurred there historically but rather in nearby areas that were destroyed. In the 1800s before urbanization of Las Vegas, the Las Vegas Wash is thought to have flowed only ephemerally, following heavy rains, and did not necessarily support vegetation associated with perennial surface water (Whitney et al. 2015). Contemporarily, the wash is a perennial stream carrying outflow from Las Vegas. Historically, springs and wetlands in parts of what is now Las Vegas did support herbaceous and forested wetland communities associated with high water tables and surface water (Malmberg 1965). Nearly all such vegetation was destroyed as Las Vegas urbanized through the 1900s. However, habitat for this type of vegetation is now suitable in Wetlands Park around the wash as surface water was “re-routed” there as part of watershed management. Suitable habitat including surface water has thus been “moved” from one place (where it was destroyed through urbanization) to another (where it did not occur historically but resembles that of former destroyed locations) in the Las Vegas Valley (Figure 2).
To what extent does planting and establishing vegetation associated with shallow water tables and surface waters constitute strict or looser restoration, in terms of consistency with reference conditions, given that the historical environment destroyed elsewhere has been recreated contemporarily in a different location? One potential perspective is that revegetation activities in the park focusing on native species could be viewed as spanning a range of activities such as ecological engineering, habitat enhancement, or mitigation, all with elements of restoration. Another perspective could be that this does represent stricter restoration given that contemporary vegetation structure may mimic historical structure that was lost, if one accepts that the suitable environmental conditions associated with the reference conditions are able to have been “moved” to a location they did not occur historically. In practice, providing ecological functions to humans and wildlife was the prime goal for the park rather than strict restoration. This raises further considerations in restoration generally, such as how many or to what degree elements of restoration must be achieved to distinguish restoration from related management activities (Gann et al. 2019).
Part of a managed wetland in Clark County Wetlands Park, Nevada, USA, with the City of Las Vegas in the background before the Spring Mountains rise to the west from the Las Vegas Valley (photo by S.R. Abella, September 2024).
Another consideration illustrated at the park is the challenge of native populations of a species potentially having their genetics swamped by invading non-native strains. Common reed (Phragmites australis) is a tall, perennial grass with a cosmopolitan distribution in wetland habitats on all continents except Antarctica. There are numerous genetic strains of this species native to different regions and that have been introduced elsewhere and become invasive. In and around the Las Vegas Wash, mixtures of a native strain, an invasive non-native strain, and a hybrid between them are all thought to occur based on genetic and morphological analyses (Saltonstall et al. 2016). Extensive areas of the invasive or invasive hybrid strains occur in the park and form monocultures that provide low habitat diversity and hazardous fuels for wildfires, particularly undesirable given the park’s setting on the eastern edge of urban Las Vegas (Abella et al. 2024). As a result, removal of invasive Phragmites monocultures is ongoing. This poses challenges and interesting questions for the restoration of native species, however, such as how native strains of Phragmites might be conserved without being swamped by non-native strains or removed due to being embedded within the hybrid (Figure 2).
A third consideration for restoration the park illustrates is a situation where habitats become suitable for wildlife that then might aid or hinder further restoration or maintenance of habitat. Although it may seem surprising that beaver (Castor canadensis) inhabit the outskirts of Las Vegas in view of the iconic Las Vegas Strip, beaver occur in the park. They chew down planted trees (if not protected) and flood locations not always consistent with human hydrological management goals. Beaver were historically native along the nearby Colorsado River (which the Las Vegas Wash empties into now as Lake Mead; Mueller and Marsh 2002) but their historical nativity to the Las Vegas Valley is less certain. Despite recovery in some areas, beaver populations in North America overall are believed to be sharply lower than in the 1600s before the eras of fur trapping and habitat changes and loss (Baker and Hill 2003). This raises an interesting situation of habitat now suitable in Las Vegas contributing to overall beaver population recovery in North America whether or not beaver were historically native specifically to the Las Vegas Valley. This is accompanied by a need to accommodate beaver effects, adding complexity to ecological restoration or management activities focusing on other goals such as human regulation of water flows for municipal water system management.
Top left: riparian forest along Las Vegas Creek, early 1900s, near what is now downtown Las Vegas, Nevada, USA (photo snv001969, Ferron and Bracken Photograph Collection, Special Collections and Archives, University Libraries, University of Nevada, Las Vegas.). Bottom left: most of the historical natural vegetation was converted to other land uses, such as in this circa 1918 image of Fremont Street and 2nd Street (now Casino Center Boulevard) in what is present-day downtown Las Vegas (pho017633, Jacob E. Von Tobel Photograph Collection, Special Collections and Archives, University Libraries, University of Nevada, Las Vegas). Top right: contemporary view in Clark County Wetlands Park of mature and new (covered with wire mesh to limit damage by beaver and other herbivores) riparian tree plantings along a managed surface water stream as part of the Las Vegas water management system (image credit: S.R. Abella). Bottom right: contemporary view from the Wetlands Park visitor center of a recent wildfire mostly fueled by Phragmites australis, with unburned Phragmites monoculture in the background behind the burned area (image credit S.R. Abella). Replacement of invasive Phragmites monocultures with more diverse native riparian assemblages is an ongoing management activity in the park (Abella et al. 2024).
The three considerations discussed here—reference conditions related to the continuum of restoration-related management actions, conserving native genetics during biological invasions, and managing wildlife complicating restoration management of habitat—highlight some of the numerous areas where basic and applied science can help advance restoration practice and its association with related habitat enhancement activities. These are all topics welcomed for consideration from studies across the world in this journal among its variety of article types for advancing the science and practice of ecological restoration.
North American beaver (Castor canadensis). Sarah Cooper. 1887. Animal Life: In the Sea and On the Land. New York, NY: Harper & Brothers, fcit.usf.edu.
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