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[fr] Ces dernières décades les changements subis dans la région Méditerranéenne ont affecté la diversité végétale dont les variations affectent aussi le fonctionnement des écosystèmes. Ainsi des la fin du siècle dernier les peuplements de châtaigniers ont été abandonnés. Notre objectif était d'analyser les conséquences sur la diversité végétale de différents traitements dans deux châtaigneraies méditerranéennes des Cévennes (France) et de l'Etna en Italie. Les résultats indiquent qu'il y a peu d'espèces communes aux deux zones d'étude; environ 9%. Ces différences peuvent être justifiées par les facteurs écologiques (climat; sol; etc.) mais aussi par les différences de traitement (plantation pour le fruit et bosquets pour le bois en Cévennes; bosquets pour le bois à l'Etna) et les caractéristiques du peuplement (densité des pousses; diamètre à 1 m du sol; etc.). Ainsi la diversité végétale est plus haute dans les plantations régulières -exploitées pour le fruit- que dans les bosquets exploités pour le bois. Nous avons également montré que les plantations régulières étaient caractérisées par des petites espèces annuelles héliophiles. Par contre; les plantations abandonnées et les jeunes bosquets étaient caractérisés par des hémicriptophytes anémochores et par des chamaephytes. En plus; les parcelles constituées par bosquets d'âge moyen ou âgés -pour le bois- étaient caractérisées par des phanérophytes à dispersion zoochore. Une conséquence générale de l'abandon des cultures de châtaignier est l'homogénéisation de la végétation et la diminution de la diversité végétale. Pour surmonter cette situation une solution pourrait être le maintien d'un paysage en mosaïque formé par sous-parcelles diversement influencées par l'homme (plantations cultivées ou abandonnées; bosquets). C'est comme cela qu'on arriverait à conserver la plus haute diversité végétale régionale. [es] En las últimas décadas han tenido lugar notables cambios en la región Mediterránea. Dichos cambios tienen un gran impacto en la diversidad vegetal cuyas variaciones pueden afectar al funcionamiento del ecosistema. Esto es particularmente cierto en áreas de castaño (Castanea sativa Mili); que han sido más o menos abandonadas desde finales del siglo pasado. Debido a ello; nuestro objetivo fue analizar las consecuencias en la diversidad vegetal de varios tipos de gestión forestal en parcelas de castaño en dos regiones mediterráneas; en las Cévennes (Francia) y en la zona del volcán Etna (Italia). Nuestros resultados indican que hay pocas especies en común entre las dos áreas mediterráneas; solamente un 9%. Estas diferencias pueden explicarse por las diferentes características edafoclimáticas entre dichas áreas; pero también por los diferentes tipos de manejo forestal (castaños dedicados a madera y fruto en la zona de las Cévennes y sólo castaños dedicados a madera en la zona del Etna); o a las características de las parcelas seleccionadas (densidad del arbolado; DBH; ...). La diversidad vegetal es mayor en castañares dedicados a fruto que en aquellos dedicados a madera. Los castañares de fruto cultivados generalmente se caracterizan por pequeños terófitos heliófilos mientras que los cultivos de fruto abandonados y aquellos castañares más jóvenes dedicados a madera; por hemicriptófitos con dispersión anemócora y caméfitos. Los castañares medios y viejos dedicados a la producción de madera se caracterizan por fanerófitos con dispersión zoócora. Una consecuencia en los castañares abandonados es que contienen una vegetación homogénea; y decrece su biodiversidad vegetal. Una solución podría ser el mantener un mosaico paisajístico condicionado por diversos tipos de manejo forestal; de esa manera podríamos aumentar dicha biodiversidad vegetal regional.

[fr] L'étude réalisée porte sur la végétation et la radiation solaire incidente sur les pentes de la Sierra de Béjar, selon leur orientation et leur inclinaison, en vue d'une milleure utilisation de ses ressources écologiques. Sur le plan chorologique, la zone d'étude se situe dans la province carpetano-ibérico- leonesa, secteur bejarano-gredense, sous-secteur bejarano-tormantino. Elle présente des reliefs très marqués et, par suite de sa situation péninsulaire, trois étages climatiques sont représentés: supraméditerranéen, oroméditerranéen et crioroméditerranéen. Sur les pentes situes à plus de 1500 m d'altitude, on observe les plus basses valeurs de radiation moyenne en expositions N, NE, NNE, NNW et NW (186,9 cal.cm-2.jour-1 en hiver; 246, 8 cal.cm-2.jour-1 en automne; 486,5 cal.cm-2.jour-1 au printemps et 543 cal.cm-2.jour-1 en été) et se développe la plus forte biomasse végétale, principalement due aux boisements de Pinus pinaster et P. sylvestris. En expositions S, SE, SSE, SSW et SW, on observe les plus fortes valeurs de radiation moyenne de la zone étudiée (246,8 cal.cm-2.jour-1 en hiver, 303,4 en automne, 515, 2 au printemps et 582,6 en été); le développement de la végétation y est plus faible, principalement représenté par des arbustes comme Cytisus purgans, et le sols sont moins profonds. À une altitude voisine de 1300 m, les pentes sont plus faibles, la radiation moyenne atteint des valeurs intermédiaires (212 cal.cm-2.jour-1 en hiver, 242,2 en automne, 913,2 au printemps et 580,5 en été) et la végétation dominante est composée de forêts de Quercus pyrenaica; à plus basse altitude, les boisements de Castanea sativa dominent. [es] Se ha llevado a cabo un estudio detallado de la vegetación y radiación solar que inciden en laderas de la Sierra de Béjar de acuerdo con su orientación y pendiente para una mejor explotación de sus recursos ecológicos. Desde el punto de vista corológico el área estudiada se halla enmarcada en el seno de la provincia corológica carpetano-ibérico-leonesa, sector bejarano-gredense, subsector bejarano-tormantino. La zona de estudio presenta relieves muy acusados, por ello y dada su localización a nivel peninsular, en estas áreas se van a manifestar, de forma clara, tres pisos climáticos: Supramediterráneo, oromediterráneo y crioromediterráneo. En laderas a partir de 1500 m, los valores más bajos de radiación media se han estimado en orientaciones N, NE, NEN, NON y NO (186.9 cal.cm-2.día-1 en invierno, 246.8 cal.cm-2.día-1 en otoño, 486.5 cal.cm-2.día-1 en primavera y 543.0 cal.cm-2.día-1 en verano), se desarrolla una mayor biomasa aérea vegetal, debido sobre todo al establecimiento de bosques de Pinus pinaster y P. sylvestris. En orientaciones S, SE, SES, SOS y SO se han determinado los mayores valores de radiación media para el área de estudio (246.8 cal.cm-2.día-1 en invierno, 303.4 cal.cm-2.día-1 en otoño, 515.2 cal.cm-2.día-1 en primavera y 582.6 cal.cm-2.día-1 en verano), el desarrollo de vegetación es más escaso, representada en su mayor parte por arbustos como Cytisus purgans y los suelos son menos profundos. Alrededor de la cota de 1.300 m de altitud las pendientes son más suaves, los valores de radiación media alcanzados son intermedios (212.0.cal.cm-2.día-1 en invierno, 242.2cal.cm-2.día-1 en otoño, 513.2 cal.cm-2.día-1 en primavera y 580.5 cal.cm-2.día-1 en verano), la vegetación predominante está representada por bosques de Quercus pyrenaica y en la zona baja de dicha cota, bosques de Castanea sativa.

[fr] Les biomasses aériennes, les retombées de litières, leur accumulation à la surface du sol et leur décomposition, ont été étudiées dans trois hêtraies méditerranéennes d'Italie, de France et d'Espagne, pour mieux connaître la restitution au sol des bioéléments par l'intermédiaire de la matière organique. Les biomasses aériennes s'élevaient respectivement à 131.9 Mg ha-1 dans la hêtraie de l'Etna (Italie), 134.2 Mg ha-1 dans celle de Sierra de la Demanda (Espagne) et à 223.9 Mg ha-1 au Mont Lozère (France). Les retombées de litière les plus fortes sont observées dans la hêtraie de la Sierra de la Demanda (4.7 Mg ha-1 an-1), suivie de celles du Mont Lozère (4.4 Mg ha-1 an-1) et de l'Etna (3.9 Mg ha-1 an-1). L'ensemble de la matière organique accumulée à la surface du sol des trois hêtraies était de 25.8 Mg ha-1 au Mont Lozère, 14.4 Mg ha-1 à Sierra de la Demanda et 12.6 Mg ha-1 dans l'Etna. Les proportions respectives de la fraction feuilles par rapport à la litière totale étaient proches dans les stations de l'Etna et de la Sierra de la Demanda (72 - 70%) et voisines de celle du Mont Lozère (65%). Toutes les forêts de Fagus sylvatica dans le climat Méditerranéen sont très similaires par rapport à la distribution et aux flux, malgré que les conditions de climat et de sol soient différentes. [es] Se han estudiado la biomasa aérea, la caída, acumulación y descomposición de la hojarasca en tres ecosistemas forestales de hayedo en Italia, Francia y España en orden a conocer mejor el reciclado de elementos- biógenos asociados al reciclaje de materia orgánica. La biomasa aérea estimada es de 131.0 Mg ha-1 en Etna (Italia), 134.2 Mg ha-1 en la Sierra de la Demanda (España) y 223.9 Mg ha-1 en Mont Lozère (Francia). La mayor cantidad de caída de hojarasca se ha observado en la Sierra de la Demanda (4.7 Mg ha-1 año-1) seguida de Mont Lozère (4.4 Mg ha-1 año-1). La materia orgánica acumulada en la superficie del suelo en los tres ecosistemas forestales estudiados fue de 25.8 Mg ha-1 en Mont Lozère, 14.4 Mg ha-1 en la Sierra de la Demanda y 12.6 Mg ha-1 en Etna. El porcentaje relativo de las hojas con relación a la hojarasca total fue similar en las parcelas de Etna y Sierra de la Demanda (72-70%) y algo más bajo en Mont Lozère (65%). Los bosques de Fagus sylvatica estudiados reflejaron valores similares respecto a la distribución y flujos de materia orgánica, aunque se han evidenciado diferencias en cuanto a condiciones locales de clima y suelo.

[es] El balance de agua en dos ecosistemas forestales de la "Sierra de la Demanda", un hayedo climácico (Fagus sylvatica L.) y un pinar de reforestación (Pinus sylvestris L.) en área de potencialidad hayedo, ha sido determinado. La precipitación que alcanza el suelo representa el 61,7% por pluviolavado en el hayedo y el 52,1% en el pinar, el 6,5% y 0,4% por escurrimiento fustal, y el 31 7% y 42,5% por intercepción en hayedo y pinar respectivamente. Estos valores fluctúan mensualmente dependiendo de las características de la lluvia incidente. [fr] Le bilan de l'eau dans deux écosystèmes forestiers de la "Sierra de la Demanda", une hetraie climacique (Fagus sylvatica L.) et une plantation de pin blanc (Pinus sylvestris L.) dans une zone de potentialité hetraie a été determiné. La précipitation qu'arrive au sol représente le 61,7 % par l'égouttement dans l'hetraie, et le 52,1 % dans une pinède; le 6,5%o et 0,4% par écolulement et le 31,7% et 42,5% par interceptation dans lahetraie et la pinède respectivement. Ces valeurs fluctuent mensuelment en dépendant des caractéristiques de la pluie incidente.

Se ha estimado el retorno anual de bioelementos a través del agua de lluvia en un bosque de repoblación de pino albar (Pinus sylvestris L.) en la Cuenca de Candelario (sistema Central). Del total de elementos aportados al suelo, la inmensa mayoría del carbono, nitrógeno, fósforo, calcio, potasio, sodio y zinc, penetran por medio del agua de pluviolavado, sólo un 10% lo hace, a través del agua de escurrimiento fustal; el magnesio alcanza el suelo en un 82% por él agua de pluviolavado y el resto por escurrimiento fustal; el manganeso y el hierro lo hacen en un 70% y 30% respectivamente, mientras que el aporte predominante de cobre se realiza a través del agua de escurrimiento fustal (más del 60%).

The production of litter, the weight loss dynamic of forest litter decomposition, and the dynamics of bioelement loss during leaf litter decomposition were determined in three forest ecosystems located in a semi‐arid zone of the Duero basin, Province of Zamora, Spain, over 2 years. The three ecosystems were a climax evergreen oak (Quercus rotundifolia Lam.) woodland, a paraclimax stone pine (Pinus pinea L.) forest, and a disclimax maritime pine (Pinus pinaster Sol.) forest. The mean total production of litter in the oak forest was 2320 kg ha−1 year−1, quite similar to the P. pinea pine forest, at 2400 kg ha−1 year−1 and higher than that of the P. pinaster pine forest at 1728 kg ha−1 year−1 . Leaves and needles accounted for most of this total production (78, 89 and 96 per cent, respectively). No significant differences were found among the different leaf decomposition processes, except for the oak leaves introduced in the pine ecosystems. A relationship between time (independent variable) and the remaining leaf weight was found, which followed a negative exponential curve, DM (dry matter) = A + B exp(−Ct). About 30 per cent of the weight was lost during the first 4 months. This indicates that climate (semi‐arid conditions) speeds decomposition in the short term. The decomposition indices were determined for leaves only and for total litter. Considering total litter and leaves separately, several relations were established for K, Ko and Kd decomposition indices. K and Ko in natural conditions decrease in the following order: evergreen oak > stone pine > maritime pine. The Q. rotundifolia woodland potentially returns a greater amount of N and Ca than both Pinus forests. A litter‐bag method was used for the determination of the dynamics of the decomposing leaves. A progressive loss of P and Mg in the decomposing oak leaves and pine needles, and a sharp loss of K were observed: in contrast, a tendency to retain N and Ca was also seen. Pinus pinaster forest had the lowest annual N and P returns. [ABSTRACT FROM AUTHOR]

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives., (© 2019 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)

During a study on biodiversity of bacteria inhabiting rhizospheric soil of rockrose ( Cistus ladanifer L.), we isolated a strain coded RD25 T in a soil from Northern Spain. The 16S rRNA gene sequence showed 99.5 % identity with respect to the closest related species Pseudomonas brenneri DSM15294 T , and 99.4 % with respect to P. paralactis WS4672 T . The following related Pseudomonas species showed 99.3 % or less identity, and therefore RD25 T was classified within genus Pseudomonas . The phylogenetic analysis of 16S rRNA and the housekeeping genes rpoB , rpoD and gyrB suggested that this strain could be a novel species. The strain RD25 T has several polar-subpolar flagella. It can grow at 36 °C, at 0-6 % NaCl concentration and a range of pH 5-9. Positive for arginine dihydrolase and urease production, and negative for reduction of nitrate. The strain is catalase and oxidase positive. Major fatty acids are C 16 : 1  ω7 c / C 16 : 1  ω6 c in summed feature 3, C 16 : 0 , and C 18 : 1  ω7 c / C 18 : 1  ω6 c in summed feature 8. The respiratory ubiquinone is Q9. The DNA G+C content was 59.9 mol%. The digital DNA-DNA hybridisation average values (dDDH) ranged between 30-61.2 % relatedness and the ANIb values ranged between 93.9-80.5 % with respect to the type strains of the closely related species. Therefore, the genotypic, genomic, phenotypic and chemotaxonomic data support the classification of strain RD25 as a novel species of genus Pseudomonas , for which the name P. edaphica sp. nov. is proposed. The type strain is RD25 T (=LMG 30152 T =CECT 9373 T ).

The phyllosphere supports a large and complex bacterial community that varies both across plant species and geographical locations. Phyllosphere bacteria can have important effects on plant health. The sweet chestnut ( Castanea sativa Mill.) is an economically important tree species affected worldwide by the fungal pathogens Cryphonectria parasitica and Phytophthora cinnamomi . We examined the culturable phyllosphere bacterial community of the sweet chestnut at two nearby locations in Central Spain in order to know its geographical variability and to explore its potential as source of biological control agents against these two pathogenic fungi. The bacterial diversity at strain level was high but it varied significantly between locations; however, phylotype richness and diversity were more comparable. The isolates were affiliated with the phyla Actinobacteria , Firmicutes and Proteobacteria . Most of them were members of recognized bacterial species, with a notable proportion of representative of the genera Dietzia and Lonsdalea , but a small fraction of the strains revealed the existence of several potential novel species or even genera. Antagonism tests showed the occurrence in the chestnut phyllosphere of bacterial strains potentially useful as biological control agents against the two pathogenic fungi, some of which belong to species never before described as fungal antagonists. Chestnut phyllosphere, therefore, contains a great diversity of culturable bacteria and may represent an untapped source of potential biocontrol agents against the fungi causing blight and ink diseases of this tree species., Competing Interests: Conflict of Interest: All authors declare no conflicts of interest in this paper.

A mining area affected by the abandoned exploitation of an arsenical tungsten deposit was studied in order to assess its arsenic pollution level and the feasibility of native plants for being used in phytoremediation approaches. Soil and plant samples were collected at different distances from the polluting sources and analysed for their As content and distribution. Critical soil total concentrations of As were found, with values in the range 70-5330 mg kg(-1) in the uppermost layer. The plant community develops As tolerance by exclusion strategies. Of the plant species growing in the most polluted site, the shrubs Salix atrocinerea Brot. and Genista scorpius (L.) DC. exhibit the lowest bioaccumulation factor (BF) values for their aerial parts, suggesting their suitability to be used with revegetation purposes. The species Scirpus holoschoenus L. highlights for its important potential to stabilise As at root level, accumulating As contents up to 3164 mg kg(-1)., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

We studied the bacterial diversity at a single location (the Terrubias mine; Salamanca province, Spain) with a gradient of soil As contamination to test if increasing levels of As would (1) change the preponderant groups of arsenic-resistant bacteria and (2) increase the tolerance thresholds to arsenite [As(III)] and arsenate [As(V)] of such bacteria. We studied the genetic and taxonomic diversity of culturable arsenic-resistant bacteria by PCR fingerprinting techniques and 16S rRNA gene sequencing. Then, the tolerance thresholds to As(III) and As(V) were determined for representative strains and mathematically analyzed to determine relationships between tolerances to As(III) and As(V), as well as these tolerances with the soil contamination level. The diversity of the bacterial community was, as expected, inversely related to the soil As content. The overall preponderant arsenic-resistant bacteria were Firmicutes (mainly Bacillus spp.) followed by γ-Proteobacteria (mainly Pseudomonas spp.), with increasing relative frequencies of the former as the soil arsenic concentration increased. Moreover, a strain of the species Rahnella aquatilis (γ-Proteobacteria class) exhibited strong endurance to arsenic, being described for the first time in literature such a phenotype within this bacterial species. Tolerances of the isolates to As(III) and As(V) were correlated but not with their origin (soil contamination level). Most of the strains (64%) showed relatively low tolerances to As(III) and As(V), but the second most numerous group of isolates (19%) showed increased tolerance to As(III) rather than to As(V), even though the As(V) anion is the prevalent arsenic species in soil solution at this location. To our knowledge, this is the first study to report a shift towards preponderance of Gram-positive bacteria (Firmicutes) related to high concentrations of soil arsenic. It was also shown that, under aerobic conditions, strains with relatively enhanced tolerance to As(III) predominated over the most As(V)-tolerant ones., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The study was conducted to characterize mineralogical and elemental composition of mine tailings in order to evaluate the environmental hazards, and identify the metal accumulation potential of native plant species from São Domingos mine, one of the long-term activity mines of the Iberian Pyrite Belt dating back to pre-Roman times. The mine tailings including soils and different plant species from São Domingos were analyzed for determination of tailings characteristics and chemical element contents in tailings and plants. The large amounts of mining wastes are causing significant adverse environment impacts due to acid mine drainage production and mobilization of potentially toxic metals and metalloids in residential areas, agricultural fields, downstreams, and rivers. The typical mineralogical composition is as follows: quartz, micas, K-feldspar, olivine-group minerals, magnetite, goethite, hematite, jarosite, and sulfides. The mine tailings were highly contaminated by As, Ag, Cr, Hg, Sn, Sb, Fe, and Zn; and among them, As and Sb, main contaminants, attained the highest concentrations except Fe. Arsenic has exhibited very good correlations with Au, Fe, Sb, Se, and W; and Sb with As, Au, Fe, Se, Sn, and W in tailings. Among the all plant species, the higher concentrations of all the metals were noted in Erica andevalensis, Erica australis, Echium plantagium, and Lavandula luisierra. Considering the tolerant behavior and abundant growth, the plant species Erica australis, Erica andevalensis, Lavandula luisierra, Daphne gnidium, Rumex induratus, Ulex eriocladus, Juncus, and Genista hirsutus are of major importance for the rehabilitation and recovery of degraded São Domingos mining area.

During a screening of phosphate solubilizing bacteria (PSB) in agricultural soils, two strains, IH9 and OCI1, were isolated from the rhizosphere of grasses in Spain, and they showed a high ability to solubilize phosphate in vitro. Inoculation experiments in chickpea and barley were conducted with both strains and the results demonstrated their ability to promote plant growth. The 16S rRNA gene sequences of these strains were nearly identical to each other and to those of Acinetobacter calcoaceticus DSM 30006(T), as well as the strain CIP 70.29 representing genomospecies 3. Their phenotypic characteristics also coincided with those of strains forming the A. calcoaceticus-baumannii complex. They differed from A. calcoaceticus in the utilization of l-tartrate as a carbon source and from genomospecies 3 in the use of d-asparagine as a carbon source. The 16S-23S intergenic spacer (ITS) sequences of the two isolates showed nearly 98% identities to those of A. calcoaceticus, confirming that they belong to this phylogenetic group. However, the isolates appeared as a separate branch from the A. calcoaceticus sequences, indicating their molecular separation from other A. calcoaceticus strains. The analysis of three housekeeping genes, recA, rpoD and gyrB, confirmed that IH9 and OCI1 form a distinct lineage within A. calcoaceticus. These results were congruent with those from DNA-DNA hybridization, indicating that strains IH9 and OCI1 constitute a new genomovar for which we propose the name A. calcoaceticus genomovar rhizosphaerae.

A bacterial strain, designated Ch-32(T), was isolated from the phyllosphere of Castanea sativa in Spain. Phylogenetic analysis based on 16S rRNA gene sequences placed the isolate in the genus Paenibacillus within the same subgroup as Paenibacillus xinjiangensis and Paenibacillus glycanilyticus, with similarities of 96.3 and 96.8 %, respectively. DNA-DNA hybridization values for strain Ch-32(T) with these two species were lower than 20 %. The novel isolate was a Gram-variable, motile, sporulating rod. It produced catalase and oxidase and hydrolysed cellulose, gelatin and aesculin. Acetoin and urease production, nitrate reduction and starch hydrolysis were negative. Growth was supported by many carbohydrates and organic acids as carbon sources. MK-7 was the only menaquinone detected and anteiso-C(15 : 0), iso-C(16 : 0) and C(16 : 0) were the major fatty acids. The DNA G+C content was 46 mol%. Phylogenetic, DNA relatedness and phenotypic analyses showed that strain Ch-32(T) should be classified as a novel species of the genus Paenibacillus, for which the name Paenibacillus castaneae sp. nov. is proposed; the type strain is Ch-32(T) (=CECT 7279(T)=DSM 19417(T)).

Elevated levels of bioavailable As in mining soils, agricultural areas and human habitats may cause potential toxicity to human health, plants and microbe. Therefore, it is essential to determine proper soil chemical extraction method in order to estimate plant-available As in mining soils and protect agricultural and environmental ecosystems by evaluation of environmental risk and implementation of remediation measures. In this study, six single soil chemical extraction processes and four-step sequential chemical extraction protocol were used to determine the relative distribution of As in different chemical forms of soils and their correlations with total As in plants grown in mining areas and greenhouse experiments. The strongest relationship between As determined by single soil chemical extraction and As in plant biomass was found for sodium acetate and mixed acid extractant. The mean percent of total As extracted was: ammonium oxalate (41%)>hydroxylamine hydrochloride (32%)>mixed acid (16%)>phosphate (6%)>sodium acetate (1.2%)>water (0.13%). This trend suggests that most of the As in these soils is inside the soil mineral matrix and can only be released when iron oxides and other minerals are dissolved by the stronger chemical extractant. Single soil chemical extraction methods using sodium acetate and mixed acids, that extract As fractions complexed to soil particles or on the surface of mineral matrix of hydrous oxides of Fe, Mn and Al (exchangeable+sorbed forms) can be employed to estimate and predict the bioavailable As fraction for plant uptake in mining affected soils. In sequential chemical extraction methods, ammonium nitrate and hydroxylamine hydrochloride may be used to provide closer estimates of plant-available As in mining soils.

Pseudomonas chlororaphis, Pseudomonas aureofaciens and Pseudomonas aurantiaca were considered as separate species until 1989, when P. aureofaciens was proposed as a later heterotypic synonym of P. chlororaphis with P. aurantiaca remaining as a separate species. Nevertheless, analysis of the almost complete 16S rRNA gene sequences revealed that the type strain of P. aurantiaca, NCIMB 10068(T), shows gene sequence similarities close to 99.5 % with respect to P. chlororaphis DSM 50083(T) and P. aureofaciens DSM 6698(T). DNA-DNA hybridization experiments among strains of P. aurantiaca, P. chlororaphis and P. aureofaciens showed values higher than 70 %, confirming that they represent members of the same species. The results of fatty acid analysis and phenotypic traits showed that these strains are closely related, although there are some differences among the strains belonging to P. aurantiaca, those from P. chlororaphis and those from P. aureofaciens. All these results confirm the previous reclassification of P. aureofaciens into P. chlororaphis and support the reclassification of P. aurantiaca as a synonym of P. chlororaphis. Phenotypic and molecular data permit the description of three novel subspecies within this last species, for which the following names are proposed: P. chlororaphis subsp. chlororaphis subsp. nov. [with the type strain DSM 50083(T) (=ATCC 9446(T)=NCIMB 9392(T))], P. chlororaphis subsp. aureofaciens subsp. nov., comb. nov. [with the type strain DSM 6698(T) (=ATCC 13985(T)=NCIMB 9030(T))] and P. chlororaphis subsp. aurantiaca subsp. nov., comb. nov. [with the type strain NCIMB 10068(T) (=ATCC 33663(T)=CIP 106718(T))].

A Gram-negative, non-spore-forming bacterial strain with the ability to solubilize highly insoluble phosphatic minerals was isolated from a high-phosphorous iron ore from Minas Gerais State, Brazil. This strain, designated FeGl01(T), was subjected to a polyphasic taxonomic investigation. Comparative 16S rRNA gene sequence analysis indicated that it formed a distinct phylogenetic lineage within the genus Burkholderia together with several other species of the genus, e.g. Burkholderia sacchari, Burkholderia tropica and Burkholderia unamae. Partial nucleotide sequencing and analysis of the recA gene roughly corroborated the phylogenetic position of strain FeGl01(T) within the genus Burkholderia. The chemotaxonomic properties of strain FeGl01(T), such as ubiquinone Q-8 as the predominant quinone system and C(16 : 0), C(17 : 0) cyclo, C(18 : 1)omega7c and C(19 : 0)omega8c cyclo as the major fatty acids, were also consistent with its classification within the genus Burkholderia. DNA-DNA hybridization experiments between strain FeGl01(T) and the type strains of B. unamae, B. sacchari and B. tropica yielded reassociation values of 40 % or lower, which, together with qualitative and quantitative differences in fatty acid composition and with differences in several phenotypic traits, support the separation of the new isolate from the phylogenetically most closely related species. Therefore, it is suggested that strain FeGl01(T) represents a novel species of the genus Burkholderia, for which the name Burkholderia ferrariae sp. nov. is proposed. The type strain is FeGl01(T) (=LMG 23612(T)=CECT 7171(T)=DSM 18251(T)).

A phosphate-solubilizing bacterial strain designated OK2(T) was isolated from rhizospheric soil of grasses growing spontaneously in a soil from Spain. Cells of the strain were Gram-negative, strictly aerobic, rod-shaped and motile. Phylogenetic analysis of the 16S rRNA gene indicated that this bacterium belongs to the gamma-subclass of Proteobacteria within the genus Pseudomonas and that the closest related species is Pseudomonas graminis. The strain produced catalase but not oxidase. Cellulose, casein, starch, gelatin and urea were not hydrolysed. Aesculin was hydrolysed. Growth was observed with many carbohydrates as carbon sources. The main non-polar fatty acids detected were hexadecenoic acid (16 : 1), hexadecanoic acid (16 : 0) and octadecenoic acid (18 : 1). The hydroxy fatty acids detected were 3-hydroxydecanoic acid (3-OH 10 : 0), 3-hydroxydodecanoic acid (3-OH 12 : 0) and 2-hydroxydodecanoic acid (2-OH 12 : 0). The G+C DNA content determined was 59.3 mol%. DNA-DNA hybridization showed 48.7 % relatedness between strain OK2(T) and P. graminis DSM 11363(T) and 26.2 % with respect to Pseudomonas rhizosphaerae LMG 21640(T). Therefore, these results indicate that strain OK2(T) (=LMG 21974(T)=CECT 5822(T)) belongs to a novel species of the genus Pseudomonas, and the name Pseudomonas lutea sp. nov. is proposed.

Two permanent sampling sites were selected at the two extremes of a rainfall gradient in natural forests of Quercus pyrenaica Willd. located in the Sierra de Gata (Salamanca Province, Spain). During 1991 and 1992, diurnal courses of transpiration rate (E), stomatal conductance (g(s)) and leaf water potential (Psi(l)) were studied at different levels in the tree canopy. Leaf water potential fell from a high value in the early morning to a minimum at midday and then increased again in the afternoon. Values of Psi(l) in the early morning and at midday were lower at Fuenteguinaldo (dry site) than at Navasfrías (wet site) and were related to soil water availability. Stomatal conductance increased during the morning and maximum g(s) occurred about 3 h before Psi(l) was at its lowest value. The highest values of g(s) were found at Navasfrías during July. The lowest Psi(l) values were found in the upper parts of the canopy and differences among canopy levels were greatest when soil water availability was low. In August, minimum values of Psi(l) differed among canopy levels by 1.0 MPa at Navasfrías and by 0.8 MPa at Fuenteguinaldo. The maximum difference in g(s) among canopy levels was about 150 mmol m(-2) s(-1) at Navasfrías and about 300 mmol m(-2) s(-1) at Fuenteguinaldo. The results indicate a nonconservative pattern of water use in Quercus pyrenaica.