Status and management of non-native plant invasion in three of the largest national parks in the United States

Abstract

Globally, invasion by non-native plants threatens resources that nature reserves are designated to protect. We assessed the status of non-native plant invasion on 1,662, 0.1-ha plots in Death Valley National Park, Mojave National Preserve, and Lake Mead National Recreation Area. These parks comprise 2.5 million ha, 23% of the national park land in the contiguous USA. At least one non-native species inhabited 82% of plots. Thirty-one percent of plots contained one non-native species, 30% two, 17% three, and 4% four to ten non-native species. Red brome (Bromus rubens), an 'ecosystem engineer' that alters fire regimes, was most widespread, infesting 60% of plots. By identifying frequency of species through this assessment, early detection and treatment can target infrequent species or minimally invaded sites, while containment strategies could focus on established invaders. We further compared two existing systems for prioritizing species for management and found that a third of species on plots had no rankings available. Moreover, rankings did not always agree between ranking systems for species that were ranked. Presence of multiple non-native species complicates treatment, and while we found that 40% of plots contained both forb and grass invaders, exploiting accelerated phenology of non-natives (compared to native annuals) might help manage multi-species invasions. Large sizes of these parks and scale of invasion are formidable challenges for management. Yet, precisely because of their size, these reserves represent opportunities to conserve large landscapes of native species by managing non-native plant invasions. RESEARCH ARTICLE Launched to accelerate biodiversity conservationA peer-reviewed open-access journal Scott R. Abella et al. / Nature Conservation 10: 71-94 (2015) 72

Persistence and turnover in desert plant communities during a 37‐yr period of land use and climate change

“…Nonnative annuals, more extensively distributed across the Mojave Desert than nonnative perennials (Abella et al. ), were not prevalent in the study area either based on a previous investigation (Abella et al. ).…”

“…Our results were also inconsistent with the idea that nonnative plant invasion is accelerating at the highest elevations (Pauchard et al 2009). Nonnative annuals, more extensively distributed across the Mojave Desert than nonnative perennials (Abella et al 2015b), were not prevalent in the study area either based on a previous investigation (Abella et al 2012). It is unclear why the study area is relatively free of nonnative plants, as the Colorado River on the eastern border and highways on the western and southern borders could serve as dispersal vectors, along with a main dirt road through the study area.…”

Management of invasive Phragmites australis in the Adirondacks: a cautionary tale about prospects of eradication

“…However, deciding which plant species to target for control is difficult, especially when multiple species co-occur and each is associated with or facilitated by other biotic or abiotic stressors (Simberloff and Von Holle 1999;Bertness et al 2002;Minchinton and Bertness 2003;Nuzzo et al 2009;Fisichelli et al 2013;Kuebbing et al 2013;Dávalos et al 2014Dávalos et al , 2015Craven et al 2016). An abundance of prioritization schemes exist, largely developed by scientists, to help land managers make better informed decisions that focus control efforts (Robertson et al 2003;Fox and Gordon 2009;Downey et al 2010;Esler et al 2010b;Darin et al 2011;Barney et al 2013;Abella et al 2015;Adams and Setterfield 2015;Lindenmayer et al 2015). Depending on a particular scheme's focus, species, habitats, ecosystem services, control strategies, probability of achieving success, expected impacts, and costs may be evaluated.…”

“…Conservation and land management organizations spend an ever-increasing amount of their limited resources to manage threats to native biodiversity caused by spread of non-indigenous species (henceforth NIS) (D'Antonio et al 2004;Pullin et al 2004;Chornesky et al 2005;Abella et al 2015). For example, the 2002 U.S. federal budget for NIS control and related activities was reported at $777 million, and expenditures have increased to [$2.2 billion by 2016 (https://www.doi.gov/invasivespecies/nisc-resources, accessed 16 January 2017).…”

Enhancing and Restoring Habitat for the Desert Tortoise

“…By the late 1800s, nonnative plant species were introduced that ubiquitously altered the composition of plant communities (Brooks and Esque 2002). In an inventory conducted from 2009 to 2011, at least one nonnative plant species inhabited 82% of 1,662 sites within 25,000 km 2 of national parks in the Mojave Desert (Abella et al 2015c). In designated critical habitat for the desert tortoise in the western Mojave Desert, nonnative annual plants comprised 6% of the flora and 66% of the biomass in a wet year, and 27% of the flora and 91% of the biomass in a dry year .…”