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Concern about spread of non-native riparian trees in the western USA has led to Congressional proposals to accelerate control efforts. Debate over these proposals is frustrated by limited knowledge of non-native species distribution and abundance. We measured abundance of 44 riparian woody plants at 475 randomly selected stream gaging stations in 17 western states. Our sample indicates that Tamarix ramosissima and Elaeagnus angustifolia are already the third and fourth most frequently occurring woody riparian plants in the region. Although many species of Tamarix have been reported in the region, T. ramosissima (here including T. chinensis and hybrids) is by far the most abundant. The frequency of occurrence of...
One of the fastest growing areas of natural gas production is coal bed methane (CBM) due to the large monetary returns and increased demand for energy from consumers. The Powder River Basin, Wyoming is one of the most rapidly expanding areas of CBM development with projections of the establishment of up to 50,000 wells. CBM disturbances may make the native ecosystem more susceptible to invasion by non-native species, but there are few studies that have been conducted on the environmental impacts of this type of resource extraction. To evaluate the potential effects of CBM development on native plant species distribution and patterns of non-native plant invasion, 36 modified Forest Inventory and Analysis plots (each...
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Freshwater fish are among the most vulnerable taxa to climate change globally but are generally understudied in tropical island ecosystems. Climate change is predicted to alter the intensity, frequency, and variability of extreme flow events on the Caribbean island of Puerto Rico. These changes may impact Caribbean native and non-native stream ecosystems and biota complex ways. We compiled an extensive dataset of native and non-native fish assemblages collected at 119 sites across Puerto Rico from 2005 to 2015. We coupled these data with stream flow indices and dam height to understand how flow dynamics drive fish assemblage structure. Sixteen percent of sites contained exclusively non-native species, 34% contained...
Most current conservation literature focuses on the preservation of hotspots of species diversity and endemism, as if the two were geographically synonymous. At landscape scales this may not be the case. We collected data from 367 1000-m2 plots in the Grand Staircase–Escalante National Monument, Utah, USA, to show that: (1) the vast majority of plant species are locally rare; (2) species-rich areas are generally in rare, mesic, or high-elevation habitats such as aspen stands or riparian zones high in soil N and P; (3) endemic species (to the Colorado Plateau and the Monument) were generally found in relatively species-rich, but low-elevation, xeric vegetation type areas low in soil P; (4) unique species assemblages...
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Predicting suitable habitat and the potential distribution of invasive species is a high priority for resource managers and systems ecologists. Most models are designed to identify habitat characteristics that define the ecological niche of a species with little consideration to individual species’ traits. We tested five commonly used modelling methods on two invasive plant species, the habitat generalist Bromus tectorum and habitat specialist Tamarix chinensis, to compare model performances, evaluate predictability, and relate results to distribution traits associated with each species. Most of the tested models performed similarly for each species; however, the generalist species proved to be more difficult...
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Many studies have quantified plant invasions by determining patterns of non-native species establishment (i.e. richness and absolute cover). Until recently, dominance has been largely overlooked as a significant component of invasion. Therefore, we re-examined a 6-year data set of 323 0.1 ha plots within 18 vegetation types collected in the Grand Staircase-Escalante National Monument from 1998 to 2003, including dominance (i.e. relative cover) in our analyses. We specifically focused on the non-native species Bromus tectorum, a notable dominant annual grass in this system. We found that non-native species establishment and dominance are both occurring in species-rich, mesic vegetation types. Therefore, non-native...
Naturalized populations of nonnative salmonid fishes have been implicated in the decline of many native aquatic organisms, including amphibians (Bradford 1989), invertebrates (Polhemus 1993), and fishes (Moyle et al. 1986). Potential mechanisms by which nonnative fishes may interact with native biota include predation, competition, parasite and disease transmission, and hybridization, which may operate directly or indirectly (see Taylor et al. 1984 for a general review). Nonnative salmonids are frequently implicated in declines of native salmonids in the western United States (Allendorf and Leary 1988, Young 1995, Duff 1996). For example, loss of threatened Lahontan cutthroat trout (Oncorhynchus clarki henshawi)...
    map background search result map search result map Evaluating dominance as a component of non-native species invasions Modelling invasion for a habitat generalist and a specialist plant species The Effects of Flow Extremes on Native and Non-Native Stream Fishes in Puerto Rico The Effects of Flow Extremes on Native and Non-Native Stream Fishes in Puerto Rico Modelling invasion for a habitat generalist and a specialist plant species Evaluating dominance as a component of non-native species invasions