Статті в журналах: "Invasive annual grasses"

1

Villarreal, Miguel, Christopher Soulard, and Eric Waller. "Landsat Time Series Assessment of Invasive Annual Grasses Following Energy Development." Remote Sensing 11, no. 21 (October 30, 2019): 2553. http://dx.doi.org/10.3390/rs11212553.

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Invasive annual grasses are of concern in much of the western United States because they tolerate resource variability and have high reproductive capacity, with propagules that are readily dispersed in disturbed areas like those created and maintained for energy development. Early season invasive grasses “green up” earlier than most native plants, producing a distinct pulse of greenness in the early spring that can be exploited to identify their location using multi-date imagery. To determine if invasive annual grasses increased around energy developments after the construction phase, we calculated an invasives index using Landsat TM and ETM+ imagery for a 34-year time period (1985–2018) and assessed trends for 1755 wind turbines installed between 1988 and 2013 in the southern California desert. The index uses the maximum Normalized Difference Vegetation Index (NDVI) for early season greenness (January-June), and mean NDVI (July–October) for the later dry season. We estimated the relative cover of invasive annuals each year at turbine locations and control sites and tested for changes before and after each turbine was installed. The time series was also mapped across the region and temporal trends were assessed relative to seasonal precipitation. The results showed an increase in early season invasives at turbine sites after installation, but also an increase in many of the surrounding control areas. Maps of the invasive index show a region-wide increase starting around 1998, and much of the increase occurred in areas surrounding wind development sites. These results suggest that invasions around the energy developments occurred within the context of a larger regional invasion, and while the development did not necessarily initiate the invasion, annual grasses were more prevalent around the developments.

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Parker, Sophie S., and Joshua P. Schimel. "Invasive Grasses Increase Nitrogen Availability in California Grassland Soils." Invasive Plant Science and Management 3, no. 1 (May 2010): 40–47. http://dx.doi.org/10.1614/ipsm-09-046.1.

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AbstractAs Europeans colonized California, they introduced annual grasses from the Mediterranean Basin. These exotic annual grasses eventually invaded grasslands throughout the state, some of which were once dominated by native perennial grass species. Annual grasses differ from perennials in their phenology, longevity, rooting depth, litter chemistry, and interaction with the microbial community. As these traits may influence plant nitrogen (N) use, it is likely that the invasion by annual species resulted in changes in the availability and cycling of N in California grassland systems. We addressed the question of how invasive annual grasses influence rates of N cycling by measuring N pool sizes and rates of net and gross mineralization and nitrification, gross immobilization, and the denitrification potential of soils from experimentally planted annual and perennial-dominated grasslands. With an increase in annual grass cover, we saw increases in ammonium (NH4+) pool sizes and rates of N mineralization, nitrification, and denitrification in soils. These differences in N status suggest that N cycling in California grasslands was altered at sites where native perennial bunchgrasses were invaded by nonnative annual grasses. One consequence of annual grass invasion may be a legacy of NH4+-enriched soils that hinder the reestablishment of native perennial grass species.

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Rinella, Matthew J., Robert A. Masters, and Susan E. Bellows. "Effects of Growth Regulator Herbicide on Downy Brome (Bromus tectorum) Seed Production." Invasive Plant Science and Management 6, no. 1 (March 2013): 60–64. http://dx.doi.org/10.1614/ipsm-d-12-00033.1.

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AbstractPrevious research showed growth regulator herbicides, such as picloram and aminopyralid, have a sterilizing effect on Japanese brome (Bromus japonicus Thunb.) that can reduce this invasive annual grass's seed production nearly 100%. This suggests growth regulators might be used to control invasive annual grasses by depleting their short-lived seed banks. The goal of this study was to extend the previous Japanese brome research to downy brome (Bromus tectorum L.), the most damaging invasive annual grass of U.S. grasslands. In a greenhouse, we found picloram did not greatly influence downy brome seed production, while point estimates suggest aminopyralid reduced seed production 55 to 80%. If not for a highly abnormal retillering response that we somewhat doubt would occur in the field, point estimates suggest aminopyralid would have reduced downy brome seed production approximately 90% when applied at the heading stage and approximately 98% when applied at three earlier growth stages. Our greenhouse study should encourage field studies designed to further explore the potential for using growth regulators to control downy brome and other invasive annual grasses.

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4

Clark, Shannon L. "Using Herbicides to Restore Native Species and Improve Habitat on Rangelands and Wildlands." Outlooks on Pest Management 31, no. 2 (April 1, 2020): 57–60. http://dx.doi.org/10.1564/v31_apr_02.

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Invasive winter annual grasses are one of the largest threats to the arid and semiarid rangelands and wildlands in the Intermountain West of North America. The most impactful species include downy brome (Bromus tectorum), medusahead (Taeniatherum caput-medusae), ventenata (Ventenata dubia), and to a lesser extent Japanese brome (Bromus japonicus), feral rye (Secale cereale), and jointed goatgrass (Aegilops cylindrica). These winter annuals can germinate in the fall, winter or early spring, exploiting soil moisture and nutrients before native plant communities begin active growth in the spring. These characteristics impart a competitive advantage in the perennial grass dominated natural landscapes of the Intermountain West. Downy brome, a winter annual grass native to Eurasia, is the most widespread invasive species in the western US covering an estimated 22 million ha and a projected 14% annual spread rate. Invasive winter annuals negatively impact these ecosystems by depleting soil moisture and nutrients, reducing native plant productivity and diversity, altering fire frequency, and diminishing pollinator and wildlife habitat. Large amounts of litter which act as a fuel source are left after these grasses senesce early in the summer, greatly increasing the frequency and spread of wildfires in invaded areas. Historically, fire frequency in the 41 million ha sagebrush steppe occurred every 60 to 110 years, but this interval has been shortened to less than every five years since the introduction of invasive annual grasses. Annual grasses quickly (re)invade after these fires while sagebrush (Artemisia spp.), the dominant vegetation type in the sagebrush steppe, can take decades to recover. Therefore, the altered fire regime has resulted in a substantial loss of sagebrush and converted millions of hectares into monocultures of winter annual grass. This altered fire regime also negatively impacted the abundance of small mammals, birds, larger browsing mammals, and pollinating insects in the sagebrush steppe. Managing the weed seedbank is the key to long-term control of invasive winter annual grasses on rangelands and wildlands. Past herbicides have provided adequate short-term control but have often failed due to annual grasses reinvading from the soil seedbank. Indaziflam is a new tool for land managers to achieve multi-year control of the annual grass seedbank while promoting restoration of native species. As wildlife and pollinator habitat continue to be degraded and fragmented through development and agricultural production, indaziflam is a viable option for restoring the rangelands and wildlands impacted by winter annual grasses in the Intermountain West that serve as critical habitat areas.

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5

Mauritz, M., and D. L. Lipson. "Altered phenology and temperature sensitivity of invasive annual grasses and forbs changes autotrophic and heterotrophic respiration rates in a semi-arid shrub community." Biogeosciences Discussions 10, no. 4 (April 3, 2013): 6335–75. http://dx.doi.org/10.5194/bgd-10-6335-2013.

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Abstract. Many invasions, like the wide-spread establishment of annual grasses and forbs in semi-arid shrublands, are associated with climate change. In order to predict ecosystem carbon (C) storage it is critical that we understand how invasion affects soil respiration (Rt). Because plants and microbes have different seasonal dynamics, determining the relative contribution of autotrophic (Ra) and heterotrophic (Rh) respiration provides critical insight into soil C processes. Using automated soil respiration measurements and root exclusion cores we evaluated the moisture and temperature sensitivity of Rt and Rh and calculated the contribution of Ra in native shrub and invaded areas. Invasion increased cumulative Rt by 40% from 695 (±51) g C m−2 under shrubs to 1050 g C m−2 (±44) in invaded areas. Cumulative Rh did not change but invasion altered the seasonal pattern of Rh. Throughout the season Rt and Rh responded positively to temperature increases when soils were wet and negatively when soils were dry. Invasion increased temperature sensitivity of Rt and Rh in wet soils and decreased temperature sensitivity in dry soils. The altered temperature sensitivity of invasives was attributed largely to differences in phenology. Early phenology of invasive grasses caused rapid Ra increases early in the season; late phenology of invasive forbs resulted in the surprising maintenance of diurnal Ra and Rh signals despite high temperatures and low soil moisture. Invasion extended the respiration season of the system. Ability of the invasive community to withstand high temperatures and drought could confer greater resilience if temperature and precipitation patterns in the region change. The high contribution of Ra by invasive annuals means ecosystem C storage will depend heavily on seasonal rainfall dynamics and productivity of invasive annuals. In semi-arid ecosystems even small scale changes in plant community composition alter Rt, Ra and Rh and should be considered when attempting to predict Rt.

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6

Kyser, Guy B., Joseph M. Ditomaso, Morgan P. Doran, Steve B. Orloff, Robert G. Wilson, Donald L. Lancaster, David F. Lile, and Marni L. Porath. "Control of Medusahead (Taeniatherum caput-medusae) and other Annual Grasses with Imazapic." Weed Technology 21, no. 1 (March 2007): 66–75. http://dx.doi.org/10.1614/wt-06-027.1.

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Invasive annual grasses, such as medusahead, can reduce forage production capacity and interfere with revegetation projects in California rangelands. Because of the taxonomic similarity to other more desirable grasses, achieving selective control of invasive annual grasses can be difficult. In selectivity trials conducted in Yolo and Siskiyou counties, CA, the herbicide imazapic gave control of many nonnative annual grasses yet provided some level of selectivity to specific perennial grasses used in revegetation projects throughout the western United States. The selectivity difference between newly seeded perennial and annual grasses was greater with PRE applications than with POST treatments. Both perennial and annual grasses within the tribe Hordeae were more tolerant to imazapic than other grass species. In addition, field experiments were conducted at three sites in northern California (Yuba, Yolo, and Lassen counties) and one in southern Oregon (Lake County) to test the response of imazapic to varying management conditions. Imazapic was applied PRE in fall (and also spring in Lake County) at rates from 35 to 210 g/ha on undisturbed rangeland, in comparison with rangeland cleared of standing plant material and thatch by either tillage, mowing and raking, or burning. Imazapic generally showed enhanced weed control when applied following disturbance. Rates as low as 70 g/ha, if combined with thatch removal, provided significant suppression of medusahead. In addition, disturbance alone generally reduced medusahead cover in the following year. Although imazapic showed potential for control of medusahead and other annual grasses, its selectivity window was relatively narrow.

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7

Nyamai, Priscilla A., Timothy S. Prather, and John M. Wallace. "Evaluating Restoration Methods across a Range of Plant Communities Dominated by Invasive Annual Grasses to Native Perennial Grasses." Invasive Plant Science and Management 4, no. 3 (September 2011): 306–16. http://dx.doi.org/10.1614/ipsm-d-09-00048.1.

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AbstractPrairies are imperiled habitats, with remnants being generally small and often existing in isolation. Invasive plants have the potential to invade not just the edge of small remnants but also the interior because smaller remnants experience greater edge effects than do large, contiguous prairies. Additionally, invasive plants limit recruitment of native plants, which can arrest secondary succession. We proposed to assess techniques for restoration that included removing annual grasses and supplementing native species recruitment with seeding of native grass and forb species. We also assessed the effect of specific factors affecting recruitment: soil moisture and seed predation. Treatments included broadcast, spot, or no application of the herbicides imazapic and glyphosate and with or without seeding plus mulch. With treatments nested within each of three plant communities, ranging from annual- to perennial-dominated communities, in four blocks per community, plant characteristics (percentage of cover and plant density), soil moisture availability, and seed-predation losses were measured along a plant community gradient within one season at two locations. A combination of broadcast herbicide application and seeding with mulching was found to be more effective in reducing annual grasses and enhancing the establishment of native grass species in predominately annual and mixed communities (annuals and perennials). Spot herbicide application was effective in predominately perennial communities, whereas only seeding native species did not improve recruitment. Although seed predation reduced seedling recruitment, mulch provided seed protection and enhanced soil moisture retention. Plant community response to imposed treatments differed among communities, suggesting that a decision support tool would facilitate management decisions tailored for each plant community. The decision tool would be useful to ensure that appropriate treatments are applied and that specific factors affecting recruitment, such as seed predation and soil moisture, are addressed.

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8

James, Jeremy J., L. Ziegenhagen, and Z. T. Aanderud. "Exploitation of Nutrient-Rich Soil Patches by Invasive Annual and Native Perennial Grasses." Invasive Plant Science and Management 3, no. 2 (August 2010): 169–77. http://dx.doi.org/10.1614/ipsm-d-09-00033.1.

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AbstractInvasion of nutrient-poor habitats might be related to the ability of a species to exploit nutrient-rich microsites. Recent research suggests fast-growing species might have a greater ability to allocate root biomass to nutrient-rich microsites (root foraging precision) than slow-growing species. We examined if differences in relative growth rate (RGR) between invasive and native species were related to differences in foraging precision. We hypothesized that invasive species would: (1) have greater foraging precision than native species but (2) greater foraging precision would come at a cost in terms of root nutrient uptake rate. Foraging precision was evaluated on plants growing in soils with uniform or patchy nutrient distribution. Plants were harvested at a common time and a common developmental stage to separate indirect effects of RGR on foraging. Nutrient uptake rate was examined by exposing plants to a low or high nitrogen pulse. Invasives foraged more precisely than natives but had lower nitrogen uptake rate. Although these results support the idea of a positive relationship between RGR and foraging precision, biomass production in heterogeneous soils showed no relationship to foraging precision. Instead, species with greater RGR produced more biomass and root length across all treatments, allowing greater nutrient capture in heterogeneous soils. Although these results do not exclude a role for proliferation in influencing invasion of nutrient-poor systems or the potential for heterogeneity to influence population processes, these results suggest other traits may have an overriding importance in determining invader success in these systems.

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Weisberg, Peter J., Thomas E. Dilts, Jonathan A. Greenberg, Kerri N. Johnson, Henry Pai, Chris Sladek, Christopher Kratt, Scott W. Tyler, and Alice Ready. "Phenology-based classification of invasive annual grasses to the species level." Remote Sensing of Environment 263 (September 2021): 112568. http://dx.doi.org/10.1016/j.rse.2021.112568.

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10

Spackman, Casey N., Thomas A. Monaco, Clinton A. Stonecipher, and Juan J. Villalba. "Plant silicon as a factor in medusahead (Taeniatherum caput-medusae) invasion." Invasive Plant Science and Management 13, no. 3 (July 14, 2020): 143–54. http://dx.doi.org/10.1017/inp.2020.20.

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AbstractMedusahead [Taeniatherum caput-medusae (L.) Nevski] is one of the most detrimental invasive annual grasses impacting the sustainability and function of rangeland in the western United States. This annual grass possesses high concentrations of tissue silicon (Si) that may facilitate invasion through key plant characteristics such as increased plant fitness, structure, and antinutritive qualities. These characteristics may affect known invasive processes such as increased plant productivity, slow litter decomposition, and decreased herbivory, facilitating a positive feedback cycle of invasion. However, Si is not considered an essential element and is often overlooked as a factor of T. caput-medusae invasion. Thus, this article provides a synthesis of plant Si, T. caput-medusae, and the self-reinforcing feedback cycle of invasion. We also discuss how current control strategies address plant characteristics determined by Si and suggest research avenues that may aid in novel or improved control strategies that target the T. caput-medusae–silica relationship.

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11

Rinella, Matthew J., Susan E. Bellows, and Aaron D. Roth. "Aminopyralid Constrains Seed Production of the Invasive Annual Grasses Medusahead and Ventenata." Rangeland Ecology & Management 67, no. 4 (July 2014): 406–11. http://dx.doi.org/10.2111/rem-d-13-00138.1.

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Malmstrom, Carolyn M., April J. McCullough, Hope A. Johnson, Linsey A. Newton, and Elizabeth T. Borer. "Invasive annual grasses indirectly increase virus incidence in California native perennial bunchgrasses." Oecologia 145, no. 1 (May 4, 2005): 153–64. http://dx.doi.org/10.1007/s00442-005-0099-z.

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13

Sheley, Roger L., Edward A. Vasquez, Anna-Marie Chamberlain, and Brenda S. Smith. "Landscape-Scale Rehabilitation of Medusahead (Taeniatherum caput-medusae)-Dominated Sagebrush Steppe." Invasive Plant Science and Management 5, no. 4 (December 2012): 436–42. http://dx.doi.org/10.1614/ipsm-d-12-00030.1.

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AbstractProducers facing infestations of invasive annual grasses regularly voice the need for practical revegetation strategies that can be applied across broad landscapes. Our objective was to determine the potential for scaling up the single-entry approach for revegetating medusahead-infested rangeland to broader, more heterogeneous landscape-scale revegetation of winter annual grass–infested rangeland. We hypothesized, when applied on a highly variable landscape scale, the combination of imazapic and seeding would provide highest abundance of perennial grasses and lowest amount of annual grasses. Treatments included a control, seeding of crested wheatgrass (‘Hycrest’) and Sandberg's bluegrass, spraying (60 g ai ha−1 imazapic), and a simultaneously applied combination of spraying and seeding. The HyCrest and Sandberg's bluegrass seeding rates were 19 and 3.4 kg ha−1, respectively. The treatments were applied to large plots (1.4 to 8 ha) and replicated five times, with each replication located in different watersheds throughout southeastern Oregon. This study shows that the single-entry approach can be scaled up to larger landscapes, but variation within establishment areas will likely be high. This procedure should reduce the costs over multientry treatment applications and make revegetating annual grass–infested rangeland across landscapes more affordable.

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Tozer, Katherine N., David F. Chapman, Paul E. Quigley, Peter M. Dowling, Roger D. Cousens, Gavin A. Kearney, and J. Richard Sedcole. "Controlling invasive annual grasses in grazed pastures: population dynamics and critical gap sizes." Journal of Applied Ecology 45, no. 4 (August 2008): 1152–59. http://dx.doi.org/10.1111/j.1365-2664.2008.01500.x.

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Mangla, S., R. L. Sheley, and J. J. James. "Field growth comparisons of invasive alien annual and native perennial grasses in monocultures." Journal of Arid Environments 75, no. 2 (February 2011): 206–10. http://dx.doi.org/10.1016/j.jaridenv.2010.09.015.

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H. S., Arathi, and Janet Hardin. "Pollinator-friendly flora in rangelands following control of cheatgrass (Bromus tectorum): a case study." Invasive Plant Science and Management 14, no. 4 (December 2021): 270–77. http://dx.doi.org/10.1017/inp.2021.33.

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Abstract Invasive winter annual grasses, such as cheatgrass (Bromus tectorum L.) are considered serious threats to regional biodiversity. Pollinator populations that depend on the native flora are likely to be negatively impacted as these native species may be displaced by the invasive grass species. Colonization by cheatgrass is also predicted to increase risk of wildfires, as dead plant parts provide fuel in the already dry and arid regions of the western United States. Biocontrol, grazing, prescribed burning, or use of broad-spectrum nonselective herbicides have been suggested as possible means to control B. tectorum. Efficient control may facilitate regrowth of native flora that could in turn support other ecosystem functions. Reporting our findings as a case study, we describe here the results of the application of a preemergent herbicide, indaziflam, that limits germination of B. tectorum seeds. Herbicide was applied to the study locations during the months of December 2016, January 2017, and February 2017. The data reported here on the diversity of flowering plants were collected between May through September 2018. Herbicide-treated plots showed an increase in diversity and abundance of flowering plants compared to the untreated control within two seasons after cheatgrass control was implemented, suggesting that effective reduction of the population of the invasive annual cheatgrass may help facilitate the growth of native forbs. Further studies are necessary to understand mechanisms that facilitate reestablishment of native flowering species, the long-term consequences of reducing invasive annual grasses and to document any residual effects of the herbicide on ground-nesting pollinators.

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Harvey, Audrey J., Lisa J. Rew, Tim S. Prather, and Jane M. Mangold. "Effects of Elevated Temperature and CO2 Concentration on Seedling Growth of Ventenata dubia (Leers) Coss. and Bromus tectorum L." Agronomy 10, no. 11 (November 5, 2020): 1718. http://dx.doi.org/10.3390/agronomy10111718.

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The impacts of climate change are expected to alter the abundance and distribution of invasive annual grasses, such as Bromus tectorum L. (cheatgrass) and Ventenata dubia (Leers) Coss. (ventenata). High temperature extremes will be more frequent and for longer periods, and increased atmospheric CO2 is expected to double even with the most conservative estimates. Climate change draws concern for the potential success of winter annual grasses in arid and semi-arid plant communities. Information on B. tectorum’s growth response to climate change in laboratory and field experiments are available for monocultures; however, more knowledge is needed on the response when growing with other invasive grasses, such as V. dubia. We examined differences in seedling growth for V. dubia and B. tectorum growing alone and with each other under current (4 °C/23 °C at 400 ppm CO2) and elevated (10.6 °C/29.6 °C at 800 ppm CO2) climate conditions. There was one trial per climate scenario with 10 replications per competition type (inter-, intra-specific competition for each species). Bromus tectorum was larger than V. dubia across climate and competition treatments, but contrary to previous studies, both species were smaller in the elevated climate treatment. Ventenata dubia allocated more growth to its roots than B. tectorum across both climate treatments, indicating V. dubia may have a competitive advantage for soil resources now and in the future.

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McIntyre, S., T. G. Martin, K. M. Heard, and J. Kinloch. "Plant traits predict impact of invading species: an analysis of herbaceous vegetation in the subtropics." Australian Journal of Botany 53, no. 8 (2005): 757. http://dx.doi.org/10.1071/bt05088.

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The need to predict potential invasion impact of plant species is important for setting weed-management priorities and determining quarantine restrictions for newly imported plant material. We analysed the naturalised plant component of a herbaceous plant community in sub-tropical eucalypt woodlands subjected to various disturbances associated with agricultural activities. The native and naturalised plant species did not differ in the proportions of different life forms, although life-history differed, with the naturalised group having more annual and biennial, and relatively fewer perennial species. We classified the naturalised assemblage into high- and low-impact species and compared the plant-trait and habitat characteristics of the two groups. Low-impact species covered a range of levels of habitat specialisation whereas high-impact species tended to have moderate to low levels of specialisation and to be less tolerant of grazing. Seven traits were found to be significantly associated with impact. Stepwise regression indicated a high level of redundancy in the data, owing to attributes being correlated. For all species, four attributes were significant in determining impact: very wide lateral spread, C4 photosynthesis, tall height and large leaves. For forbs, only two attributes (large seeds, adhesion/ingestion mode of seed dispersal) were significant in the overall model. We identified the following eight functional types amongst the naturalised species: (i) high-impact C4 lawn grasses, (ii) high-impact C4 bulky tussock grasses, (iii) moderate-impact annual grasses, (iv) moderate-impact tall annual forbs, (v) moderate-impact spreading forbs, (vi) moderate-impact woody forbs, (vii) low-impact legumes and (viii) low-impact small ruderals. In the subtropical woodland environment perennial C4 grasses appear to present the greatest invasive threat to herbaceous native communities, whereas forbs of wide lateral spread, with large animal-dispersed seeds are also problematic. The results support a case for limiting further importation of horticultural and forage material into Australia.

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Abatzoglou, John T., and Crystal A. Kolden. "Climate Change in Western US Deserts: Potential for Increased Wildfire and Invasive Annual Grasses." Rangeland Ecology & Management 64, no. 5 (September 2011): 471–78. http://dx.doi.org/10.2111/rem-d-09-00151.1.

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Sheley, Roger, Jordan Sheley, and Brenda Smith. "Cost/Benefit Analysis of Managing Invasive Annual Grasses in Partially Invaded Sagebrush Steppe Ecosystems." Weed Science 62, no. 1 (March 2014): 38–44. http://dx.doi.org/10.1614/ws-d-13-00056.1.

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Our objective was to evaluate the cost/benefit of a single herbicide application or targeted grazing of invasive annual grasses during restoration of partially invaded sagebrush steppe ecosystems used for livestock production. The cost/benefit model used is based on estimating the production of vegetation in response to implementing management and modeling cost/benefit economics associated with that prediction. The after-tax present value of added animal unit months (AUMs) obtained was lower than the present value of after-tax treatment costs after 20 yr for a single herbicide treatment, but higher than the present value of after-tax treatment costs for the grazing management scenario. Even at the highest weed utilization level, the value of added AUMs did not offset the cost of the treatment after 20 yr. However, the grazing treatment resulted in a value of added AUMs higher than the costs after 20 yr. Depending on the invasive weed utilization level, break-even points with targeted grazing occurred at anywhere from the first year to 7 yr. This assessment clearly shows that grazing management can be economically viable for managing annual grass-infested rangeland. In the future, models like the one used here can be improved by incorporating the rangeland management and restoration benefits on the wide variety of goods and services gained from rangeland.

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Goldstein, Leah J., and Katharine N. Suding. "Intra-annual rainfall regime shifts competitive interactions between coastal sage scrub and invasive grasses." Ecology 95, no. 2 (February 2014): 425–35. http://dx.doi.org/10.1890/12-0651.1.

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Rabon, J. C., C. M. V. Nuñez, P. S. Coates, M. A. Ricca, and T. N. Johnson. "Ecological correlates of fecal corticosterone metabolites in female Greater Sage-Grouse (Centrocercus urophasianus)." Canadian Journal of Zoology 99, no. 9 (September 2021): 812–22. http://dx.doi.org/10.1139/cjz-2020-0258.

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Measurement of physiological responses can reveal effects of ecological conditions on an animal and correlate with demographic parameters. Ecological conditions for many animal species have deteriorated as a function of invasive plants and habitat fragmentation. Expansion of juniper (genus Juniperus L.) trees and invasion of annual grasses into sagebrush (genus Artemisia L.) ecosystems have contributed to habitat degradation for Greater Sage-Grouse (Centrocercus urophasianus (Bonaparte, 1827); hereinafter Sage-Grouse), a species of conservation concern throughout its range. We evaluated relationships between habitat use in a landscape modified by juniper expansion and annual grasses and corticosterone metabolite levels (stress responses) in feces (FCORTm) of female Sage-Grouse. We used remotely sensed data to estimate vegetation cover within the home ranges of hens and accounted for factors that influence FCORTm in other vertebrates, such as age and weather. We collected 35 fecal samples from 22 radio-collared hens during the 2017–2018 brood-rearing season (24 May–26 July) in southwestern Idaho (USA). Concentrations of corticosterone increased with home range size but decreased with reproductive effort and temperature. The importance of home range size suggests that maintaining or improving habitats that promote smaller home ranges would likely facilitate a lower stress response by hens, which should benefit Sage-Grouse survival and reproduction.

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Shynder, Oleksandr I., Vitaliy P. Kolomiychuk, and Olga V. Melezhyk. "Spontaneous flora of O.V. Fomin Botanical Garden of Taras Shevchenko National University of Kyiv, Ukraine." Environmental & Socio-economic Studies 10, no. 1 (March 1, 2022): 38–56. http://dx.doi.org/10.2478/environ-2022-0004.

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Abstract For the first time we compiled a full checklist of the spontaneous flora of O.V. Fomin Botanical Garden of Taras Shevchenko National University, Kyiv. Native (281) and alien (243) taxa of the flora were analyzed. Among the alien species there are 115 xenophytes (including 71 archaeophytes and 44 neophytes), 128 ergasiophygophytes (including 3 archaeophytes and 125 neophytes). Four species of alien plants were listed for the first time for the flora of Ukraine: Arabis procurrens, Lactuca sibirica, Polanisia dodecandra subsp. trachysperma and Talinum paniculatum. It was found that the alien fraction of the flora is dominated by a stable component (54.7%), and among the ergasiophygophytes, most taxa (86.3%) are unstable components. Among the native plants, those species with a polyregional distribution predominate. This ratio is typical for transformed flora that have lost their natural structure. Among the alien species, the majority are sub-Mediterranean (43.6%), American (23.9%) and Asian (18.1%) in origin. In the biomorphological structure of the species of native plants perennial grasses predominate (65.3%), among xenophytes - annual grasses are dominant (74.8%), and among ergasiophygophytes perennial grasses predominate (43.8%). But despite the large number of alien plants in the botanical garden, their invasion can be mostly contained. The most widespread invasive plant is Parthenocissus vitacea, in addition, a number of potentially invasive plants need monitoring, in particular Parietaria officinalis, Phytolacca acinosa, Thladiantha dubia and some others. In addition, there is a list of introductions which have high naturalization rates and over time could replenish the composition of the spontaneous flora.

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Pastick, Neal J., Devendra Dahal, Bruce K. Wylie, Sujan Parajuli, Stephen P. Boyte, and Zhouting Wu. "Characterizing Land Surface Phenology and Exotic Annual Grasses in Dryland Ecosystems Using Landsat and Sentinel-2 Data in Harmony." Remote Sensing 12, no. 4 (February 22, 2020): 725. http://dx.doi.org/10.3390/rs12040725.

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Invasive annual grasses, such as cheatgrass (Bromus tectorum L.), have proliferated in dryland ecosystems of the western United States, promoting increased fire activity and reduced biodiversity that can be detrimental to socio-environmental systems. Monitoring exotic annual grass cover and dynamics over large areas requires the use of remote sensing that can support early detection and rapid response initiatives. However, few studies have leveraged remote sensing technologies and computing frameworks capable of providing rangeland managers with maps of exotic annual grass cover at relatively high spatiotemporal resolutions and near real-time latencies. Here, we developed a system for automated mapping of invasive annual grass (%) cover using in situ observations, harmonized Landsat and Sentinel-2 (HLS) data, maps of biophysical variables, and machine learning techniques. A robust and automated cloud, cloud shadow, water, and snow/ice masking procedure (mean overall accuracy >81%) was implemented using time-series outlier detection and data mining techniques prior to spatiotemporal interpolation of HLS data via regression tree models (r = 0.94; mean absolute error (MAE) = 0.02). Weekly, cloud-free normalized difference vegetation index (NDVI) image composites (2016–2018) were used to construct a suite of spectral and phenological metrics (e.g., start and end of season dates), consistent with information derived from Moderate Resolution Image Spectroradiometer (MODIS) data. These metrics were incorporated into a data mining framework that accurately (r = 0.83; MAE = 11) modeled and mapped exotic annual grass (%) cover throughout dryland ecosystems in the western United States at a native, 30-m spatial resolution. Our results show that inclusion of weekly HLS time-series data and derived indicators improves our ability to map exotic annual grass cover, as compared to distribution models that use MODIS products or monthly, seasonal, or annual HLS composites as primary inputs. This research fills a critical gap in our ability to effectively assess, manage, and monitor drylands by providing a framework that allows for an accurate and timely depiction of land surface phenology and exotic annual grass cover at spatial and temporal resolutions that are meaningful to local resource managers.

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Dyer, Andrew R. "The seed ecology of Aegilops triuncialis: linking trait variation to growing conditions." Seed Science Research 27, no. 3 (May 24, 2017): 183–98. http://dx.doi.org/10.1017/s0960258517000174.

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AbstractAdaptive plastic responses in invasive species allow for establishment and persistence despite the lack of genetic matching to new environments. The capacity of annual species to invade habitats to which they are not adapted is likely to be predicated on post-invasion seed trait variation correlated with conditions in the new habitat. To test this, I compared variation in seed traits and germination patterns of Aegilops triuncialis, an invasive annual grass, from 69 sample populations from 24 sites in California (USA) across 13 years. Seed mass, germination fractions, seed viability, and strength of induced dormancy between dimorphic seed pairs were used to investigate plastic variation within and among populations, across two general soil types, and among two widespread maternal genotypes. I found that seed mass variation was constrained although both seed types showed a 3-fold range among populations, 20–25% variation within populations between years, and was positively correlated with longer growing seasons. However, induced seed dormancy in the small seed type was correlated with large seed mass and to late-season precipitation, suggesting that longer growing seasons influence the strength of maternal and sibling chemical signals that induce dormancy in the small seeds. Thus variation in small seed germination fractions varies with the growing conditions experienced by the maternal plant. The greater longevity of the small seed type suggests that plasticity in germination in this species may contribute to seed bank formation, which is atypical of invasive annual grasses in California, and this may contribute to the persistence and spread of A. triuncialis in invaded ranges.

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Parker-Allie, F., C. F. Musil, and W. Thuiller. "Effects of climate warming on the distributions of invasive European annual grasses: A southern African perspective." South African Journal of Botany 73, no. 2 (April 2007): 306. http://dx.doi.org/10.1016/j.sajb.2007.02.098.

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Parker-Allie, F., C. F. Musil, and W. Thuiller. "Effects of climate warming on the distributions of invasive Eurasian annual grasses: a South African perspective." Climatic Change 94, no. 1-2 (February 17, 2009): 87–103. http://dx.doi.org/10.1007/s10584-009-9549-7.

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Sebastian, Derek J., Margaret B. Fleming, Eric L. Patterson, James R. Sebastian, and Scott J. Nissen. "Indaziflam: a new cellulose-biosynthesis-inhibiting herbicide provides long-term control of invasive winter annual grasses." Pest Management Science 73, no. 10 (June 12, 2017): 2149–62. http://dx.doi.org/10.1002/ps.4594.

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Sebastian, Derek J., Scott J. Nissen, James R. Sebastian, Paul J. Meiman, and K. George Beck. "Preemergence Control of Nine Invasive Weeds with Aminocyclopyrachlor, Aminopyralid, and Indaziflam." Invasive Plant Science and Management 10, no. 01 (March 2017): 99–109. http://dx.doi.org/10.1017/inp.2017.7.

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There are an estimated 400 million hectares of non-cropland in the United States primarily designated as rangeland and pastureland, and there are more than 300 invasive weeds found on these sites, causing an estimated annual loss of $5 billion. Among the most invasive and problematic weeds are Dalmatian toadflax, diffuse knapweed, downy brome, and musk thistle. Currently, herbicides are the most common management strategy for broadleaf weeds and invasive winter annual grasses. Indaziflam, a new herbicide for invasive plant management in non-crop areas, is a cellulose-biosynthesis inhibitor capable of providing residual invasive winter annual grass control up to 3 yr after treatment (YAT). A field experiment was conducted to determine whether residual Dalmatian toadflax and downy brome control by aminocyclopyrachlor, imazapic, and picloram could be extended by tank mixing these herbicides with indaziflam. Indaziflam tank mixed with aminocyclopyrachlor, imazapic, and picloram provided increased Dalmatian toadflax (84% to 91%) and downy brome (89% to 94%) control 4 YAT, compared with treatments excluding indaziflam. Treatments without indaziflam controlled 50% to 68% of Dalmatian toadflax and <25% downy brome 4 YAT. Based on these results, a greenhouse dose–response experiment was conducted with aminocyclopyrachlor, aminopyralid, and indaziflam to compare preemergence control of nine common non-crop weeds. Averaged across species, aminocyclopyrachlor and aminopyralid GR50values (herbicide concentration resulting in 50% reduction in plant biomass) were 29 and 52 times higher compared with indaziflam, respectively. These data suggest that indaziflam could be used for residual control of non-crop weeds as a tank-mix partner with other foliar-applied broadleaf herbicides.

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Ditomaso, Joseph M., Matthew L. Brooks, Edith B. Allen, Ralph Minnich, Peter M. Rice, and Guy B. Kyser. "Control of Invasive Weeds with Prescribed Burning." Weed Technology 20, no. 2 (June 2006): 535–48. http://dx.doi.org/10.1614/wt-05-086r1.1.

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Prescribed burning has primarily been used as a tool for the control of invasive late-season annual broadleaf and grass species, particularly yellow starthistle, medusahead, barb goatgrass, and several bromes. However, timely burning of a few invasive biennial broadleaves (e.g., sweetclover and garlic mustard), perennial grasses (e.g., bluegrasses and smooth brome), and woody species (e.g., brooms and Chinese tallow tree) also has been successful. In many cases, the effectiveness of prescribed burning can be enhanced when incorporated into an integrated vegetation management program. Although there are some excellent examples of successful use of prescribed burning for the control of invasive species, a limited number of species have been evaluated. In addition, few studies have measured the impact of prescribed burning on the long-term changes in plant communities, impacts to endangered plant species, effects on wildlife and insect populations, and alterations in soil biology, including nutrition, mycorrhizae, and hydrology. In this review, we evaluate the current state of knowledge on prescribed burning as a tool for invasive weed management.

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Ingham, Claudia S. "Himalaya Blackberry (Rubus armeniacus) Response to Goat Browsing and Mowing." Invasive Plant Science and Management 7, no. 3 (September 2014): 532–39. http://dx.doi.org/10.1614/ipsm-d-13-00065.1.

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AbstractHimalaya blackberry is a nonnative shrub that has invaded sites throughout the Pacific Northwest. Its persistent canopy and large underground crowns create a competitive environment that prevents desirable species from germinating, establishing, or both. Cutleaf blackberry grows in association with Himalaya blackberry, and control efforts frequently target these two species. Control of Himalaya blackberry is complicated by vigorous vegetative regrowth after mechanical control, including mowing, and variable response to chemical methods. Recent interest in the use of goat browsing for invasive plant control has led land managers to use a variety of browsing regimes to control unwanted species through disturbance by herbivory. This study examined changes in functional group percent cover in a perennial grass pasture invaded by Himalaya blackberry and cutleaf blackberry in the southern Willamette Valley of Oregon. The appearance of species and their functional group membership after three treatment protocols are evaluated. Changes in the percentage of cover by Himalaya and cutleaf blackberries, annual grasses, perennial grasses, annual forbs, and perennial forbs were examined after two annual treatments with (1) high-intensity–short-duration goat browsing, (2) mowing, and (3) high-intensity–short-duration goat browsing followed by mowing. These data were then compiled by functional group to assess trends in the plants' revegetating the pasture after treatment. All treatments caused a significant decline in the percent cover of the invasive blackberries (P < 0.0001), but differences among treatments were not significant. The increase in the percent cover of perennial forbs for plots treated with goat browsing followed by mowing was significantly greater (P = 0.008) than it was in plots browsed only and those mowed only. Changes in percent cover of other functional groups were not significantly different with browsing or mowing treatments. Individual species within the perennial grass and perennial forb groups are discussed.

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Lazarus, Brynne E., Matthew J. Germino, Martha Brabec, Logan Peterson, Ryan N. Walker, and Ann Moser. "Post-Fire Management-Scale Trials of Bacterial Soil Amendment MB906 Show Inconsistent Control of Invasive Annual Grasses." Rangeland Ecology & Management 73, no. 6 (November 2020): 741–48. http://dx.doi.org/10.1016/j.rama.2020.03.005.

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Bansal, Sheel, Jeremy J. James, and Roger L. Sheley. "The effects of precipitation and soil type on three invasive annual grasses in the western United States." Journal of Arid Environments 104 (May 2014): 38–42. http://dx.doi.org/10.1016/j.jaridenv.2014.01.010.

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McGlone, Christopher M., Carolyn Hull Sieg, Thomas E. Kolb, and Ty Nietupsky. "Established native perennial grasses out-compete an invasive annual grass regardless of soil water and nutrient availability." Plant Ecology 213, no. 3 (October 19, 2011): 445–57. http://dx.doi.org/10.1007/s11258-011-9992-1.

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Sbatella, Gustavo M., Robert G. Wilson, Stephen F. Enloe, and Charlie Hicks. "Propoxycarbazone-Sodium and Imazapic Effects on Downy Brome (Bromus tectorum) and Newly Seeded Perennial Grasses." Invasive Plant Science and Management 4, no. 1 (March 2011): 78–86. http://dx.doi.org/10.1614/ipsm-d-10-00010.1.

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AbstractVigorous stands of perennial grasses can effectively provide long-term control of many invasive plants on rangelands. However, in degraded conditions, successful reestablishment of perennial grasses can be compromised by invasive annual grasses, such as downy brome. Propoxycarbazone-sodium is a selective herbicide currently labeled for downy brome control in small grains, but its potential use on rangelands is unknown. Studies were conducted from 2004 through 2008 at three rangeland sites in Colorado and Nebraska to evaluate downy brome control and perennial grass injury with propoxycarbazone-sodium and imazapic. Propoxycarbazone-sodium provided satisfactory downy brome control with grass injury equal to or less than imazapic when rainfall followed the fall application. A second set of studies was conducted from 2007 to 2008 at Lingle, WY, and Scottsbluff, NE, to determine the plant-back interval and postemergence application response of seven perennial grass species to propoxycarbazone-sodium and imazapic. Grass tolerance to both herbicides was good when applied 90 and 120 d before planting (DBP). However, grass injury increased as plant-back interval decreased. The greatest impact on plant biomass was observed from herbicide applied at planting or after planting. Crested and intermediate wheatgrass (Agropyron cristatumandThinopyrum intermedium) biomass production was not affected when herbicides were applied 90 or 120 DBP. Western wheatgrass (Pascopyrum smithii) and Russian wildrye (Psathyrostachys juncea) showed tolerance to imazapic applied before planting. Smooth brome (Bromus inermis), sheep fescue (Festuca ovina), and orchardgrass (Dactylis glomerata) showed the least amount of tolerance to propoxycarbazone-sodium and imazapic.

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Lambert, Adam M., Tom L. Dudley, and Kristin Saltonstall. "Ecology and Impacts of the Large-Statured Invasive Grasses Arundo donax and Phragmites australis in North America." Invasive Plant Science and Management 3, no. 4 (December 2010): 489–94. http://dx.doi.org/10.1614/ipsm-d-10-00031.1.

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AbstractLarge-statured invasive grasses (LSIGs) constitute a distinct functional group with characteristic life history traits that facilitate colonization and aggressive growth in aquatic ecosystems, particularly those modified by human activities. These species typically form monocultures in the systems they invade and have wide-ranging and negative impacts on biodiversity and ecosystem processes. In March 2008, a special symposium was held as part of the Western Society of Weed Scientists annual meeting to synthesize our current knowledge of the ecological impacts and management of two notorious LSIGs: Arundo donax and Phragmites australis. In this volume of Invasive Plant Science and Management, symposium participants provide articles summarizing existing knowledge, recent research progress, and research needs for these two taxa. Here, we summarize the basic biology of these species and suggest the use of a more holistic approach to deal with the effects and management of LSIG invasions.

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Abella, Scott R., Lindsay P. Chiquoine, Jeremy M. Moss, Eric D. Lassance, and Charles D. Schelz. "Developing minimal-input techniques for invasive plant management: perimeter treatments enlarge native grass patches." Invasive Plant Science and Management 13, no. 2 (March 27, 2020): 108–13. http://dx.doi.org/10.1017/inp.2020.9.

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AbstractThere is a continual need for invasive plant science to develop approaches for cost-effectively benefiting native over nonnative species in dynamic management and biophysical contexts, including within predominantly nonnative plant landscapes containing only small patches of native plants. Our objective was to test the effectiveness of a minimal-input strategy for enlarging native species patches within a nonnative plant matrix. In Pecos National Historical Park, New Mexico, USA, we identified 40 native perennial grass patches within a matrix of the nonnative annual forb kochia [Bassia scoparia (L.) A.J. Scott]. We mechanically cut B. scoparia in a 2-m-wide ring surrounding the perimeters of half the native grass patches (with the other half as uncut controls) and measured change in native grass patch size (relative to pretreatment) for 3 yr. Native grass patches around which B. scoparia was cut grew quickly the first posttreatment year and by the third year had increased in size four times more than control patches. Treated native grass patches expanded by an average of 25 m2, from 4 m2 in October 2015 before treatment to 29 m2 in October 2018. The experiment occurred during a dry period, conditions that should favor B. scoparia and contraction of the native grasses, suggesting that the observed increase in native grasses occurred despite suboptimal climatic conditions. Strategically treating around native patches to enlarge them over time showed promise as a minimal-input technique for increasing the proportion of the landscape dominated by native plants.

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CRESPO, MANUEL B., Mª ÁNGELES ALONSO, and MARIO MARTÍNEZ-AZORÍN. "Melinis maroccana (Melinidinae, Paniceae, Poaceae), a new combination for the Moroccan flora, and comments on related taxa." Phytotaxa 433, no. 1 (February 13, 2020): 77–80. http://dx.doi.org/10.11646/phytotaxa.433.1.9.

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In the framework of a revision of the Iberian Paniceae Brown (1814: 582) for the Flora iberica project, we came across the aggregate of the “Natal grass”, Melinis repens (Willdenow 1797: 322) Zizka (1988: 55), a group of annual to short-lived perennial grasses being native and widely distributed in Tropical Africa, Arabian Peninsula, India, Cape Verde, and the Canary Islands. Only M. repens s.str. is currently naturalised in the Mediterranean basin, America, Australia, southeastern Asia and the Pacific Islands, where it was mostly introduced for ornamental use, forage or stabilization and cover on disturbed sites, and has become an invasive alien species (Kaufman 2012).

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Silvério, Divino V., Paulo M. Brando, Jennifer K. Balch, Francis E. Putz, Daniel C. Nepstad, Claudinei Oliveira-Santos, and Mercedes M. C. Bustamante. "Testing the Amazon savannization hypothesis: fire effects on invasion of a neotropical forest by native cerrado and exotic pasture grasses." Philosophical Transactions of the Royal Society B: Biological Sciences 368, no. 1619 (June 5, 2013): 20120427. http://dx.doi.org/10.1098/rstb.2012.0427.

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Changes in climate and land use that interact synergistically to increase fire frequencies and intensities in tropical regions are predicted to drive forests to new grass-dominated stable states. To reveal the mechanisms for such a transition, we established 50 ha plots in a transitional forest in the southwestern Brazilian Amazon to different fire treatments (unburned, burned annually (B1 yr ) or at 3-year intervals (B3 yr )). Over an 8-year period since the commencement of these treatments, we documented: (i) the annual rate of pasture and native grass invasion in response to increasing fire frequency; (ii) the establishment of Brachiaria decumbens (an African C 4 grass) as a function of decreasing canopy cover and (iii) the effects of grass fine fuel on fire intensity. Grasses invaded approximately 200 m from the edge into the interiors of burned plots (B1 yr : 4.31 ha; B3 yr : 4.96 ha) but invaded less than 10 m into the unburned plot (0.33 ha). The probability of B. decumbens establishment increased with seed availability and decreased with leaf area index. Fine fuel loads along the forest edge were more than three times higher in grass-dominated areas, which resulted in especially intense fires. Our results indicate that synergies between fires and invasive C 4 grasses jeopardize the future of tropical forests.

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Aigner, Paul A., and Rhett J. Woerly. "Herbicides and Mowing to Control Barb Goatgrass (Aegilops triuncialis) and Restore Native Plants in Serpentine Grasslands." Invasive Plant Science and Management 4, no. 4 (December 2011): 448–57. http://dx.doi.org/10.1614/ipsm-d-11-00027.1.

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AbstractSerpentine grasslands are relatively free of the invasive species that typify other California grasslands, but recently are threatened by the spread of barb goatgrass, a Eurasian annual that is unique in its tolerance of serpentine soils. We evaluated two graminicides (clethodim and fluazifop), one broad-spectrum herbicide (glyphosate), mowing, and hand pulling for their effectiveness in controlling barb goatgrass and for restoring native species cover and diversity. We also evaluated application timing for the graminicides: before goatgrass flowering (early season), at flower initiation (midseason), and at early seed development (late season). Glyphosate was applied at early seed development. The 10 treatment combinations were applied to 10 blocks of 4-m2 (43-ft2) experimental plots in an inner Coast Range serpentine grassland with high cover of barb goatgrass but few other nonnative species. After 2 yr of treatment, all treatments except glyphosate reduced goatgrass frequency. Hand pulling, fluazifop, and mowing were most effective at controlling goatgrass, reducing frequency by 60, 51, and 48%, respectively (compared to a 30% increase on control plots). Midseason applications of clethodim and fluazifop were more effective than those applied early or late. Hand pulling, fluazifop, and clethodim increased native forb frequency by 31, 46, and 74%, respectively, with the benefit of the graminicides decreasing with later applications. Native grasses were at least partially resistant to the graminicides. Cover of one sided blue grass (Poa secunda), the most widespread native grass, might have been reduced slightly by early-season applications but was increased by late-season applications. Cover of soft brome (Bromus hordeaceus), the only other widespread nonnative species in the study, was reduced by early-season applications of the graminicides. Clethodim and fluazifop show great potential to selectively remove barb goatgrass and other nonnative annual grasses in grasslands that are otherwise dominated by native grasses and forbs. Mowing is a less selective, but viable alternative.

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Jones, Thomas A., Thomas A. Monaco, and Jeremy J. James. "Launching the Counterattack: Interdisciplinary Deployment of Native-Plant Functional Traits for Repair of Rangelands Dominated by Invasive Annual Grasses." Rangelands 32, no. 1 (February 2010): 38–42. http://dx.doi.org/10.2111/rangelands-d-09-00011.1.

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James, J. J. "Leaf nitrogen productivity as a mechanism driving the success of invasive annual grasses under low and high nitrogen supply." Journal of Arid Environments 72, no. 10 (October 2008): 1775–84. http://dx.doi.org/10.1016/j.jaridenv.2008.05.001.

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Durigan, Giselda, Marinez Ferreira de Siqueira, and Geraldo Antonio Daher Correa Franco. "Threats to the Cerrado remnants of the state of São Paulo, Brazil." Scientia Agricola 64, no. 4 (August 2007): 355–63. http://dx.doi.org/10.1590/s0103-90162007000400006.

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Patches of natural vegetation remaining in landscapes occupied by man are continuously under threat due to the edge effects and also to land use types around these remnants. The most frequent threats and land use types in the vicinity of 81 Cerrado (tropical savanna type) fragments in the State of São Paulo, Brazil, were analyzed in order to verify if the frequency of every type of disturbance to the natural ecosystem depends on the neighboring land use. The hypothesis of the study assumes that environmental threats are correlated with land use around protected areas. From the 81 areas, the most frequent human-induced land cover types around the Cerrado remnants were: pasture (recorded in 78% of the areas), sugarcane plantations (26%), roads (19%), annual crops and reforestation (14% each). The most frequent sources of threats were invasive grasses (35% of the areas partially or totally invaded) and cattle (observed in 32% of the areas), followed by deforestation (21%), and fire (21%). The chi-square analysis revealed that, with the exception of deforestation, which does not depend on land use, all other threats are influenced by the neighboring land use. The occurrence of invasive grasses and fires are strongly favored by the presence of roads and urban areas. Sugarcane, reforestation, and permanent crops were the less impacting land use types found in the study area, when only considering impact frequency. These land use types have fire and weed control, and also exclude cattle, indirectly protecting natural ecosystems.

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Ostoja, Steven M., Matthew L. Brooks, Tom Dudley, and Steven R. Lee. "Short-Term Vegetation Response Following Mechanical Control of Saltcedar (Tamarix spp.) on the Virgin River, Nevada, USA." Invasive Plant Science and Management 7, no. 2 (June 2014): 310–19. http://dx.doi.org/10.1614/ipsm-d-13-00064.1.

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AbstractTamarisk (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.

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Belovsky, Gary E., and Jennifer B. Slade. "Climate change and primary production: Forty years in a bunchgrass prairie." PLOS ONE 15, no. 12 (December 23, 2020): e0243496. http://dx.doi.org/10.1371/journal.pone.0243496.

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Over the past 109 years, a Montana intermountain bunchgrass prairie annually became warmer (0.7°C) and drier (27%). The temperature and precipitation trends continued since 1978, as we studied nitrogen availability, annual aboveground primary production (ANPP), plant phenology and species composition. Given the annual increase in temperature and decrease in precipitation, ANPP might be expected to decline; however, it increased by 110%, as the period of greatest production (late-May–June) became wetter and cooler, counter to the annual pattern, and this was strongest at lower elevations. Grass production increased by 251%, while dicot production declined by 65%, which increased grass relative abundance by 54%. Summer temperatures increased 12.5% which increased plant senescence by 119% and decreased fall plant regrowth by 68%. More intense summer senescence changed plant species composition in favor of more drought tolerant species. The greater ANPP and summer senescence may increase susceptibility for fire, but fire tolerance of the plant species composition did not change. Invasive plant species increased 108% over the study with annual grasses accounting for >50% of this increase, which further increased summer plant senescence. Therefore, seasonal climate changes at a smaller geographical scale (local), rather than average annual climate changes over a larger geographical scale (regional), may better reflect plant community responses, and this makes ecological forecasting of climate change more difficult.

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Concilio, Amy L. "Effectiveness and Cost of Downy Brome (Bromus tectorum) Control at High Elevation." Invasive Plant Science and Management 6, no. 4 (December 2013): 502–11. http://dx.doi.org/10.1614/ipsm-d-13-00008.1.

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AbstractDowny brome (Bromus tectorum) is an invasive, annual grass that has spread through much of the Great Basin desert but remains patchy at high elevation. This study evaluates control options for outlier infestations in the eastern Sierra Nevada, CA, based on their ecological effectiveness and their economic and practical feasibility. I tested the efficacy of hand-pulling, sheet-mulching, and soil solarization followed by broadcast and seedball seeding of native forbs and grasses. Downy brome cover, density, and dominance in the seed bank decreased with all removal treatments. Soil solarization and sheet mulching were most successful at eliminating downy brome (decreasing density by 99% after just 1 yr of treatment in both cases), but they had negative nontarget impacts on other herbaceous species. Germination of native seeds was low with both broadcast and seedball seeding, probably because of dry conditions. Each of the methods tested has potential for decreasing or eliminating small-scale, outlier infestations of downy brome along roadsides and in disturbed sites and thereby helping to contain the invasion.

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Allen, Edith B., Louise M. Egerton-Warburton, Bridget E. Hilbig, and Justin M. Valliere. "Interactions of arbuscular mycorrhizal fungi, critical loads of nitrogen deposition, and shifts from native to invasive species in a southern California shrubland." Botany 94, no. 6 (June 2016): 425–33. http://dx.doi.org/10.1139/cjb-2015-0266.

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Anthropogenic nitrogen (N) deposition and invasive species are causing declines in global biodiversity, and both factors impact the diversity and functioning of arbuscular mycorrhizal (AM) fungi. Shifts in arbuscular mycorrhizal fungal (AMF) communities can generate feedback to native plants and affect their success, as was observed in California’s coastal sage scrub, which is a Mediterranean-type shrubland threatened by invasive grasses. As vegetation-type conversion from native shrubland to exotic annual grassland increased along a gradient of increasing N deposition, the richness of native plant species and of spore morphotypes decreased. Rapid declines in all plant and fungal values occurred at the critical load (CL) of 10–11 kg N·ha−1·year−1, indicating that AM fungi respond to the same environmental signals as the plants, and can be used to assess CL. Shrub root colonization also decreased along the N gradient, but colonization of the invasive grass was dominated by a fine AMF endophyte that was unresponsive to elevated N. A greenhouse experiment to assess AMF functioning showed that the native shrub Artemisia californica Less. had a negative growth response to an inoculum from high-N but not low-N soils, whereas the invasive grass Bromus rubens L. had a positive response to both inocula. Differential functioning of AM fungi under N deposition may in part explain vegetation-type conversion and the decline of this native shrubland.

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Souza, A., CZ Sandrin, MFA Calió, ST Meirelles, VR Pivello, and RCL Figueiredo-Ribeiro. "Seasonal variation of soluble carbohydrates and starch in Echinolaena inflexa, a native grass species from the Brazilian savanna, and in the invasive grass Melinis minutiflora." Brazilian Journal of Biology 70, no. 2 (May 2010): 395–404. http://dx.doi.org/10.1590/s1519-69842010000200023.

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Echinolaena inflexa (Poir.) Chase is an abundant C3 grass species with high biomass production in the Brazilian savanna (cerrado); Melinis minutiflora Beauv. is an African C4 forage grass widespread in cerrado and probably displacing some native herbaceous species. In the present work, we analysed seasonally the content and composition of soluble carbohydrates, the starch amounts and the above-ground biomass (phytomass) of E. inflexa and M. minutiflora plants harvested in two transects at 5 and 130 m from the border in a restrict area of cerrado at the Biological Reserve and Experimental Station of Mogi-Guaçu (SP, Brazil). Results showed that water soluble carbohydrates and starch amounts from the shoots of both species varied according to the time of the year, whilst in the underground organs, variations were observed mainly in relation to the transects. Marked differences in the pattern of the above-ground biomass production between these two grasses relative to their location in the Reserve were also observed, with two peaks of the invasive species (July and January) at the Reserve border. The differences in carbohydrate accumulation, partitioning and composition of individual sugars concerning time of the year and location in the Reserve were more related to the annual growth cycle of both grasses and possibly to specific physiological responses of M. minutiflora to disturbed environments in the Reserve border.

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Faris, Ashleigh M., Michael J. Brewer, and Norman C. Elliott. "Parasitoids and Predators of the Invasive Aphid Melanaphis sorghi Found in Sorghum and Non-Crop Vegetation of the Sorghum Agroecosystem." Insects 13, no. 7 (July 6, 2022): 606. http://dx.doi.org/10.3390/insects13070606.

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Melanaphis sorghi (Theobald) (sorghum aphid), (=Melanaphis sacchari Zehntner) (Hemiptera: Aphididae), is an invasive pest of Sorghum bicolor (L.) in North America. Over 19 species of predators and parasitoids have been found to prey on M. sorghi. Natural enemies may reside in vegetation such as sorghum in cultivation (in-season) and persist after harvest (off-season), in Johnson grass (Sorghum halepense) (L.) and riparian areas consisting of shrubs and grasses, including Johnson grass. The objective was to assess the ability of these vegetation types to harbor M. sorghi natural enemies during and between annual grain sorghum production. Predator diversity was greatest in riparian vegetation in-season, with twelve species detected across seven families, and four orders of insects. Six lady beetle (Coleoptera: Coccinellidae) species were abundant in-season, and Cycloneda sanguinea (L.) persisted at relatively high abundance off-season. Parasitoid diversity was more limited (two primary parasitoids and one hyperparasitoid detected) with the primary parasitoids commonly detected. Aphelinus nigritus (Howard) (Hymenoptera: Aphelinidae), accounted for 85% and 57% of parasitoids in- and off-season, respectively. Aphelinus nigritus abundance was steady across the annual sorghum season in all vegetation types. Results from this study will inform land-management strategies on how diverse vegetations can play a role in the biological control of M. sorghi.

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Chichizola, Giselle Ailin, Sofía Laura Gonzalez, and Adriana Edit Rovere. "Alien plant species on roadsides of the northwestern Patagonian steppe (Argentina)." PLOS ONE 16, no. 2 (February 11, 2021): e0246657. http://dx.doi.org/10.1371/journal.pone.0246657.

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The introduction of alien species represents one of the greatest threats to biodiversity worldwide. Highway construction increases the dispersal and invasion of exotic plant species. This study examined the assembly process of the plant communities to determine whether the roadsides of the Patagonian steppe represent a reservoir and dispersal source of invasive exotic species. We analyzed the composition of exotic and native species and functional groups present in the established vegetation and seed banks of roadsides and reference areas nearby. The type of dispersal of exotic and native species at the roadsides was also evaluated. Total cover and that of exotic and native species was lower at the roadsides than in the reference areas; however, at the roadsides the cover and seed abundance of exotic species was higher than that of native species. In the roadsides vegetation, native shrubs such as Acaena splendens predominated, along with exotic perennial herbs and grasses which were mainly represented by Rumex acetosella. In the seed bank the predominant species were exotic perennial herbs, also represented by R. acetosella, annual exotic species such as Epilobium brachycarpum and Verbascum thapsus, and annual native species such as Heliotropium paronychioides. No exotic shrubs were found either at the roadsides or in the reference areas. The species at the roadsides did not present a dominant type of dispersal. The abundance of exotic species at the roadsides, both in the aboveground vegetation and the seed bank, may be due to the stressful environment and the characteristics of the species themselves, such as the ability to form seed banks. This work revealed that the roadsides of the Patagonian steppe constitute reservoirs of invasive exotic species, highlighting the importance of identifying them and controlling their spread, with a view to generating ecosystem management programs.

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