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Sample records for banderita bouteloua curtipendula

  1. MORFOLOGÍA Y MORFOMETRÍA DE DOS ESPECIES DE BANDERITAS (ORCHIDACEAE: MASDEVALLIA EN COLOMBIA Morphology and Morphometry of Two Banderitas Species (Orchidaceae: Masdevallia in Colombia

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    MÓNICA ADRIANA CUERVO MARTÍNEZ

    2012-12-01

    Full Text Available Masdevallia coccinea y Masdevallia ignea (Orchidaceae conocidas como "banderitas", son orquídeas ornamentales muy apreciadas por cultivadores aficionados y coleccionistas. En Colombia, la presión de colecta sobre estas especies ha sido enorme y pocas poblaciones naturales sobreviven en los departamentos de Boyacá (Arcabuco, Páramo de Berlín, Duitama y Santander (entre Málaga y Bucaramanga, estas poblaciones son reducidas y de difícil acceso; razón por la cual se encuentran en el apéndice II de CITES. Poco se sabe sobre su biología reproductiva, sistema reproductivo y polinización y parte de lo que consta en la literatura es incompleto. En este marco el objetivo general del trabajo fue estudiar la morfología y morfometría floral de M. coccinea y M. ignea en condiciones de semicultivo al aire libre en la finca Villa Rosa ubicada en el municipio de Guasca, Cundinamarca, para lo cual se realizó fotografía digital, pruebas histoquímicas, morfometría y Microscopía Electrónica de Barrido. Los resultados principales de la morfometría mostraron que los sépalos dorsal y lateral fueron más largos en M. coccinea (X= 53,0 mm σ = 7,4 mm y X = 44,4 mm y σ = 8,3 mm en comparación a M. ignea (X = 34 mm σ = 7,7 mm y X = 31,5 mm y σ = 6,1 mm, pero las coloraciones de las partes florales de esta última fueron más intensas y su labelo fue más largo (X = 7,1 mm y σ = 0,6 mm. En las dos especies el labelo estuvo articulado a la columna y no se encontró presencia de glándulas con estructuras secretoras como nectarios ni osmóforos.Masdevallia coccinea and the Masdevallia ignea "banderitas" are ornamental orchids which are very prized by amateur farmers and collectors. In Colombia, the harvest pressure on these species has been enormous and few natural populations survive in the departments of Boyacá (Arcabuco of Berlin Páramo, Duitama and Santander (between Málaga and Bucaramanga, in which these populations are reduced and of

  2. Morphology and morphometry of two banderitas species (Orchidaceae: masdevallia) in Colombia

    International Nuclear Information System (INIS)

    Masdevallia coccinea and the Masdevallia ignea (Banderitas) are ornamental orchids which are very prized by amateur farmers and collectors. In Colombia, the harvest pressure on these species has been enormous and few natural populations survive in the departments of Boyaca (Arcabuco of Berlin Paramo, Duitama) and Santander (between Malaga and Bucaramanga), in which these populations are reduced and of difficult access. For this reason these species are in the II appendix of cites. However, little is known on their reproductive biology, floral biology and pollination and the literature about this is incomplete. Under this framework, the goal of the project was to study the morphology and morphometry of m. coccinea and m. ignea (pleurothallidinae) under semicultivation conditions in the Villa Rosa Farm located in the municipality of Guasca, Cundinamarca (Colombia). The floral morphology was analyzed by digital photography, morphometry and scanning electron microscope. The main results were differences in color and length of dorsal and lateral sepals between m. coccinea (x = 53.0 mm Sigma = 7.4 mm and x = 44.4 mm and Sigma = 8.3 mm) and m. ignea (x = 34 mm Sigma = 7.7 mm and x = 31.5 mm and Sigma = 6.1 mm). These parts were longest in m. coccinea in contrast to m. ignea. However the lip was longest in m. ignea (x = 7.1 mm y Sigma = 0.6 mm). On the other hand both species had lip articulated to the column but without rewards as nectar and osmophores.

  3. Soil sterilization alters interactions between the native grass Bouteloua gracilis and invasive Bromus tectorum

    Science.gov (United States)

    Aims: The invasive grass Bromus tectorum negatively impacts grassland communities throughout the western U.S. We asked whether soil biota growing in association with a native grass (Bouteloua gracilis) increase growth and competitive ability of Bromus, and whether responses vary between soils collec...

  4. Rediscovery of Bouteloua vaneedenii (Gramineae: Chloridoideae: endemic species from the West Indies Redescubrimiento de Bouteloua vaneedenii (Gramineae: Chloridoideae: especie endémica de las Indias Occidentales

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    María Elena Siqueiros-Delgado

    2011-12-01

    Full Text Available Bouteloua vaneedenii is an endemic and extremely rare grass of the West Indies. Very few collections are known, and the most recent collection is from 1922. With the aim of finding the species, a team of Mexican and Cuban agrostologists conducted a field trip and found B. vaneedenii in the same locality where it was collected in 1922 on dry limestone rocks. Although it was stated that B. vaneedenii probably was extinct from Cuba, vigorous populations remain in at least 2 localities in Pastelillo. Further exploration may lead to the discovery of additional populations and the reevaluation of its current conservation status.Bouteloua vaneedenii es un pasto extremadamente raro, nativo de Las Indias Occidentales y del que muy pocas recolectas se conocen hasta ahora, la última se realizó en 1922. Con el objetivo de encontrar la especie, un equipo de agrostólogos mexicanos y cubanos condujeron un viaje de campo en busca de B. vaneedenii , la cual fue hallada en la misma localidad donde se recolectó sobre rocas calizas en 1922, a pesar de que se había señalado como probable extinta para Cuba. Se ubicaron 2 poblaciones en buenas condiciones; no obstante, es necesaria una exploración más intensa confirmar su estado actual de conservación.

  5. Effects of vesicular-arbuscular mycorrhizae on survival and growth of perennial grasses in lignite overburden in Texas

    Energy Technology Data Exchange (ETDEWEB)

    Call, C.A.; Davies, F.T.

    1988-12-01

    Seedlings of sideoats grama (Bouteloua curtipendula), Indiangrass (Sorghastrum nutans), and kleingrass (Panicum coloratum) were inoculated with vesicular-arbuscular mycorrhizal (VAM) fungi (Glomus fasciculatum and Gigaspora margarita) in a containerized system and transplanted into lignite overburden in the Post Oak Savannah region of Texas, U.S.A. After three growing seasons without cultural inputs, plants inoculated with VAM fungi had greater survival percentages, basal diameters, and above-ground biomass than noninoculated plants. Inoculated plants had higher levels of nitrogen and phosphorus in above-ground biomass than noninoculated plants. Root colonization percentages of inoculated plants remained fairly stable while noninoculated plants showed low levels of colonization over the 3-year study period. Vesicular-arbuscular mycorrhizae enhanced the survival and growth of the 3 grass species by making effective use of limited resources in the lignite overburden. 31 refs., 3 tabs.

  6. Characteristics of a ringtail (Bassariscus astutus) population in Trans Pecos, Texas

    Science.gov (United States)

    Ackerson, B.K.; Harveson, L.A.

    2006-01-01

    Despite the common occurrence of ringtails (Bassariscus astutus) few studies have been conducted to assess population characteristics. The objectives of this study were to determine (1) habitat selection, (2) home range, (3) denning characteristics, and (4) food habits of ringtails in the Trans Pecos region of west Texas. Seventeen ringtails were captured between November 1999 and January 2001 using Havahart live box traps. Second- and third-order habitat selection was determined for a ringtail population using range sites, slope, elevation, and vegetation communities. Diets were determined from volumetric scat analysis. The mean summer and winter range sizes (100% Minimum Convex Polygon [MCP]) for ringtails (n = 5) were 0.28 ?? 0.163 km2 and 0.63 ?? 0.219 km2, respectively. Overlap between ringtail ranges averaged 33.3%. Ringtails preferred catclaw (Mimosa biuncifera), persimmon (Diospyros texana), oak (Quercus sp.) bottom and catclaw/goldeneye (Viguiera stenoloba), sideoats (Bouteloua curtipendula) slope communities. Rock dens were used exclusively by ringtails, with 80.6% of dens found on slopes between 30-60%. Plant (seeds and miscellaneous vegetation) and animal material were found in 74.6 and 86.6% of scats, respectively. Findings suggest that ringtails in Trans Pecos, Texas, are an important component of the ecosystem and that management practices should conserve canyon habitats and adjacent slopes for ringtails.

  7. Rooting depths of plants on low-level waste disposal sites

    International Nuclear Information System (INIS)

    In 1981-1982 an extensive bibliographic study was done to reference rooting depths of native plants in the United States. The data base presently contains 1034 different rooting citations with approximately 12,000 data elements. For this report, data were analyzed for rooting depths related to species found on low-level waste (LLW) sites at Los Alamos National Laboratory. Average rooting depth and rooting frequencies were determined and related to present LLW maintenance. The data base was searched for information on rooting depths of 53 species found on LLW sites at Los Alamos National Laboratory. The study indicates 12 out of 13 grasses found on LLW sites root below 91 cm. June grass [Koeleria cristata (L.) Pers.] (76 cm) was the shallowest rooting grass and side-oats grama [Bouteloua curtipendula (Michx.) Torr.] was the deepest rooting grass (396 cm). Forbs were more variable in rooting depths. Indian paintbrush (Castelleja spp.) (30 cm) was the shallowest rooting forb and alfalfa (Medicago sativa L.) was the deepest (>3900 cm). Trees and shrubs commonly rooted below 457 cm. The shallowest rooting tree was elm (Ulmus pumila L.) (127 cm) and the deepest was one-seed juniper [Juniperus monosperma (Engelm) Sarg.] (>6000 cm). Apache plume [Fallugia paradoxa (D. Don) Endl.] rooted to 140 cm, whereas fourwing saltbush [Atriplex canecens (Pursh) Nutt.] rooted to 762 cm

  8. Soil Respiration Responses to Variation in Temperature Treatment and Vegetation Type

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    Liu, S.; Pavao-zuckerman, M.

    2013-12-01

    Complex linkages exist between terrestrial vegetation, soil moisture, soil organic matter (SOM), local climate, and soil microorganisms. Thus, large-scale changes in vegetation, such as the woody plant encroachment observed in many historically semiarid and arid grasslands worldwide, could potentially alter the flux of carbon from soil reserves to the atmosphere. Mathematical models that attempt to project the long-term impact of vegetative shifts on soil fluxes largely rely on assumptions such as first-order donor control rather than incorporate the biological aspects of soil respiration such as microbial activity. To examine the impact of vegetation type on soil physicochemical properties and soil microbial respiration and provide experimental data to refine existing predictive models, we compared soil (ground basalt from northern Arizona) in mesocosms established with no vegetation, velvet mesquites (Prosopis velutina; woody shrub), or sideoats gramas (Bouteloua curtipendula; grass) for 2 years, The temperature sensitivity of soil respiration was examined by incubating soil (0-10 and 10-30 cm depth fractions) from each vegetation treatment at 10, 20, 30, and 40 °C for 24 hours. Vegetated soils contained more SOM (~0.1% for mesquite and grass mesocosms) than non-vegetated soils (~0.02%). Respiration rates were generally highest from grass-established soils, intermediate from mesquite-established soils, and lowest from non-vegetated soils. Respiration rates of samples incubated without the addition of substrate peaked at approximately 30 °C, whereas respiration rates of samples incubated with dextrose were highest at 40 °C. Further, the respiration assays suggest that while respiration rates are overall higher in grass-established soils, mesquite-established soils are more temperature sensitive which may have significant implications in the context of global warming and current fire management practices.

  9. Estudios en gramíneas (poaceae) de colombia: veinte novedades corológicas

    OpenAIRE

    2012-01-01

    Se dan a conocer veinte novedades para la flora de Colombia: Agrostis mertensii, Agrostis perennans, Agrostis stolonifera, Agrostis subrepens, Agrostis tolucensis, Aristida schiedeana, Arundo donax, Bouteloua aristidoides, Bouteloua simplex, Cenchrus ciliaris, Cortaderia selloana, Cynodon dactylon, Cynodon nlemfuensis, Heteropogon contortus, Microchloa kunthii, Paspalidium geminatum, Pharus parvifolius, Tragus berteronianus, Urochloa distachya y Zoysia matrella. Se presentan la distribución g...

  10. La contaminación de aguas subterráneas por nitratos en áreas periurbanas : Caso ejemplo en cuencas próximas a la ciudad de La Plata, Argentina

    OpenAIRE

    González, Nilda; Hernández, Mario Alberto

    1997-01-01

    Se analizan los contenidos de nitratos en el acuífero freático, en una comarca situada al Noroeste de la ciudad de La Plata, en el partido homónimo, sobre la base de cincuenta puntos de control periódico secuente, desde el año 1994. Se localizaron tres máximos principales: uno en la zona próxima a Villa Elisa (125 mg/l), otro en los alrededores de Abasto (70 mg/l) y el tercero en un sector de producción flori-hortícola en el entorno de Colonia Urquiza-Las Banderitas (100 mg/l con extremo punt...

  11. Fire in Chihuahuan Desert grassland: Short-term effects on vegetation, small mammal populations, and faunal pedoturbation

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    A prescribed burn resulted in significant decreases in canopy cover of the grasses: Bouteloua eriopoda, Sporobolus flexuosus, and Aristida purpurea. One year post-burn, basal cover of B. eriopoda remained significantly lower in burned patches than in unburned areas but there were no differences in b...

  12. Small mammal herbivory: Feedbacks that help maintain desertified ecosystems

    Science.gov (United States)

    We tested the hypothesis that herbivores contribute to feedbacks maintaining arid ecosystems in a degraded state. We studied small mammal herbivory on a subshrub, broom snakeweed (Gutierrezia sarothrae), and perennial grasses at three sites: (1) ungrazed black grama (Bouteloua eriopoda) grassland; (...

  13. Using transplants to measure accumulation rates of epiphytic bryophytes in forests of western Oregon

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    Rosso, A.L.; Muir, Patricia S.; Rambo, T.

    2001-01-01

    We sought a simple and effective transplant method that could be used to measure biomass accumulation rates of epiphytic bryophytes. Trials were carried out in the Pseudotsuga menziesii-dominated forests of western Oregon. We tested multiple transplant methods over a 13-month period while comparing accumulation rates of Antitrichia curtipendula (Hedw.) Brid. and Isothecium myosuroides Brid. among an old-growth stand, a young stand, and a recent clearcut. In our study area, Antitrichia is considered to be an old-growth associate while Isothecium is a more ubiquitous species. Methods tested included containment in net bags, containment in hairnets, and directly tying mats to substrates. Three sizes of transplants were tested with both natural and inert artificial substrates. Transplants of approximately five g enclosed in plastic net bags and tied to either natural or artificial substrates worked well for our purposes. Only minor differences were found in mean accumulation rates between the old growth and young stand, though variation in accumulation rates was higher in the old growth. Neither species appeared capable of surviving in the clearcut. Antitrichia accumulated biomass 60% faster in the canopy than in the understory on average. Antitrichia also accumulated at a faster rate than Isothecium, with mean 13-month biomass increases of 11.8 and 3.7% respectively for 5 g transplants in the understory. Our results suggest that Antitrichia's association with old growth may be due more to dispersal or establishment limitations than to a decreased ability to grow in young stands.

  14. Understanding the erosion of semi-arid landscapes subject to vegetation change: a combined approach using monitoring, isotope and 14c analysis

    International Nuclear Information System (INIS)

    The degradation of grasslands is a common problem across semi-arid areas worldwide.over the last 150 years much of the south-Western USA has experienced significant land degradation, with desert grasslands becoming dominated by shrubs and concurrent changes in runoff and erosion which are thought to propagate further the process of degradation. Field-based experiments were carried out to determine how runoff and erosion vary at stages over a transition from a black grama (Bouteloua eriopoda) grassland to creosote bush (Larrea tridentata) shrub land at the Sevilleta NWR LTER site in New Mexico. δ13 C and δ15 N analyses were carried out to investigate the age and potential provenance of eroded sediment. (Author) 4 refs.

  15. Determination of varying consumption rates from radiotracer data

    International Nuclear Information System (INIS)

    Data obtained on the uptake and elimination of phosphorus-32 by foraging grasshoppers were utilized to estimate consumption rates of blue grama grass (Bouteloua gracilis). Grasshoppers were caged in field enclosures containing blue grama grass labeled with 32P. Periodic measurements were made to determine the body burdens of the grasshoppers and concentration of 32P in the grass. This information, along with a two-component exponential function which was observed to best mathematically describe the retention of acutely ingested phosphorus, provided the basis for a convolution integral of the consumption rate. The consumption rate was estimated by dividing the observed body burden of the grasshopper by the convolution integral of the input (grass concentration) and impulse (retention curve) function over each observation period. Successive calculations of the consumption rates were made at various points in time as the body burden changed from continued feeding on labeled forage

  16. Establishment and performance of an experimental green roof under extreme climatic conditions

    International Nuclear Information System (INIS)

    Green roofs alter the surface energy balance and can help in mitigating urban heat islands. However, the cooling of green roofs due to evapotranspiration strongly depends on the climatic conditions, and vegetation type and density. In the Southern Central Plains of the United States, extreme weather events, such as high winds, heat waves and drought conditions pose challenges for successful implementation of green roofs, and likely alter their standard performance. The National Weather Center Experimental Green Roof, an interdisciplinary research site established in 2010 in Norman, OK, aimed to investigate the ecological performance and surface energy balance of green roof systems. Starting in May 2010, 26 months of vegetation studies were conducted and the radiation balance, air temperature, relative humidity, and buoyancy fluxes were monitored at two meteorological stations during April–October 2011. The establishment of a vegetative community trended towards prairie plant dominance. High mortality of succulents and low germination of grasses and herbaceous plants contributed to low vegetative coverage. In this condition succulent diversity declined. Bouteloua gracilis and Delosperma cooperi showed typological dominance in harsh climatic conditions, while Sedum species experienced high mortality. The plant community diversified through volunteers such as Euphorbia maculate and Portulaca maculate. Net radiation measured at a green-roof meteorological station was higher than at a control station over the original, light-colored roofing material. These findings indicate that the albedo of the green roof was lower than the albedo of the original roofing material. The low vegetative coverage during the heat and drought conditions in 2011, which resulted in the dark substrate used in the green roof containers being exposed, likely contributed to the low albedo values. Nevertheless, air temperatures and buoyancy fluxes were often lower over the green roof indicating

  17. Establishment and performance of an experimental green roof under extreme climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Petra M., E-mail: pkklein@ou.edu [School of Meteorology, University of Oklahoma, Norman, OK (United States); Coffman, Reid, E-mail: rcoffma4@kent.edu [College of Architecture and Environmental Design, Kent State University, Kent, OH (United States)

    2015-04-15

    Green roofs alter the surface energy balance and can help in mitigating urban heat islands. However, the cooling of green roofs due to evapotranspiration strongly depends on the climatic conditions, and vegetation type and density. In the Southern Central Plains of the United States, extreme weather events, such as high winds, heat waves and drought conditions pose challenges for successful implementation of green roofs, and likely alter their standard performance. The National Weather Center Experimental Green Roof, an interdisciplinary research site established in 2010 in Norman, OK, aimed to investigate the ecological performance and surface energy balance of green roof systems. Starting in May 2010, 26 months of vegetation studies were conducted and the radiation balance, air temperature, relative humidity, and buoyancy fluxes were monitored at two meteorological stations during April–October 2011. The establishment of a vegetative community trended towards prairie plant dominance. High mortality of succulents and low germination of grasses and herbaceous plants contributed to low vegetative coverage. In this condition succulent diversity declined. Bouteloua gracilis and Delosperma cooperi showed typological dominance in harsh climatic conditions, while Sedum species experienced high mortality. The plant community diversified through volunteers such as Euphorbia maculate and Portulaca maculate. Net radiation measured at a green-roof meteorological station was higher than at a control station over the original, light-colored roofing material. These findings indicate that the albedo of the green roof was lower than the albedo of the original roofing material. The low vegetative coverage during the heat and drought conditions in 2011, which resulted in the dark substrate used in the green roof containers being exposed, likely contributed to the low albedo values. Nevertheless, air temperatures and buoyancy fluxes were often lower over the green roof indicating

  18. Cervus elaphus Foraging Impacts on Plants and Soils at an Ungrazed Desert Grass/Shrubland in Northwestern New Mexico, USA

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    Louis C. Bender

    2015-01-01

    Full Text Available We evaluated Cervus elaphus herbivory and trampling impacts on plants and soils on Chaco Culture National Historical Park (Chaco, a desert grass/shrubland in northwestern New Mexico, USA, most (63% of which has been protected from grazing by domestic livestock since 1948. We conducted grazing, browse, and water infiltration surveys in areas which received different amounts of C. elaphus use (use and control, 2004–2007. Browse utilization was <32% on monitored species and Odocoileus hemionus use accounted for the majority of browsing. Live plant cover was greater on areas receiving more C. elaphus use, and no grass species were used above recommended levels. Stubble heights of Bouteloua spp. were positively related to relative C. elaphus use on some areas, suggesting possible stimulation of grassland productivity by C. elaphus grazing. Water infiltration rates either did not differ among use or control sites or were faster in use sites, indicating no impacts of C. elaphus use on soil compaction. At current C. elaphus densities (0.2–0.4/km2, negative impacts to plants and soils were not seen on Chaco, and some evidence suggests that light grazing is optimizing desert grasslands of Chaco.

  19. Establishment of Native Grasses with Biosolids on Abandoned Croplands in Chihuahua, Mexico

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    Pedro Jurado-Guerra

    2013-01-01

    Full Text Available The objective of the work was to evaluate establishment and forage production of native grasses with application of biosolids, a byproduct of waste-water treatment, at an abandoned field, in Ejido Nuevo Delicias, Chihuahua, Mexico. Four biosolids rates from 0 (control to 30 dry Mg ha−1 and two methods of application, surface applied (BioSur and soil incorporated (BioInc, were evaluated. Seedbed preparation included plowing and harrowing before rainfall. Field plots of 5 × 5 m were manually sown with a mix of blue grama (Bouteloua gracilis (50% and green sprangletop (Leptochloa dubia (50% in early August 2005. Experimental design was a randomized block with a split plot arrangement. Grass density, height, and forage production were estimated for three years. Data were analyzed with mixed linear models and repeated measures. Green sprangletop density increased under all biosolids rates regardless of method of application, while blue grama density slightly decreased. Biosolids were more beneficial for green sprangletop height than for blue grama height. Blue grama forage production slightly increased, while green sprangletop forage production increased the most at 10 Mg ha−1 biosolids rate under BioSur method. It was concluded that BioSur application at 10 and 20 Mg ha−1 rates had positive effects on the establishment and forage production of native grasses, especially green sprangletop.

  20. Baseline tritium concentrations in soils and vegetation: The Tshirege woodland site at TA-54

    International Nuclear Information System (INIS)

    In compliance with Department of Energy (DOE) Order 5400.1, a preoperational environmental survey was conducted for the Tshirege woodland site--an experimental area managed by the Earth and Environmental Science Group (EES-15)--where radioactive tritium (3H) will be injected ten cm deep in and around the base of pinyon (Pinus edulis) and one-seeded juniper (Juniperus monosperma) trees during the summer of 1990. The site is located at the lower end of Canada del Buey close to the intersection of Pajarito and State Road 4. Baseline values of 3H were measured in soil and plant samples from five locations immediately surrounding the study area. Mean values of 3H in soils collected from the 0--5 and 25--30 cm depths were 1.24 (±0.22) and 1.08 (±0.41) pCi mL-1, respectively. Pinyon needles averaged 1.68 (±0.18) pCi mL-1 and blue grama grass (Bouteloua gracilis) averaged 1.16 (±0.95) pCi mL-1

  1. Pistil Smut Infection Increases Ovary Production, Seed Yield Components, and Pseudosexual Reproductive Allocation in Buffalograss

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    Ambika Chandra

    2014-12-01

    Full Text Available Sex expression of dioecious buffalograss [Bouteloua dactyloides Columbus (syn. Buchloë dactyloides (Nutt. Engelm.] is known to be environmentally stable with approximate 1:1, male to female, sex ratios. Here we show that infection by the pistil smut fungus [Salmacisia buchloëana Huff & Chandra (syn. Tilletia buchloëana Kellerman and Swingle] shifts sex ratios of buffalograss to be nearly 100% phenotypically hermaphroditic. In addition, pistil smut infection decreased vegetative reproductive allocation, increased most seed yield components, and increased pseudosexual reproductive allocation in both sex forms compared to uninfected clones. In female sex forms, pistil smut infection resulted in a 26 fold increase in ovary production and a 35 fold increase in potential harvest index. In male sex forms, pistil smut infection resulted in 2.37 fold increase in floret number and over 95% of these florets contained a well-developed pistil. Although all ovaries of infected plants are filled with fungal teliospores and hence reproductively sterile, an average male-female pair of infected plants exhibited an 87 fold increase in potential harvest index compared to their uninfected clones. Acquiring an ability to mimic the effects of pistil smut infection would enhance our understanding of the flowering process in grasses and our efforts to increase seed yield of buffalograss and perhaps other grasses.

  2. Prospects for optimizing soil microbial functioning to improve plant nutrient uptake and soil carbon sequestration under elevated CO2

    Science.gov (United States)

    Nie, M.; Pendall, E. G.

    2013-12-01

    Potential to mitigate climate change through increasing plant productivity and its carbon (C) input to soil may be limited by soil nitrogen (N) availability. Using a novel 13C-CO2 and 15N-soil dual labeling method, we investigated whether plant growth-promoting bacteria would interact with atmospheric CO2 concentration to alter plant productivity and soil C storage. We grew Bouteloua gracilis under ambient (380 ppm) or elevated CO2 (700 ppm) in climate-controlled chambers, and plant individuals were grown with or without Pseudomonas fluorescens inoculum, which can produce N catabolic enzymes. We observed that both eCO2 and P. fluorescens increased plant productivity and its C allocation to soil. P. fluorescens relative to eCO2 enhanced plant N uptake from soil organic matter, which highly correlated with soil N enzyme activities and rhizosphere exudate C. More importantly, P. fluorescens increased microbial biomass and deceased specific microbial respiration in comparison with eCO2. These results indicate that application of plant growth-promoting bacteria can increase microbial C utilization efficiency with subsequent N mineralization from soil organic matter, and may improve plant N availability and soil C sequestration. Together, our findings highlight the potential of plant growth-promoting bacteria for global change mitigation by terrestrial ecosystems.

  3. A reliable method for spectrophotometric determination of glycine betaine in cell suspension and other systems.

    Science.gov (United States)

    Valadez-Bustos, Ma Guadalupe; Aguado-Santacruz, Gerardo Armando; Tiessen-Favier, Axel; Robledo-Paz, Alejandrina; Muñoz-Orozco, Abel; Rascón-Cruz, Quintin; Santacruz-Varela, Amalio

    2016-04-01

    Glycine betaine is a quaternary ammonium compound that accumulates in a large variety of species in response to different types of stress. Glycine betaine counteracts adverse effects caused by abiotic factors, preventing the denaturation and inactivation of proteins. Thus, its determination is important, particularly for scientists focused on relating structural, biochemical, physiological, and/or molecular responses to plant water status. In the current work, we optimized the periodide technique for the determination of glycine betaine levels. This modification permitted large numbers of samples taken from a chlorophyllic cell line of the grass Bouteloua gracilis to be analyzed. Growth kinetics were assessed using the chlorophyllic suspension to determine glycine betaine levels in control (no stress) cells and cells osmotically stressed with 14 or 21% polyethylene glycol 8000. After glycine extraction, different wavelengths and reading times were evaluated in a spectrophotometer to determine the optimal quantification conditions for this osmolyte. Optimal results were obtained when readings were taken at a wavelength of 290 nm at 48 h after dissolving glycine betaine crystals in dichloroethane. We expect this modification to provide a simple, rapid, reliable, and cheap method for glycine betaine determination in plant samples and cell suspension cultures. PMID:26774956

  4. Competition, resources, and vegetation during 10 years in native grassland.

    Science.gov (United States)

    Wilson, Scott D

    2007-12-01

    A 10-year experiment tested for variation in competition intensity over time in a natural grassland at the northern edge of the Great Plains. Growing-season precipitation varied fivefold during the study. All ecosystem-level variables varied significantly among years, and most covaried in expected ways. The covers of all common grasses possessing the C3 photosynthetic pathway varied significantly among years; in contrast, all common species with traits associated with drought tolerance (a C4 grass, a lichen, a spikemoss, and a subshrub) did not vary. Annual transplant experiments measured the competitive effects of neighbors on the growth of individuals of the native grass Bouteloua gracilis. A significant interaction between year and competition showed that competition intensity varied among years. The size of this effect, however, was small (eta2 = 0.074) relative to the size of the direct effect of competition (eta2 = 0.20) or the year in which the experiment was conducted (eta2 = 0.51). Further, competition intensity was not significantly related to any variable describing standing crop or resources, or species richness. Species richness was highest in years with high precipitation, standing crop, and individual growth, due to the recruitment of rare species that were absent from dry years. In summary, variation in competition intensity was statistically significant but had small effects relative to the direct effects of climate. PMID:18229830

  5. Conservation and yield aspects of old European aspen Populus tremula L. in Swedish forestry

    Energy Technology Data Exchange (ETDEWEB)

    Hazell, Per [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Forest Management and Products

    1999-06-01

    Biodiversity issues are becoming integrated parts of Swedish forest management. In this context, the amount and distribution of broadleaved species, including aspen, are important. This thesis summarises results of two studies in which species from the rich epiphytic flora on aspen were used to evaluate important features of aspens, and two studies relating these features to production losses due to retention of aspen. The presence and abundance of four epiphytic, bark-living bryophytes in relation to stand and host-tree characteristics, were investigated in four mixed forest stands in central Sweden. There was no general and consistent relation between aspen density and bryophyte presence. Large diameter and rough bark of the aspen host, together with site factors and stand density around the host, were important. On 35 clearfelled areas, the bryophyte Antitrichia curtipendula (Hedw.) Brid. and the lichen Lobaria pulmonaria (L.) Hoffm., species considered sensitive to clearfelling, were transplanted on retained aspen stems. As a reference, transplants were made on aspens in adjacent old stands. After two years the bryophyte showed its highest vitality in the forest, but was also vigorous on the north side of retained trees. The lichen thrived best on the clearfelled areas, on the north side of trees retained in groups. For conservation purposes, aspen are best retained in groups. Qualitative and quantitative aspects of retained large aspens (diameter 49.6{+-}7.0 cm and height 29.4{+-}1.0 m) were studied in a 110-year-old aspen stand. Twelve trees were destructively analysed to establish allometric equations relating stem, bark and branch biomass and current annual stem increment (CAI{sub s}) to diameter at breast height. Biomass of the mean tree was 1172 kg, of which 80% was stemwood. CAI{sub s} was 1.5% of total stem biomass. Finally, the yield of a 44-year-old Norway spruce stand under an aspen overstorey was compared with that of pure Norway spruce, estimated

  6. Composición y abundancia del banco de semillas en una región semiárida del trópico mexicano: patrones de variación espacial y temporal Composition and abundance of the seed bank in a semiaridregion in tropical Mexico: spatial and temporal patterns

    Directory of Open Access Journals (Sweden)

    Adriana Cano-Salgado

    2012-06-01

    Full Text Available Se estudió la estructura del banco de semillas en el valle semiárido de Zapotitlán, Puebla. El registro de la composición y abundancia del banco de semillas se realizó en 2 tipos de vegetación (tetechera y matorral espinoso en los microhábitats (bajo arbustos, espacio abierto y basureros de la hormiga granívora Pogonomyrmex barbatus. Las semillas se recolectaron en las épocas de secas, lluvias y finales de lluvias durante 2 años. No se encontraron diferencias en la densidad de semillas entre las épocas y años, pero sí hubo diferencias entre los microhábitats evaluados. El microhábitat del hormiguero presentó la mayor abundancia de semillas, lo que resalta la importancia de las hormigas en la conformación espacial de la estructura de las comunidades en estos ecosistemas. Se registraron semillas de 38 especies de plantas. La densidad promedio varió de 23 800 a 28 000 semillas m-2, concordando con otros registros de regiones semiáridas y áridas. Las especies más frecuentes fueron las anuales Eragrostis mexicana, Bouteloua barbata, Kallstroemia rosei y Portulaca pilosa. Los resultados muestran que la heterogeneidad de sitios y de microhábitats en esta zona es alta. Es necesaria la realización de más estudios sobre patrones espacio-temporales en los bancos de semillas y su relación con la vegetación en pie en zonas áridas y semiáridas en México.The seed bank structure in the semiarid valley of Zapotitlán, Puebla was studied. The record of the composition and abundance of the seed bank was conducted in 2 types of vegetation (tetechera and thorny scrub in the microhabitats (under shrubs, open space and refuse- dumps of granivorous ants Pogonomyrmex barbatus. Seed collection was carried out in dry, rainy and late rainy seasons for 2 years. There were no differences in seed density between seasons and years, but there were differences between microhabitats evaluated. The microhabitat of the ant refuse-dumps had the highest

  7. Regional signatures of plant response to drought and elevated temperature across a desert ecosystem

    Science.gov (United States)

    Munson, Seth M.; Muldavin, Esteban H.; Belnap, Jayne; Peters, Debra P.C.; Anderson, John P.; Reiser, M. Hildegard; Gallo, Kirsten; Melgoza-Castillo, Alicia; Herrick, Jeffrey E.; Christiansen, Tim A.

    2013-01-01

    The performance of many desert plant species in North America may decline with the warmer and drier conditions predicted by climate change models, thereby accelerating land degradation and reducing ecosystem productivity. We paired repeat measurements of plant canopy cover with climate at multiple sites across the Chihuahuan Desert over the last century to determine which plant species and functional types may be the most sensitive to climate change. We found that the dominant perennial grass, Bouteloua eriopoda, and species richness had nonlinear responses to summer precipitation, decreasing more in dry summers than increasing with wet summers. Dominant shrub species responded differently to the seasonality of precipitation and drought, but winter precipitation best explained changes in the cover of woody vegetation in upland grasslands and may contribute to woody-plant encroachment that is widespread throughout the southwestern United States and northern Mexico. Temperature explained additional variability of changes in cover of dominant and subdominant plant species. Using a novel empirically based approach we identified ‘‘climate pivot points’’ that were indicative of shifts from increasing to decreasing plant cover over a range of climatic conditions. Reductions in cover of annual and several perennial plant species, in addition to declines in species richness below the long-term summer precipitation mean across plant communities, indicate a decrease in the productivity for all but the most drought-tolerant perennial grasses and shrubs in the Chihuahuan Desert. Overall, our regional synthesis of long-term data provides a robust foundation for forecasting future shifts in the composition and structure of plant assemblages in the largest North American warm desert.

  8. Competitive effects of introduced annual weeds on some native and reclamation species in the Powder River Basin, Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Allen, E.B.; Knight, D.H.

    1980-01-01

    Four experiments were conducted to examine the competitive effects of introduced annual weeds on certain native and reclamation species. The first experiment was initiated by discing three sites in the Powder River Basin, Wyoming, at three distances from introduced weed seed sources. Introduced weed colonization was greatest when a seed source was located nearby. Higher weed cover resulted in reductions of percent cover, density, and richness of the native species. The second experiment was conducted in the greenhouse and was designed to determine if there are changes in response of S. kali and the native grasses Agropyron smithii and Bouteloua gracilis to competition and water regime. Both grass species had lower biomass and higher stomatal resistance when growing in mixed culture with S. kali than in pure culture in the dry regime, but there were no significant differences in the wet regime. In general, the difference in plant response between mixed and pure cultures was more pronounced in the dry than in the wet regime. The third study was a greenhouse experiment on germination and competition of S. kali (a C/sub 4/ species) with native species Lepidium densiflorum (C/sub 3/), Chenopodium pratericola (C/sub 3/), A. smithii (C/sub 3/), and B. gracilis (C/sub 4/) under May, June, and July temperature regimes. Salsola kali germinated equally well in all three regimes, but the other C/sub 4/ species had highest germination in the July regime and the C/sub 3/ species in the May and June regimes. The fourth study was designed to examine the effect of weed colonization on the success of mine reclamation. Little effect was observed, but colonization by introduced annuals was very low. (ERB)

  9. Root development during soil genesis: effects of root-root interactions, mycorrhizae, and substrate

    Science.gov (United States)

    Salinas, A.; Zaharescu, D. G.

    2015-12-01

    A major driver of soil formation is the colonization and transformation of rock by plants and associated microbiota. In turn, substrate chemical composition can also influence the capacity for plant colonization and development. In order to better define these relationships, a mesocosm study was set up to analyze the effect mycorrhizal fungi, plant density and rock have on root development, and to determine the effect of root morphology on weathering and soil formation. We hypothesized that plant-plant and plant-fungi interactions have a stronger influence on root architecture and rock weathering than the substrate composition alone. Buffalo grass (Bouteloua dactyloides) was grown in a controlled environment in columns filled with either granular granite, schist, rhyolite or basalt. Each substrate was given two different treatments, including grass-microbes and grass-microbes-mycorrhizae and incubated for 120, 240, and 480 days. Columns were then extracted and analyzed for root morphology, fine fraction, and pore water major element content. Preliminary results showed that plants produced more biomass in rhyolite, followed by schist, basalt, and granite, indicating that substrate composition is an important driver of root development. In support of our hypothesis, mycorrhizae was a strong driver of root development by stimulating length growth, biomass production, and branching. However, average root length and branching also appeared to decrease in response to high plant density, though this trend was only present among roots with mycorrhizal fungi. Interestingly, fine fraction production was negatively correlated with average root thickness and volume. There is also slight evidence indicating that fine fraction production is more related to substrate composition than root morphology, though this data needs to be further analyzed. Our hope is that the results of this study can one day be applied to agricultural research in order to promote the production of crops

  10. Establishment and performance of an experimental green roof under extreme climatic conditions.

    Science.gov (United States)

    Klein, Petra M; Coffman, Reid

    2015-04-15

    Green roofs alter the surface energy balance and can help in mitigating urban heat islands. However, the cooling of green roofs due to evapotranspiration strongly depends on the climatic conditions, and vegetation type and density. In the Southern Central Plains of the United States, extreme weather events, such as high winds, heat waves and drought conditions pose challenges for successful implementation of green roofs, and likely alter their standard performance. The National Weather Center Experimental Green Roof, an interdisciplinary research site established in 2010 in Norman, OK, aimed to investigate the ecological performance and surface energy balance of green roof systems. Starting in May 2010, 26 months of vegetation studies were conducted and the radiation balance, air temperature, relative humidity, and buoyancy fluxes were monitored at two meteorological stations during April-October 2011. The establishment of a vegetative community trended towards prairie plant dominance. High mortality of succulents and low germination of grasses and herbaceous plants contributed to low vegetative coverage. In this condition succulent diversity declined. Bouteloua gracilis and Delosperma cooperi showed typological dominance in harsh climatic conditions, while Sedum species experienced high mortality. The plant community diversified through volunteers such as Euphorbia maculate and Portulaca maculate. Net radiation measured at a green-roof meteorological station was higher than at a control station over the original, light-colored roofing material. These findings indicate that the albedo of the green roof was lower than the albedo of the original roofing material. The low vegetative coverage during the heat and drought conditions in 2011, which resulted in the dark substrate used in the green roof containers being exposed, likely contributed to the low albedo values. Nevertheless, air temperatures and buoyancy fluxes were often lower over the green roof indicating

  11. Regional signatures of plant response to drought and elevated temperature across a desert ecosystem.

    Science.gov (United States)

    Munson, Seth M; Muldavin, Esteban H; Belnap, Jayne; Peters, Debra P C; Anderson, John P; Reiser, M Hildegard; Gallo, Kirsten; Melgoza-Castillo, Alicia; Herrick, Jeffrey E; Christiansen, Tim A

    2013-09-01

    The performance of many desert plant species in North America may decline with the warmer and drier conditions predicted by climate change models, thereby accelerating land degradation and reducing ecosystem productivity. We paired repeat measurements of plant canopy cover with climate at multiple sites across the Chihuahuan Desert over the last century to determine which plant species and functional types may be the most sensitive to climate change. We found that the dominant perennial grass, Bouteloua eriopoda, and species richness had nonlinear responses to summer precipitation, decreasing more in dry summers than increasing with wet summers. Dominant shrub species responded differently to the seasonality of precipitation and drought, but winter precipitation best explained changes in the cover of woody vegetation in upland grasslands and may contribute to woody-plant encroachment that is widespread throughout the southwestern United States and northern Mexico. Temperature explained additional variability of changes in cover of dominant and subdominant plant species. Using a novel empirically based approach we identified "climate pivot points" that were indicative of shifts from increasing to decreasing plant cover over a range of climatic conditions. Reductions in cover of annual and several perennial plant species, in addition to declines in species richness below the long-term summer precipitation mean across plant communities, indicate a decrease in the productivity for all but the most drought-tolerant perennial grasses and shrubs in the Chihuahuan Desert. Overall, our regional synthesis of long-term data provides a robust foundation for forecasting future shifts in the composition and structure of plant assemblages in the largest North American warm desert. PMID:24279274

  12. Mechanisms of grass response in grasslands and shrublands during dry or wet periods.

    Science.gov (United States)

    Peters, Debra P C; Yao, Jin; Browning, Dawn; Rango, Albert

    2014-04-01

    Multi-year climatic periods are expected to increase with global change, yet long-term data are often insufficient to document factors leading to ecological responses. We used a suite of long-term datasets (1993-2010) to examine the processes underlying different relationships between aboveground net primary production (ANPP) and precipitation in wet and dry rainfall periods in shrublands and grasslands in the Chihuahuan Desert. We hypothesized that trends in ANPP can be explained by different processes associated with their dominant grasses [Bouteloua eriopoda (grasslands); Sporobolus flexuosus (shrublands)] and with ecosystem properties that influence soil water dynamics with feedbacks to ANPP. We compared datasets on recruitment and growth for 7 years with no trend in precipitation followed by a 4-year drought and 5 consecutive wet years. We integrated these data in a simulation model to examine the importance of positive feedbacks. In grasslands, ANPP was linearly related to precipitation regardless of rainfall period, primarily as a result of stolon recruitment by B. eriopoda. A lag in responses suggests the importance of legacies associated with stolon density. In shrublands, ANPP was only related to rainfall in the wet period when it increased nonlinearly as the number of wet years increased. Seed availability increased in the first wet year, and seedling establishment occurred 2-4 years later. Increases in biomass, litter and simulated transpiration beginning in the third year corresponded with increases in ANPP. Understanding the processes underlying ecosystem dynamics in multi-year dry or wet periods is expected to improve predictions under directional increases or decreases in rainfall. PMID:24263235

  13. Spatial partitioning of water use by herbaceous and woody lifeforms in semiarid woodlands

    International Nuclear Information System (INIS)

    Ecological studies of soil moisture, plant water uptake, and community composition in semiarid regions have focused on differences with depth in the soil profile, yet there are many reasons to expect that moisture also varies with the presence or absence of woody vegetation. Plant and soil moisture relationships for three dominant species in a semiarid woodland, Bouteloua gracilis, Juniperus monosperma, and Pinus edulis, were studied for 1.5 years. Soil moisture varied by type of plant cover as well as by depth. Plant water potential and conductance differed among species and was related to spatial variability in soil moisture. Water potential for blue grama was most correlated with soil moisture in the 0-15 cm layer of intercanopies; juniper water potential was highly correlated with soil moisture in the 0-15 cm layer beneath tree canopies of either species, and pinyon water potential was only weakly correlated with soil moisture in the 15-30 cm depth interval beneath pinyons. Pinyons had consistently greater maximum conductance rates than junipers, even though pinyon conductance was more sensitive to reductions in soil moisture. The results from this study indicate that horizontal differences in the soil moisture profile associated with type of plant cover may be as important as differences in depth for predicting plant-water relationships. A simple model was hypothesized for predicting community composition of three lifeforms: Herbaceous plants, shallow-rooted woody plants, and deeper-rooted woody plants. Distributions of roots of each lifeform and plant-available water were defined with respect to four soil compartments that distinguish upper vs. lower and canopy vs. intercanopy soil regions. The model predicts that multiple combinations of herbaceous and woody biomass can exist at a site and was qualitatively consistent with field data from a climatic gradient

  14. A classification of the Chloridoideae (Poaceae) based on multi-gene phylogenetic trees.

    Science.gov (United States)

    Peterson, Paul M; Romaschenko, Konstantin; Johnson, Gabriel

    2010-05-01

    We conducted a molecular phylogenetic study of the subfamily Chloridoideae using six plastid DNA sequences (ndhA intron, ndhF, rps16-trnK, rps16 intron, rps3, and rpl32-trnL) and a single nuclear ITS DNA sequence. Our large original data set includes 246 species (17.3%) representing 95 genera (66%) of the grasses currently placed in the Chloridoideae. The maximum likelihood and Bayesian analysis of DNA sequences provides strong support for the monophyly of the Chloridoideae; followed by, in order of divergence: a Triraphideae clade with Neyraudia sister to Triraphis; an Eragrostideae clade with the Cotteinae (includes Cottea and Enneapogon) sister to the Uniolinae (includes Entoplocamia, Tetrachne, and Uniola), and a terminal Eragrostidinae clade of Ectrosia, Harpachne, and Psammagrostis embedded in a polyphyletic Eragrostis; a Zoysieae clade with Urochondra sister to a Zoysiinae (Zoysia) clade, and a terminal Sporobolinae clade that includes Spartina, Calamovilfa, Pogoneura, and Crypsis embedded in a polyphyletic Sporobolus; and a very large terminal Cynodonteae clade that includes 13 monophyletic subtribes. The Cynodonteae includes, in alphabetical order: Aeluropodinae (Aeluropus); Boutelouinae (Bouteloua); Eleusininae (includes Apochiton, Astrebla with Schoenefeldia embedded, Austrochloris, Brachyachne, Chloris, Cynodon with Brachyachne embedded in part, Eleusine, Enteropogon with Eustachys embedded in part, Eustachys, Chrysochloa, Coelachyrum, Leptochloa with Dinebra embedded, Lepturus, Lintonia, Microchloa, Saugetia, Schoenefeldia, Sclerodactylon, Tetrapogon, and Trichloris); Hilariinae (Hilaria); Monanthochloinae (includes Distichlis, Monanthochloe, and Reederochloa); Muhlenbergiinae (Muhlenbergia with Aegopogon, Bealia, Blepharoneuron, Chaboissaea, Lycurus, Pereilema, Redfieldia, Schaffnerella, and Schedonnardus all embedded); Orcuttiinae (includes Orcuttia and Tuctoria); Pappophorinae (includes Neesiochloa and Pappophorum); Scleropogoninae (includes

  15. Understanding the erosion of semi-arid landscapes subject to vegetation change: a combined approach using monitoring, isotope and 14C analysis

    Science.gov (United States)

    Brazier, R. E.; Turnbull, L.; Bol, R.; Dixon, L.; Wainwright, J.

    2009-04-01

    The degradation of grasslands is a common problem across semi-arid areas worldwide. Over the last 150 years much of the South-Western USA has experienced significant land degradation, with desert grasslands becoming dominated by shrubs and concurrent changes in runoff and erosion which are thought to propagate further the process of degradation. Field-based experiments were carried out to determine how runoff and erosion vary at stages over a transition from a black grama (Bouteloua eriopoda) grassland to creosotebush (Larrea tridentata) shrubland at the Sevilleta NWR LTER site in New Mexico. 14C and δ13C analyses were carried out to investigate the age and potential provenance of eroded sediment. Results show an overall increase in runoff and erosion over the transition from grassland to shrubland, associated with an increase in connectivity of bare, runoff-generating areas, although these increases do not appear to follow a linear trajectory. Erosion rates increased over the transition from grassland to shrubland, related in part to changes in runoff characteristics and the increased capacity of the runoff to detach, entrain and transport sediment. Over all plots fine material was preferentially eroded which has potential implications for nutrient cycling since nutrients tend to be associated with fine sediment. There are significant differences in the isotopic signatures of eroded sediment between the grass- and shrub-dominated plots. The positive correlation between event runoff and δ13C signatures of eroded sediment that is consistent over plots 1, 3 and 4 suggests that the δ13C signatures can be used to distinguish between changes in erosion dynamics over events of different magnitudes and over different vegetation types. 14C analysis of sediment revealed that sediment eroded from all plots is considerably younger than the surface soils over all plots, which is likely to indicate that eroded sediments tend to source form very near surface areas that are

  16. Efficient breakdown of lignocellulose using mixed-microbe populations for bioethanol production.

    Energy Technology Data Exchange (ETDEWEB)

    Murton, Jaclyn K.; Ricken, James Bryce; Powell, Amy Jo

    2009-11-01

    (DoE) Joint Genome Institute (JGI) to perform metatranscriptomic functional profiling of eukaryotic microbial communities of blue grama grass (Bouteloua gracilis) rhizosphere (RHZ) soils and (2) isolated and provided initial genotypic and phenotypic characterization data for thermophilic fungi. Our preliminary results show that many strains in our collection of thermophilic fungi frequently outperform industry standards in key assays; we also demonstrated that this collection is taxonomically diverse and phenotypically compelling. The studies summarized here are being performed in collaboration with University of New Mexico and are based at the Sevilleta LTER research site.

  17. Evaluating channel morphology in small watersheds of oak savannas Southeastern New Mexico, USA: Do seasonal prescribed burn treatments have a significant impact on sediment processes?

    Science.gov (United States)

    Koestner, Karen; Neary, Daniel; Gottfried, Gerald; Tecle, Aregai

    2010-05-01

    Oak-savannas comprise over 80,000 km2 of the southwestern United States and northern Mexico. However, there is a paucity of data to assist in the management of this vast ecotype. Fire, which was once the most important natural disturbance in this system, has been excluded due to over-grazing and fire suppression practices. This has resulted in ecosystem changes and fuel accumulations. Prescribed fire is one management technique to restore natural processes within southwestern oak-savannas by reducing woody species density, increasing herbaceous plant production, and creating vegetative mosaics on the landscape. However, questions concerning the seasonality of burn treatments and the overall effects of these treatments on physical and ecological processes need to be addressed prior to broad management application. The Cascabel Watershed Study is a collaborative effort between multiple government agencies, universities, local land managers, and environmental interest groups to evaluate the impacts of warm and cool season burn treatments on an array of ecosystem processes. Established in 2000, the Cascabel Watershed study takes an "ecosystem approach" to watershed research by examining an array of physical and biological components, including geomorphologic, climatologic, hydrologic, and biologic (flora and fauna) data to determine ecosystem response to prescribed fire. The 182.6 ha study area is located in the eastern Peloncillo Mountains, New Mexico at about the 1,640 m elevation. It consists of 12 small watersheds dominated by an oak (Quercus spp.) overstory and bunch-grass (Bouteloua spp.), savanna component. The parent material is fine-grained Tertiary rhyolite that is part of an extensive lava field that was formed about 25 to 27 M ybp. A US Forest Service soil survey in the area classified 45% of the soils as Typic Haplustolls, coarse-loamy, mixed, mesic, 25% as Typic Haplustalfs, and 15% rock outcrops. Here, we evaluate within-channel processes to establish

  18. Plant phenological responses to extreme events - A long term perspective from the Chihuahuan Desert

    Science.gov (United States)

    Browning, D. M.; Peters, D. P.; Anderson, J.; Yao, J.

    2011-12-01

    Arid and semi-arid regions of the southwestern USA are especially sensitive to changes in temperature as well as drought frequency and intensity. Timing of periodic life cycle events (i.e., phenology) is an integrated and salient indicator of plant responses to climate change. We examine an 18-year dataset of monthly observations of plant phenology for two species of perennial grasses and a deciduous shrub (honey mesquite) distributed across three upland grassland sites and three mesquite-dominated sites on the Jornada Basin USDA-LTER in southern New Mexico, USA. Precipitation is highly variable between years and across space. Long-term phenology data collection spanned a multi-year drought (1994-2003) followed by a sequence of years with average to very high rainfall (2004 - 2008). Our objective was to compare and contrast responses to extreme dry and wet cycles in the timing and duration of first leaf and fruit production for two grasses (Bouteloua eriopoda [black grama], Sporobolus flexuosus [mesa dropseed]) with one co-existing shrub that has displaced grasses in this system (Prosopis glandulosa [honey mesquite]). Monthly field observations yield estimates of phenological status and abundance for 18 growing seasons from 1993 to 2010. All three species most commonly initiated new growth prior to onset of the monsoon rains (March or April). Timing of first growth for mesquite was less variable (standard deviation = 0.47) than for black grama (SD = 1.42) and mesa dropseed (SD = 1.22) grasses. Initial growth for grasses was delayed to September in 2006 following twelve months of deficit values for PDSI. The appearance of first fruit for grasses occurred consistently in August or September, although the number of plants producing fruit was highly variable from year to year. The largest numbers of fruit-bearing grasses were observed in late fall 2008 in response to heavy monsoon rains in 2006 and 2008. Mesquite demonstrated remarkable synchrony in the production of

  19. Seasonal Soil Nitrogen Mineralization within an Integrated Crop and Livestock System in Western North Dakota, USA

    Science.gov (United States)

    Landblom, Douglas; Senturklu, Songul; Cihacek, Larry; Pfenning, Lauren; Brevik, Eric C.

    2015-04-01

    pipes were pressed into the soil as enclosures to restrict root access to soil nitrogen. Soil samples were taken as close to 2-week intervals as possible from both inside and outside the enclosures. The crop rotation N values were also compared to triple replicated perennial native grassland plot areas (predominate sp. Western wheatgrass - Pascopyrum smithii, Blue grama - Bouteloua gracilis, Little bluestem - Schizachyrium scoparium, Switchgrass - Panicum virgatum). Trends identified for both NH4-N and NO3-N indicate that the values are relatively similar with respect to seasonal change over time. There was a greater amount of soil nitrogen accumulation inside the enclosures indicating that outside the enclosures roots scavenge nitrogen for plant growth and production. Seasonally, comparing the cropping system crops, NO3-N declined mid-July and then rebounded by mid-August and continued to increase until leveling off in September. Corn NO3-N, however, did not follow this pattern, but increased from early June to the end of June and remained high until the first of September. We will present the results of bulk density data and seasonal N fertility data providing evidence for the impact of previous CC on corn production. Probable explanation for the mid-summer nitrogen decline will be presented and justification for reduced fertilizer application will be discussed.