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Sample records for andropogon gerardii vitman

  1. Single nucleotide polymorphism discovery via genotyping by sequencing to assess population genetic structure and recurrent polyploidization in Andropogon gerardii.

    Science.gov (United States)

    McAllister, Christine A; Miller, Allison J

    2016-07-01

    Autopolyploidy, genome duplication within a single lineage, can result in multiple cytotypes within a species. Geographic distributions of cytotypes may reflect the evolutionary history of autopolyploid formation and subsequent population dynamics including stochastic (drift) and deterministic (differential selection among cytotypes) processes. Here, we used a population genomic approach to investigate whether autopolyploidy occurred once or multiple times in Andropogon gerardii, a widespread, North American grass with two predominant cytotypes. Genotyping by sequencing was used to identify single nucleotide polymorphisms (SNPs) in individuals collected from across the geographic range of A. gerardii. Two independent approaches to SNP calling were used: the reference-free UNEAK pipeline and a reference-guided approach based on the sequenced Sorghum bicolor genome. SNPs generated using these pipelines were analyzed independently with genetic distance and clustering. Analyses of the two SNP data sets showed very similar patterns of population-level clustering of A. gerardii individuals: a cluster of A. gerardii individuals from the southern Plains, a northern Plains cluster, and a western cluster. Groupings of individuals corresponded to geographic localities regardless of cytotype: 6x and 9x individuals from the same geographic area clustered together. SNPs generated using reference-guided and reference-free pipelines in A. gerardii yielded unique subsets of genomic data. Both data sets suggest that the 9x cytotype in A. gerardii likely evolved multiple times from 6x progenitors across the range of the species. Genomic approaches like GBS and diverse bioinformatics pipelines used here facilitate evolutionary analyses of complex systems with multiple ploidy levels. © 2016 Botanical Society of America.

  2. CANOPY ARCHITECTURE, LIGHT EXTINCTION AND SELF-SHADING OF A PRAIRIE GRASS, ANDROPOGON GERARDII. (R825796)

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    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  3. Plant-fungus competition for nitrogen erases mycorrhizal growth benefits of Andropogon gerardii under limited nitrogen supply

    Czech Academy of Sciences Publication Activity Database

    Püschel, David; Janoušková, Martina; Hujslová, M.; Slavíková, R.; Gryndlerová, H.; Jansa, J.

    2016-01-01

    Roč. 6, č. 13 (2016), s. 4332-4346 ISSN 2045-7758 Institutional support: RVO:67985939 Keywords : arbuscular mycorrhizal fungi * nutrient uptake response * mycorrhizal benefits and costs Subject RIV: EF - Botanics Impact factor: 2.440, year: 2016

  4. Plant-fungus competition for nitrogen erases mycorrhizal growth benefits of Andropogon gerardii under limited nitrogen supply

    Czech Academy of Sciences Publication Activity Database

    Püschel, David; Janoušková, Martina; Hujslová, Martina; Slavíková, Renata; Gryndlerová, Hana; Jansa, Jan

    2016-01-01

    Roč. 6, č. 13 (2016), s. 4332-4346 ISSN 2045-7758 R&D Projects: GA ČR(CZ) GA14-19191S; GA MŠk(CZ) LK11224 Institutional support: RVO:61388971 Keywords : Arbuscular mycorrhizal fungi * belowground carbon drain * inoculation Subject RIV: EE - Microbiology, Virology Impact factor: 2.440, year: 2016

  5. Performance and goats behavior in pasture of Andropogon grass under different forage allowances

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    Daniel Louçana da Costa Araújo

    2015-07-01

    Full Text Available This study was accomplished to evaluate the behavior and performance of goats in to grazing on grass Andropogon gayanus Kunth var. Bisquamulatus (Hochst Hack. cv. Planaltina submitted to three forage allowances: 11, 15 and 19% BW/day, under continuous grazing. The experimental design to assess the grazing behaviour was randomized blocks in a split-plot with five replicates within the block. In the plots, we evaluated the effect of forage allowances and in the subplots, the months May and June. While for evaluation of animal performance was in complete block design with five replicates within the block. The different forage allowance did not cause structural changes in the pasture, except in height. However, there was an increase of dead material, leaf/stem ratio and reducing of height during the grazing period. The behavioral variables were not affected by forage allowance, except for the time of displacement, whereby goats spent more time in pastures with offer of 11% BW. The goats remained most part of the time in grazing and idle, corresponding to 89% and 5% of the evaluation time, respectively. Higher bit rate was observed in June, among the offerings, and 15 and 19% BW. The ingestive and grazing behaviour in goats is changed by the accumulation of dead material and stem in pasture from Andropogon grass during at rainy season. The forage supply 11% of BW increases the time of displacement of goats grazing on Andropogon grass. The management of grazing Andropogon grass with forage allowance being 11 and 19% of BW provides low weight gains in goats during the rainy season.

  6. INTAKE AND APPARENT DIGESTIBILITY OF Andropogon gayanus HAY AT THREE DIFFERENT AGES

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    André Cayô Cavalcanti

    2016-10-01

    Full Text Available The aim of this study was to evaluate the voluntary intake and apparent digestibility of dry matter, crude protein, fiber fractions, energy, and the nitrogen balance of Andropogon gayanus hay at three different stages (56, 84 and 112 days. The statistical design was completely randomized, with three treatments and six replicates. Dry matter, fiber fractions, and energy apparent digestibility were higher (P<0.05 for hay harvested at 56 and 84 days. Crude protein intake and apparent digestibility of A. gayanus hay harvested at 56 days of growth were greater (P<0.05 than the hay harvested at 84 and 112 days. The A. gayanus hay showed the best voluntary intake and digestibility at 56 and 84 days of age. Keywords: forage; nutritive value; sheep.

  7. Andropogon scoparius uptake of 45Ca and production from two contrasting soil types

    International Nuclear Information System (INIS)

    Waller, S.S.; Dodd, J.D.

    1976-01-01

    Total foliage production of Andropogon scoparius was greater on the Heiden-Hunt clay soil complex (Udic chromusterts and pellusterts) than on he Tabor fine sandy loam (Udertic paleustalfs). Foliage production on both soil types increased as clipping frequency decreased. Foliage production and 45 C uptake exhibited a positive relationship with precipitation during the growing season. Total uptake and concentration were greater in the sand-grown clones than in the clay-grown clones. Foliage concentration was inversely related to stable soil Ca and reflected the ratio of radioactive to stable Ca in the soil. However, uptake at the end of the growing season was less than 0.20% of that applied on either soil type. Increased clipping frequency increased foliage 45 Ca concentration on both soil types

  8. Invasive Andropogon gayanus (gamba grass) is an ecosystem transformer of nitrogen relations in Australian savanna.

    Science.gov (United States)

    Rossiter-Rachor, N A; Setterfield, S A; Douglas, M M; Hutley, L B; Cook, G D; Schmidt, S

    2009-09-01

    Invasion by the African grass Andropogon gayanus is drastically altering the understory structure of oligotrophic savannas in tropical Australia. We compared nitrogen (N) relations and phenology of A. gayanus and native grasses to examine the impact of invasion on N cycling and to determine possible reasons for invasiveness of A. gayanus. Andropogon gayanus produced up to 10 and four times more shoot phytomass and root biomass, with up to seven and 2.5 times greater shoot and root N pools than native grass understory. These pronounced differences in phytomass and N pools between A. gayanus and native grasses were associated with an altered N cycle. Most growth occurs in the wet season when, compared with native grasses, dominance of A. gayanus was associated with significantly lower total soil N pools, lower nitrification rates, up to three times lower soil nitrate availability, and up to three times higher soil ammonium availability. Uptake kinetics for different N sources were studied with excised roots of three grass species ex situ. Excised roots of A. gayanus had an over six times higher-uptake rate of ammonium than roots of native grasses, while native grass Eriachne triseta had a three times higher uptake rate of nitrate than A. gayanus. We hypothesize that A. gayanus stimulates ammonification but inhibits nitrification, as was shown to occur in its native range in Africa, and that this modification of the soil N cycle is linked to the species' preference for ammonium as an N source. This mechanism could result in altered soil N relations and could enhance the competitive superiority and persistence of A. gayanus in Australian savannas.

  9. Estimating the financial risks of Andropogon gayanus to greenhouse gas abatement projects in northern Australia

    Science.gov (United States)

    Adams, Vanessa M.; Setterfield, Samantha A.

    2013-06-01

    Financial mechanisms such as offsets are one strategy to abate greenhouse gas emissions, and the carbon market is expanding with a growing demand for offset products. However, in the case of carbon offsets, if the carbon is released due to intentional or unintentional reversal through environmental events such as fire, the financial liability to replace lost offsets will likely fall on the provider. This liability may have implications for future participation in programmes, but common strategies such as buffer pool and insurance products can be used to minimize this liability. In order for these strategies to be effective, an understanding of the spatial and temporal distributions of expected reversals is needed. We use the case study of savanna burning, an approved greenhouse gas abatement methodology under the Carbon Farming Initiative in Australia, to examine potential risks to carbon markets in northern Australia and quantify the financial risks. We focus our analysis on the threat of Andropogon gayanus (gamba grass) to savanna burning due to its documented impacts of increased fuel loads and altered fire regimes. We assess the spatial and financial extent to which gamba grass poses a risk to savanna burning programmes in northern Australia. We find that 75% of the eligible area for savanna burning is spatially coincident with the high suitability range for gamba grass. Our analysis demonstrates that the presence of gamba grass seriously impacts the financial viability of savanna burning projects. For example, in order to recuperate the annual costs of controlling 1 ha of gamba grass infestation, 290 ha of land must be enrolled in annual carbon abatement credits. Our results show an immediate need to contain gamba grass to its current extent to avoid future spread into large expanses of land, which are currently profitable for savanna burning.

  10. Estimating the financial risks of Andropogon gayanus to greenhouse gas abatement projects in northern Australia

    International Nuclear Information System (INIS)

    Adams, Vanessa M; Setterfield, Samantha A

    2013-01-01

    Financial mechanisms such as offsets are one strategy to abate greenhouse gas emissions, and the carbon market is expanding with a growing demand for offset products. However, in the case of carbon offsets, if the carbon is released due to intentional or unintentional reversal through environmental events such as fire, the financial liability to replace lost offsets will likely fall on the provider. This liability may have implications for future participation in programmes, but common strategies such as buffer pool and insurance products can be used to minimize this liability. In order for these strategies to be effective, an understanding of the spatial and temporal distributions of expected reversals is needed. We use the case study of savanna burning, an approved greenhouse gas abatement methodology under the Carbon Farming Initiative in Australia, to examine potential risks to carbon markets in northern Australia and quantify the financial risks. We focus our analysis on the threat of Andropogon gayanus (gamba grass) to savanna burning due to its documented impacts of increased fuel loads and altered fire regimes. We assess the spatial and financial extent to which gamba grass poses a risk to savanna burning programmes in northern Australia. We find that 75% of the eligible area for savanna burning is spatially coincident with the high suitability range for gamba grass. Our analysis demonstrates that the presence of gamba grass seriously impacts the financial viability of savanna burning projects. For example, in order to recuperate the annual costs of controlling 1 ha of gamba grass infestation, 290 ha of land must be enrolled in annual carbon abatement credits. Our results show an immediate need to contain gamba grass to its current extent to avoid future spread into large expanses of land, which are currently profitable for savanna burning. (letter)

  11. Arbuscular mycorrhizal fungi alter phosphorus relations of broomsedge (Andropogon virginicus L.) plants

    Energy Technology Data Exchange (ETDEWEB)

    Ning, J.C.; Cumming, J.R.

    2001-07-01

    Broomsedge (Andropogon virginicus L.) is a dominant grass revegetating many abandoned coal-mined lands in West Virginia, USA. Residual soils on such sites are often characterized by low pH, low nutrients, and high aluminium. Experiments were conducted to assess the resistance of broomsedge to limited phosphorus (Pi) availability and to investigate the role that arbuscular mycorrhizal (AM) fungi play in aiding plant growth under low Pi conditions. Pregerminated mycorrhizal and non-mycorrhizal seedlings were grown in a sand-culture system with nutrient solutions containing Pi concentrations ranging from 10 to 100 {mu}M for 8 weeks. Non-mycorrhizal plants exhibited severe inhibition of growth under Pi limitation ({lt}60 {mu}M). Colonization by AM fungi greatly enhanced host plant growth at low Pi concentrations, but did not benefit growth when Pi was readily available (100 {mu}M). In comparison to non-mycorrhizal plants, mycorrhizal plants had higher phosphorus use efficiency at low Pi concentrations and maintained nearly constant tissue nutrient concentrations across the gradient of Pi concentrations investigated. Manganese (Mn) and sodium (Na) accumulated in shoots of nonmycorrhizal plants under Pi limitation. Mycorrhizal plants exhibited lower instantaneous Pi uptake rates and significantly lower C-min values compared to non-mycorrhizal plants. These patterns suggest that the symbiotic association between broomsedge roots and AM fungi effectively maintains nutrient homeostasis through changes in physiological properties, including nutrient uptake, allocation and use. The mycorrhizal association is thus a major adaptation that allows broomsedge to become established on infertile mined lands.

  12. Isolasi Minyak Atsiri dari Sereh Merah (Andropogon citratus DC.) Segar dan Kering Serta Analisis Komponen Secara GC-MS

    OpenAIRE

    Situmorang, Betty Meilya

    2013-01-01

    Essential oil is a term used for volatile oil and obtained from part of plant such as leaves, flowers, fruit, bark and roots. Lemongrass oil is a major export commodities among the various types of essential oil. The main content of lemongrass oil are sitronellal and geraniol, and content oil of lemongrass is 0.5 to 1.2%. Andropogon citratus DC. of the family Poaceae is one of plant that contains essential oil and is widely used as a liniment. The objective of this research is to determine th...

  13. Description du système racinaire de trois espèces fourragères en zone soudano-sahélienne: Andropogon gayanus, Vigna unguiculata et Stylosanthes hamata

    OpenAIRE

    Groot, J.J.R.; Traoré, M.; Koné, D.

    1998-01-01

    Description of root systems of three fodder crops in the Soudano-Sahelian area: Andropogon gayanus, Vigna unguiculata and Stylosanthes hamata. Root systems of fodder crops (Andropogon gayanus, Vigna unguiculata and Stylosanthes hamata) were studied at two Research Stations in Mali in 1992, using soil monoliths. In this method, roots are studied throughout the soil profile in cubical compartments of 1 dm3. Root biomass production of A. gayanus planted in 1951 was 4 t.ha-1 against 5 t.ha-1 ...

  14. Potentiel des jachères artificielles à Andropogon spp. dans l’amélioration des propriétés chimiques et biologiques des sols en zone soudanienne (Burkina Faso

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    Moustapha Tassembedo

    2007-01-01

    Full Text Available Potential of the artificial fallows on Andropogon spp. in the improvement of the chemical and biological properties of soil in Sudanian zone (Burkina Faso. In order to find solutions to the decrease in yield consecutive to the decrease of soil fertility in ferruginous soil an experiment was carried out at Sobaka, in the Sudanian zone of Burkina Faso. An artificial fallow containing Andropogon spp. was created and the biological activity of the tropical ferruginous soil was evaluated at the end of three years of fallow. The following parameters were evaluated: total carbon and nitrogen, respirometric activity, CO2, carbon production and microbial biomass. The results after three years show that the organic matter produced by the litter and the roots of andropogonnées increase significantly the organic matter of the soil over 40% compared to the natural fallow or to the cultivated soil. The artificial fallows significantly improve the produced carbon and the microbial biomass. It is thus possible to recommend the artificial fallow with Andropogon spp. to improve the soil fertility and to shorten the duration of the fallow.

  15. Evaluación de Andropogon gayanus, Centrosema acutifolium y Pueraria phaseoloides en la cría de terneros destetados precozmente en los Llanos Orientales de Colombia

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    Vera Raul R.

    1988-06-01

    Full Text Available Se midió el desarrollo corporal de terneros destetados a los tres meses de edad en pasturas de Andropogon gayanus, A. gayanus + Centrosema acutifolium y A. gayanus + Pueraria phaseoloides. Se utilizaron 10 terneros/tratamiento (70.3 ± 1.73 kg. El ensayo empezó en plena temporada de lluvias, que en este año fueron excesivas y afectaron negativamente la recuperación de las praderas. El desarrollo de los animales se redujo seriamente por la falta de forraje. Se hicieron algunas comparaciones subjetivas con un grupo de terneros que permaneció con sus madres en sabana nativa, hasta los nueve meses de edad, en la cual se realiza el destete tradicional. La cantidad de lluvia no permitió hacer comparaciones entre las pasturas. Los terneros destetados precozmente mostraron un desempeño muy pobre con respecto a los que permanecieron con sus madres; sin embargo, el grupo que pastoreó A. gayanus presentó los peores resultados en ganancia de peso vivo, porcentaje de proteína y minerales en suero, hematocrito, etc., muriendo tres animales por efecto del tratamiento. El destete precoz redujo el anestro posparto de las vacas y mejoró la recuperación de peso de las mismas.The development of early-weaned calves (three months old in Andropogon gayanus, A. gayanus, Centrosema acutifolium and A. gayanus + Pueraria phaseoloides was investigated. Ten animals were used per treatment; the experiment beginning at the start of the rainy season. In this year 100 % and 45 % more rain fell in may and june respectively than the yearly average for these months. Several subjective comparison were made between the calves in the improved and group maintaned with their mothers in the native savannah until traditional early weaning occurs. The abnormally high rain-fall adverselty affected pasture recovery to the extent that it was impossible to make comparisons between the three pasture treatments. In general, however, all early-weaned calves did not perform as well as

  16. Impacts of managing perennial grasses in the northern Midwest United States for bioenergy on soil organic C and nitrous oxide emission

    Science.gov (United States)

    In the USA perennial grasses [e.g., switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerdardii Vitman)] are proposed as cellulosic feedstock. Perennial grasses are often touted as being low input and as having a C-neutral foot print, but managing them as bioenergy feedstock means addin...

  17. Nitrous oxide emission and soil carbon sequestration from herbaceous perennial biofuel feedstocks

    Science.gov (United States)

    Greenhouse gas (GHG) mitigation and renewable, domestic fuels are needed in the United States. Switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerdardii Vitman) are potential bioenergy feedstocks that may meet this need. However, managing perennial grasses for feedstock requires nitro...

  18. Composição bromatológica e produtividade do capim-andropógon em diferentes idades de rebrota em sistema silvipastoril = Bromatological composition and productivity of Andropogon grass at different ages of resprout in silvopastoral system

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    Marlúcia da Silva Bezerra Lacerda

    2009-04-01

    Full Text Available Avaliou-se a composição e produtividade do capim-andropógon (Andropogon gayanus Kunth. em diferentes idades de rebrota, associado às espécies arbóreas pau-d’arco (Tabebuia serratifolia e jatobá (Hymenaea courbaril no período chuvoso, em Teresina, Piauí.Adotou-se o delineamento de blocos ao acaso, em esquema fatorial 3 x 2, com parcelas subdivididas, sendo as parcelas os ambientes (sombreamento com jatobá e pau-d’arco e área aberta e posições (nascente e poente, e as subparcelas as idades (35, 49 e 63 dias, com cinco repetições. Houve interação ambiente x idade para MS na planta, FDN e FDA na planta e nas folhas e NIDN nas folhas. A PB nas folhas à sombra foi superior (9,65 ± 0,94% em relação à área aberta (9,16 ± 1,41%. Houve efeito linear decrescente (p The study evaluated composition and productivity of Andropogon grass at different ages of resprout, associated with the species Tabebuiaserratifolia and Hymenaea courbaril, during the rainy period, in Teresina, Piauí. A random blocks design was adopted, in a 3 x 2 factorial scheme, with subdivided parcels, being the parcels theenvironments (shading with Tabebuia serratifolia, Hymenaea courbaril and open area and position (rising and setting, and subparcels the ages (35, 49 and 63 days, with five repetitions. There wasinteraction between the environment and age for DM in the plant, NDF and ADF in the plant and leaves, and NDIN in leaves. The CP in leaves in the shade was higher (9.65 ± 0.94% compared to the open area (9.16 ± 1.41%. There was a linear effect (p < 0.01 of the age on CPin the plant and leaves. From days 47.7 and 48.8 there was a reduction in the leaf/steam ratio of Andropogon grass under T. serratifolia and H. courbaril, respectively. The culture of the grass in silvopastoral systems is viable, due to the stability in the composition of DM and ADF in the ratios of NDIN and ADIN in the plant and leaves, as well as for CP in plant and NDF in leaves, with

  19. Composição bromatológica e produtividade do capim-andropógon em diferentes idades de rebrota em sistema silvipastoril - DOI: 10.4025/actascianimsci.v31i2. Bromatological composition and productivity of Andropogon grass at different ages of resprout in silvopastoral system - DOI: 10.4025/actascianimsci.v31i2.4549

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    Teodoreto Barbosa Carvalho

    2009-08-01

    Full Text Available Avaliou-se a composição e produtividade do capim-andropógon (Andropogon gayanus Kunth. em diferentes idades de rebrota, associado às espécies arbóreas pau-d’arco (Tabebuia serratifolia e jatobá (Hymenaea courbaril no período chuvoso, em Teresina, Piauí. Adotou-se o delineamento de blocos ao acaso, em esquema fatorial 3 x 2, com parcelas subdivididas, sendo as parcelas os ambientes (sombreamento com jatobá e pau-d’arco e área aberta e posições (nascente e poente, e as subparcelas as idades (35, 49 e 63 dias, com cinco repetições. Houve interação ambiente x idade para MS na planta, FDN e FDA na planta e nas folhas e NIDN nas folhas. A PB nas folhas à sombra foi superior (9,65 ± 0,94% em relação à área aberta (9,16 ± 1,41%. Houve efeito linear decrescente (p The study evaluated composition and productivity of Andropogon grass at different ages of resprout, associated with the species Tabebuia serratifolia and Hymenaea courbaril, during the rainy period, in Teresina, Piauí. A random blocks design was adopted, in a 3 x 2 factorial scheme, with subdivided parcels, being the parcels the environments (shading with Tabebuia serratifolia, Hymenaea courbaril and open area and position (rising and setting, and subparcels the ages (35, 49 and 63 days, with five repetitions. There was interaction between the environment and age for DM in the plant, NDF and ADF in the plant and leaves, and NDIN in leaves. The CP in leaves in the shade was higher (9.65 ± 0.94% compared to the open area (9.16 ± 1.41%. There was a linear effect (p Andropogon grass under T. serratifolia and H. courbaril, respectively. The culture of the grass in silvopastoral systems is viable, due to the stability in the composition of DM and ADF in the ratios of NDIN and ADIN in the plant and leaves, as well as for CP in plant and NDF in leaves, with higher CP levels in leaves of the grass. There was no difference in the levels of NDF in the grass in function of

  20. Arbuscular common mycorrhizal networks mediate intra- and interspecific interactions of two prairie grasses.

    Science.gov (United States)

    Weremijewicz, Joanna; da Silveira Lobo O'Reilly Sternberg, Leonel; Janos, David P

    2018-01-01

    Arbuscular mycorrhizal fungi form extensive common mycorrhizal networks (CMNs) that may interconnect neighboring root systems of the same or different plant species, thereby potentially influencing the distribution of limiting mineral nutrients among plants. We examined how CMNs affected intra- and interspecific interactions within and between populations of Andropogon gerardii, a highly mycorrhiza dependent, dominant prairie grass and Elymus canadensis, a moderately dependent, subordinate prairie species. We grew A. gerardii and E. canadensis alone and intermixed in microcosms, with individual root systems isolated, but either interconnected by CMNs or with CMNs severed weekly. CMNs, which provided access to a large soil volume, improved survival of both A. gerardii and E. canadensis, but intensified intraspecific competition for A. gerardii. When mixed with E. canadensis, A. gerardii overyielded aboveground biomass in the presence of intact CMNs but not when CMNs were severed, suggesting that A. gerardii with intact CMNs most benefitted from weaker interspecific than intraspecific interactions across CMNs. CMNs improved manganese uptake by both species, with the largest plants receiving the most manganese. Enhanced growth in consequence of improved mineral nutrition led to large E. canadensis in intact CMNs experiencing water-stress, as indicated by 13 C isotope abundance. Our findings suggest that in prairie plant communities, CMNs may influence mineral nutrient distribution, water relations, within-species size hierarchies, and between-species interactions.

  1. Dry matter production and nutrient accumulation after successive crops of lettuce, tomato, rice, and andropogongrass in a substrate with zeolite Produção de matéria seca e acúmulo de nutrientes após cultivos sucessivos com alface, tomate, arroz e capim andropogon em substrato com zeólita

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    Alberto C. de Campos Bernardi

    2010-04-01

    Full Text Available Zeolites are hydrated crystalline aluminosilicate minerals of natural occurrence, structured in rigid third dimension net that can be used as slow release plant-nutrient source. The main objective of this study was to evaluate the effects of plant growth substrate under zeolite application, enriched with N, P and K, on dry matter yield and on nutrient contents in consecutive crops of lettuce, tomato, rice, and andropogon grass. The experiment was carried out in a greenhouse, with 3 kg pots with an inert substrate, evaluated in a randomized block design with three replications. Treatments consisted of four types of enrichment of concentrated natural zeolite: concentrated zeolite (Z only, zeolite + KNO3 (ZNK, zeolite + K2HPO4 (ZPK and zeolite + H3PO4 + apatite (ZP, and a control grown in substrate fertilized with a zeolite-free nutrient solution. Four levels of enriched zeolite were tested: 20, 40, 80, and 160 g/pot. Four successive crops were grown on the same substrate in each pot: lettuce, tomato, rice, and andropogon grass. Results indicated that N, P and K enriched zeolite was an adequate slow-release nutrient source for plants. The total dry matter production of above-ground biomass of four successive crops followed a descending order: ZP > ZPK > ZNK > Z.Zeólitas são minerais aluminossilicatos cristalinos hidratados de ocorrência natural, estruturados em redes cristalinas tridimensionais rígidas que podem ser usados como fonte de liberação lenta de nutrientes para as plantas. O objetivo deste trabalho foi avaliar o efeito da adição de zeólita enriquecida com N, P e K ao substrato de cultivo sobre a produção de matéria seca e o acúmulo de nutrientes pelas culturas sucessivas de alface, de tomate, de arroz e de capim-andropogon. O experimento foi conduzido em vasos em casa de vegetação, em vasos contendo 3 kg de substrato inerte. O delineamento experimental foi o de blocos ao acaso, com três repetições. A zeólita natural

  2. Timing Effects of Heat-Stress on Plant Ecophysiological Characteristics and Growth.

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    Wang, Dan; Heckathorn, Scott A; Mainali, Kumar; Tripathee, Rajan

    2016-01-01

    Heat-waves with higher intensity and frequency and longer durations are expected in the future due to global warming, which could have dramatic impacts in agriculture, economy and ecology. This field study examined how plant responded to heat-stress (HS) treatment at different timing in naturally occurring vegetation. HS treatment (5 days at 40.5°C) were applied to 12 1 m 2 plots in restored prairie vegetation dominated by a warm-season C 4 grass, Andropogon gerardii , and a warm-season C 3 forb, Solidago canadensis , at different growing stages. During and after each heat stress (HS) treatment, temperature were monitored for air, canopy, and soil; net CO 2 assimilation ( A net ), quantum yield of photosystem II (Φ PSII ), stomatal conductance ( g s ), and internal CO 2 level ( C i ), specific leaf area (SLA), and chlorophyll content of the dominant species were measured. One week after the last HS treatment, all plots were harvested and the biomass of above-ground tissue and flower weight of the two dominant species were determined. HS decreased physiological performance and growth for both species, with S. canadensis being affected more than A. gerardii , indicated by negative HS effect on both physiological and growth responses for S. canadensis . There were significant timing effect of HS on the two species, with greater reductions in the net photosynthetic rate and productivity occurred when HS was applied at later-growing season. The reduction in aboveground productivity in S. canadensis but not A. gerardii could have important implications for plant community structure by increasing the competitive advantage of A. gerardii in this grassland. The present experiment showed that HS, though ephemeral, may promote long-term effects on plant community structure, vegetation dynamics, biodiversity, and ecosystem functioning of terrestrial biomes when more frequent and severe HS occur in the future.

  3. Timing effects of heat-stress on plant physiological characteristics and growth: a field study with prairie vegetation

    Directory of Open Access Journals (Sweden)

    Dan Wang

    2016-11-01

    Full Text Available More intense, more frequent, and longer heat-waves are expected in the future due to global warming, which could have dramatic agricultural, economic and ecological impacts. This field study examined how plant responded to heat-stress (HS treatment at different timing in naturally-occurring vegetation. HS treatment (5 days at 40.5 ºC were applied to 12 1m2 plots in restored prairie vegetation dominated by Andropogon gerardii (warm-season C4 grass and Solidago canadensis (warm-season C3 forb at different growing stages. During and after HS, air, canopy, and soil temperature were monitored; net CO2 assimilation (Pn, quantum yield of photosystem II (ФPSII, stomatal conductance (gs, and internal CO2 level (Ci of the dominant species were measured. One week after the last HS treatment, all plots were harvested and the biomass of above-ground tissue and flower weight of the two dominant species was determined. HS decreased physiological performance and growth for both species, with S. canadensis being affected more than A. gerardii, indicated by negative heat stress effect on both physiological and growth responses. There were significant timing effect of heat stress on the two species, with greater reductions in the photosynthesis and productivity occurred when heat stress was applied at later-growing season. The reduction in aboveground productivity in S. canadensis but not A. gerardii could have important implications for plant community structure by increasing the competitive advantage of A. gerardii in this grassland. The present experiment showed that heat stress, though ephemeral, may promote long-term effects on plant community structure, vegetation dynamics, biodiversity, and ecosystem functioning of terrestrial biomes when more frequent and severe heat stress occur in the future.

  4. Effects of N on plant response to heat-wave: a field study with prairie vegetation.

    Science.gov (United States)

    Wang, Dan; Heckathorn, Scott A; Mainali, Kumar; Hamilton, E William

    2008-11-01

    More intense, more frequent, and longer heat-waves are expected in the future due to global warming, which could have dramatic ecological impacts. Increasing nitrogen (N) availability and its dynamics will likely impact plant responses to heat stress and carbon (C) sequestration in terrestrial ecosystems. This field study examined the effects of N availability on plant response to heat-stress (HS) treatment in naturally-occurring vegetation. HS (5 d at ambient or 40.5 degrees C) and N treatments (+/-N) were applied to 16 1 m(2) plots in restored prairie vegetation dominated by Andropogon gerardii (warm-season C4 grass) and Solidago canadensis (warm-season C3 forb). Before, during, and after HS, air, canopy, and soil temperature were monitored; net CO2 assimilation (P(n)), quantum yield of photosystem II (Phi(PSII)), stomatal conductance (g(s)), and leaf water potential (Psi(w)) of the dominant species and soil respiration (R(soil)) of each plot were measured daily during HS. One week after HS, plots were harvested, and C% and N% were determined for rhizosphere and bulk soil, and above-ground tissue (green/senescent leaf, stem, and flower). Photosynthetic N-use efficiency (PNUE) and N resorption rate (NRR) were calculated. HS decreased P(n), g(s), Psi(w), and PNUE for both species, and +N treatment generally increased these variables (+/-HS), but often slowed their post-HS recovery. Aboveground biomass tended to decrease with HS in both species (and for green leaf mass in S. canadensis), but decrease with +N for A. gerardii and increase with +N for S. canadensis. For A. gerardii, HS tended to decrease N% in green tissues with +N, whereas in S. canadensis, HS increased N% in green leaves. Added N decreased NRR for A. gerardii and HS increased NRR for S. canadensis. These results suggest that heat waves, though transient, could have significant effects on plants, communities, and ecosystem N cycling, and N can influence the effect of heat waves.

  5. Caracterización de fincas adoptadoras del pasto Andropogon gayanus en el departamento del Cesar, Colombia Caracterización de fincas adoptadoras del pasto Andropogon gayanus en el departamento del Cesar, Colombia

    Directory of Open Access Journals (Sweden)

    Sere Carlos

    1987-09-01

    Full Text Available La razón expuesta por ganaderos para adoptar el pasto A. gayanus es la de poseer una especie que les provea forraje en la época seca. Quienes mayor éxito han obtenido, hasta el momento, son los adoptadores de suelos arenosos o de sabana en la parte central del departamento. En dicha zona se presentan factores de suelo como acidez, existencia de aluminio, texturas arenosas y buenos drenajes; la temperatura promedio es de 26°C, precipitaciones anuales entre 1200 y 2500 mm con una época seca (150 días sumamente fuerte. El comportamiento del pasto está limitado en la parte sur del departamento por exceso de humedad y en el norte por la presencia de bases y pH elevados. Desde el punto de vista económico, el éxito de la introducción de A. gayanus está relacionado con factores como el bajo costo de oportunidad de las tierras, la baja inversión adicional en ganados, los bajos costos de establecimiento, la complementaridad con otras pasturas en tierras mejores en la misma finca y la elevada rentabilidad marginal de la tecnología que posibilita la adopción aún en años sin incentivos para invertir en ganadería.This study was carried out in the Cesar Department, Colombia, to identify factors that have led to the adoption of A. gayanus. The expressed reason of r a n e hers is the need for a species that will supply forage during the dry season. Adopters on sandy soils in the middle part of the Zone are up to now those that most succes have been. Soils in this region are characterized by its acidity, presence of aluminum, sandy textures and good drainage. Mean annual temperatures are of 26°C with annual rainfall ranging between 1200 and 2500 mm with a marked dry season (150 days. In the south of the department rainfall is excessive while in the north high base saturation and pH of the soils do not allow the grass success fully competence. Economically, the success of promoting A. gayanus is in relation to some factors such as low opportunity costs of lands; low additional investment costs; ability to completing with other pastures in the best lands within the same farm; and higher marginal profitability from technology, which facilitates adoption even in these seasons without encouragement for investing in livestock .

  6. Accelerated development in Johnsongrass seedlings (Sorghum halepense) suppresses the growth of native grasses through size-asymmetric competition.

    Science.gov (United States)

    Schwinning, Susanne; Meckel, Heather; Reichmann, Lara G; Polley, H Wayne; Fay, Philip A

    2017-01-01

    Invasive plant species often dominate native species in competition, augmenting other potential advantages such as release from natural enemies. Resource pre-emption may be a particularly important mechanism for establishing dominance over competitors of the same functional type. We hypothesized that competitive success of an exotic grass against native grasses is mediated by establishing an early size advantage. We tested this prediction among four perennial C4 warm-season grasses: the exotic weed Johnsongrass (Sorghum halepense), big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparius) and switchgrass (Panicum virgatum). We predicted that a) the competitive effect of Johnsongrass on target species would be proportional to their initial biomass difference, b) competitive effect and response would be negatively correlated and c) soil fertility would have little effect on competitive relationships. In a greenhouse, plants of the four species were grown from seed either alone or with one Johnsongrass neighbor at two fertilizer levels and periodically harvested. The first two hypotheses were supported: The seedling biomass of single plants at first harvest (50 days after seeding) ranked the same way as the competitive effect of Johnsongrass on target species: Johnsongrass critical mechanism by which exotic invasive species displace functionally similar native species and alter the functional dynamics of native communities.

  7. Native Michigan plants stimulate soil microbial species changes and PAH remediation at a legacy steel mill.

    Science.gov (United States)

    Thomas, John C; Cable, Edward; Dabkowski, Robert T; Gargala, Stephanie; McCall, Daniel; Pangrazzi, Garett; Pierson, Adam; Ripper, Mark; Russell, Donald K; Rugh, Clayton L

    2013-01-01

    A 1.3-acre phytoremediation site was constructed to mitigate polyaromatic hydrocarbon (PAH) contamination from a former steel mill in Michigan. Soil was amended with 10% (v/v) compost and 5% (v/v) poultry litter. The site was divided into twelve 11.89 m X 27.13 m plots, planted with approximately 35,000 native Michigan perennials, and soils sampled for three seasons. Soil microbial density generally increased in subplots of Eupatorium perfoliatum (boneset), Aster novae-angliae (New England aster), Andropogon gerardii (big bluestem), and Scirpus atrovirens (green bulrush) versus unplanted subplots. Using enumeration assays with root exudates, PAH degrading bacteria were greatest in soils beneath plants. Initially predominant, Arthrobacter were found capable of degrading a PAH cocktail in vitro, especially upon the addition of root exudate. Growth of some Arthrobacter isolates was stimulated by root exudate. The frequency of Arthrobacter declined in planted subplots with a concurrent increase in other species, including secondary PAH degraders Bacillus and Nocardioides. In subplots supporting only weeds, an increase in Pseudomonas density and little PAH removal were observed. This study supports the notion that a dynamic interplay between the soil, bacteria, and native plant root secretions likely contributes to in situ PAH phytoremediation.

  8. Interspecific nutrient transfer in a tallgrass prairie plant community

    International Nuclear Information System (INIS)

    Walter, L.E.F.; Hartnett, D.C.; Hetrick, B.A.D.; Schwab, A.P.

    1996-01-01

    Interplant nutrient transfer may be an important ecological process in grasslands, and may significantly influence plant neighborhood interactions. We investigated the potential for phosphorus transfer between the dominant grass Andropogon gerardii and several neighboring plant species in tallgrass prairie via a field 32PO4 labelling experiment. The mean amount of 32P received from donor shoots differed significantly among neighboring species and decreased with increasing distance from the donor. In general, forbs and cool-season C3 grasses received more labelled 32P than warm-season C4 grasses. Phosphorus transfer occurred over distances up to 0.5 m. The effects of species and distance on movement of phosphorus changed with increasing time after labelling. The relative mass of receiver and donor shoots did not affect amounts of 32P transfer. A benomyl fungicide treatment, applied to suppress mycorrhizal activity, likely did not affect existing vegetative hyphae and did not affect the amount of 32P transferred. These studies demonstrate that: (1) phosphorus is transferred among neighboring species in tallgrass prairie plant communities, (2) phosphorus may be transferred over significantly greater distances than reported in other grasslands, and (3) there is differential transfer among co-occurring species. Hypothesized mechanisms accounting for these patterns in tallgrass prairie include mycorrhizal hyphal interconnections and/or extensive and differential root and rhizosphere overlap among neighboring species

  9. Utilization of organic nitrogen by arbuscular mycorrhizal fungi-is there a specific role for protists and ammonia oxidizers?

    Science.gov (United States)

    Bukovská, Petra; Bonkowski, Michael; Konvalinková, Tereza; Beskid, Olena; Hujslová, Martina; Püschel, David; Řezáčová, Veronika; Gutiérrez-Núñez, María Semiramis; Gryndler, Milan; Jansa, Jan

    2018-04-01

    Arbuscular mycorrhizal (AM) fungi can significantly contribute to plant nitrogen (N) uptake from complex organic sources, most likely in concert with activity of soil saprotrophs and other microbes releasing and transforming the N bound in organic forms. Here, we tested whether AM fungus (Rhizophagus irregularis) extraradical hyphal networks showed any preferences towards certain forms of organic N (chitin of fungal or crustacean origin, DNA, clover biomass, or albumin) administered in spatially discrete patches, and how the presence of AM fungal hyphae affected other microbes. By direct 15 N labeling, we also quantified the flux of N to the plants (Andropogon gerardii) through the AM fungal hyphae from fungal chitin and from clover biomass. The AM fungal hyphae colonized patches supplemented with organic N sources significantly more than those receiving only mineral nutrients, organic carbon in form of cellulose, or nothing. Mycorrhizal plants grew 6.4-fold larger and accumulated, on average, 20.3-fold more 15 N originating from the labeled organic sources than their nonmycorrhizal counterparts. Whereas the abundance of microbes (bacteria, fungi, or Acanthamoeba sp.) in the different patches was primarily driven by patch quality, we noted a consistent suppression of the microbial abundances by the presence of AM fungal hyphae. This suppression was particularly strong for ammonia oxidizing bacteria. Our results indicate that AM fungi successfully competed with the other microbes for free ammonium ions and suggest an important role for the notoriously understudied soil protists to play in recycling organic N from soil to plants via AM fungal hyphae.

  10. Common mycorrhizal networks amplify competition by preferential mineral nutrient allocation to large host plants.

    Science.gov (United States)

    Weremijewicz, Joanna; Sternberg, Leonel da Silveira Lobo O'Reilly; Janos, David P

    2016-10-01

    Arbuscular mycorrhizal (AM) fungi interconnect plants in common mycorrhizal networks (CMNs) which can amplify competition among neighbors. Amplified competition might result from the fungi supplying mineral nutrients preferentially to hosts that abundantly provide fixed carbon, as suggested by research with organ-cultured roots. We examined whether CMNs supplied (15) N preferentially to large, nonshaded, whole plants. We conducted an intraspecific target-neighbor pot experiment with Andropogon gerardii and several AM fungi in intact, severed or prevented CMNs. Neighbors were supplied (15) N, and half of the target plants were shaded. Intact CMNs increased target dry weight (DW), intensified competition and increased size inequality. Shading decreased target weight, but shaded plants in intact CMNs had mycorrhizal colonization similar to that of sunlit plants. AM fungi in intact CMNs acquired (15) N from the substrate of neighbors and preferentially allocated it to sunlit, large, target plants. Sunlit, intact CMN, target plants acquired as much as 27% of their nitrogen from the vicinity of their neighbors, but shaded targets did not. These results suggest that AM fungi in CMNs preferentially provide mineral nutrients to those conspecific host individuals best able to provide them with fixed carbon or representing the strongest sinks, thereby potentially amplifying asymmetric competition below ground. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  11. Evaluating plant-soil feedback together with competition in a serpentine grassland.

    Science.gov (United States)

    Casper, Brenda B; Castelli, Jeffrey P

    2007-05-01

    Plants can alter biotic and abiotic soil characteristics in ways that feedback to change the performance of that same plant species relative to co-occurring plants. Most evidence for this plant-soil feedback comes from greenhouse studies of potted plants, and consequently, little is known about the importance of feedback in relation to other biological processes known to structure plant communities, such as plant-plant competition. In a field experiment with three C4 grasses, negative feedback was expressed through reduced survival and shoot biomass when seedlings were planted within existing clumps of conspecifics compared with clumps of heterospecifics. However, the combined effects of feedback and competition were species-specific. Only Andropogon gerardii exhibited feedback when competition with the clumps was allowed. For Sorghastrum nutans, strong interspecific competition eliminated the feedback expressed in the absence of competition, and Schizachyrium scoparium showed no feedback at all. That arbuscular mycorrhizal (AM) fungi may play a role in the feedback was indicated by higher AM root colonization with conspecific plant neighbours. We suggest that feedback and competition should not be viewed as entirely separate processes and that their importance in structuring plant communities cannot be judged in isolation from each other.

  12. Harvesting Effects on Species Composition and Distribution of Cover Attributes in Mixed Native Warm-Season Grass Stands

    Directory of Open Access Journals (Sweden)

    Vitalis W. Temu

    2015-05-01

    Full Text Available Managing grasslands for forage and ground-nesting bird habitat requires appropriate defoliation strategies. Subsequent early-summer species composition in mixed stands of native warm-season grasses (Indiangrass (IG, Sorghastrum nutans, big bluestem (BB, Andropogon gerardii and little bluestem (LB, Schizachyrium scoparium responding to harvest intervals (treatments, 30, 40, 60, 90 or 120 d and durations (years in production was assessed. Over three years, phased May harvestings were initiated on sets of randomized plots, ≥90 cm apart, in five replications (blocks to produce one-, two- and three-year-old stands. Two weeks after harvest, the frequencies of occurrence of plant species, litter and bare ground, diagonally across each plot (line intercept, were compared. Harvest intervals did not influence proportions of dominant plant species, occurrence of major plant types or litter, but increased that of bare ground patches. Harvest duration increased the occurrence of herbaceous forbs and bare ground patches, decreased that of tall-growing forbs and litter, but without affecting that of perennial grasses, following a year with more September rainfall. Data suggest that one- or two-year full-season forage harvesting may not compromise subsequent breeding habitat for bobwhites and other ground-nesting birds in similar stands. It may take longer than a year’s rest for similar stands to recover from such changes in species composition.

  13. Bridging the Divide: Linking Genomics to Ecosystem Responses to Climate Change: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Melinda D.

    2014-03-15

    Over the project period, we have addressed the following objectives: 1) assess the effects of altered precipitation patterns (i.e., increased variability in growing season precipitation) on genetic diversity of the dominant C4 grass species, Andropogon gerardii, and 2) experimentally assess the impacts of extreme climatic events (heat wave, drought) on responses of the dominant C4 grasses, A. gerardii and Sorghastrum nutans, and the consequences of these response for community and ecosystem structure and function. Below is a summary of how we have addressed these objectives. Objective 1 After ten years of altered precipitation, we found the number of genotypes of A. gerardii was significantly reduced compared to the ambient precipitation treatments (Avolio et al., 2013a). Although genotype number was reduced, the remaining genotypes were less related to one another indicating that the altered precipitation treatment was selecting for increasingly dissimilar genomes (based on mean pairwise Dice distance among individuals). For the four key genotypes that displayed differential abundances depending on the precipitation treatment (G1, G4, and G11 in the altered plots and G2 in the ambient plots), we identified phenotypic differences in the field that could account for ecological sorting (Avolio & Smith, 2013a). The three altered rainfall genotypes also have very different phenotypic traits in the greenhouse in response to different soil moisture availabilities (Avolio and Smith, 2013c). Two of the genotypes that increased in abundance in the altered precipitation plots had greater allocation to root biomass (G4 and G11), while G1 allocated more biomass aboveground. These phenotypic differences among genotypes suggests that changes in genotypic structure between the altered and the ambient treatments has likely occurred via niche differentiation, driven by changes in soil moisture dynamics (reduced mean, increased variability and changes in the depth distribution of

  14. The role of ecotypic variation and the environment on biomass and nitrogen in a dominant prairie grass.

    Science.gov (United States)

    Mendola, Meredith L; Baer, Sara G; Johnson, Loretta C; Maricle, Brian R

    2015-09-01

    Knowledge of the relative strength of evolution and the environment on a phenotype is required to predict species responses to environmental change and decide where to source plant material for ecological restoration. This information is critically needed for dominant species that largely determine the productivity of the central U.S. grassland. We established a reciprocal common garden experiment across a longitudinal gradient to test whether ecotypic variation interacts with the environment to affect growth and nitrogen (N) storage in a dominant grass. We predicted plant growth would increase from west to east, corresponding with increasing precipitation, but differentially among ecotypes due to local adaptation in all ecotypes and a greater range of growth response in ecotypes originating from west to east. We quantified aboveground biomass, root biomass, belowground net primary production (BNPP), root C:N ratio, and N storage in roots of three ecotypes of Andropogon gerardii collected from and reciprocally planted in central Kansas, eastern Kansas, and s6uthern Illinois. Only the ecotype from the most mesic region (southern Illinois) exhibited more growth from west to east. There was evidence for local adaptation in the southern Illinois ecotype by means of the local vs. foreign contrast within a site and the home vs. away contrast when growth in southern Illinois was compared to the most distant 'site in central Kansas. Root biomass of the eastern Kansas ecotype was higher at home than at either away site. The ecotype from the driest region, central Kansas, exhibited the least response across the environmental gradient, resulting in a positive relationship between the range of biomass response and precipitation in ecotype region of origin. Across all sites, ecotypes varied in root C:N ratio (highest in the driest-origin ecotype) and N storage in roots (highest in the most mesic-origin ecotype). The low and limited range of biomass, higher C:N ratio of roots

  15. Legacies from extreme drought increase ecosystem sensitivity to future extremes

    Science.gov (United States)

    Smith, M. D.; Knapp, A.; Hoover, D. L.; Avolio, M. L.; Felton, A. J.; Wilcox, K. R.

    2016-12-01

    Climate extremes, such as drought, are increasing in frequency and intensity, and the ecological consequences of these extreme events can be substantial and widespread. Although there is still much to be learned about how ecosystems will respond to an intensification of drought, even less is known about the factors that determine post-drought recovery of ecosystem function. Such knowledge is particularly important because post-drought recovery periods can be protracted depending on the extent to which key plant populations, community structure and biogeochemical processes are affected. These drought legacies may alter ecosystem function for many years post-drought and may impact future sensitivity to climate extremes. We experimentally imposed two extreme growing season droughts in a central US grassland to assess the impacts of repeated droughts on ecosystem resistance (response) and resilience (recovery). We found that this grassland was not resistant to the first extreme drought due to reduced productivity and differential sensitivity of the co-dominant C4 grass (Andropogon gerardii) and C3 forb (Solidago canadensis) species. This differential sensitivity led to a reordering of species abundances within the plant community. Yet, despite this large shift in plant community composition, which persisted post-drought, the grassland was highly resilient post-drought, due to increased abundance of the dominant C4 grass. Because of this shift to increased C4 grass dominance, we expected that previously-droughted grassland would be more resistant to a second extreme drought. However, contrary to these expectations, previously droughted grassland was more sensitive to drought than grassland that had not experienced drought. Thus, our result suggest that legacies of drought (shift in community composition) may increase ecosystem sensitivity to future extreme events.

  16. Accelerated development in Johnsongrass seedlings (Sorghum halepense suppresses the growth of native grasses through size-asymmetric competition.

    Directory of Open Access Journals (Sweden)

    Susanne Schwinning

    Full Text Available Invasive plant species often dominate native species in competition, augmenting other potential advantages such as release from natural enemies. Resource pre-emption may be a particularly important mechanism for establishing dominance over competitors of the same functional type. We hypothesized that competitive success of an exotic grass against native grasses is mediated by establishing an early size advantage. We tested this prediction among four perennial C4 warm-season grasses: the exotic weed Johnsongrass (Sorghum halepense, big bluestem (Andropogon gerardii, little bluestem (Schizachyrium scoparius and switchgrass (Panicum virgatum. We predicted that a the competitive effect of Johnsongrass on target species would be proportional to their initial biomass difference, b competitive effect and response would be negatively correlated and c soil fertility would have little effect on competitive relationships. In a greenhouse, plants of the four species were grown from seed either alone or with one Johnsongrass neighbor at two fertilizer levels and periodically harvested. The first two hypotheses were supported: The seedling biomass of single plants at first harvest (50 days after seeding ranked the same way as the competitive effect of Johnsongrass on target species: Johnsongrass < big bluestem < little bluestem/switchgrass, while Johnsongrass responded more strongly to competition from Johnsongrass than from native species. At final harvest, native plants growing with Johnsongrass attained between 2-5% of their single-plant non-root biomass, while Johnsongrass growing with native species attained 89% of single-plant non-root biomass. Fertilization enhanced Johnsongrass' competitive effects on native species, but added little to the already severe competitive suppression. Accelerated early growth of Johnsongrass seedlings relative to native seedlings appeared to enable subsequent resource pre-emption. Size-asymmetric competition and resource

  17. Heavy metal leaching from mine tailings as affected by plants

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, D.; Schwab, A.P.; Banks, M.K.

    1999-12-01

    A column experiment was conducted to determine the impact of soil cover and plants on heavy metal leaching from mine tailings and heavy metal contaminated soil. Columns made of PVC were constructed with 30 cm subsoil covered by 30 cm of mine tailings followed by 0, 30, or 60 cm subsoil covered by 30 cm of mine tailings followed by 0, 30, or 60 cm of clean topsoil. Two grasses, tall fescue (Festuca arundinacea Schreb.) and big bluestem (Andropogon gerardii), were grown in the columns. The columns were leached at a slow rate for 1 yr with a 0.001 M CaCl{sub 2} solution under unsaturated conditions. The presence of both tall fescue and big bluestem increased Zn and Cd concentrations in the leachate. Lead concentrations in leachates were not affected by the presence of plants. Although plants generally reduced the total amount of water leached, total mass of Zn and Cd leached generally was not impacted by plants. Total mass of Pb leached was positively correlated with total leachate collected from each column. Covering the mine tailings with 60 cm of topsoil increased the mass of Zn and Cd leached relative to no topsoil. When the subsoil was absent, Zn and Cd leaching increased by as much as 20-fold, verifying the ability of soil to act as a sink for metals. Mine tailing remediation by establishing vegetation can reduce Pb movement but may enhance short-term Cd and Zn leaching. However, the changes were relatively small and do not outweigh the benefits of using vegetation in mine tailings reclamation.

  18. Plant Community Richness Mediates Inhibitory Interactions and Resource Competition between Streptomyces and Fusarium Populations in the Rhizosphere.

    Science.gov (United States)

    Essarioui, Adil; LeBlanc, Nicholas; Kistler, Harold C; Kinkel, Linda L

    2017-07-01

    Plant community characteristics impact rhizosphere Streptomyces nutrient competition and antagonistic capacities. However, the effects of Streptomyces on, and their responses to, coexisting microorganisms as a function of plant host or plant species richness have received little attention. In this work, we characterized antagonistic activities and nutrient use among Streptomyces and Fusarium from the rhizosphere of Andropogon gerardii (Ag) and Lespedeza capitata (Lc) plants growing in communities of 1 (monoculture) or 16 (polyculture) plant species. Streptomyces from monoculture were more antagonistic against Fusarium than those from polyculture. In contrast, Fusarium isolates from polyculture had greater inhibitory capacities against Streptomyces than isolates from monoculture. Although Fusarium isolates had on average greater niche widths, the collection of Streptomyces isolates in total used a greater diversity of nutrients for growth. Plant richness, but not plant host, influenced the potential for resource competition between the two taxa. Fusarium isolates had greater niche overlap with Streptomyces in monoculture than polyculture, suggesting greater potential for Fusarium to competitively challenge Streptomyces in monoculture plant communities. In contrast, Streptomyces had greater niche overlap with Fusarium in polyculture than monoculture, suggesting that Fusarium experiences greater resource competition with Streptomyces in polyculture than monoculture. These patterns of competitive and inhibitory phenotypes among Streptomyces and Fusarium populations are consistent with selection for Fusarium-antagonistic Streptomyces populations in the presence of strong Fusarium resource competition in plant monocultures. Similarly, these results suggest selection for Streptomyces-inhibitory Fusarium populations in the presence of strong Streptomyces resource competition in more diverse plant communities. Thus, landscape-scale variation in plant species richness may be

  19. Dual, differential isotope labeling shows the preferential movement of labile plant constituents into mineral-bonded soil organic matter.

    Science.gov (United States)

    Haddix, Michelle L; Paul, Eldor A; Cotrufo, M Francesca

    2016-06-01

    The formation and stabilization of soil organic matter (SOM) are major concerns in the context of global change for carbon sequestration and soil health. It is presently believed that lignin is not selectively preserved in soil and that chemically labile compounds bonding to minerals comprise a large fraction of the SOM. Labile plant inputs have been suggested to be the main precursor of the mineral-bonded SOM. Litter decomposition and SOM formation are expected to have temperature sensitivity varying with the lability of plant inputs. We tested this framework using dual (13) C and (15) N differentially labeled plant material to distinguish the metabolic and structural components within a single plant material. Big Bluestem (Andropogon gerardii) seedlings were grown in an enriched (13) C and (15) N environment and then prior to harvest, removed from the enriched environment and allowed to incorporate natural abundance (13) C-CO2 and (15) N fertilizer into the metabolic plant components. This enabled us to achieve a greater than one atom % difference in (13) C between the metabolic and structural components within the plant litter. This differentially labeled litter was incubated in soil at 15 and 35 °C, for 386 days with CO2 measured throughout the incubation. After 14, 28, 147, and 386 days of incubation, the soil was subsequently fractionated. There was no difference in temperature sensitivity of the metabolic and structural components with regard to how much was respired or in the amount of litter biomass stabilized. Only the metabolic litter component was found in the sand, silt, or clay fraction while the structural component was exclusively found in the light fraction. These results support the stabilization framework that labile plant components are the main precursor of mineral-associated organic matter. © 2016 John Wiley & Sons Ltd.

  20. Impacts of nitrogen fertilization and plant species diversity on soil C accumulation in a lignocellulosic bioenergy cropping system nine years following land conversion

    Science.gov (United States)

    De Graaff, M. A.; Jastrow, J. D.

    2017-12-01

    Ethanol production from second generation biofuel feedstocks, including the perennial grasses switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii) has expanded rapidly, with the aim to reduce greenhouse gas emissions. However, land conversion for bioenergy production releases carbon (C) stored in soil to the atmosphere as CO2, and creates a C debt in ecosystems. If biofuels are to aid in curbing atmospheric CO2 concentrations, it is important that this initial C debt be repaid rapidly. A variety of management approaches aimed at increasing NPP and soil C input may be used to accelerate the repayment of soil C. We conducted a long-term field experiment located at the Fermilab National Environmental Research Park in IL, that compares a variety of approaches for perennial feedstock production following conversion of an old-field dominated by C3 grasses to a grassland dominated by C4 perennial grasses. Treatments included a variety of big bluestem and switchgrass cultivars grown in monoculture, diversity manipulated at both the species- and cultivar level, and nitrogen (N) applied at two levels (0 and 67 kg/ha). Previous results from this experiment indicated that four years following initiation of this experiment, only choice of plant species significantly affected the rate of bulk soil C-debt repayment. Here we quantified how nine years of fertilization, plant species, and inter- and intra-specific diversity treatments affect soil C accumulation. To increase our detection of changes in soil C and our mechanistic understanding of the processes that drive C accumulation in this experiment, we used the natural abundance C isotope ratio technique to estimate the contribution and fate of root-derived C to soil organic matter pools. Additionally, we evaluated how the different management approaches affected the ecological sustainability of bioenergy production, by quantifying impacts of the treatments on soil micro-and meso fauna abundance and diversity

  1. Burning management in the tallgrass prairie affects root decomposition, soil food web structure and carbon flow

    Science.gov (United States)

    Shaw, E. A.; Denef, K.; Milano de Tomasel, C.; Cotrufo, M. F.; Wall, D. H.

    2015-09-01

    Root litter decomposition is a major component of carbon (C) cycling in grasslands, where it provides energy and nutrients for soil microbes and fauna. This is especially important in grasslands where fire is a common management practice and removes aboveground litter accumulation. In this study, we investigated whether fire affects root decomposition and C flow through the belowground food web. In a greenhouse experiment, we applied 13C-enriched big bluestem (Andropogon gerardii) root litter to intact tallgrass prairie soil cores collected from annually burned (AB) and infrequently burned (IB) treatments at the Konza Prairie Long Term Ecological Research (LTER) site. Incorporation of 13C into microbial phospholipid fatty acids and nematode trophic groups was measured on six occasions during a 180-day decomposition study to determine how C was translocated through the soil food web. Results showed significantly different soil communities between treatments and higher microbial abundance for IB. Root decomposition occurred rapidly and was significantly greater for AB. Microbes and their nematode consumers immediately assimilated root litter C in both treatments. Root litter C was preferentially incorporated in a few groups of microbes and nematodes, but depended on burn treatment: fungi, Gram-negative bacteria, Gram-positive bacteria, and fungivore nematodes for AB and only omnivore nematodes for IB. The overall microbial pool of root litter-derived C significantly increased over time but was not significantly different between burn treatments. The nematode pool of root litter-derived C also significantly increased over time, and was significantly higher for the AB treatment at 35 and 90 days after litter addition. In conclusion, the C flow from root litter to microbes to nematodes is not only measurable, but significant, indicating that higher nematode trophic levels are critical components of C flow during root decomposition which, in turn, is significantly

  2. Economic and conservation implications of converting exotic forages to native warm-season grass

    Directory of Open Access Journals (Sweden)

    Adrian P. Monroe

    2017-07-01

    Full Text Available Intensive agriculture can have negative environmental consequences such as nonpoint source pollution and the simplification of biotic communities, and land sharing posits that conservation can be enhanced by integrating agricultural productivity and biodiversity on the same land. In the Southeastern United States, native warm-season grasses (NWSG may be a land sharing alternative to exotic forages currently in production because of greater livestock gains with lower fertilizer inputs, and habitat for grassland birds. However, uncertainty regarding costs and risk poses an important barrier to incorporating NWSG in livestock operations. We evaluated the economic and conservation implications of NWSG conversion among small, operational-scale pastures (6.8–10.5 ha during 2011–2012 at the Prairie Research Unit in Monroe Co., Mississippi (USA. We used partial budgets to compare the marginal rate of return (MRRe from converting exotic grass pastures to either a NWSG monoculture of Indiangrass (Sorghastrum nutans or a NWSG mix of Indiangrass, little bluestem (Schizachyrium scoparium, and big bluestem (Andropogon gerardii. We similarly compared changes in productivity of dickcissels (Spiza americana, a grassland bird specializing in tall structure. Average daily gain (ADG of steers and revenue were consistently higher for NWSG treatments than exotic grass pasture, but ADG declined between years. Indiangrass pastures yielded consistently positive MRRe, indicating producers would receive 16–24% return on investment. Marginal rate of return was lower for mixed NWSG (−12 to 3%, driven by slightly lower livestock ADG and higher establishment costs than for Indiangrass. Sensitivity analyses indicated that MRRe also was influenced by cattle selling price. Conversely, mixed NWSG increased dickcissel productivity by a greater degree than Indiangrass per amount invested in NWSG conversion, suggesting a tradeoff between livestock and dickcissel production

  3. Radiocesium levels in vegetation colonizing a contaminated floodplain

    International Nuclear Information System (INIS)

    Garten, C.T. Jr.; Briese, L.A.; Geiger, R.A.; Sharitz, R.; Smith, M.H.

    1975-01-01

    Radiocesium concentrations in herbaceous and woody plants inhabiting a floodplain contaminated by nuclear production reactor effluents were measured. Leaves and stems of herbaceous plants (Andropogon sp. and Scirpus cyperinus) contained higher concentrations of radiocesium than those of woody plants (Alnus serrulata, Myrica cerifera, and Salix nigra). Andropogon and Alnus fruits had higher concentrations than the leaves or stems. Radiocesium concentrations in fruits and leaves were significantly correlated with stem radiocesium levels in some or all of the species sampled. Mean radiocesium levels in the plant parts exceeded mean soil concentrations; this indicates concentration of radiocesium by the vegetation

  4. Accumulation of cadmium by halophytic and non-halophytic Juncus species

    Czech Academy of Sciences Publication Activity Database

    Vaněk, Tomáš; Moťková, Kateřina; Podlipná, Radka

    2016-01-01

    Roč. 28, č. 4 (2016), s. 415-423 ISSN 2197-0025 R&D Projects: GA MŠk(CZ) OC10028; GA MPO FR-TI3/778 Institutional support: RVO:61389030 Keywords : plant-responses * salt-tolerance * heavy-metals * salinity tolerance * abiotic stress * rice seedlings * amino-acids * proline * phytoremediation * detoxification * Halophyte * Cadmium accumulation * Proline * Juncus gerardii * Juncus inflexus Subject RIV: DJ - Water Pollution ; Quality Impact factor: 1.045, year: 2016

  5. C:\\Users\\AISA\\Desktop\\OBULBIGA MFxps

    African Journals Online (AJOL)

    AISA

    species in terms of fodder and stem in the climatic condition of north Soudan. ... in the area. Keywords : Andropogon gayanus kunth, agropastoral people, rhythm of exploitation, forage, stems, Burkina. Faso. .... L'analyse statistique révèle une.

  6. Proceedings of Indian Academy of Sciences, Section B- Vol.93

    Indian Academy of Sciences (India)

    Activity of certain enzymes of amino acid metabolism in the liver and kidney ... Rhizosphere effect of Andropogon pumilus Roxb. on soil nematodes, soil ... Adaptation to thermal stress in the freshwater eurythermal teleost ... Interactions of insect vectors with plants in relation to transmission of plant viruses - S Mukhopadyay

  7. Comparação entre dois métodos analíticos para determinação da lignina de algumas gramíneas forrageiras Comparison between two analytical methods for determining lignin concentration of some grass forages

    Directory of Open Access Journals (Sweden)

    Romualdo Shigueo Fukushima

    1999-06-01

    Full Text Available Foram comparados dois métodos analíticos para a determinação da lignina (lignina em detergente ácido - LDA e lignina permanganato de potássio - LPer bem como para averiguar a possível relação dos teores desse componente com a digestibilidade da fibra dos seguintes fenos: andropogon (Andropogon gayanus; aveia (Avena sativa; e dois tipos de coast-cross (Cynodon dactylon, um bem fenado e outro de baixa qualidade. Os valores de LDA e LPer foram diferentes (p This work was carried out aiming to compare lignin concentration of some grass forages through two analytical methods (acid detergent lignin - ADL and permanganate lignin - PerL as well to verify a possible relationship of lignin concentration with fiber digestion of the following grass hays: andropogon (Andropogon gayanus; oats (Avena sativa; a good quality and another of poor quality coast-cross (Cynodon dactylon. Acid detergent and permanganate lignin values were different (p <= 0.05 among the hays, however PerL concentrations were consistently lower than ADL values. There were differences (p <= 0.05 among the digestibility of neutral and acid detergent fiber fractions, however a clear relationship between these values with lignin concentration could not be assessed. The data suggested that lignin concentration, taken individually, is not the only factor to explain a given value of digestibility.

  8. Changes of biomass in some perennial grass species. | M.C. ...

    African Journals Online (AJOL)

    Patterns of seasonal herbaceous biomass change in a burned, ungrazed savanna woodland are reported. A standard clipping technique was used and material farmed in the current season was separated from that formed in the previous season for three perennial grass species: Brachiaria nigropedata, Andropogon ...

  9. Predicting animal production on sourveld: a species-based approach

    African Journals Online (AJOL)

    The model was based upon measured ingestive and digestive characteristics of different grass species and incorporates an explicit digestive constraint based upon rumen mass and turnover rate. Illustrates with graphs, diagrams and tables. Keywords: ADG; Andropogon appendiculatus; Average daily gain; Cattle; Cynodon ...

  10. Lemongrass productivity oil content and composition as a function of nitrogen sulfur and harvest time

    Science.gov (United States)

    Lemongrass [Cymbopogon flexuosus (Steud.) Wats, (syn. Andropogon nardus var. flexuosus Hack; A. flexuosus Nees)] is one of the most widely grown essential oil plants in the world. Field experiments were conducted at Verona and Poplarville, Mississippi, to evaluate the effects of N (0, 40, 80, and 16...

  11. Soil nitrogen mineralization not affected by grass species traits

    Science.gov (United States)

    Maged Ikram Nosshi; Jack Butler; M. J. Trlica

    2007-01-01

    Species N use traits was evaluated as a mechanism whereby Bromus inermis (Bromus), an established invasive, might alter soil N supply in a Northern mixed-grass prairie. We compared soils under stands of Bromus with those from three representative native grasses of different litter C/N: Andropogon...

  12. 155-IJBCS-Article-Dr Onana

    African Journals Online (AJOL)

    RHUMSIKI

    Andropogon pinguipes, à Setaria pumila, et à Loudetia simplex des zones humides,. - de deux lignes pour les groupements à. Hyparrhenia rufa, à Loudetia simplex des stations mésophiles, à Brachiaria jubata, et à Loudetia togoensis,. - de trois lignes pour les groupements à. Aristida kerstingii, et à Echiochloa pyramidalis,.

  13. Density, distribution and feeding strategies of roan antelope ...

    African Journals Online (AJOL)

    Fourteen plant species are used for food by H. equinus in the Park, including Andropogon gayanus, A. schirensis, A. tectorum, Hyparrhenia rufa, H. dissoluta, H. diplandra and H. cyanescens. Their percentage crude protein and fat ranged between 4.8 and 8.8, and between 4.7 and 18.9, respectively. Measures to sustain ...

  14. Effect of an Invasive Grass on Ambient Rates of Decomposition and Microbial Community Structure: A Search for Causality

    Science.gov (United States)

    In sutu decomposition of above and below ground plant biomass of the native grass species Andropogon glmoeratus (Walt.) B.S.P and exotic Imperata cylindrica (L.) Beauv. (cogongrass) was investigated using litter bags over the course of a 12 month period. The above and below ground biomass of the inv...

  15. Species of Concern (SOC) on Department of Defense Installations

    Science.gov (United States)

    2002-07-15

    ARISTIDA STRICTA; DRY, UPLAND FLAT, FILTERED LIGHT; WITH BAPTISIA CINEREA, VIOLA PEDATA, DALEA PINNATA.* SUBPOP A=PINE/SCRUB OAK SANDHILL; FEW SCATTERED...DIOSPYROS VIRG., GAYLUSSACIA DUMOSA, EPIGAEA REPENS, ANDROPOGON SP., BAPTISIA TINCT., TEPHROSIA VIRG., VACCINIUM CRASS., LESPEDEZA SP., DALEA PINNATA...ADENOCAULON BICOLOR , PHACELIA NEMORALIS, CAREX HENDERSONII. CIRSIUM VULGARE COMMON WHERE DISTURBED.* Cedar-hemlock forest on lower slopes of logged

  16. Environmental Assessment for Tinker Aerospace Complex Tinker Air Force Base, Oklahoma

    Science.gov (United States)

    2008-05-01

    Boutelova curtipendula silver bluestem Andropogon saccharoides slippery elm Ulmus rubra sugarberry Celtis laevigata switchgrass...areas; Crutcho Creek, Elm Creek, and Hog Creek. The Crutcho Creek drainage area consists of two additional water bodies, Kulhman Creek and Solider...Crutcho Creek flows to the north and discharges into the North Canadian River; the North Canadian River then discharges into the Arkansas River. Elm

  17. Short Communication: Soil carbon pools in different pasture systems

    Energy Technology Data Exchange (ETDEWEB)

    Cardozo, F.M. Jr.; Carneiro, R.F.V.; Leite, L.F.C.; Araujo, A.S.F.

    2016-11-01

    The aim of this study was to assess the carbon pools of a tropical soil where the native forest was replaced with different pasture systems. We studied five pasture production systems, including four monoculture systems with forage grasses such as Andropogon, Brachiaria, Panicum, and Cynodon, and an agroforestry system as well as a native vegetation plot. Greater availability of fulvic acid was detected in the agroforestry system as compared with that in the other systems. Higher lability of C was detected in the Andropogon system during the dry and rainy seasons and during the dry season in Cynodon. During the dry season, all pastures systems showed deficits in the net removal of atmospheric CO2. The structure and practices of the agroforestry system enables more carbon to be sequestered in the soil as compared with the monoculture pasture, suggesting that it is an important practice to mitigate climatic change and to improve soil quality. (Author)

  18. Caracterização da fauna edáfica em sistemas de manejo para produção de forragens no Estado do Piauí Characterization of edaphic fauna in management systems for forage production in the State of Piauí

    Directory of Open Access Journals (Sweden)

    Luís Alfredo Pinheiro Leal Nunes

    2012-03-01

    Full Text Available O objetivo desse trabalho foi avaliar a distribuição da fauna em função da umidade do solo em diferentes sistemas de manejo para a produção de forragens com capim-Tifton 85 (Cynodon dactylon Pers. x C. niemfuensis Vanderys, capim-Tanzânia (Panicum maximum Jacq. cv. Tanzânia, capim-Andropogon (Andropogon gayanus Kunth, Leucena (Leucaena leucocephala (Lam. R. de Wit. tendo como controle uma Mata dos Cocais. A coleta da fauna foi feita utilizando-se armadilhas do tipo Pitfall em duas épocas do ano: setembro de 2007 e março de 2008, período seco e chuvoso, respectivamente. Os sistemas com capim-Tifton, capim-Tanzânia e Leucena mostraram maior número de indivíduos nos dois períodos avaliados. A queimada ocorrida no capim-Andropogon antes da primeira coleta resultou em uma redução na abundância e diversidade da fauna edáfica. Os maiores valores em riqueza, diversidade e uniformidade de fauna foram obtidos na amostragem realizada no período úmido. A mata mostrou maior diversidade e equitabilidade nos dois períodos avaliados. Em situação de estresse hídrico alguns grupos como Formicidae e Collembola predominaram nos sistemas de manejo diminuindo a uniformidade, enquanto no período úmido vários grupos mostraram boa representatividade o que favoreceu a uniformidade. A análise multivariada de componentes principais evidenciou que os sistemas com mata, capim-Tifton e capim-Tanzania e Leucena mostraram associação com vários grupos da fauna edáfica nos dois períodos avaliados enquanto que o sistema com capim-Andropogon, que sofreu queimada, apresentou afinidade apenas com o grupo Heteroptera, no período seco.The objective of this study was to evaluate the distribution of fauna as a function of soil moisture in different fodder-production management systems of Tifton 85 grass (Cynodon dactylon Pers. x C. niemfuensis Vanderys, Tanzania grass (Panicum maximum Jacq. cv. Tanzânia, Andropogon Grass (Andropogon gayanus Kunth and

  19. Soil carbon pools in different pasture systems

    Directory of Open Access Journals (Sweden)

    Francisco M. Cardozo, Jr.

    2016-03-01

    Full Text Available The aim of this study was to assess the carbon pools of a tropical soil where the native forest was replaced with different pasture systems. We studied five pasture production systems, including four monoculture systems with forage grasses such as Andropogon, Brachiaria, Panicum, and Cynodon, and an agroforestry system as well as a native vegetation plot. Greater availability of fulvic acid was detected in the agroforestry system as compared with that in the other systems. Higher lability of C was detected in the Andropogon system during the dry and rainy seasons and during the dry season in Cynodon. During the dry season, all pastures systems showed deficits in the net removal of atmospheric CO2. The structure and practices of the agroforestry system enables more carbon to be sequestered in the soil as compared with the monoculture pasture, suggesting that it is an important practice to mitigate climatic change and to improve soil quality.

  20. Soil fauna and organic amendment interactions affect soil carbon and crop performance in semi-arid West Africa

    OpenAIRE

    Ouédraogo, E.; Brussaard, L.; Stroosnijder, L.

    2007-01-01

    A field experiment was conducted at Kaibo in southern Burkina Faso on an Eutric Cambisol during the 2000 rainy season to assess the interaction of organic amendment quality and soil fauna, affecting soil organic carbon and sorghum ( Sorghum bicolor L. Moench) performance. Plots were treated with the pesticides Dursban and Endosulfan to exclude soil fauna or left untreated. Sub-treatments consisted of surface-placed maize straw ( C/N ratio= 58), Andropogon straw ( C/N ratio= 153), cattle dung ...

  1. Effects of varying dietary zinc levels on energy and nitrogen ...

    African Journals Online (AJOL)

    Parameters determined were dry matter intake (DMI), energy utilization and nitrogen utilization. The mean±SE of Panicum maximum, Andropogon gayanus, Pennisetum purpureum, Leucaena leucocephala and Gliricidia sepium, contained 31.2±5.0; 29.1± 3.0;34.6± 6.0; 45.0± 5.0 and 47.1± 4.0mg Zn/kg DM respectively.

  2. Atributos físicos e químicos de um latossolo vermelho-amarelo sob pastagens com diferentes históricos de uso Physical and chemical properties of an oxisol cultivated under pastures with distinct use history

    Directory of Open Access Journals (Sweden)

    Iara Terezinha Pignataro Netto

    2009-10-01

    Full Text Available O uso sustentável dos sistemas de pastagens depende, principalmente, de um manejo que possa promover a qualidade do solo. O objetivo deste estudo foi avaliar as alterações nos atributos físicos e químicos do solo sob quatro pastagens, formadas com as espécies Andropogon gayanus, Brachiaria decumbens e Brachiaria brizantha cv. marandu, com diferentes históricos de uso, empregando como referência o Cerrado nativo. O solo foi avaliado pela quantificação dos seguintes atributos: capacidade de troca de cátions, matéria orgânica, densidade do solo, porosidade total e resistência mecânica à penetração. A capacidade de troca de cátions e o teor de matéria orgânica mostraram-se pouco afetados pelo manejo e pelo tempo de uso. A densidade do solo, a porosidade total e a resistência mecânica à penetração foram bastante afetadas, tendo grande influência na redução da qualidade do solo. Quantidade grande de animais, uso de máquinas e implementos, e cobertura deficiente, ocasionada pelo manejo inadequado, foram os principais fatores que promoveram as alterações no solo. O índice de qualidade do solo mostrou uma sequência decrescente, 0,83, 0,62, 0,51 e 0,23, respectivamente, para as áreas sob Andropogon gayanus (AN, Andropogon gayanus (AV, Brachiaria brizantha (BN e Brachiaria decumbens (BV.The sustainable use of pasture systems depends mainly on a management that promotes soil quality. This study aimed to evaluate changes in the physical and chemical soil properties of four areas under pasture growing the species Andropogon gayanus, Brachiaria decumbens and Brachiaria brizantha, cv. marandu, with different usage histories, in comparison to the reference of the natural Cerrado. The soil was evaluated based on the following properties: cation exchange capacity, soil organic matter, bulk density, porosity and soil mechanical penetration resistance. The cation exchange capacity and soil organic matter content were little

  3. A successional stage community dominated by Pteridium aquilinum (L.) Kuhn. in Lavras County, MG, Brazil

    OpenAIRE

    Martins, G. de; Carvalho, D.A. de

    1982-01-01

    Numa área situada no município de Lavras, MG, o desmatamento realizado há cerca de dez anos propiciou a formação de uma comunidade infestante dominada por Pteridium aquilium (L.) Khun., te ndo como codominantes Imperara brasiliensis Trin. e Andropogon bicornis L.. Como fatores que mantém esta comu nidade devem ser considerados: a) as queimadas intermiten te s; b) a acidez do solo; c) a alta percentagem de saturação de aluminio ; d) a ação fitotóxica do próprio P. aquilinum; e) a falta de pala...

  4. Uma comunidade sucessional dominada por Pteridium aquilinum ( L. Kuhn. no município de Lavras, estado de Minas Gerais A successional stage community dominated by Pteridium aquilinum (L. Kuhn. in Lavras County, MG, Brazil

    Directory of Open Access Journals (Sweden)

    G. de Martins

    1982-06-01

    Full Text Available Numa área situada no município de Lavras, MG, o desmatamento realizado há cerca de dez anos propiciou a formação de uma comunidade infestante dominada por Pteridium aquilium (L. Khun., te ndo como codominantes Imperara brasiliensis Trin. e Andropogon bicornis L.. Como fatores que mantém esta comu nidade devem ser considerados: a as queimadas intermiten te s; b a acidez do solo; c a alta percentagem de saturação de aluminio ; d a ação fitotóxica do próprio P. aquilinum; e a falta de palatabilidade das espécies dominantes.A forest was clearcutted about 10 years ago in Lavras county, MG, Brazil and today a natural successional stage community can be found. The dominant weed, in fitomass, coverage an hcight is the bracken-fern Pteridium aquilinum (L. Kuhn. The West Indian foxta il (Andropogon bicornis L. and the brazilian cogon grass (Imperata brasiliensis Trin. are the co-dominats weeds. Periodic burnings, soil acidity, high aluminium saturation and the phytotoxicity of the P. aquilinum itself are probably the factors which could explain the present community successional stage.

  5. Pasture research in the wet and dry tropics of Nigeria with particular reference to isotope applications

    International Nuclear Information System (INIS)

    Adegbola, A.A.; Adepoju, A.

    1983-01-01

    Pasture research in western Nigeria, which typifies the wet and dry tropics of Nigeria, is discussed fully. Interest in pasture research in the area was kindled in 1930 with the introduction of Cynodon nlemfuensis var. robusta, but systematic work did not start until the 1950s. Early agronomic studies centred on easy means of establishing the adapted species from cuttings, sprigs or seeds. The most important species in the dry tropics is Andropogon gayanus, while in the wet tropics it is Panicum maximum. Later, investigations on yield of dry matter, intervals and height of cutting and response to fertilizer applications were carried out. Radioactive fertilizer 32 P- and 15 N-urea were also used to study the yield response of pasture to fertilizer application and to determine the percentage uptake of nutrients by plants. The results of such trials in different locations in the area are discussed extensively. Also, 32 P was used to determine the depth of active absorption of the root system of Andropogon gayanus and Panicum maximum, thus establishing their rooting pattern. (author)

  6. Traditional ecological knowledge underlying herding decisions of pastoralists.

    Science.gov (United States)

    Tamou, C; de Boer, I J M; Ripoll-Bosch, R; Oosting, S J

    2018-04-01

    Pastoralists have traditional ecological knowledge (TEK), which is important for their livelihoods and for policies and interventions. Pastoralism is under pressure, however, which may result in a decline of pastoral lifestyle and its related TEK. We, therefore, addressed the following objectives (i) to inventorise and assess how pastoralists characterise and value soils and forages in their environment, (ii) to analyse how soil, forage and livestock (i.e. cattle) characteristics relate to herding decisions and (iii) to determine whether TEK underlying herding decisions differs across generations. Data were collected through focus groups and individual interviews with 72 pastoralists, belonging to three generations and to three agro-ecological zones. Using a three-point scale (high, medium, low), four grasses and three tree forages were assessed in terms of nutritional quality for milk, meat, health and strength. Using their own visual criteria, pastoralists identified five different soils, which they selected for herding at different times of the year. Pastoralists stated that Pokuri was the best soil because of its low moisture content, whereas Karaal was the worst because forage hardly grows on it. They stated that perennials, such as Andropogon gayanus and Loxoderra ledermannii, were of high nutritional quality, whereas annuals such as Andropogon pseudapricus and Hyparrhenia involucrata were of low nutritional quality. Afzelia africana was perceived of high quality for milk production, whereas Khaya senegalensis had the highest quality for meat, health and strength. Pastoralists first used soil, then forage and finally livestock characteristics in their herding decisions. Pastoralists' TEK was not associated with their generations, but with their agro-ecological zones. This study suggests that pastoralists had common and detailed TEK about soils, forages and livestock characteristics, underlying their herding decisions. To conclude, pastoralists use a holistic

  7. Soil macrofauna in a Cerrado/Caatinga ecotone under different crops in Southwestern Piauí State, Brazil

    Directory of Open Access Journals (Sweden)

    Djavan Pinheiro Santos

    2017-09-01

    Full Text Available ABSTRACT: The aim of this study was to characterize the soil macrofauna under different crop systems and compare them to the macrofauna under the native vegetation of a Cerrado/Caatinga ecotone in southwestern Piauí State, Brazil. The areas studied included areas under sweetsop cultivation (Annona squamosa L., andropogon grass with three years of use, andropogon grass with six years of use, pivot-irrigated corn, Napier grass, and native vegetation. In each area, soil layers of 0-0.1, 0.1-0.2, and 0.2-0.3m, including the surface litter, were evaluated following the Tropical Soil Biology and Fertility Program (TSBF recommendations. The soil macrofauna from the different land-use systems were identified to the family level, and the mean density of each taxon was calculated for each soil-management type and layer. The structure of the soil macrofauna was negatively altered under the different crops in comparison to the native Cerrado/Caatinga vegetation, with macrofaunal occurrence varying in the different soil layers. A correlation existed between the functional groups and the soil grain-size distribution and moisture. Napier grass cultivation favored greater soil macrofaunal abundance, with a predominance of families belonging to the orders Isoptera and Hymenoptera. Number of soil macrofaunal families under pivot-irrigated corn was more like the number observed with the native vegetation, and corn also had greater family diversity compared to the other crops studied. Therefore, pivot-irrigated corn can reduce the impact of anthropogenic land use on the diversity of soil macrofauna.

  8. OCORRÊNCIA E ATIVIDADE DE BACTÉRIAS DIAZOTRÓFICAS EM FORRAGEIRAS CULTIVADAS NA REGIÃO SEMIÁRIDA NO BRASIL

    Directory of Open Access Journals (Sweden)

    MÁRCIA CARNEIRO MONTEIRO DOS SANTOS

    2013-01-01

    Full Text Available Diazotrophic bacteria play important role on economy nitrogen fertilizer in forage glasses and environmental sustainability. With the objective of evaluate the occurrence of diazotrophic bacteria associated associated with native forage at two different times and identify isolates with potential for fixing N2 in the semiarid region. Was conducted in the Soil Laboratory of the Centro de Saúde e Tecnologia Rural in Federal University of Campina Grande, Campus de Patos, Paraíba. A study was carried out at the Soil Laboratory of the Centro de Saúde e Tecnologia Rural of the Federal University of Campina Grande, in Patos, Paraíba. The objective this study was to verify in the native diazotrophic endophytic bacteria associated with forage glasses and to identify isolates in NBF hability, during the rainy and dry seasons in semiarid region. Root samples of three forage grasses [Andropogon gayanus Kunth (Andropogon, Panicum maximum Jacq. cv. Tanzania (Tanzânia and Cenchrus ciliaris L. (Buffel] cultivated in the field experiment was utilized. The bacteria were isolated in NFb culture media free-N specific for Azospirillum spp., the isolates was quantified, phenotypically characterized, purified. From caracterized after, was evaluated for their nitrogenase activity in vitro. The resultas show diazotrophics bacteria growth in the three forage grasses tested. The ocorrency diazotrophics bacteria be influencied by genotipic plant and seasonal variation. A more density of NSDB of the genus Azospirillum associated in the root grasses were obtained in dry season. The NSDB isolates, show a high potencial for new studies on the genetic caracteristcs and avaliation the inoculo potential to (BNF associated on grasses in semiarid region.

  9. Sinopse das espécies nativas e subespontâneas de Andropogoneae Dumort. (Poaceae na Ilha de Santa Catarina, Brasil A synopsis of the Andropogoneae Dumort. (Poaceae native and subspontaneous to the Island of Santa Catarina, Florianópolis, SC, Brazil

    Directory of Open Access Journals (Sweden)

    Bárbara Toncic Neves

    2011-12-01

    Full Text Available O presente trabalho consiste no levantamento dos táxons da tribo Andropogoneae (Panicoideae - Poaceae ocorrentes na Ilha de Santa Catarina, Florianópolis, Brasil. A partir da revisão de materiais de herbários e coletas a campo foi confirmada a ocorrência de 10 gêneros e 20 espécies, 17 nativas e duas subespontâneas: Andropogon L. (7 spp., Bothriochloa Kuntze (2, Eriochrysis P. Beauv. (1, Hyparrhenia Andersson ex E. Fourn. (1, Imperata Cirillo (1, Ischaemum L. (1, Rhytachne Desv. (1, Saccharum L. (3, Schizachyrium Nees (2 e Sorghum Moench (1. Os gêneros Bothriochloa e Rhytachne são registrados pela primeira vez para a Ilha de Santa Catarina. São apresentadas chaves de identificação para gêneros e espécies, ilustrações, informações sobre distribuição geográfica, habitat, período de floração e comentários para cada táxon.The present work is a survey of the taxa in the tribe Andropogoneae (Panicoideae - Poaceae that occur on the Island of Santa Catarina, Florianópolis, Brazil. Based on a review of herbarium specimens and fieldwork, 20 species were recorded in the following 10 genera: Andropogon L. (7 spp., Bothriochloa Kuntze (2, Eriochrysis P. Beauv. (1, Hyparrhenia Andersson ex E. Fourn. (1, Imperata Cirillo (1, Ischaemum L. (1, Rhytachne Desv. (1, Saccharum L. (3, Schizachyrium Nees (2 and Sorghum Moench (1. Seventeen of the species are native, and two species are subspontaneous. Bothriochloa and Rhytachne are recorded here, for the first time, for the Island of Santa Catarina. This work provides key to the genera and species, as well as illustrations, information about geographic distribution, habitat, phenology, and comments about each taxon presented in the study.

  10. Características de carcaça, componentes não-carcaça e composição tecidual e química da 12ª costela de cordeiros Santa Inês terminados em pasto com três gramíneas no período seco Carcass traits, non-carcass components and tissues and chemical composition the 12th rib of Santa Inês sheep finished on three different grasses during the dry season

    Directory of Open Access Journals (Sweden)

    Luizângele Figueiredo de Oliveira Menezes

    2008-07-01

    Full Text Available Foram avaliadas as características de carcaça, os componentes não-carcaça e o rendimento da 12ª costela de cordeiros Santa Inês terminados em pastejo rotacionado com três forrageiras tropicais (A. gayanus Kunth, cv. Planaltina, P. maximum Jacq., cv. Aruana e P. maximum Jacq., cv. Tanzânia, no período seco do ano. Utilizou-se delineamento inteiramente casualizado, com 11 ovinos (3 meses de idade e 18,8 ± 2,88 kg PV em cada tratamento. Os animais receberam suplementação com concentrado em níveis crescentes, conforme o avançar do período seco, além de sal mineral à vontade. Ao final de 82 dias de experimento, os animais foram abatidos; no dia anterior ao abate, a área de olho-de-lombo (AOL foi mensurada com ultra-som (AOLUS. Avaliaram-se o peso ao abate (PA, o peso de carcaça quente (PCQ, o rendimento de carcaça quente (RCQ, o comprimento da carcaça (CC, o escore de gordura subcutânea (EGS, o peso da meia-carcaça quente (PMCQ, os cortes da meia-carcaça (costela/fralda, costeleta, lombo, paleta, pernil, e pescoço e os pesos da pele (PELE, das vísceras torácicas (VT e abdominais (VA e dos testículos (TE. A 12ª costela foi avaliada quanto ao peso total (PT, AOL, aos pesos e às porcentagens de músculo (MUSC, osso (OSSO e gordura (GORD e os constituintes químicos. As características PA, PCQ, RCQ, PELE e GORD não diferiram entre os animais terminados em pastos de capim-aruana e capim-tanzânia, mas foram superiores nos animais terminados em pasto de capim-andropogon. Os rendimentos de pescoço, costela/fralda e costeleta dos animais terminados em capim-tanzânia foram superiores aos obtidos nos animais terminados em capim-andropogon e aruana, que não diferiram entre si. As demais características de carcaça, dos componentes não-carcaça e da 12ª costela não diferiram entre os tratamentos. Os ovinos mantidos em pastagem de capim-aruana e capim-tanzânia apresentaram melhores características de carcaça e desempenho

  11. Anthropocene Survival of Southern New England's Salt ...

    Science.gov (United States)

    In southern New England, salt marshes are exceptionally vulnerable to the impacts of accelerated sea level rise. Regional rates of sea level rise have been as much as 50 % greater than the global average over past decades, a more than fourfold increase over late Holocene background values. In addition, coastal development blocks many potential marsh migration routes, and compensatory mechanisms relying on positive feedbacks between inundation and sediment deposition are insufficient to counter inundation increases in extreme low-turbidity tidal waters. Accordingly, multiple lines of evidence suggest that marsh submergence is occurring in southern New England. A combination of monitoring data, field re-surveys, radiometric dating, and analysis of peat composition have established that, beginning in the early and mid-twentieth century, the dominant low-marsh plant, Spartina alterniflora, has encroached upward in tidal marshes, and typical high-marsh plants, including Juncus gerardii and Spartina patens, have declined, providing strong evidence that vegetation changes are being driven, at least in part, by higher water levels. Additionally, aerial and satellite imagery show shoreline retreat, widening and headward extension of channels, and new and expanded interior depressions. Papers in this special section highlight changes in marsh-building processes, patterns of vegetation loss, and shifts in species composition. The final papers turn to strategies for minimiz

  12. Degradação de pastagens na Região Amazônica: propriedades físicas do solo e crescimento de raízes Pasture degradation in the Amazon region: soil physical properties and root growth

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    Marcelo Marques Lopes Muller

    2001-11-01

    Full Text Available O objetivo deste trabalho foi avaliar: (i a relação entre a degradação de pastagens de colonião manejadas com queima, e as modificações nas propriedades físicas e morfológicas de um Argissolo Vermelho-Amarelo da Amazônia; (ii o crescimento radicular de pastagens com diferentes níveis de degradação; (iii o potencial de recuperação de pastagens degradadas de colonião com a introdução de andropógon. Numa propriedade rural da Região de Marabá, PA, foram estudados quatro tipos de pastagem: pastagem produtiva de colonião (Panicum maximum Jacq.; pastagem de colonião em declínio produtivo; pastagem de colonião degradada (capoeira; pastagem de colonião degradada e recuperada com andropógon (Andropogon gayanus Kunth. Como referência das propriedades do solo antes do desmatamento, estudou-se, também, uma reserva de mata nativa. A queima das pastagens foi prática usual, e apesar disso, estas não foram adubadas. A degradação da pastagem diminuiu a cobertura do solo e o deixou exposto à chuva e ao pisoteio do gado, o que resultou em aumento da densidade do solo na camada superficial e diminuição do grau de floculação da argila e da porosidade total. A diminuição da produção da parte aérea na pastagem degradada foi acompanhada de diminuição do número de raízes no perfil do solo, e da concentração do sistema radicular próximo à superfície. O andropógon demonstrou bom potencial para recuperação das áreas de pastagens degradadas, na Região Amazônica.The objective of this study was to evaluate: (i the relation between the degradation of burned Guinea grass pastures and the modifications of some physical and morphological properties of an Amazonian Ultisol; (ii the root growth of pastures in different degradation stages; and (iii the potential of rehabilitation of degraded Guinea grass pastures by introducing Gamba grass. On a farm at the eastern Amazon, region of Marabá, PA, Brazil, four pasture types were

  13. Establishment, Growth and Biomass yield of three Grass species on a degraded Ultisol and their effect on soil loss.

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    2016-11-01

    Full Text Available Erosion is a cause for concern; this is because of its effects on the soil used for both agricultural and non-agricultural purposes. Experiments were carried out to check the establishment, growth and biomass field of 3 tropical plants and their effects on soil loss during 2007 planting season. The treatments comprised 3 grasses viz. Azonopus compressus. Panicum maximum and Andropogon gayanus. The grasses were laid our in the field using a randomized complete block design replicated 4 times. Bare soil was used as the control. The parameters tested were plant height, leaf area index, root density, root establishment and the amount of soil loss using erosion pins. The result showed that Andropogon gayanus has an edge over Panicum maximum and Axonopus compressus with reference to plant height, root establishment, root density and leaf area index. Andropogon gayanus had a higher plant height from 3,6,9 and 12WAP with plant heights of 3.30cm, 3.63cm,3.93cm and 4.30cm representing 15.7%, 19.3% and 28.8% respectively. It was followed by P. maximum while A. compressus maintained the lowest plant height from 3,6,9 and 12 WAP with plant height of 2.83cm, 3.05cm, 3.20cm and 3.45cm respectively. In terms of root density, A. compressus did not have much root density which was 0.02t/ha, also at 12WAP, P. maximum did not have much root density which was 0.06t/ha though it was higher than A. compressus. The trend was the same for A. gayanus whose root density was 0.75t/ha. In terms of leaf area index (LAI, it was shown that at 3WAP and 6WAP, A. compressus had the lowest leaf area index of 58.25 and 65.75 respectively. Also at 9WAP and 12WAP A. compressus had 72.28 and 75.08t/ha respectively. At 3WAP and 6WAP P.maximum had a high leaf area index of 66.60 and 77.25 respectively. A. gayanus at 3WAP and 6WAP had 87.73 gayanus at 3WAP and 6WAP had 87.73 and 90.80 for 9WAP and 12WAP respectively. A. compressus protected the soil, reducing soil loss as a total of 9

  14. THE LEVELS OF SELENIUM IN CERRADOS PASTURES AND THE EFFECTS OF ITS SUPPLEMENTATION IN PERFORMANCE OF LAMBS NÍVEIS DE SELÊNIO EM PASTAGENS DE CERRADO E EFEITOS DA SUPLEMENTAÇÃO SOBRE O DESEMPENHO DE CORDEIROS

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    José Henrique Stringhini

    2007-09-01

    Full Text Available

    This experiment was carried out in the Água Limpa Farm, of the University of Brasília, aiming to estimate the level of selenium and its variation during the year in some cultivated pastures of the cerrados region (Andropogon gayanus var. bisquamulatus, Brachiaria decumbens and Brachiaria ruziziensis. On the other hand, it was determined the effects of the supplementation, through intramuscular applications, in 24 Bergamacia weaned lambs. Pastures samples were collected trying to simulate the animal grazing, at intervals of 84 days, and different chemical methods of determination of selenium were evaluated. The fluorometric method has the best response and the levels of the samples varied from 0.025 to 0.075 ppm. In relation to the lambs, difference in weight gains were not statistically significant (P>0.05.

    KEY-WORDS: Brazilian savannas (“cerrados”; sheep; selenium supplementation.

    O presente experimento foi conduzido na Fazenda Água Limpa, da Universidade de Brasília, e teve como objetivos verificar os níveis estacionais de selênio encontrados nas pastagens de Andropogon gayanus var. bisquamulatus, Brachiaria decunbens e Brachiaria ruziziensis e avaliar os efeitos da suplementação de selênio por via intramuscular em 24 ovinos desmamados da raça Bergamácia. Foram efetuadas quatro coletas de forragem procurando imitar o pastejo dos animais e testados os métodos químicos para análise de selênio. O método fluorométrico foi o mais adequado e determinaram-se os níveis que variaram entre 0,025 e 0,075 ppm para as pastagens estudadas. Com relação aos cordeiros, não se observou efeito significativo para o ganho de peso dos cordeiros (P>0

  15. Avaliação de gramíneas forrageiras na região sul de Minas Gerais Evaluation of forage grasses for the south region of Minas Gerais

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    Milton de Andrade Botrel

    1999-04-01

    Full Text Available Foram conduzidos dois experimentos na região do sul de Minas Gerais para avaliar o potencial de gramíneas forrageiras. No experimento 1 foram avaliadas as seguintes espécies, consideradas de baixa exigência nutricional: Andropogon gayanus, Kunt; Brachiaria brizantha, Stapf; Brachiaria decumbens, Stapf; Brachiaria ruziziensis, Germain Evrard; Brachiaria humidicola (Rendle Schweickt e Melinis minutiflora, Beauv. No experimento 2 foram avaliadas as gramíneas consideradas de média e alta exigência nutricional, a saber: Setaria sphacelata (Schum. Moss; Hemarthria altissima (Poir. Stapf; Chloris gayana, Kunt; Cynodon nlemfuensis, Vanderyst var. nlemfuensis; Hyparrhenia rufa, (Ness Stapf. e as cultivares de Panicum maximum, Jacq.: Tobiatã, Green Panic e Makueni. O delineamento experimental foi de blocos ao acaso com três repetições. Os níveis de calagem e de adubação para estabelecimento e manutenção foram diferenciados para os dois experimentos. Cada espécie foi avaliada nos seguintes aspectos: produção de forragem e teor de proteína bruta no período da seca e das chuvas e cobertura vegetal do solo. As gramíneas do experimento 1 que se destacaram na maioria dos aspectos avaliados foram: B. brizantha, B. decumbens, A. gayanus enquanto que no experimento 2 as espécies que apresentaram maior potencial forrageiro foram: S. sphacelata, P. maximum cv. Tobiatã.experiments were undertaken in the South region of Minas Gerais State, Brazil, to evaluate the yield potential of forage grasses. In experiment 1, the following species, considered as having low nutritional requirements, were evaluated: Andropogon gayanus, Kunt; Brachiaria brizantha, Stapf; Brachiaria decumbens, Stapf; Brachiaria ruziziensis, Germain Evrard; Brachiaria humidicola (Rendle Schweickt and Melinis minutiflora, Beauv. In experiment 2, the species considered as having medium and high nutritional requirements, that is: Setaria sphacelata (Schum.; Hemarthria altissima

  16. Population of bacteria from soil in Tudu-Aog village, Passi district, Bolaang Mongondow, North Sulawesi

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    RIANI HARDININGSIH

    2004-01-01

    Full Text Available An experiment was conducted in order to know the population of bacteria from soil in Tudu-Aog village, Passi district, Bolaang Mongondow, North Sulawesi, the purpose of the research was to study the population of bacteria from soil. Fourthy six soil samples were taken from two location, namelyTudu-Aog village and Bugis mountain. Isolation was done by dilution methods on YEMA medium (for Rhizobium bacteria, Winogradsky’s (for Azotobacter bacteria, Pycosvkaya (for Phosphat Solubilizing Bacteria, and selective Difco Pseudomonas (for Pseudomonas bacteria. Incubation at room temperature (27-280C until 15 days, and the enumeration with plate count method. The highest enumeration of Rhizobium bacteria with plant rhizosphere of Alocasia esculenta (27x105 CFU/g soil, Theobroma cacao (29x105 CFU/g soil,and Euphorbia paniculata (26x105 CFU/g soil, Azotobacter bacteria with plant rhizosphere of Lycopersicum esculantum (38x105 CFU/g soil, Eugenia aromaticum (43x105 CFU/g soil, Andropogon sp. (34x105 CFU/g soil, Phosphat Solubilizing bacteria with plant rhizosphere of Sechium edule (27x105 CFU/g soil, Cinnamomum sp. (48x105 CFU/g soil, Cyathea sp. (72x105 CFU/g soil, and Pseudomonas bacteria with plant rhizosphere of Oryza sativa (18x105 CFU/g soil, Vanilla sp. (12x105 CFU/g soil, dan Saurauia sp.(19x105 CFU/g soil.

  17. Monitoring the Distribution and Dynamics of an Invasive Grass in Tropical Savanna Using Airborne LiDAR

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    Shaun R. Levick

    2015-04-01

    Full Text Available The spread of an alien invasive grass (gamba grass—Andropogon gayanus in the tropical savannas of Northern Australia is a major threat to habitat quality and biodiversity in the region, primarily through its influence on fire intensity. Effective control and eradication of this invader requires better insight into its spatial distribution and rate of spread to inform management actions. We used full-waveform airborne LiDAR to map areas of known A. gayanus invasion in the Batchelor region of the Northern Territory, Australia. Our stratified sampling campaign included wooded savanna areas with differing degrees of A. gayanus invasion and adjacent areas of native grass and woody tree mixtures. We used height and spatial contiguity based metrics to classify returns from A. gayanus and developed spatial representations of A. gayanus occurrence (1 m resolution and canopy cover (10 m resolution. The cover classification proved robust against two independent field-based investigations at 500 m2 (R2 = 0.87, RMSE = 12.53 and 100 m2 (R2 = 0.79, RMSE = 14.13 scale. Our mapping results provide a solid benchmark for evaluating the rate and pattern of A. gayanus spread from future LiDAR campaigns. In addition, this high-resolution mapping can be used to inform satellite image analysis for the evaluation of A. gayanus invasion over broader regional scales. Our research highlights the huge potential that airborne LiDAR holds for facilitating the monitoring and management of savanna habitat condition.

  18. Production et coûts des semences utilisées pour l'amélioration des jachères et des aménagements antiérosifs : "Le cas des zones de savane du Nord Cameroun"

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    Dugué, P.

    1999-01-01

    Full Text Available Seeds Production for Fallow and Anti-Erosion Management : "The Case of the Savannah Areas in North Cameroon". The maintenance of cultivated soils' fertility in North Cameroon relies on the extension of the techniques of water erosion control and improved legume crop fallows. These innovations require that seeds must become available to farmers. These seeds are legume seeds (Calopogonium mucunoides, Stylosanthes hamata, Mucuna pruriens, Cajans cajan or perennial grasses (Panicum maximum, Andropogon gayanus, Cenchrus ciliaris. On station research has developed the techniques of seeds production which can be introduced in the farmer's environment on the one hand, and on the other hand can be used to evaluate the cost of legumes seeds production. Depending on the species, the total price of seeds production varies from 250 to 1160 FCFA/kg (0, 5 U$ to 2 U$/kg. Based on these prices, it seems possible in the first step to diffuse these seeds varieties. The diffusion of the vegetal material depends firstly on the interest that farmers attach to techniques of soil restauration which are proposed to them. If they adopt these innovations, they can easily produce seeds that they need after been trained to the techniques developed by research.

  19. Dry Matter Production, Nutrient Cycled and Removed, and Soil Fertility Changes in Yam-Based Cropping Systems with Herbaceous Legumes in the Guinea-Sudan Zone of Benin

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    Raphiou Maliki

    2016-01-01

    Full Text Available Traditional yam-based cropping systems (shifting cultivation, slash-and-burn, and short fallow often result in deforestation and soil nutrient depletion. The objective of this study was to determine the impact of yam-based systems with herbaceous legumes on dry matter (DM production (tubers, shoots, nutrients removed and recycled, and the soil fertility changes. We compared smallholders’ traditional systems (1-year fallow of Andropogon gayanus-yam rotation, maize-yam rotation with yam-based systems integrated herbaceous legumes (Aeschynomene histrix/maize intercropping-yam rotation, Mucuna pruriens/maize intercropping-yam rotation. The experiment was conducted during the 2002 and 2004 cropping seasons with 32 farmers, eight in each site. For each of them, a randomized complete block design with four treatments and four replicates was carried out using a partial nested model with five factors: Year, Replicate, Farmer, Site, and Treatment. Analysis of variance (ANOVA using the general linear model (GLM procedure was applied to the dry matter (DM production (tubers, shoots, nutrient contribution to the systems, and soil properties at depths 0–10 and 10–20 cm. DM removed and recycled, total N, P, and K recycled or removed, and soil chemical properties (SOM, N, P, K, and pH water were significantly improved on yam-based systems with legumes in comparison with traditional systems.

  20. Production indices for dual purpose cattle in central Brazil

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    Concepta McManus

    2011-07-01

    Full Text Available This study examined the effects of crossbreeding low genetic potential cows of Bos indicus origin characterized by Gyr crossed with Holstein-Friesian and Simmental bulls to produce animals in a low input dual purpose system. The farm is situated near Brasilia, in the savannah region of Brazil. The climate of the region is classified as Aw by Köppen. Data was available on 1580 calvings and completed lactations of cows with three genetic types: Gyr, Holstein-Friesian × Gyr and Simmental × Gyr. The bulls ran with the cows all year round and the diet comprised of pasture (mainly Brachiaria and Andropogon during the summer (rainy season and milled sugar cane with added urea during the winter (dry season. A mineral salt mixture was available ad libitum. Data was analysed using Statistical Analysis System. The results show that, under low input management conditions, the crossbred cows produce approximately twice the volume of milk per lactation, calve at a younger age and have a shorter open period, but there are no significant differences between crosses for growth rates of the calves or body condition of the cows. In this system, crossbred cows had production higher indices than zebu cattle. The best indices were found for cows calving in the rainy season (September to December and thinner cows (with body condition 3-5 on a scale of 9.

  1. Abundance of food plant species and food habits of Rhinoceros unicorns Linn. in Pobitora Wildlife Sanctuary, Assam, India

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    P. Konwar

    2009-09-01

    Full Text Available Food habits and abundance of food plant species of Rhinoceros unicornis in Pobitora Wildlife Sanctuary were studied from January 1999 through December 2001. Totally 32 numbers of Rhino food plants were identified, of which 15 were grasses, four shrubs, five aquatic hydrophytes and eight tree species (21 terrestrial and 11 aquatic. During the dry season, the Rhino feeds on almost 90% food items from Hemarthria compressa, Arundo donax, Phragmites karka, Cerex rubro-brumee etc. The other short grasses such as Cynodon dactylon, Andropogon ssp., Cenchrus ciliaris, Chrysopogon aciculatus and tender and young shoots and twigs of Schelristechya fuesche, Saccharum spontaneum, Lagerstroemia flosreginae etc. are consumed in limited portions. The rhino consumes 11 cultivated crops and vegetables, viz., Ricinus communis, Oryza sativa, Solanum melongena, Lycopersicon esculentum, Solanum tuberosum, Brassica nigra, Luffa cylindrica, Luffa acutangula, Cucurbita moschata, Cucumis sativus and Ipomoea batatas etc. Highest density of food plant species observed in the study area were Cynodon dactylon (167.5/m2, Hemarthria compressa (73.75/m2, Vetiveria zizanioides (56/m2, Saccharum ravannae (51.5/m2, Pharagmites karka (50.75/m2, Leersia hexandra (46.75/m2, Brachiarea pseudointerrupta (40/m2 and Eichhornia crassipes (35/m2.

  2. Parámetros indicadores de valor nutritivo en cinco pastos tropicales en la época lluviosa en el trópico seco de Cota Rica

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    Rafael Angel Arroyo

    2016-03-01

    Full Text Available This essay was carried out in Hojancha, Guanacaste to evaluate the nutritive values of the following grasses: jaragua (Hyparrhenia rufa (Nees, african star grass (Cynodon nlenfuensis (L(Pers, transvala (Digitaria decumbens veranero (Andropogon gayanus(Kunth y congo (Brachiaria ruziziensis(Germain et Everard, under three cut intervals (28, 35 and 42 days. The evaluated variables were: Dry Matter Production (DMP, kg/ha/cut, In vitro Dry Matter Digestibility (IVDMD, %, Digestible Dry Matter (DDM, kg/ha/cut, Crude Protein Content (CP, %, Crude protein production (CPP, kg/ha/cut, Digestible Crude Protein Production (DCPP, kg/ha/cut, Ruminal Dry Matter Disappeareance (RDMD, %/hour, Ruminal Dry Matter Disappeareance Mean Time (RDMDMT, hours. The largest DMP was found for the veranero grass at 28 and 35 day intervals (1527,5 and 2424,4 kg/ha/cut while at the 42 day interval the congo grass (2886,8 kg/ha/cut had the largest DMP, followed by veranero grass with 2705,0 kg/ha/cut. The veranero and transvala grasses showed the highest RDMD and RDMDMT as compared to the other grasses in the study, as a consequence of their better chemical composition. Between the jaragua and veranero grasses there were no differences with respect to their chemical composition and ruminal characteristics. The poorest DMP, chemical composition (excluding CP and RDMD was shown by the african star grass.

  3. Ecological recovery of affected areas by a forest fire in the Tintales watershed (Boyacá, Colombia

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    Fernando Fernández-Méndez

    2016-07-01

    Full Text Available The tintales watershed, located in the Santuario de Flora y Fauna (SFF of Iguaque, Boyaca, was affected by a wildfire. In that area, the natural regeneration was evaluated in 29 permanent plots. Two phyto-physiognomies, a rocky outcrop and oak were evaluated to compare their richness, diversity and dominance, with rocky outcrop yielding a greater richness and diversity. The Asteraceae family was the one that obtained greater representation, with a dominance of species such as Hypoxis decumbens, Pterídium aquilinum and Andropogon bicornis. The diversity in the whole sampling was low and uniform due to the repeated incidence of forest fires that have caused changes in the structure and composition of vegetation. The vegetation found did not differ substantially from other studies reported for this life zone and the region, where the dynamics of land use are similar, with high deforestation and fires. The vegetation established after the fire is dominated by colonizing and pioneering species. In the two phyto physiognomies studied after a year of the fire, two plant communities with statistically significant differences in wealth and homogeneity could be stablished. To start the restoration process, it is recommended to use as one of the inputs, the taxonomic differences found between oak  and rocky outcrop.

  4. Evaluation of carcass traits, non-carcass components and 12th rib analysis of hair sheep supplemented with phosphorus Avaliação das características de carcaça, constituintes corporais e da 12ª costela de ovinos deslanados suplementados com fósforo

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    Helder Louvandini

    2006-04-01

    Full Text Available The aim of this study was to evaluate the performance of sheep supplemented with phosphorus (P using carcass traits and analysis of 12th rib. Twenty male lambs weighing 13.88 ± 2.51 kg and grazing Andropogon gayanus pasture were divided in two treatments of 10 animals each. In group P, animals were supplemented with 3 g phosphorus/animal/day, while in group NP no P supplementation was given. After 82 days the animals were slaughtered and carcass measurements were taken. The 12th rib was also removed for analysis. No significant differences in body weight, carcass yield, or commercial cut weights were found between both treatments, except for liver and kidneys that were heavier in the supplemented group (p=0.0954. The 12th rib analysis showed that the group P had higher rib, bone, and muscle weights when compared to animals not supplemented with P. Other measurements such as carcass fatness and rib eye area were not significantly affected by treatments as well as contents of crude protein, ether extract, ash and P. It was shown that P supplementation improved performance in young sheep, including bone and muscle tissue and liver and kidney weights.Este trabalho foi realizado com a finalidade de avaliar o desempenho de ovinos suplementados com fósforo (P, utilizando-se as análises das características de carcaça e da 12ª costela. Foram utilizados 20 ovinos com 13,88 ± 2,51 kg de PV, mantidos em pastagem de Andropogon gayanus, distribuídos em dois tratamentos com dez animais: um com suplementação de 3g/fósforo/animal/dia e o outro sem suplementação. Após 82 dias, os animais foram abatidos, tomando-se as medidas da carcaça e da 12ª costela, para posterior análise. Não foram encontradas diferenças significativas entre os valores de peso vivo, rendimento de carcaça, cobertura de gordura e cortes comerciais entre os dois tratamentos, exceto os pesos do fígado e dos rins, que foram superiores (p=0,0954 no grupo suplementado. Na an

  5. Semeadura direta de forrageiras de estação fria em campo natural submetido à aplicação de herbicidas: II. Composição botânica No-till seeding of cold season forage on native pasture under herbicides application: II. Botanical composition

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    Enrique Pérez Gomar

    2004-06-01

    Full Text Available A semeadura direta de espécies forrageiras de estação fria permite reduzir a marcada estacionalidade da sua produção em campos naturais. Durante quatro anos, conduziu-se um experimento de aplicação de herbicidas sobre campo nativo, em um solo Argissolo Vermelho-Amarelo, de textura arenosa do norte do Uruguai visando introduzir forrageiras de estação fria e estudar o impacto dos herbicidas na composição botânica de espécies estivais. Foram testadas doses de herbicidas (glifosate 1L ha-1, glifosate 4L ha-1, paraquat 3L ha-1 e testemunha, como tratamento principal, aplicadas no ano 1994, em um delineamento blocos ao acaso. A repetição ou não das mesmas doses no ano 1995 constituiu a subparcela e a aplicação ou não das mesmas doses no ano de 1996 constituiu a sub-subparcela. No levantamento de espécies da vegetação existentes no outono de 1998, observou-se que o maior distúrbio sobre a composição botânica do campo nativo foi provocado com a aplicação continuada da dose de 4L ha-1 de glifosate, onde foram identificadas seis espécies. No levantamento de espécies existentes no tratamento testemunha, no outono, foram identificadas onze espécies, sendo que as espécies Andropogon lateralis, Paspalum notatum, Conyza bonariensis, Eryngium horridum, Desmodium incanum, Cyperus sp. e Digitaria sp. constituiram 90% da composição botânica. Com a aplicação de herbicida, ocorreu uma substituição de espécies perenes por anuais.No-till seeding of winter species may reduce seasonal fluctuations of forage production of natural grasslands. An experiment of herbicide application on native grasses was conducted for four years, on a fine-loamy, mixed Mollic Hapludalf in northern of Uruguay to introduce winter forage and study the impact of herbicide on botanical composition of grass field. The experimental design was split-splitplot with three randomized blocks, with types and dosis of herbicides (gliphosate 1L ha-1, gliphosate 4L

  6. UJI TOKSISITAS BEBERAPA EKSTRAK TANAMAN TERHADAP LARVA AEDES AEgYPTI VEKTOR DEMAM BERDARAH DENGUE

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    Hasan Boesri

    2015-09-01

    Full Text Available Mosquito vector control are still using insecticide  from pyrethroid, carbamates and organophosphates groups because they are effective, having fast result but having less concern for the negative impact to the environment. In order to solve the side effects the side effect, it was necessary to find bio-insecticides which are sustainable, accessible and effective to kill mosquitoes and larvae. In this study the extract of Nicotiana tabacum / tobacco with minimum concentration of 1,56 % was effective to kill larvae with of 100% mortality, with of LC90  0,628 %, LC50 0,194 %. The extract contain chemical dominant alkaloids, Euvodia gravolens / zodiac with minimum concentration 1,56 % the mortality effects 100%, is with LC90 0,628 %, and LC50 0,194 %, the extract concentration 1,56 %, the mortality effect is 100 %, is with LC90a of 0,628% and dominant chemical contains Evodiamine, Alpinia galanga/ of  / galanga with minimum concentration of 1,56 %, the mortality effects is 29,3% and LC90 8,216 %, LC50 2,980 % and dominant chemical contain flavonoids, Andropogon nardus/ lemongrass with minimum concentration of 1,56% the mortality effect is 68% and LC90 4,898 %, LC50 1,068 % and dominant chemical contain of vetivetate acid, rosemary ( Rosmarinus officinalis L with minimum concentration of 1,56% gives mortality effect 78,7% and LC90 3,175 %, LC50 0,659 %. The dominant contain of the chemical is alkaloid = Pengendalian  nyamuk vektor masih menggunakan bahan insektisida dari golongan piretroid, karbamat, dan organofosfat karena  efektif, cepat diketahui hasilnya, namun kurang memperhitungkan dampak negatif terhadap lingkungan. Oleh sebab itu perlu dicari insektisida alernatif, yaitu insektisida nabati yang ramah lingkungan, mudah diperoleh, efektif membunuh nyamuk dewasa dan pradewasa. Pada penelitian diperoleh hasil Nicotiana tabacum/tembakau konsentrasi ekstrak minimal 1,56%, mampu membunuh larva nyamuk sebesar 100 % dan LC90 0,628 %, LC50 0

  7. Variación en la actividad microbiana por cambio de uso en suelos en sabanas, Llanos Orientales, Venezuela

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    Yrma Gómez

    2011-03-01

    Full Text Available En los llanos orientales de Venezuela la forma tradicional de uso de las sabanas de Trachypogon ha sido el pastoreo extensivo. La presión sobre éstas para obtener una mayor productividad animal ha estimulado la introducción de plantas exóticas para forrajes, tales como: Brachiaria brizantha y Andropogon gayanus. A pesar de que grandes extensiones de sabanas están siendo sometidas a este cambio de uso de la tierra, es escasa la información acerca del efecto que estas pasturas y la actividad de pastoreo tienen sobre la actividad microbiana en el suelo; por lo que el objetivo del presente estudio fue determinar el impacto que el pastoreo extensivo y la substitución de la cobertura nativa tienen sobre la actividad microbiana en estos suelos. El muestreo fue llevado a cabo durante las temporadas de sequía y lluvias. Los parámetros empleados para determinar cambios en la actividad microbiana fueron la respiración inducida por sustrato (RIS, la respiración basal (RB, la actividad de la deshidrogenasa (DHS, la hidrólisis del diacetato de fluorisceína (DAF y la amonificación de la arginina (AA. La similitud de las características estructurales de los suelos estudiados nos permite inferir, que las diferencias en los parámetros microbiológicos, están determinadas por las condiciones climáticas y el manejo del suelo. Los resultados muestran que en estos suelos existe una baja actividad microbiana. La temporada lluviosa provocó un incremento en todos los parámetros microbiológicos determinados. B. brizantha hizo un mayor aporte de carbono al suelo y promovió una mayor actividad heterotrófica. El pastoreo extensivo y la baja carga animal en las sabanas de los llanos orientales de Venezuela no afectaron la actividad microbiana del suelo.Soil microbial activity variation after land use changes in savannah, Llanos Orientales, Venezuela. In West plains of Venezuela, the traditional land use of the Trachypogon savannah, has been the

  8. Riqueza, relevância e estratégias para a conservação de fisionomias campestres do Cerrado no Horto Florestal de Botucatu, SP, Brasil. Richness, relevance and conservation strategies for savanna grasslands in the Horto Florestal of Botucatu, SP, Brazil.

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    Natashi Aparecida Lima PILON

    2017-06-01

    Full Text Available As fitofisionomias campestres e as plantas do estrato herbáceo-arbustivo têm sido pouco estudadas em todo o mundo e, pelo seu desconhecimento, poucos esforços têm sido empreendidos em sua conservação. Visando contribuir para preencher esta lacuna, efetuamos a caracterização florística e do espectro biológico das fisionomias campo sujo e campo limpo úmido em um remanescente de vegetação de Cerrado no Horto Florestal de Botucatu, SP. Registramos, no total, 210 espécies, sendo a maioria ervas (61%, seguidas de arbustos (17% e subarbustos (17%. Espécies arbóreas representam apenas 6% da riqueza da flora local. Apenas 12 espécies foram comuns às duas fisionomias, indicando alta especificidade de habitat (alta diversidade beta. O campo sujo apresentou maior riqueza de espécies e diversidade de formas de vida, mas o número de famílias foi maior no campo úmido. Entre as espécies observadas, seis estão ameaçadas de extinção no estado de SP e no Brasil: Evolvulus fuscus Meisn., Curtia tenuifolia (Aubl. Knobl., Camarea hirsuta A.St-Hil., Andropogon hypogynus Hack., Richardia stellaris (Cham. & Schltdl. Steud. e Xyris brevifolia Michx. Embora a área estudada seja pequena, com 33,88 ha de extensão, sujeita a impactos diversos devido à sua localização na zona urbana do município, a elevada biodiversidade ainda existente nesta rara amostra remanescente das fisionomias campestres de Cerrado no estado de São Paulo fortalece sua relevância para a conservação do bioma e a recomendação de que seja categorizada como Estação Ecológica.Tropical grassy biomes and the small plants forming the ground layer have been rarely assessed in the entire world. Unknown, they have been globally neglected by science and conservation policies. Aiming at filling this gap, we assessed the plant species composition and the biological spectrum of dry and wet grasslands within a small remnant of Cerrado vegetation, in Botucatu, SP, Brazil. We

  9. Coberturas do solo e crescimento da macieira na implantação de um pomar em sistema orgânico de produção Soil coverage and apple tree growth on the establishment of an orchard under organic production system

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    Tânia Regina Pelizza

    2009-09-01

    , pinus sawdust, pinus needle mulch, Andropogon sp mulch, annual ryegrass (Lolium multiflorum, black oat (Avena strigosa, black oat + common vetch (Vicia sativa, black oat + fodder radish (Raphanus sativus, annual ryegrass + white clover (Trifolium repens + spontaneous plant cover, weed mowing. The soil covered by weeds was monthly measured, during the spring/summer season, over the second and third years of the orchard establishment, and this was related to the apple trees growth. The treatments with manual weeding, black plastic film, pinus needle and Andropogon mulch maintained the soil cover by weeds below 20 %. The apple tree height and diameter decreased with the increase of soil cover by weeds, reflecting weeds competition with apple trees.

  10. Diversidad y cuantía de la flora en un pastizal disturbado y pastoreado de forma racional Diversity and quantity of the flora in a disturbed and rationally grazed pastureland

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    R Machado

    2009-09-01

    Full Text Available Con el fin de estudiar los cambios en la diversidad y cuantía de la flora en un pastizal manejado de forma racional y disturbado por la quema, se determinó la composición botánica durante cuatro años y medio, utilizando un marco cuadrado en 20 puntos de cada cuartón. Al concluir el período experimental existió una fuerte hegemonía de las gramíneas y las leguminosas perennes con relación a las especies de otras familias con igual ciclo, tanto en número (22 vs 1 como en área cubierta (92,7 vs 0,004%. Un patrón similar se detectó en las especies anuales, independientemente de la familia. El área cubierta por las gramíneas se incrementó después de la quema y en las leguminosas tendió a disminuir, así como su número (7 vs 4. Panicum maximum cv. Likoni fue la especie predominante, al aumentar de 27,3 a 68,0%; Brachiaria decumbens se incrementó ligeramente (1,0 a 4,6%; mientras que Andropogon gayanus disminuyó (21,4 a 6,0%. Especies adventicias como Dichanthium annulatum, Dichanthium aristatum e Indigofera mucronata incrementaron o mantuvieron poblaciones fluctuantes; otras como Dichanthium caricosum y Centrosema molle disminuyeron; mientras que Acacia farnesiana y Alysicarpus vaginalis tendieron a desaparecer. Se concluye que en estas condiciones se creó una cubierta muy diferente a la que se produjo con un manejo racional intensivo aplicado con anterioridad y se corroboró la importancia del índice de composición de especies para explicar las variaciones que se producen en pastoreo.With the objective of studying the changes in the diversity and quantity of the flora in a pastureland rationally managed and disturbed by burning, the botanical composition was determined during four years and a half, using a square frame in 20 spots of each paddock. By the end of the experimental period there was a strong hegemony of grasses and perennial legumes with regards to the species from other families with equal cycle, in number (22 vs

  11. Intoxicação natural por Brachiaria spp. em ovinos no Brasil Central Brachiaria spp. poisoning in sheep in Central Brazil

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    Vanessa S. Mustafa

    2012-12-01

    Full Text Available Brachiaria spp. é a principal forrageira utilizada para ruminantes no Brasil Central, mas a sua toxicidade, devida à presença de saponinas esteroidais, torna-se um importante entrave à sua utilização. Neste trabalho descrevem-se 34 surtos e um foco de intoxicação por Brachiaria spp em ovinos, que ocorreram em diferentes épocas do ano. A morbidade geral foi de 23,2% e a letalidade foi 88,3%. O tempo que os animais permaneceram no pasto até o surgimento dos sinais clínicos da intoxicação por Brachiaria spp. variou de 15 dias até mais de 12 meses. Em 90,1% dos surtos os animais eram menores de 12 meses de idade. O curso clínico da intoxicação variou de 2 a 45 dias. Os sinais clínicos e as lesões macroscópicas foram características de fotossenssibilização hepatógena, no entanto, nos casos mais agudos não foram observadas dermatite nem icterícia, ocorrendo severo edema em face e orelhas. Na histologia do fígado as lesões mais características foram a presença de macrófagos com citoplasma espumoso, encontrados principalmente nos sinusoides hepáticos e, às vezes, com imagens negativas de cristais acutiformes no citoplasma. Em oito das 11 fazendas visitadas os surtos ocorreram em pastagens de Brachiaria decumbens; em duas em pastagens de B. brizantha e uma em pastagem de B. decumbens, B. humidicola e Andropogon sp. As concentrações de saponinas nas pastagens, em 5 surtos, variou de 0.3% a 2.56%. As informações geradas neste trabalho permitem a proposta de medidas para controle e profilaxia da intoxicação por Brachiaria spp. no Brasil Central.Brachiaria spp. is the main pasture for ruminants in Central-Brazil, but the crucial problem for their utilization is the toxicity due to the presence of steroidal saponins. This paper reports 35 outbreaks of poisoning by Brachiaria spp in sheep. The poisoning occurred in different seasons of the year. Mean morbidity was 23.2% and mean lethality was 88.3%. The occurrence of

  12. CO2, Temperature, and Soil Moisture Interactions Affect NDVI and Reproductive Phenology in Old-Field Plant Communities

    Science.gov (United States)

    Engel, C.; Weltzin, J.; Norby, R.

    2004-12-01

    Plant community composition and ecosystem function may be altered by global atmospheric and climate change, including increased atmospheric [CO2], temperature, and varying precipitation regimes. We are conducting an experiment at Oak Ridge National Laboratory (ORNL) utilizing open-top chambers to administer experimental treatments of elevated CO2 (+300 ppm), warming (+ 3 degrees Celsius), and varying soil moisture availability to experimental plant communities constructed of seven common old-field species, including C3 and C4 grasses, forbs, and legumes. During 2004 we monitored plant community phenology (NDVI) and plant reproductive phenology. Early in the year, NDVI was greater in wet treatment plots, and was unaffected by main effects of temperature or CO2. This result suggests that early in the season warming is insufficient to affect early canopy development. Differences in soil moisture sustained throughout the winter and into early spring may constitute an important control on early canopy greenup. Elevated CO2 alleviated detrimental effects of warming on NDVI, but only early in the season. As ambient temperatures increased, elevated temperatures negatively impacted NDVI only in the dry plots. Wetter conditions ameliorate the effects of warming on canopy greenness during the warmer seasons of the year. Warming increased rates of bolting, number of inflorescences, and time to reproductive maturity for Andropogon virginicus (a C4 bunchgrass). Solidago Canadensis (a C3 late-season forb) also produced flowers earlier in elevated temperatures. Conversely, none of the C3 grasses and forbs that bolt or flower in late spring or early summer responded to temperature or CO2. Results indicate that warming and drought may impact plant community phenology, and plant species reproductive phenology. Clearly community phenology is driven by complex interactions among temperature, water, and CO2 that change throughout the season. Our data stresses the importance of

  13. Resource Utilization by Native and Invasive Earthworms and Their Effects on Soil Carbon and Nitrogen Dynamics in Puerto Rican Soils

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    Ching-Yu Huang

    2016-11-01

    Full Text Available Resource utilization by earthworms affects soil C and N dynamics and further colonization of invasive earthworms. By applying 13C-labeled Tabebuia heterophylla leaves and 15N-labeled Andropogon glomeratus grass, we investigated resource utilization by three earthworm species (invasive endogeic Pontoscolex corethrurus, native anecic Estherella sp, and native endogeic Onychochaeta borincana and their effects on soil C and N dynamics in Puerto Rican soils in a 22-day laboratory experiment. Changes of 13C/C and 15N/N in soils, earthworms, and microbial populations were analyzed to evaluate resource utilization by earthworms and their influences on C and N dynamics. Estherella spp. utilized the 13C-labeled litter; however, its utilization on the 13C-labeled litter reduced when cultivated with P. corethrurus and O. borincana. Both P. corethrurus and O. borincana utilized the 13C-labeled litter and 15C-labeled grass roots and root exudates. Pontoscolex corethrurus facilitated soil respiration by stimulating 13C-labeled microbial activity; however, this effect was suppressed possibly due to the changes in the microbial activities or community when coexisting with O. borincana. Increased soil N mineralization by individual Estherella spp. and O. borincana was reduced in the mixed-species treatments. The rapid population growth of P. corethrurus may increase competition pressure on food resources on the local earthworm community. The relevance of resource availability to the population growth of P. corethrurus and its significance as an invasive species is a topic in need of future research.

  14. Resource-use efficiency explains grassy weed invasion in a low-resource savanna in north Australia

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    Emilie eEns

    2015-08-01

    Full Text Available Comparative studies of plant resource use and ecophysiological traits of invasive and native resident plant species can elucidate mechanisms of invasion success and ecosystem impacts. In the seasonal tropics of north Australia, the alien C4 perennial grass Andropogon gayanus (gamba grass has transformed diverse, mixed tree-grass savanna ecosystems into dense monocultures. To better understand the mechanisms of invasion, we compared resource acquisition and usage efficiency using leaf-scale ecophysiological and stand-scale growth traits of A. gayanus with a co-habiting native C4 perennial grass Alloteropsis semialata. Under wet season conditions, A. gayanus had higher rates of stomatal conductance, assimilation and water use, plus a longer daily assimilation period than the native species A. semialata. Growing season length was also ~2 months longer for the invader. Wet season measures of leaf scale water use efficiency (WUE and light use efficiency (LUE did not differ between the two species, although photosynthetic nitrogen use efficiency (PNUE was significantly higher in A. gayanus. By May (dry season the drought avoiding native species A. semialata had senesced. In contrast, rates of A. gayanus gas exchange was maintained into the dry season, albeit at lower rates that the wet season, but at higher WUE and PNUE, evidence of significant physiological plasticity. High PNUE and leaf 15N isotope values suggested that A. gayanus was also capable of preferential uptake of soil ammonium, with utilisation occurring into the dry season. High PNUE and fire tolerance in an N-limited and highly flammable ecosystem confers a significant competitive advantage over native grass species and a broader niche width. As a result A. gayanus is rapidly spreading across north Australia with significant consequences for biodiversity and carbon and retention.

  15. Production of Cellulosic Polymers from Agricultural Wastes

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    A. U. Israel

    2008-01-01

    Full Text Available Cellulosic polymers namely cellulose, di-and triacetate were produced from fourteen agricultural wastes; Branch and fiber after oil extraction from oil palm (Elais guineensis, raffia, piassava, bamboo pulp, bamboo bark from raphia palm (Raphia hookeri, stem and cob of maize plant (Zea mays, fruit fiber from coconut fruit (Cocos nucifera, sawdusts from cotton tree (Cossypium hirsutum, pear wood (Manilkara obovata, stem of Southern gamba green (Andropogon tectorus, sugarcane baggase (Saccharium officinarum and plantain stem (Musa paradisiaca. They were subjected to soda pulping and hypochlorite bleaching system. Results obtained show that pulp yield from these materials were: 70.00, 39.59, 55.40, 86.00, 84.60, 80.00, 40.84, 81.67, 35.70, 69.11, 4.54, 47.19, 31.70 and 52.44% respectively. The pulps were acetylated with acetic anhydride in ethanoic acid catalyzed by conc. H2SO4 to obtain cellulose derivatives (Cellulose diacetate and triacetate. The cellulose diacetate yields were 41.20, 17.85, 23.13, 20.80, 20.23, 20.00, 39.00, 44.00, 18.80, 20.75, 20.03, 41.20, 44.00, and 39.00% respectively while the results obtained as average of four determinations for cellulose triacetate yields were: 52.00, 51.00, 43.10, 46.60, 49.00, 35.00, 40.60, 54.00, 57.50, 62.52, 35.70. 52.00, 53.00 and 38.70% respectively for all the agricultural wastes utilized. The presence of these cellulose derivatives was confirmed by a solubility test in acetone and chloroform.

  16. The prioritisation of a short list of alien plants for risk analysis within the framework of the Regulation (EU No. 1143/2014

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    Rob Tanner

    2017-06-01

    Full Text Available Thirty-seven alien plant species, pre-identified by horizon scanning exercises were prioritised for pest risk analysis (PRA using a modified version of the EPPO Prioritisation Process designed to be compliant with the EU Regulation 1143/2014. In Stage 1, species were categorised into one of four lists – a Residual List, EU List of Minor Concern, EU Observation List and the EU List of Invasive Alien Plants. Only those species included in the latter proceeded to the risk management stage where their priority for PRA was assessed. Due to medium or high spread potential coupled with high impacts twenty-two species were included in the EU List of Invasive Alien Plants and proceeded to Stage 2. Four species (Ambrosia trifida, Egeria densa, Fallopia baldschuanica and Oxalis pes-caprae were assigned to the EU Observation List due to moderate or low impacts. Albizia lebbeck, Clematis terniflora, Euonymus japonicus, Lonicera morrowii, Prunus campanulata and Rubus rosifolius were assigned to the residual list due to a current lack of information on impacts. Similarly, Cornus sericea and Hydrilla verticillata were assigned to the Residual List due to unclear taxonomy and uncertainty in native status, respectively. Chromolaena odorata, Cryptostegia grandiflora and Sphagneticola trilobata were assigned to the Residual List as it is unlikely they will establish in the Union under current climatic conditions. In the risk management stage, Euonymus fortunei, Ligustrum sinense and Lonicera maackii were considered a low priority for PRA as they do not exhibit invasive tendencies despite being widely cultivated in the EU over several decades. Nineteen species were identified as having a high priority for a PRA (Acacia dealbata, Ambrosia confertiflora, Andropogon virginicus, Cardiospermum grandiflorum, Celastrus orbiculatus, Cinnamomum camphora, Cortaderia jubata, Ehrharta calycina, Gymnocoronis spilanthoides, Hakea sericea, Humulus scandens, Hygrophila polysperma

  17. Método para avaliação da potencialidade ornamental de flores e folhagens de corte nativas e não convencionais.

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    Elisabeth R. Tempel Stumpf

    2007-06-01

    Full Text Available Para garantir o êxito no mercado de novos produtos da Floricultura, é preciso estabelecer critérios objetivos de escolha das características ornamentais desejáveis. Este trabalho tem como objetivo propor e validar um método para a avaliação do potencial ornamental de plantas nativas e não-convencionais, para uso como flores e folhagens de corte. A partir de uma planilha de avaliação especialmente elaborada para tal fim, foi testado o grau de potencialidade ornamental de 11 espécies nativas do Rio Grande do Sul, resultante do somatório das notas dadas para cada uma das dez características escolhidas por sua importância para a arte floral e para o mercado. Para a validação da eficácia do método, foi efetuada uma pesquisa de opinião on line. Andropogon bicornis, Baccharis articulata, B. usterii, Eryngium ebracteatum, E. eriophorum, E. sanguisorba, Hypericum connatum, Limonium brasiliense, Myrsine umbellata, Schinus lentiscifolius e S. terebinthifolius receberam pontuação superior a 70 pontos, sendo categorizadas como de alta potencialidade ornamental. A eficácia da escolha destas espécies com base em atributos estéticos visuais ficou comprovada nos resultados obtidos pela aplicação da planilha e posteriormente validados pela pesquisa de opinião. Os resultados indicam que o método aqui proposto é uma ferramenta eficaz para avaliar o grau de potencialidade ornamental de flores e folhagens de corte nativas e não-convencionais

  18. Allelopathic exudates of cogongrass (Imperata cylindrica): implications for the performance of native pine savanna plant species in the southeastern US.

    Science.gov (United States)

    Hagan, Donald L; Jose, Shibu; Lin, Chung-Ho

    2013-02-01

    We conducted a greenhouse study to assess the effects of cogongrass (Imperata cylindrica) rhizochemicals on a suite of plants native to southeastern US pine savanna ecosystems. Our results indicated a possible allelopathic effect, although it varied by species. A ruderal grass (Andropogon arctatus) and ericaceous shrub (Lyonia ferruginea) were unaffected by irrigation with cogongrass soil "leachate" (relative to leachate from mixed native species), while a mid-successional grass (Aristida stricta Michx. var. beyrichiana) and tree (Pinus elliottii) were negatively affected. For A. stricta, we observed a 35.7 % reduction in aboveground biomass, a 21.9 % reduction in total root length, a 24.6 % reduction in specific root length and a 23.5 % reduction in total mycorrhizal root length, relative to the native leachate treatment. For P. elliottii, there was a 19.5 % reduction in percent mycorrhizal colonization and a 20.1 % reduction in total mycorrhizal root length. Comparisons with a DI water control in year two support the possibility that the treatment effects were due to the negative effects of cogongrass leachate, rather than a facilitative effect from the mixed natives. Chemical analyses identified 12 putative allelopathic compounds (mostly phenolics) in cogongrass leachate. The concentrations of most compounds were significantly lower, if they were present at all, in the native leachate. One compound was an alkaloid with a speculated structure of hexadecahydro-1-azachrysen-8-yl ester (C23H33NO4). This compound was not found in the native leachate. We hypothesize that the observed treatment effects may be attributable, at least partially, to these qualitative and quantitative differences in leachate chemistry.

  19. Temperaturas cardinales de desarrollo en la etapa siembra- emergencia de 11 pastos forrajeros

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    Noé Durán Puga

    2011-01-01

    Full Text Available Los objetivos del presente estudio fueron determinar las temperaturas cardinales de desarrollo (temperatura umbral mínima Tb, temperatura óptima To y temperatura umbral máxima Tu, e identificar un método que estime con precisión los requerimientos térmicos para la etapa siembra-emergencia (E de 11 pastos forrajeros. Ciento veinte (120 semillas de cada uno se sembraron en recipientes en condiciones controladas con un diseño experimental completamente al azar y tres repeticiones a temperaturas constantes de 15 hasta 46 ºC, en cámaras de ambiente controlado del Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias (INIFAP en Guadalajara, Jalisco, México. Las temperaturas cardinales y requerimiento térmico se estimaron mediante el método bilineal (MB y el método curvilíneo (MC, se evaluó su ajuste mediante comparación directa con los valores de desarrollo observados en ambiente controlado y coeficiente de variación de la duración de E expresada en términos de unidades calor acumuladas (UCA. Los resultados mostraron que el MB fue mejor para estimar Tb y To, y el MC fue mejor para estimar Tu. Los valores de Tb, To, Tu y UCA, fueron, Lolium perenne 9, 31, 41, 80, Festuca arundinacea 10, 31, 41, 78, Hyparrhenia rufa 12, 32, 42, 62, Eragrostis curvula 13, 32, 47, 40, Chloris gayana 13, 31, 47, 40, Melinis minutiflora 13, 31, 43, 50, Pennisetum clandestinum 12, 32, 43, 65, Brachiaria mutica 14, 32, 43, 57, Andropogon gayanus 12, 37, 48, 66, Cynodon dactylon 14, 29, 44, 48, Pennicetum ciliare 13, 30, 42, 61.

  20. Controle de Meloidogyne javanica em mudas de bananeira 'prata-anã' por compostos orgânicos

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    Bruna Hanielle Carneiro dos Santos

    2013-06-01

    Full Text Available O trabalho teve como objetivo avaliar o efeito de compostos orgânicos no controle de Meloidogyne javanica, e no desenvolvimento de mudas de bananeiras 'Prata-Anã. O experimento foi conduzido em DIC, com dez repetições, e os tratamentos consistiram em quatro compostos constituídos de diferentes matérias-primas (restos da cultura da banana, cana-de-açúcar, esterco bovino, cascas de banana, plantas daninhas, capim andropogon, o esterco bovino, a torta de mamona e testemunhas (adubação mineral, carbofuran e testemunha absoluta (sem adição de composto orgânico. Em cada vaso, foram colocados 3 kg de solo autoclavado, incorporado com cada um dos tratamentos avaliados e inoculado com suspensão contendo 4.000 ovos de M. javanica. Após quatro dias, transplantou-se uma muda de bananeira 'Prata-Anã' micropropagada, e aos 60 dias, avaliaram-se: altura das plantas, diâmetro, número de folhas e peso de matéria seca da parte aérea, e número de galhas, massas de ovos, número de ovos e o número de juvenis de segundo estádio (J2, por 100 cm³ de solo. Testou-se in vitro o efeito das frações húmicas dos quatro compostos (que não causaram fitotoxidez e esterco bovino sobre a mortalidade e motilidade de J2 de M. javanica. O ensaio foi montado em placas de ELISA em DIC, com cinco repetições. Os compostos orgânicos e o esterco bovino aumentaram o desenvolvimento das mudas. A torta de mamona provocou efeito fitotóxico às mudas. Menor número de variáveis nematológicas foi proporcionado pela torta de mamona e pelo carbofuran. O número de J2 também foi menor nas parcelas tratadas com carbofuran e também pelo Composto 3, constituído por plantas daninhas+restos de cana-de-açúcar+ esterco bovino e pelo adubo mineral. Para o teste in vitro, as substâncias húmicas conferiram efeito nematicida e nematostático. Dentre os compostos, o C3 mostrou-se promissor por reduzir o desenvolvimento do nematoides e não apresentar efeito fitotóxico.

  1. Growth performance of goats supplemented with Mucuna pruriens in North Cameroon

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    E. Pamo Tendonkeng

    2010-01-01

    Full Text Available The influence of the level of supplementation with Mucuna pruriens on growth performances of West African Dwarf bucks and digestibility of the rations during the dry season in North Cameroon was studied at the Institute of Agricultural Research for Development polyvalent station of Garoua between November 2004 and July 2005. A total of 24 West African Dwarf male goats were divided into three groups of eight bucks each, fed with a basal diet made up of Andropogon gayanus and Ficus sycomorus, and supplemented with 0, 100 and 150 g of M. pruriens. The evaluation of the live weight, average daily weight gain and body condition score was carried out every 14 days during 90 days. At the end of this phase, the evaluation of carcass weight and yield was carried out on two slaughtered bucks per group. Then, nine goats were divided into three groups of three animals, and each group was subjected to one of the three above treatments in order to study the influence of the level of supplementation of M. pruriens on the digestibility of the basal diet. The results showed that, in absence of M. pruriens in the ration, the live weight, the average daily weight gain and the body condition score were 10.44 kg, - 10 g and 1.87, respectively. With 100 g of M. pruriens in the ration, the live weight, the average daily weight gain and the body condition score were 12.16 kg, 9 g and 2.94, whereas it was 12.98 kg, 18 g and 3.56, respectively, with a ration containing 150 g of M. pruriens. The carcass weight and yield, and the weight at slaughter increased significantly (P < 0.05 with the increase of the level of M. pruriens in the ration. The apparent digestibility of the organic matter was 45.25, 62.34 and 70.97%, respectively, with the rations containing 0, 100 and 150 g of M. pruriens. The nitrogen digestibility was 38.46, 55.29 and 60.95%, respectively, with the same ration. It appears that the supplementation of the rations with M. pruriens during the dry season

  2. Variación en la actividad microbiana por cambio de uso en suelos en sabanas, Llanos Orientales, Venezuela

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    Yrma Gómez

    2011-03-01

    Full Text Available En los llanos orientales de Venezuela la forma tradicional de uso de las sabanas de Trachypogon ha sido el pastoreo extensivo. La presión sobre éstas para obtener una mayor productividad animal ha estimulado la introducción de plantas exóticas para forrajes, tales como: Brachiaria brizantha y Andropogon gayanus. A pesar de que grandes extensiones de sabanas están siendo sometidas a este cambio de uso de la tierra, es escasa la información acerca del efecto que estas pasturas y la actividad de pastoreo tienen sobre la actividad microbiana en el suelo; por lo que el objetivo del presente estudio fue determinar el impacto que el pastoreo extensivo y la substitución de la cobertura nativa tienen sobre la actividad microbiana en estos suelos. El muestreo fue llevado a cabo durante las temporadas de sequía y lluvias. Los parámetros empleados para determinar cambios en la actividad microbiana fueron la respiración inducida por sustrato (RIS, la respiración basal (RB, la actividad de la deshidrogenasa (DHS, la hidrólisis del diacetato de fluorisceína (DAF y la amonificación de la arginina (AA. La similitud de las características estructurales de los suelos estudiados nos permite inferir, que las diferencias en los parámetros microbiológicos, están determinadas por las condiciones climáticas y el manejo del suelo. Los resultados muestran que en estos suelos existe una baja actividad microbiana. La temporada lluviosa provocó un incremento en todos los parámetros microbiológicos determinados. B. brizantha hizo un mayor aporte de carbono al suelo y promovió una mayor actividad heterotrófica. El pastoreo extensivo y la baja carga animal en las sabanas de los llanos orientales de Venezuela no afectaron la actividad microbiana del suelo.

  3. Fungos micorrízicos arbusculares em fitofisionomias do Pantanal da Nhecolândia, Mato Grosso do Sul

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    Plínio Henrique Oliveira Gomide

    2014-08-01

    Full Text Available O bioma Pantanal é reconhecido como uma das maiores extensões úmidas contínua do planeta, com fauna e flora de rara beleza e abundância. Estudos para acessar a diversidade de fungos micorrízicos arbusculares (FMA nesse ambiente são inexistentes. O objetivo deste trabalho foi avaliar a ocorrência de FMA nas diferentes fitofisionomias do Pantanal da Nhecolândia, Mato Grosso do Sul. Foram coletadas amostras de solo no período seco e chuvoso em um Neossolo Quartzarênico, em fitofisionomias sujeitas a distintos regimes de inundação: livres de inundação - Floresta Semidecídua (FS e Cerradão (CE; sujeitos à inundação ocasional - Campo limpo, predominando Elyonorus muticus (CLE e Cerrado (CC; e sujeitos à inundação sazonal - Campo limpo, predominando Andropogon spp. (CLA, borda de baias (BB e vazante/baixadas (VB. Culturas armadilhas foram estabelecidas com Brachiaria brizantha para recuperar espécies crípticas de FMA. De cada amostra de solo, foram realizadas a caracterização química do solo e extração dos esporos de FMA para determinar abundância, riqueza e identificação das espécies. Um total de 37 espécies de FMA, pertencentes a 10 gêneros e seis famílias foram detectadas nas duas estações de coleta. O número de esporos variou significativamente entre as fitofisionomias, e os maiores valores foram encontrados em CE e CLA. A maior riqueza específica foi detectada em CC (25 espécies seguida de VB e CE com 22 e 21 espécies, respectivamente. Os resultados deste estudo sugeriram que a diversidade dos FMA está relacionada com a heterogeneidade existente entre as fitofisionomias, e que características químicas do solo têm influência na estruturação das comunidades desses fungos. Considerando que o bioma Pantanal é um dos ecossistemas mais conservado do planeta, o levantamento de ocorrência de FMA realizado neste trabalho forneceu informações importantes para melhor conhecimento da biodiversidade das

  4. Macroaggregation and soil organic carbon restoration in a highly weathered Brazilian Oxisol after two decades under no-till.

    Science.gov (United States)

    de Oliveira Ferreira, Ademir; de Moraes Sá, João Carlos; Lal, Rattan; Tivet, Florent; Briedis, Clever; Inagaki, Thiago Massao; Gonçalves, Daniel Ruiz Potma; Romaniw, Jucimare

    2018-04-15

    Conclusions based on studies of the impacts of soil organic carbon (SOC) fractions and soil texture on macroaggregation and SOC stabilization in long-term (>20years) no-till (NT) fields remain debatable. This study was based on the hypothesis that the amount and frequency of biomass-C input associated with NT can be a pathway to formation of macroaggregates and to SOC buildup. The objectives were to: 1) assess the macroaggregate distribution (proportional mass, class mass) and the SOC and particulate organic carbon (POC) stocks of extra-large (8-19mm), large (2-8mm) and small (0.25-2mm) macroaggregate size classes managed for two decades by NT, and 2) assess the recovery of SOC stocks in extra-large macroaggregates compared to adjacent native vegetation (Andropogon sp., Aristida sp., Paspalum sp., and Panicum sp.). The crop rotation systems were: soybean (Glycine max L.), maize (Zea mays L.) and beans (Phaseolus vulgaris L.) in summer; and black oat (Avena strigosa Schreb), white oat (Avena sativa), vetch (Vicia sativa L.), black oat.+vetch (Avena strigosa Schreb+vetch) and wheat (Triticum aestivum L.) in winter. The experimental was laid out as 2×2 randomized block factorial with 12 replicates of a NT experiment established in 1997 on two highly weathered Oxisols. The factors comprised of: (a) two soil textural types: clay loam and sandy clay, and (b) two sampling depths: 0-5 and 5-20cm. The three classes of macroaggregates were obtained by wet sieving, and the SOC content was determined by the dry combustion method. The extra-large macroaggregate classes in 0-20cm depth for sandy clay (SdC) and clay loam (CL) Oxisol represented 75.2 and 72.4% of proportional mass, respectively. The SOC and POC stocks among macroaggregate classes in 0-5 and 5-20cm depths decreased in the order: 8-19mm>2-8mm ≈ 0.25-2mm. The SdC plots under soybean/maize at 3:1 ratio recovered 58.3%, while those at 1:1 ratio (high maize frequency) in CL recovered 73.1% of SOC stock in the extra

  5. Seasonal change in CO2 and H2O exchange between grassland and atmosphere

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    T. Oikawa

    Full Text Available The seasonal change in CO2 flux over an artificial grassland was analyzed from the ecological and meteorological point of view. This grassland contains C3 and C4 plants; the three dominant species belonging to the Gramineae; Festuca elatior (C3 dominated in early spring, and Imperata cylindrica (C4 and Andropogon virginicus (C4 grew during early summer and became dominant in mid-summer. CO2 flux was measured by the gradient method, and the routinely observed data for the surface-heat budget were used to analyze the CO2 and H2O exchange between the grassland and atmosphere. From August to October in 1993, CO2 flux was reduced to around half under the same solar-radiation conditions, while H2O flux decreased 20% during the same period. The monthly values of water use efficiency, i.e., ratio of CO2 flux to H2O flux decreased from 5.8 to 3.3 mg CO2/g H2O from August to October, the Bowen ratio increased from 0.20 to 0.30, and the ratio of the bulk latent heat transfer coefficient CE to the sensible heat transfer coefficient CH was maintained around 0.40-0.50. The increase in the Bowen ratio was explained by the decrease in air temperature from 22.3 °C in August to 16.6 °C in October without considering biological effects such as stomatal closure on the individual leaves. The nearly constant CE/CH ratios suggested that the contribution ratio of canopy resistance to aerodynamic resistance did not change markedly, although the meteorological conditions changed seasonally. The decrease in the water use efficiency, however, suggested that the photosynthetic rate decreased for individual leaves from August to October under the same radiation conditions. Diurnal variations of CO2 exchange were simulated by the multi-layer canopy model taking into account the differences in the stomatal conductance and photosynthetic pathway between C3 and C4 plants. The results suggested that C4 plants played a major role in the CO2 exchange in August, the contribution

  6. Seasonal change in CO2 and H2O exchange between grassland and atmosphere

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    N. Saigusa

    1996-03-01

    Full Text Available The seasonal change in CO2 flux over an artificial grassland was analyzed from the ecological and meteorological point of view. This grassland contains C3 and C4 plants; the three dominant species belonging to the Gramineae; Festuca elatior (C3 dominated in early spring, and Imperata cylindrica (C4 and Andropogon virginicus (C4 grew during early summer and became dominant in mid-summer. CO2 flux was measured by the gradient method, and the routinely observed data for the surface-heat budget were used to analyze the CO2 and H2O exchange between the grassland and atmosphere. From August to October in 1993, CO2 flux was reduced to around half under the same solar-radiation conditions, while H2O flux decreased 20% during the same period. The monthly values of water use efficiency, i.e., ratio of CO2 flux to H2O flux decreased from 5.8 to 3.3 mg CO2/g H2O from August to October, the Bowen ratio increased from 0.20 to 0.30, and the ratio of the bulk latent heat transfer coefficient CE to the sensible heat transfer coefficient CH was maintained around 0.40-0.50. The increase in the Bowen ratio was explained by the decrease in air temperature from 22.3 °C in August to 16.6 °C in October without considering biological effects such as stomatal closure on the individual leaves. The nearly constant CE/CH ratios suggested that the contribution ratio of canopy resistance to aerodynamic resistance did not change markedly, although the meteorological conditions changed seasonally. The decrease in the water use efficiency, however, suggested that the photosynthetic rate decreased for individual leaves from August to October under the same radiation conditions. Diurnal variations of CO2 exchange were simulated by the multi-layer canopy model taking into account the differences in the stomatal conductance and photosynthetic pathway between C3 and C4 plants. The results suggested that C4 plants played a major role in the CO2 exchange in August, the contribution

  7. Seasonal change in CO2 and H2O exchange between grassland and atmosphere

    Science.gov (United States)

    Saigusa, N.; Liu, S.; Oikawa, T.; Watanabe, T.

    1996-03-01

    The seasonal change in CO2 flux over an artificial grassland was analyzed from the ecological and meteorological point of view. This grassland contains C3 and C4 plants; the three dominant species belonging to the Gramineae; Festuca elatior (C3) dominated in early spring, and Imperata cylindrica (C4) and Andropogon virginicus (C4) grew during early summer and became dominant in mid-summer. CO2 flux was measured by the gradient method, and the routinely observed data for the surface-heat budget were used to analyze the CO2 and H2O exchange between the grassland and atmosphere. From August to October in 1993, CO2 flux was reduced to around half under the same solar-radiation conditions, while H2O flux decreased 20% during the same period. The monthly values of water use efficiency, i.e., ratio of CO2 flux to H2O flux decreased from 5.8 to 3.3 mg CO2/g H2O from August to October, the Bowen ratio increased from 0.20 to 0.30, and the ratio of the bulk latent heat transfer coefficient CE to the sensible heat transfer coefficient CH was maintained around 0.40-0.50. The increase in the Bowen ratio was explained by the decrease in air temperature from 22.3 °C in August to 16.6 °C in October without considering biological effects such as stomatal closure on the individual leaves. The nearly constant CE/CH ratios suggested that the contribution ratio of canopy resistance to aerodynamic resistance did not change markedly, although the meteorological conditions changed seasonally. The decrease in the water use efficiency, however, suggested that the photosynthetic rate decreased for individual leaves from August to October under the same radiation conditions. Diurnal variations of CO2 exchange were simulated by the multi-layer canopy model taking into account the differences in the stomatal conductance and photosynthetic pathway between C3 and C4 plants. The results suggested that C4 plants played a major role in the CO2 exchange in August, the contribution of C4 plants

  8. Influence of tropical leaf litter on nitrogen mineralization and community structure of ammonia-oxidizing bacteria

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    Diallo, MD.

    2015-01-01

    Full Text Available Description of the subject. The present study concerns the relationships among leaf litter decomposition, substrate quality, ammonia-oxidizing bacteria (AOB community composition and nitrogen (N availability. Decomposition of organic matter affects the biogeochemical cycling of carbon (C and N. Since the composition of the soil microbial community can alter the physiological capacity of the community, it is timely to study the litter quality effect on N dynamic in ecosystems. Objectives. The aim of this study was to determine the influence of leaf litter decomposition on N mineralization. The specific objectives of this study were to evaluate the influence of the litter biochemistry of five plants species (Faidherbia albida A.Chev., Azadirachta indica A.Juss., Casuarina equisetifolia L., Andropogon gayanus Kunth and Eragrostis tremula Hochst. ex Steud. on N mineralization in a tropical ferrous soil (Lixisol, nitrification, and genetic diversity of ammonia-oxidizing bacteria. Denaturing gradient gel electrophoresis (DGGE of amplified fragments of genes coding for 16S rRNA was used to study the development of bacterial communities during decomposition of leaf litter in soils. Method. Community structure of AOB was determined at two time periods: day 0 and day 140. Ten strains were tested and each of these strains produced a single band. Thus, DGGE DNA band patterns were used to estimate bacterial diversity. Plant secondary compounds such as polyphenols are purported to influence nutrient cycling by affecting organic matter degradation, mineralization rates, N availability and humus formation. In a laboratory study, we investigated the influence of six phenolic acids (ferulic, gallic, vanillic, syringic, p-coumaric and p-HBA acids commonly found in the plant residues on N mineralization and NH4+ and NO3- production in soils. Results. The results showed that litter type did affect soil nitrification. Faidherbia albida litter was associated with

  9. Carbono, nitrogênio e enxofre em frações granulométricas de dois latossolos submetidos à calagem e adubação fosfatada

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    C. A. Silva

    1999-09-01

    Full Text Available Os teores e a distribuição de carbono, nitrogênio e enxofre em frações granulométricas do solo foram analisados em dois Latossolos Vermelho-Escuros, um derivado de floresta (LE1 e outro de cerrado (LE2. O LE1, de Cordeirópolis, SP, corresponde a um solo cultivado com laranja desde 1982, sem e com calagem. O cultivo do LE2 (Planaltina, DF foi iniciado em 1976, com o plantio de trigo, soja, arroz e sorgo, sendo esse solo cultivado nos últimos 14 anos com pastagem (Andropogon gayanus L., sem e com uma única aplicação de 1.660 kg ha-1 de P2O5, na forma de superfosfato triplo. Para fins de referência, foram coletadas amostras adicionais do LE1 e LE2 em áreas sob vegetação natural. Foram determinados os teores de carbono, nitrogênio e enxofre em solo não fracionado e em suas frações granulométricas. A drástica redução nos teores de carbono, nitrogênio e enxofre do LE1 com o cultivo resultou em diminuição da CTC na área sob calagem e na testemunha, indicando a importância do manejo e conservação da matéria orgânica nesse solo. No LE2, a redução nos teores de carbono e nitrogênio com o cultivo foi menos intensa e associou-se à decomposição de compostos orgânicos ligados à fração intermediária (2-53 mm. A calagem resultou em maior preservação de matéria orgânica no LE1; não houve, porém, efeito do fósforo sobre os teores de C e N das áreas cultivadas do LE2. A fração fina (< 2 μm exerceu papel crucial na estabilização da matéria orgânica nos solos estudados, já que os maiores reservatórios de carbono, nitrogênio e enxofre nas áreas cultivadas e sob vegetação natural encontravam-se associados a essa unidade granulométrica. Os principais efeitos do cultivo sobre os reservatórios de carbono, nitrogênio e enxofre do LE1 estiveram associados ao enriquecimento relativo desses elementos na fração fina, às custas da decomposição de material orgânico associado às frações fina: (< 2

  10. CATÁLOGO DE LA FAMILIA POACEAE EN COLOMBIA

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    Diego Giraldo-Cañas

    2011-01-01

    Full Text Available Se presenta un inventario de las especies de Poaceae de Colombia junto con un análisis de la diversidad específica de esta familia según las regiones naturales colombianas, los gradientes de altitud y de precipitaciones, y la distribución sistemática. Se realizaron 96 expediciones de campo a las diez grandes regiones naturales de Colombia (Amazonia, Andes, Caribe, Chocó Biogeográfico, Guayana, islas caribeñas, Orinoquia, Sierra Nevada de Santa Marta, valle del río Cauca y valle del río Magdalena con un muestreo total de alrededor de 5800 ejemplares. Además, se consultaron colecciones de los herbarios CAUP, COAH, COL, CUVC, CHOCO, HFAB, HUA, HUQ, JAUM, MEDEL, MEXU, MO, NY, PSO, RSA, SI, UDBC, UIS, US, VALLE y VEN, y se realizó una investigación bibliográfica exhaustiva. Las Poaceae están representadas en Colombia por 840 especies y 173 géneros. Se reconocieron 74 especies y un género (Agrostopoa endémicos. Por otra parte, se documentaron 83 especies introducidas-naturalizadas y 50 introducidas-cultivadas. Los géneros más ricos en especies son Paspalum (89 especies, Panicum (42, Festuca (36, Eragrostis (29, Calamagrostis (25, Chusquea (25, Digitaria (24, Axonopus (21, Setaria (20, Cenchrus (18, Poa (17, Muhlenbergia (16, Andropogon (15, Aristida (15, Agrostis (14, Lasiacis (12, Urochloa (12, Pariana (11, Sporobolus (11, Arthrostylidium (10, Cortaderia (10, Nassella (10, Neurolepis (10 y Schizachyrium (10. Durante el desarrollo de esta investigación, se descubrieron 10 nuevos registros para la flora colombiana. La regiones Andina, Orinocense, Caribe y Guayanesa son las más ricas en especies, con 583, 233, 186 y 179 especies, respectivamente. La Región Andina presenta el mayor número de especies endémicas (57 especies. Los gradientes altitudinales más diversos corresponden a los de las tierras bajas (por debajo de 1200 m s.m.. Al igual que en otras áreas tropicales, en Colombia las subfamilias de Poaceae muestran una

  11. Metais pesados, densidade e atividade microbiana em solo contaminado por rejeitos de indústria de zinco

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    H. E. Dias-Júnior

    1998-12-01

    Full Text Available As atividades relacionadas com mineração e indústria metalúrgica são responsáveis pela poluição de extensas áreas de solo em todo o mundo, sendo seus efeitos ainda pouco conhecidos nas condições brasileiras. No presente trabalho, os teores totais e solúveis em água de metais pesados, a densidade e a atividade microbiana foram avaliados em 1996, em sete locais de uma área de deposição de rejeitos da industrialização de zinco, em elevado estádio de degradação, e num local fora da área contaminada, considerado como referência, no estado de Minas Gerais. Todos os locais contaminados apresentaram elevados teores de metais pesados totais e solúveis em água, atingindo, respectivamente, os seguintes valores máximos, em mg kg-1: 11.969 e 726 de Zn; 109 e 18 de Cd; 1.016 e 0 de Pb e 887 e 8 de Cu. Todas as características biológicas avaliadas foram afetadas pelos elevados teores de metais com exceção do número de amonificadores. O C-biomassa apresentou redução acima de 80% em quatro locais contaminados em relação ao local fora da área contaminada. A respiração basal do solo foi maior no local contaminado coberto com Andropogon sp. e menor nos sítios sem vegetação. O número de actinomicetos e de fungos cultiváveis foi menos afetado pela contaminação que o número total de bactérias. Azospirillum spp. foram detectados apenas no local de referência. Oxidantes de amônio foram verificados em somente dois locais que continham vegetação, enquanto os oxidantes de nitrito foram detectados na maioria dos locais amostrados. Verificou-se a tendência de maior densidade e atividade microbiana nos locais contaminados e com algum tipo de vegetação. A concentração total e solúvel de Zn, de Cd e de Cu correlacionou-se fracamente com as características biológicas, exceto para o qCO2, o qual se mostrou promissor como indicador da contaminação com esses metais. Os dados indicaram uma interação qu

  12. Young calves production in native, mixed or cultivated pastures in the Pantanal, Mato Grosso do Sul, Brazil Produção de bezerros jovens em pastagens nativas, mistas ou cultivadas no Pantanal Sul Mato-Grossense

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    Alexandre Menezes Dias

    2008-09-01

    Full Text Available The productive performance of 8, 9 and 10 month old calves raised, in pastures in the sub-area Nhecolândia.,was evaluated, in Pantanal, Mato Grosso do Sul, Brazil, for young calves slaughter. Fifty four calves were used, 27 males and 27 females in a randomized block, with a 3x3 factorial design (three pastures and three slaughter ages. The pastures were 1-native grass pasture, composed by Axonopus purpusii, Andropogon bicornis and Elyonurus muticus, 2-cultivated pasture, composed by Brachiaria decumbens and B. humidicula, and 3-mixed, composed by native grass and cultivated pasture. There was significant interaction (P<.05 between slaughter age and pasture type. The animals with 8 and 10 months old that grew on mixed pastures presented higher slaughter weight (SW, higher average daily gain (ADG and carcass weight (CW, compared to animals in native or cultivated pastures. Animals in mixed pasture and slaughtered with 8 months old presented ADG of 0.83 kg/day, while animals maintained in native and cultivated pastures presented 0.65 and 0.59kg/day, respectively. For animals slaughtered with 9 months old, ADG were 0.55; 0.61 and 0.64 kg/day; and, for those slaughtered with 10 months, the averages were 0.48; 0.73 and 0.51kg/day, respectively, for native, mixed and cultivated pastures. The carcass yield was not influenced by slaughter age, for native and mixed pastures. There was not significant sex effect for any of the evaluated variables. The slaughter of male or female calves, raised in mixed or cultivated pastures, between 8 and 10 months old, is recommended for veal production.Avaliou-se o desempenho produtivo de bezerros abatidos aos oito, nove e dez meses de idade, criados em pastagens no Pantanal Sul mato-grossense, visando o abate de bezerros jovens. Utilizaram-se 54 bezerros, sendo 27 machos e 27 fêmeas provenientes da sub-região pantaneira Nhecolândia. O delineamento experimental foi em blocos casualizados por sexo, em esquema

  13. An Ecological Friendly Dragee Technic Application on Crop Seeds

    Science.gov (United States)

    László, M.

    2009-04-01

    Summary: In Brazíl, in EMBRAPA/CNPH was developing a dragée technic for seeds of crops and vegetables of carrot (Daucus carota L.), onion (Allium cepa L.), tomato (Lycopersicum esculentum Mill.), lettuce (Lactuca sativa L.), micro tubers of potato (Solanum tuberosum L.), Andropogon ssp. and Eucalyptus ssp. using as inert material the dolomite (CaCO3 96%) powder fractions (0.05 to 1.00 mm) and as cementing adhesives the polyvinyl acetate (PVA) and Gumma arabicum (Ga) (0 to 80% in water). On dragée process were using fungicides with agent of metalaxyl, iprodyon, benomyl, mankoceb (1 to 5 g fungicide/kg dolomite powder) and nutrients (N, P2O5, K2O 0.05 to 0.5, MgO, Fe, Zn, Mn, B, Cu, Mo, Co 0.000005 to 0.1 g/ kg dolomite powder) were applied from 1990. to 1993. Best results obtained with fraction of dolomite powder of 0.07 to 0.60 mm of diameter and adhesive of polyvinyl acetate (PVA) with the concentration between 10 to 20%. The dragées obtained presented a mechanical resistance of 0.5 kg/cm2 had show a germination higher than 90% without any phytotoxical effects to the seedlings. Fungicides with agent of metalaxyl, iprodyon, benomyl, mankoceb with the concentration 3-3 and mineral nutrients N, P2O5, K2O, MgO, Fe, Zn, Mn, B, Cu, Mo, Co with the concentration 0.2, 0.1, 0.15, 0.06, 0.00045, 0.00025, 0.0011, 0.00057, 0.00045, 0.000084, 0.00001 g/kg dolomite powder were showed best reultes, respectively. With this dragée utilization we could make possible the intensive use of highest quality seeds wich because of their higher costs are prohibitive in the actual systems of production. Keywords:crops, vegetables, seeds, dragée, nutrients, fungicides Introduction: In Latin America, Brazíl is the far greatest producer of crops and vegetables, with an annual production estimated at 9.631.000 tons in the value of 1.576 million dollars. Fifty species are cultivated of which 35 are producing botanical seeds including 162 varieties commercialized. The average national

  14. Threatened and Endangered Species Survey for Patrick Air Force Base, Florida

    Science.gov (United States)

    Oddy, Donna M.; Stolen, Eric D.; Schmalzer, Paul A.; Larson, Vickie L.; Hall, Patrice; Hensley, Melissa A.

    1997-01-01

    A review of previous environmental work conducted at Patrick Air Force Base (PAFB) indicated that several threatened, endangered, or species of special concern occurred or had the potential to occur there. This study was implemented to collect more information on protected species at PAFB. A map of landcover types was prepared for PAFB using aerial photography, groundtruthing, and a geographic information system (GIS). Herbaceous vegetation was the most common vegetation type. The second most abundant vegetation type was disturbed shrubs/exotics. The beach and associated dune vegetation comprised 3.2% of the land area, but was the most extensive natural community within PAFB. A few isolated mangrove communities exist along the Banana River. Seventy-seven species of vascular plants occurred on the dunes, including four species listed by state agencies: spider lily (Hymenocallis latifolia), prickly pear cactus (Opuntia stricta), beach star (Remirea maritima), and inkberry (Scaevola plumien). Surveys of other habitats revealed eighty-four species of vascular plants including two state-listed species: spider lily and prickly pear cactus. Many of these areas are dominated by invasive, exotic species, particularly Brazilian pepper (Schinus terebinthifolius) and Australian pine (Casuarina equisetifolia), and native species of open or disturbed sites such as camphorweed (Heterotheca subaxillaris) and beardgrass (Andropogon spp.). Due to the isolation of PAFB from other natural areas, most exotic plant populations on the base are not an immediate threat to intact native plant communities. Dune habitat was surveyed for the southeastem beach mouse (Peromyscus polionotus niveiventris) by quarterly trapping along eight 100 m transects. No beach mice were found. The limited extent of dune habitat, its fragmented condition, and the isolation of PAFB from extant populations of the beach mouse probably accounts for its absence. Surveys of birds on PAFB found an avifauna

  15. Desempenho ponderal, aspectos econômicos, nutricionais e clínicos de caprinos submetidos a dois esquemas de suplementação mineral Daily weight gain, economic, nutritional and clinical aspects of goats receiving two types of mineral supplements

    Directory of Open Access Journals (Sweden)

    Pedro Malafaia

    2004-03-01

    maiores e, em relação à ingestão de fósforo, apenas o consumo da ração concentrada foi suficiente para suprir os requerimentos dos dois grupos de animais. As exigências de zinco foram supridas pela ingestão da ração e do volumoso. Além dos cálculos sobre o consumo de fósforo, cálcio, cobalto e zinco demonstrarem que as exigências desses minerais foram totalmente atendidas apenas com a ingestão da ração concentrada e do volumoso; clinicamente os animais não apresentaram quaisquer sinais diretos ou indiretos de deficiência desses elementos. Esses fatos reforçam a hipótese de que quando os animais são alimentados com rações concentradas e volumosos de boa qualidade, poucos serão os elementos minerais a serem supridos - especificamente, neste sistema de criação desta região, apenas o sódio e o cobre. Os resultados desse estudo endossam a idéia de que a suplementação seletiva, conceito que significa fornecer apenas os elementos minerais que efetivamente estão em falta na dieta dos animais, está correta, e implica em marcada redução nos custos com a suplementação mineral do rebanho.Daily weight gain, economic, nutritional and clinical aspects of goats receiving two types of mineral supplements were evaluated during 148 days in Seropédica county, Rio de Janeiro, Brazil. The animals were daily fed with fresh and chopped Andropogon gayanus or Pennisetum purpureum; the concentrate ration was formulated without a mineral mixture and was offered together with the forage of 300 up to 500 g/animal/day. Sixteen goats were divided into two groups of 8 animals each (4 small and 4 larger goats. For one group a commercial mineral mixture was used, and to the other group a selective mineral mixture containing only Na, P and Cu was offered. The animals were weighed every 30 days and the mineral supplement intake was measured monthly. Blood samples were collected at the beginning and the end of the experimental period. There was no difference in daily