Academic literature on the topic 'Invasive annual grasses'
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Journal articles on the topic "Invasive annual grasses"
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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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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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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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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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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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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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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.
Dissertations / Theses on the topic "Invasive annual grasses"
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Sellereite, Sharon Jones. "Conservation Reserve Program (CRP) grasses in the Columbia Plateau the effects of time, an invasive annual grass and burning /." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Fall2009/S_Sellereite_101409.pdf.
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Thesis (M.S. in environmental science)--Washington State University, December 2009.Title from PDF title page (viewed on Jan. 22, 2010). "School of Earth and Environmental Science." Includes bibliographical references (p. 18-23).
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Lenz, Tanja. "The effect of resource dynamics on invasive annual and native perennial grasses in grasslands of the mid-north of South Australia /." Title page, table of contents and abstract only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phl575.pdf.
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Rodriguez-Buriticá, Susana. "Effects of the spatial heterogeneity formed by Ambrosia dumosa on individual and population growth of the invasive annual grass Schismus barbatus." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1233264311.
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Camp, Spencer Chad. "Improving Perennial Bunchgrass Seeding Success in Annual Grass Invaded Areas Using Pre-Emergent Herbicide and Furrowing Techniques." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/8881.
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Exotic annual weeds have transformed western North America, particularly in sagebrush-steppe systems. Restoration of these invaded sites has been met with low levels of success. Pre-emergent herbicide provides a means to control annual weeds, but typically, this treatment does not allow for the concurrent seeding of desired species. Seeding within a deep, U-shaped furrow following herbicide application may be a method to reduce pre-emergent herbicide effects by transferring the herbicide away from the seed at the time of planting. We tested this potential planting technique by spraying plots with or without the pre-emergent herbicide imazapic, and planting bunchgrass seeds either with or without a deep furrow. Treatments (i.e. spraying and furrowing) were applied using mechanical equipment within a single pass, at six sites. In plots without imazapic, we found that deep furrows generally had higher seedling emergence, density of juvenile plants, and above-ground biomass when compared to no furrows. For plots with imazapic, deep furrows also generally improved measured plant metrics for the seeded species compared to plots without furrows. For example, the density of juvenile plants in deep furrows ranged, by study site, between 62% – 97% and 41% – 89% higher than the no furrow treatment, for plots with and without imazapic, respectively. Plots with imazapic and deep furrows was not always as effective as plots without imazapic and deep furrows. Deep furrows also reduced exotic annual weeds in the first year after planting, but weed reduction was generally more effective when this treatment was applied with imazapic. Overall, this research provides evidence that in most instances, the use of deep furrows alone is sufficient to improve seeding success. However, in areas with high weed cover, the application of herbicide followed by the creation of deep furrows in a one-pass system should be considered.
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Valente, Daine Valente. "Prospecção e transferibilidade de marcadores est-ssr usados para análises filogenéticas em poa annua l." Universidade Federal do Pampa, 2016. http://dspace.unipampa.edu.br:8080/xmlui/handle/riu/361.
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Poa annua L. é a única espécie invasora de plantas com flores que obteve sucesso reprodutivo na Antártica, constituindo uma ameaça para as espécies nativas desse ecossistema. A hipótese da origem e colonização dessa gramínea nesse ambiente extremo é a de que as plantas pioneiras teriam vindo da Polônia, porém não é descartada a possibilidade de mútiplos eventos de introdução e diferentes fontes de distribuição. A disponibilidade de dados de sequências expressas (EST) tem facilitado o desenvolvimento de marcadores microssatélites (SSR) que podem ser utilizados como ferramentas para estudos populacionais em diferentes níveis, fluxo gênico, níveis de parentesco e informações sobre padrões filogeográficos. O objetivo desse trabalho foi desenvolver marcadores microssatélites a partir de sequências de regiões expressas da família Poaceae, testar o potencial de transferência em P. annua e utilizar esses marcadores para análise filogeográfica de P. annua, a fim de esclarecer a origem e colonização dessa espécie na Antártica. A prospecção de marcadores microssatélites foi desenvolvida com ferramentas de bioinformática, através de análises in sílico SSR em banco de dados EST para família Poaceae, disponíveis no Genbank (NCBI). Foram utilizados os programas CAP3 e SSRLocator para prospecção dos marcadores microssatélites. Uma pesquisa de Termos Gene Ontology (GO) foi realizada no banco de dados de sequências ESTs para avaliar associações entre locus SSR e processos biológicos, componentes celulares e função molecular de genes conhecidos, utilizando os programas Blast2GO e Revigo. O teste de transferência dos primers e análise molecular de P. annua foram conduzidos através da Reação em Cadeia da Polimerase (PCR). Foram prospectadas uma lista de 568 pares de primers, destes foram sintetizados 28 marcadores microssatélites para a transferência em P. annua. 68% dos marcadores EST-SSR tiveram potencial de transferência para esta espécie. A análise sugere que as amostras da Antártica são diferentes das amostras do Chile, Brasil, Irlanda e Argentina. Além disso, foram encontrados 613 transcritos divididos em 302 famílias gênicas. Com esta análise, foi possível desenvolver ferramentas moleculares para a análise genética com P. annua e outras espécies de gramíneas, mapear os motivos mais frequentes e funções dos genes em cada locus SSR, e sugerir que os diásporos de P. annua encontrados na Antártica podem ter vindos de fontes distintas das populações da America do Sul.
Poa annua L. is the only invasive species of flowering plants that reached reproductive success in Antarctica, posing a threat to native species of this ecosystem.The hypothesis of the origin and colonization of grass in this extreme environment is the pioneer plants would have come from Poland, but it is not ruled out event of multiple introduction and different sources of distribution. Recent increase in the availability of expressed sequence data (EST) has facilitated the development of microsatellite markers (SSR) can be used as tools for population studies at different levels, gene flow, relationship of levels and patterns phylogeographical information. The objective of this study was to develop microsatellite markers from expressed sequence regions of the Poaceae family, test the potential transfer in P. annua and use these markers for phylogeographic analysis of P. annua in order to clarify the origin and colonization of this species in Antarctica. The prospect of microsatellite markers was developed with bioinformatics tools, through an analysis in silico SSR in EST database to Poaceae family, available in Genbank (NCBI). Were used the CAP3 and SSRLocator programs for prospecting of microsatellite markers. A Search terms Gene Ontology (GO) were performed in ESTs sequences database to evaluate associations between SSR locus and biological processes, cellular components and molecular function of known genes, using the Blast2GO and Revigo programs. The transfer test of primers and molecular analysis of P. annua was conducted by Polymerase Chain Reaction (PCR). Were prospected a list of 568 primer pairs, these were synthesized 28 microsatellite markers for the transfer in P. annua. 68% of EST-SSR markers have potential transfer for this species. The analysis suggests that the samples from Antarctica are different from samples from Chile, Brazil, Argentina and Ireland. In addition, they found 613 transcripts divided into 302 genic families. With this analysis, it was possible to develop molecular tools for genetic analysis with P. annua and other grass species, mapping the most frequent motifs and functions of genes in each SSR locus, and suggest that the introduction of P. annua found in Antarctica may have come from sources other than South American populations.
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Muhl, Sara Ann. "Alien grass invasion of Renosterveld : influence of soil variable gradients." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/2991.
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Thesis (MScConsEcol (Conservation Ecology and Entomology))--Stellenbosch University, 2008.This thesis examines the role of agricultural activity in the process of invasion of west coast renosterveld fragments by annual alien grass species. This highly endangered vegetation type has less than 5% remaining, it is vital to understand the mechanisms allowing invasion of annual alien grasses in order to effectively prevent the loss of the many rare and endemic species found in west coast renosterveld. This study was divided into three major components. Firstly the distribution of indigenous and alien plant species in relation to fence lines, separating active agricultural fields from untransformed vegetation, was described. Regression analysis was used to test for relationships between distances from agricultural fields and soil physical and chemical characteristics in natural vegetation. Cover by annual alien invasive grasses in untransformed vegetation decreased significantly with distance away from agricultural land. Secondly alien and indigenous grass seed banks were sampled along the transects, at the same sites, in order to establish whether the seed banks correlated with above ground cover. Results varied among sites and seed banks were correlated with the vegetation cover at only one site. It appears that there are a multitude of factors determining the distribution of annual alien grass cover. Thirdly a greenhouse experiment established the role that nitrogen plays in the success of the alien grass Avena fatua. This species was grown in competition with three indigenous species, an annual forb (Dimorphotheca pluvialis), a geophyte (Oxalis purpurea) and an indigenous perennial grass (Tribolium uniolae) at three levels of soil nitrogen. The geophyte was largely unaffected, while growth of the annual and indigenous perennial grasses was negatively affected by competition with A. fatua. Nitrogen did not seem to affect competitive interactions. Management of these renosterveld patches, in order to conserve them effectively, will require a multi-faceted approach, including prevention of further invasion and removal of invasive grasses already present.
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Arnolds, Judith Lize. "Effects of the invasive annual grass Lolium multiflorum Lam. on the growth and physiology of a Southern African Mediterranean-climate geophyte Tritonia crocata (L.) Ker. Gawl. under different resource conditions / J.L. Arnolds." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1603.
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Little is known of the physiological and biochemical mechanisms underlying competitive interactions between alien invasive grasses and native taxa, and how these are affected by resource supply. Consequently, this study compared photosystem II (PS II) function, photosynthetic gas and water exchange, enzyme and pigment concentrations, flowering and biomass accumulation in an indigenous geophyte, Tritonia crocata (L.) Ker. Gawl., grown in monoculture and admixed with the alien grass, Lolium multiflorum Lam., at different levels of water and nutrient supply. Diminished stomatal conductances were the primary cause of reduced net C02 assimilation rates, and consequent biomass accumulation in T. crocata admixed with L. multiflorum at all levels of water and nutrient supply with one exception. These corresponded with decreased soil water contents induced presumably by more efficient competition for water by L. multiflorum, whose biomass was inversely correlated with soil water content. Biochemical impairments to photosynthesis were also apparent in T. crocata admixed with L. multiflorum at low levels of water and nutrient supply. These included a decline in the density of working photosystems (reaction center per chlorophyll RC/ABS), which corresponded with a decreased leaf chlorophyll a content and a decreased efficiency of conversion of excitation energy to electron transport (¥0 / l-^o), pointing to a reduction in electron transport capacity beyond QA~, a decline in apparent carboxylation efficiency and Rubisco content. At low nutrient levels but high water supply, non-stomatal induced biochemical impairments to photosynthesis (decreased RC/ABS, chlorophyll a and Rubisco content) were apparent in T. crocata admixed with L. multiflorum. These attributed to a reallocation of fixed carbohydrate reserves to floral production which increased significantly in T. crocata under these conditions only and associated with a corresponding reduction in the mass of its underground storage organ (bulb). The results of this study did not support the hypothesis that under conditions of low water and low nutrient supply invasive annual grasses would have a lesser impact on the growth and physiology of native geophytes than under resource enriched conditions that favor growth of these grasses. Unresolved is whether resource limitation and allelopathic mechanisms functioned simultaneously in the inhibition of the native geophyte by the alien grass.Thesis (M. Environmental Science (Ecological Remediation and Sustainable Utilisation))--North-West University, Potchefstroom Campus, 2008.
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Lenz, Tanja I. "The effect of resource dynamics on invasive annual and native perennial grasses in grasslands of the mid-north of South Australia / Tanja Lenz." 2004. http://hdl.handle.net/2440/22082.
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"July 2004."Bibliography: leaves 120-136.
vii, 136 leaves : ill. (some col.), maps ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Investigates the effects of soil moisture dynamics on the growth and interactions between invasive annual grasses and native perennial grasses in the mid-north of South Australia. At most sites annual grass abundance was positively correlated with rainfall, soil moisture after rainfall and higher soil productivity. Perennial grass abundance was negatively correlated with annual grass abundance and soil moisture after rainfall, and was weakly positively correlated with percentage summer rainfall, elevation, radiation, gravel and slope. Overall perennial grasses responded little to the environmental variables investigated, but strongly to annual grass abundance, while for annual grasses soil moisture was the driving variable.
Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2004
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Lenz, Tanja I. "The effect of resource dynamics on invasive annual and native perennial grasses in grasslands of the mid-north of South Australia / Tanja Lenz." Thesis, 2004. http://hdl.handle.net/2440/22082.
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"July 2004."Bibliography: leaves 120-136.
vii, 136 leaves : ill. (some col.), maps ; 30 cm.
Investigates the effects of soil moisture dynamics on the growth and interactions between invasive annual grasses and native perennial grasses in the mid-north of South Australia. At most sites annual grass abundance was positively correlated with rainfall, soil moisture after rainfall and higher soil productivity. Perennial grass abundance was negatively correlated with annual grass abundance and soil moisture after rainfall, and was weakly positively correlated with percentage summer rainfall, elevation, radiation, gravel and slope. Overall perennial grasses responded little to the environmental variables investigated, but strongly to annual grass abundance, while for annual grasses soil moisture was the driving variable.
Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2004
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Hodder, Grace Violet. "The Impact of Habitat Alteration on the Population Dynamics of a Declining Woodland Bird in the Mount Lofty Ranges." Thesis, 2020. http://hdl.handle.net/2440/126624.
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Biotic invasions are among the main drivers of ecosystem change and contribute to species declines. In the southern hemisphere, perennial native understorey plants have been largely outcompeted by fast-growing annual crop grasses and herbs. This significant compositional change has altered patterns of seed production. Granivores such as the diamond firetail (Stagonopleura guttata) are likely to be affected by such alterations. This species has been declining nationally since large-scale land-clearance prior to 1980. Focussed, species-specific research is required to identify the threats and their interactions that contribute to ongoing declines. This thesis examined an isolated meta-population in the Mount Lofty Ranges (MLR), South Australia, subsisting in heavily degraded grassy woodland dominated by exotic annual grasses. The hypothesis that changes in grass seed phenology associated with invasion by exotic annual species has resulted in seasonal food shortages was tested. An assessment of the seed resources available to ground-foragers in the southern MLR confirmed that introduced, annual species dominate the understorey. Total seed biomass was over seven times greater in spring (4.08 g m-2) than in autumn, when biomass was just 0.53 g m-2. High spring seed biomass was predominantly produced by annual grasses. The subsequent drop in biomass coincided with breaking autumn rains, implicating mass-germination as the cause. Variation in seed biomass was attributed to seasonal changes in the seed abundance of annual weedy grasses and forbs. Diet analyses found that S. guttata diets mirrored the abundance and diversity of seasonal resources. However, during winter, when grass seed biomass was scarce, S. guttata relied heavily on the seeds of the drooping sheoak (Allocasuarina verticillata). A mark-resight study determined that S. guttata populations were affected by seasonal resource fluctuations. Stagonopleura guttata encounters were strongly correlated with seed abundance and S. guttata densities reflected seed biomasses. To further explore the reason for low numbers of S. guttata in autumn and winter, an in-field food supplementation experiment was conducted. The food-supplemented population had significantly higher survival than the non-supplemented population, indicating that food is limiting for S. guttata. Juveniles were less efficient foragers than adults, highlighting their vulnerability during times of seed scarcity. However, food supplementation appeared to increase the proportion of juveniles that survived their first winter. The transition of independent fledglings from spring/summer breeding into young breeding adults is critical for recruitment and is likely to be hampered by winter food shortages. Overall densities of S. guttata in the southern MLR were 0.023–0.062 birds/ha, lower than the minimum viable population estimate of 0.069 birds/ha. As such, this meta-population is not sustainable at current densities. To improve the persistence of S. guttata, it is essential that the grassy woodlands of the region are managed to create consistent, year-round food resources, particularly during winter. This requires the restoration of perennial native grasses in the understorey that seed more consistently and over longer time periods than annuals. In addition, rehabilitation of A. verticillata, a key resource, will improve food availability during times of scarcity.Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 2020
Books on the topic "Invasive annual grasses"
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Chambers, Jeanne C. Using resistance and resilience concepts to reduce impacts of invasive annual grasses and altered fire regimes on the sagebrush ecosystem and greater sage-grouse: A strategic multi-scale approach. Fort Collins, CO: U.S. Dept. of Agriculture, Forest Service, Rocky Mountain Research Station, 2014.
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Miller, Richard F. A field guide for rapid assessment of post-wildfire recovery potential in sagebrush and Piñon-Juniper ecosystems in the Great Basin: Evaluating resilience to disturbance and resistance to invasive annual grasses and predicting vegetation response. Fort Collins, CO: United States Department of Agriculture, Forest Service, Rocky Mountain Research Station, 2015.
Find full textBook chapters on the topic "Invasive annual grasses"
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Roy, J., M. L. Navas, and L. Sonié. "Invasion by annual brome grasses: a case study challenging the homoclime approach to invasions." In Biogeography of Mediterranean Invasions, 207–24. Cambridge University Press, 1991. http://dx.doi.org/10.1017/cbo9780511525544.019.
Full textConference papers on the topic "Invasive annual grasses"
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Shafer, David S., David DuBois, Vic Etyemezian, Ilias Kavouras, Julianne J. Miller, George Nikolich, and Mark Stone. "Fire as a Long-Term Stewardship Issue for Soils Contaminated With Radionuclides in the Western U.S." In The 11th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2007. http://dx.doi.org/10.1115/icem2007-7181.
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On both U.S. Department of Energy (DOE) and U.S. Department of Defense sites in the southwestern United States (U.S.), significant areas of surface soils are contaminated with radionuclides from atmospheric nuclear testing, and with depleted uranium, primarily from military training. At DOE sites in Nevada, the proposed regulatory closure strategy for most sites is to leave contaminants in place with administrative controls and periodic monitoring. Closure-in-place is considered an acceptable strategy because the contaminated sites exist on access-restricted facilities, decreasing the potential risk to public receptor, the high cost and feasibility of excavating contaminated soils over large areas, and the environmental impacts of excavating desert soils that recover very slowly from disturbance. The largest of the contaminated sites on the Tonopah Test Range in Nevada covers over 1,200 hectares. However, a factor that has not been fully investigated in the long-term stewardship of these sites is the potential effects of fires. Because of the long half-lives of some of the contaminants (e.g., 24,100 years for 239Pu) and changes in land-cover and climatic factors that are increasing the frequency of fires throughout the western U.S., it should be assumed that all of these sites will eventually burn, possibly multiple times, during the timeframe when they still pose a risk. Two primary factors are contributing to increased fire frequency. The first is the spread of invasive grasses, particularly cheatgrass (Bromus tectorum and Bromus rubens), which have out-competed native annuals and invaded interspaces between shrubs, allowing fires to burn easier. The second is a sharp increase in fire frequency and size throughout the western U.S. beginning in the mid-1980s. This second factor appears to correlate with an increase in average spring and summer temperatures, which may be contributing to earlier loss of soil moisture and longer periods of dry plant biomass (particularly from annual plants). The potential risk to site workers from convective heat dispersion of radionuclide contaminants is an immediate concern during a fire. Long-term, post-fire concerns include potential changes in windblown suspension properties of contaminated soil particles after fires because of loss of vegetation cover and changes in soil properties, and soil erosion from surface water runoff and fluvial processes.
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Dai, Yuan, Ahmad Abiri, Siyuan Liu, Omeed Paydar, Hyunmin Sohn, Eric P. Dutson, Warren S. Grundfest, and R. N. Candler. "Grasper integrated tri-axial force sensor system for robotic minimally invasive surgery." In 2017 39th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). IEEE, 2017. http://dx.doi.org/10.1109/embc.2017.8037717.
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Othman, Wael, and Mohammad A. Qasaimeh. "Smart Laparoscopic Grasper Utilizing Force and Angle Sensors for Stiffness Assessment in Minimally Invasive Surgery." In 2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC). IEEE, 2021. http://dx.doi.org/10.1109/embc46164.2021.9630100.
Full textReports on the topic "Invasive annual grasses"
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Chambers, Jeanne C., David A. Pyke, Jeremy D. Maestas, Mike Pellant, Chad S. Boyd, Steven B. Campbell, Shawn Espinosa, Douglas W. Havlina, Kenneth E. Mayer, and Amarina Wuenschel. Using resistance and resilience concepts to reduce impacts of invasive annual grasses and altered fire regimes on the sagebrush ecosystem and greater sage-grouse: A strategic multi-scale approach. Ft. Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 2014. http://dx.doi.org/10.2737/rmrs-gtr-326.
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Miller, Richard F., Jeanne C. Chambers, and Mike Pellant. A field guide for selecting the most appropriate treatment in sagebrush and pinon-juniper ecosystems in the Great Basin: Evaluating resilience to disturbance and resistance to invasive annual grasses, and predicting vegetation response. Ft. Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 2014. http://dx.doi.org/10.2737/rmrs-gtr-322.
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Miller, Richard F., Jeanne C. Chambers, and Mike Pellant. A field guide for rapid assessment of post-wildfire recovery potential in sagebrush and pinon-juniper ecosystems in the Great Basin: Evaluating resilience to disturbance and resistance to invasive annual grasses and predicting vegetation response. Ft. Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 2015. http://dx.doi.org/10.2737/rmrs-gtr-338.
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Leis, Sherry, and Mary Short. George Washington Carver National Monument plant community report: 2004–2020. Edited by Tani Hubbard. National Park Service, December 2021. http://dx.doi.org/10.36967/nrr-2288500.
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The Heartland Inventory and Monitoring Network completed its sixth year of plant community monitoring at George Washington Carver National Monument in 2020. Plant community monitoring focused on the restored prairie community. We visited seven monitoring sites in each of the six years and collected data on plant species and ground cover. In this report we also included two environmental factors—precipitation and recent fire history—to better understand the vegetation community status and trends. Since 2000, precipitation has often been below the 30-year normal. Moreover, annual precipitation was below normal for all but one of the monitoring years. We found that the drought in 2012 stood out as possibly influencing plant guild cover. Although prairies are adapted to drought, further analyses might reveal more about the role of climate change in these vegetation communities. Fire management also plays an important role in shaping plant communities. Prescribed fire occurrence became more frequent and consistent through the period of plant monitoring. Additional treatments, including herbicide and mowing, also supported a healthy prairie. The prairie plant community continues to be moderately diverse despite recent increases in tree seedlings and small saplings. Species richness in 2012 was different than in two of the six years monitored. However, diversity indices (H′ and J′) were very similar across monitored years. Species guilds (also known as functional groups) exhibited differing patterns. Woody plants, long a concern at the monument, were statistically similar across years. In 2020, grass-like species increased, but grass species appeared to have declined below prior years. Grass cover in 2004 was statistically different (greater) than in 2008 and 2020. The reasons for this are not clear. Of particular interest to the park is the status of two sumac species (Rhus glabra and R. copallinum). These species were in decline as a result of focused management actions since 2012. However, the blackberry species (Rubus spp.) seemed to be replacing the sumac in some sites. In 2020, nonnative species richness and cover were below peak levels, demonstrating management actions have been successful in maintaining low levels. The vegetation monitoring protocol experienced some changes between 2004 and 2020. A key difference was a shift from sampling twice during the field season to sampling only once in a monitoring year. Although a decline in species richness was anticipated, that pattern was not apparent. However, the abundance of grasses may have been affected by the shift in seasonality of sampling. Additionally, we remedied inconsistencies in how tree regeneration was recorded (stem tallies in some cases and cover estimates in other cases). We converted all cover data to stem tallies and density was calculated to be consistent with the protocol. The monument has had success with coordinating fire management and invasive species management. A decrease in sumac across the prairie is evidence of this success. These actions will continue to be important for maintaining the prairie in good condition into the future.
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Belnap, Jayne, R. D. Evans, Susan L. Phillips, Merith Reheis, Rich Reynolds, Robert Sanford, and Bruce Webb. Exotic Annual Grasses in Western Rangelands: Predicting Resistance and Resilience of Native Ecosystems to Invasion (Draft). Fort Belvoir, VA: Defense Technical Information Center, April 2004. http://dx.doi.org/10.21236/ada436874.
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Raymond, Kara, Laura Palacios, Cheryl McIntyre, and Evan Gwilliam. Status of climate and water resources at Chiricahua National Monument, Coronado National Memorial, and Fort Bowie National Historic Site: Water year 2019. National Park Service, May 2022. http://dx.doi.org/10.36967/nrr-2293370.
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Climate and hydrology are major drivers of ecosystems. They dramatically shape ecosystem structure and function, particularly in arid and semi-arid ecosystems. Understanding changes in climate, groundwater, and water quality and quantity is central to assessing the condition of park biota and key cultural resources. The Sonoran Desert Network collects data on climate, groundwater, and surface water at 11 National Park Service units in southern Arizona and New Mexico. This report provides an integrated look at climate, groundwater, and springs conditions at Chiricahua National Monument (NM), Coronado National Memorial (NMem), and Fort Bowie National Historic Site (NHS) during water year (WY) 2019 (October 2018–September 2019). Overall annual precipitation at Chiricahua NM and Coronado NMem in WY2019 was approximately the same as the normals for 1981–2010. (The weather station at Fort Bowie NHS had missing values on 275 days, so data were not presented for that park.) Fall and winter rains were greater than normal. The monsoon season was generally weaker than normal, but storm events related to Hurricane Lorena led to increased late-season rain in September. Mean monthly maximum temperatures were generally cooler than normal at Chiricahua, whereas mean monthly minimum temperatures were warmer than normal. Temperatures at Coronado were more variable relative to normal. The reconnaissance drought index (RDI) indicated that Chiricahua NM was slightly wetter than normal. (The WY2019 RDI could not be calculated for Coronado NMem due to missing data.) The five-year moving mean of annual precipitation showed both park units were experiencing a minor multi-year precipitation deficit relative to the 39-year average. Mean groundwater levels in WY2019 increased at Fort Bowie NHS, and at two of three wells monitored at Chiricahua NM, compared to WY2018. Levels in the third well at Chiricahua slightly decreased. By contrast, water levels declined in five of six wells at Coronado NMem over the same period, with the sixth well showing a slight increase over WY2018. Over the monitoring record (2007–present), groundwater levels at Chiricahua have been fairly stable, with seasonal variability likely caused by transpiration losses and recharge from runoff events in Bonita Creek. At Fort Bowie’s WSW-2, mean groundwater level was also relatively stable from 2004 to 2019, excluding temporary drops due to routine pumping. At Coronado, four of the six wells demonstrated increases (+0.30 to 11.65 ft) in water level compared to the earliest available measurements. Only WSW-2 and Baumkirchner #3 have shown net declines (-17.31 and -3.80 feet, respectively) at that park. Springs were monitored at nine sites in WY2019 (four sites at Chiricahua NM; three at Coronado NMem, and two at Fort Bowie NHS). Most springs had relatively few indications of anthropogenic or natural disturbance. Anthropogenic disturbance included modifications to flow, such as dams, berms, or spring boxes. Examples of natural disturbance included game trails, scat, or evidence of flooding. Crews observed 0–6 facultative/obligate wetland plant taxa and 0–3 invasive non-native species at each spring. Across the springs, crews observed six non-native plant species: common mullein (Verbascum thapsus), spiny sowthistle (Sonchus asper), common sowthistle (Sonchus oleraceus), Lehmann lovegrass (Eragrostis lehmanniana), rabbitsfoot grass (Polypogon monspeliensis), and red brome (Bromus rubens). Baseline data on water quality and water chemistry were collected at all nine sites. It is likely that that all nine springs had surface water for at least some part of WY2019, though temperature sensors failed at two sites. The seven sites with continuous sensor data had water present for most of the year. Discharge was measured at eight sites and ranged from < 1 L/minute to 16.5 L/minute.
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Raymond, Kara, Laura Palacios, Cheryl McIntyre, and Evan Gwilliam. Status of climate and water resources at Saguaro National Park: Water year 2019. Edited by Alice Wondrak Biel. National Park Service, December 2021. http://dx.doi.org/10.36967/nrr-2288717.
Full textAbstract:
Climate and hydrology are major drivers of ecosystems. They dramatically shape ecosystem structure and function, particularly in arid and semi-arid ecosystems. Understanding changes in climate, groundwater, and water quality and quantity is central to assessing the condition of park biota and key cultural resources. The Sonoran Desert Network collects data on climate, groundwater, and surface water at 11 National Park Service units in south-ern Arizona and New Mexico. This report provides an integrated look at climate, groundwater, and springs conditions at Saguaro National Park (NP) during water year 2019 (October 2018–September 2019). Annual rainfall in the Rincon Mountain District was 27.36" (69.49 cm) at the Mica Mountain RAWS station and 12.89" (32.74 cm) at the Desert Research Learning Center Davis station. February was the wettest month, accounting for nearly one-quarter of the annual rainfall at both stations. Each station recorded extreme precipitation events (>1") on three days. Mean monthly maximum and minimum air temperatures were 25.6°F (-3.6°C) and 78.1°F (25.6°C), respectively, at the Mica Mountain station, and 37.7°F (3.2°C) and 102.3°F (39.1°C), respectively, at the Desert Research Learning Center station. Overall temperatures in WY2019 were cooler than the mean for the entire record. The reconnaissance drought index for the Mica Mountain station indicated wetter conditions than average in WY2019. Both of the park’s NOAA COOP stations (one in each district) had large data gaps, partially due to the 35-day federal government shutdown in December and January. For this reason, climate conditions for the Tucson Mountain District are not reported. The mean groundwater level at well WSW-1 in WY2019 was higher than the mean for WY2018. The water level has generally been increasing since 2005, reflecting the continued aquifer recovery since the Central Avra Valley Storage and Recovery Project came online, recharging Central Arizona Project water. Water levels at the Red Hills well generally de-clined starting in fall WY2019, continuing through spring. Monsoon storms led to rapid water level increases. Peak water level occurred on September 18. The Madrona Pack Base well water level in WY2019 remained above 10 feet (3.05 m) below measuring point (bmp) in the fall and winter, followed by a steep decline starting in May and continuing until the end of September, when the water level rebounded following a three-day rain event. The high-est water level was recorded on February 15. Median water levels in the wells in the middle reach of Rincon Creek in WY2019 were higher than the medians for WY2018 (+0.18–0.68 ft/0.05–0.21 m), but still generally lower than 6.6 feet (2 m) bgs, the mean depth-to-water required to sustain juvenile cottonwood and willow trees. RC-7 was dry in June–September, and RC-4 was dry in only September. RC-5, RC-6 and Well 633106 did not go dry, and varied approximately 3–4 feet (1 m). Eleven springs were monitored in the Rincon Mountain District in WY2019. Most springs had relatively few indications of anthropogenic or natural disturbance. Anthropogenic disturbance included spring boxes or other modifications to flow. Examples of natural disturbance included game trails and scat. In addition, several sites exhibited slight disturbance from fires (e.g., burned woody debris and adjacent fire-scarred trees) and evidence of high-flow events. Crews observed 1–7 taxa of facultative/obligate wetland plants and 0–3 invasive non-native species at each spring. Across the springs, crews observed four non-native plant species: rose natal grass (Melinis repens), Kentucky bluegrass (Poa pratensis), crimson fountaingrass (Cenchrus setaceus), and red brome (Bromus rubens). Baseline data on water quality and chemistry were collected at all springs. It is likely that that all springs had surface water for at least some part of WY2019. However, temperature sensors to estimate surface water persistence failed...