Epilog: Threats to Great Salt Lake wetlands

Epilog

Threats to Great Salt Lake wetlands

Wetlands around the world, including Great Salt Lake (GSL) wetlands, currently face many threats. The most challenging threats to GSL wetlands are invasive plant species, urbanization, and drought. Invasive plant species are a major conservation issue at GSL wetlands because they outcompete native plants. Purple loosestrife

(Lythrum salicaria, p. 92), whitetop (Cardaria draba, p. 152), poison hemlock (Conium maculatum, p. 34), thistles (Cirsium spp., pp. 142–143) and pepperweeds (Lepidium spp., pp. 155–156) are invasive species that thrive under dry or more nutrient-rich conditions and are capable of rapidly invading disturbed areas.68 In addition to those invasive species, over 89 km² (22,000 ac) of wetland habitat around GSL’s shorelines are densely populated with an invasive lineage of phragmites (Phragmites australis, p. 50). Phragmites, colloquially called phrag, is a tall grass that grows in dense monocultures, outcompeting native vegetation, changing the course of rivers, and degrading wildlife habitat.30 Soras (Porzana carolina), rails (Family Rallidae), and blackbirds (Icteridae family), can use stands of phragmites, but very few other bird species are adapted to living in such dense vegetation.7 In addition, phragmites also causes many problems for humans and their domestic animals. Hunters frequently lose equipment and their navigation when walking through phragmites stands. Often, hunting dogs suffer cuts to their feet, faces, and tongues by phragmites leaves and broken, sharp stems.27 As with most invasive species, controlling phragmites is a daunting task that needs our attention. Dry phragmites is a fire hazard,

while phragmites growing in water control structures can clog them and prevent the flow of water to wetlands. Many emergent wetland species benefit from seasonal/summer drawdown, but during the drawdown period, exposed, unvegetated areas are at increased risk of phragmites invasion via seed, thus creating a complex management challenge. While invasive phragmites is incredibly damaging to GSL wetlands, there is also a lineage of North American native phragmites that is found throughout Utah. Shiny stems (rather than ribbed) and deciduous leaf sheaths reliably distinguish native phragmites (Phragmites australis subsp. americanus, p. 51) from the invasive strain.25 Native phragmites does not grow as densely as invasive phragmites, so other native plants can still grow alongside it and create interspersed layers of plants that can be utilized by many wildlife groups. Native phragmites is widespread in riparian and wetland areas in the southern half of the state, but occurs only rarely in GSL wetlands. Most of Utah’s population lives on the Wasatch Front in cities and suburbs adjacent to GSL, and urbanization is expected to continue. This urban expansion result in wetland habitat loss and poses threats such as water diversion and increased nutrient inputs.5 Additional homes built along the Wasatch Front increasingly push into the buffer zones around GSL wetlands. These buffer zones are necessary to protect wetlands from surrounding land and water use changes.2 The combined impacts of development and roads results in significant wetland habitat loss, and the loss of native plants can be devastating to birds.64 Water is already a scarce resource for GSL wetlands.14 Climate change models suggest water availability problems will worsen as winter snowpack is likely to decrease and summertime evapotranspiration increases.23 Urbanization further threatens water availability because water diverted to urban and suburban areas does not return to wetlands like excess runoff from irrigation.49 The water that will make it to GSL wetlands in the future will likely have higher concentrations of nutrients, leading to hypereutrophic conditions.67 Healthy GSL wetlands are important for human needs such as flood contol, erosion control, and water filtration, and they are vital for countless native species of wildlife, particularly birds. Understanding the invasive plant, urbanization, and drought threats to GSL wetlands and knowing wetland communities and their plant species, will help ensure sustainable wetland ecosystems for all stakeholders. 182

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