1000 resultados para pulgão-gigante-do-pinus
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How coniferous trees in northern China changed their distribution ranges in response to Quaternary climatic oscillations remains largely unknown. Here we report a study of the phylogeography of Pinus tabulaeformis, an endemic and dominant species of coniferous forest in northern China. We examined sequence variation of maternally inherited, seed-dispersed mitochondrial DNA (mtDNA) (nad5 intron 1 and nad4/3-4) and paternally inherited, pollen- and seed-dispersed chloroplast DNA (cpDNA) (rpl16 and trnS-trnG) within and among 30 natural populations across the entire range of the species. Six mitotypes and five chlorotypes were recovered among 291 trees surveyed. Population divergence was high for mtDNA variation (G(ST) = 0.738, N-ST = 0.771) indicating low levels of seed-based gene flow and significant phylogeographical structure (N-ST > G(ST), P < 0.05). The spatial distribution of mitotypes suggests that five distinct population groups exist in the species: one in the west comprising seven populations, a second with a north-central distribution comprising 15 populations, a third with a southern and easterly distribution comprising five populations, a fourth comprising one central and one western population, and a fifth comprising a single population located in the north-central part of the species' range. Each group apart from the fourth group is characterized by a distinct mitotype, with other mitotypes, if present, occurring at low frequency. It is suggested, therefore, that most members of each group apart from Group 4 are derived from ancestors that occupied different isolated refugia in a previous period of range fragmentation of the species, possibly at the time of the Last Glacial Maximum. Possible locations for these refugia are suggested. A comparison of mitotype diversity between northern and southern subgroups within the north-central group of populations (Group 2) showed much greater uniformity in the northern part of the range both within and between populations. This could indicate a northward migration of the species from a southern refugium in this region during the postglacial period, although alternative explanations cannot be ruled out. Two chlorotypes were distributed across the geographical range of the species, resulting in lower levels of among-population chlorotype variation. The geographical pattern of variation for all five chlorotypes provided some indication of the species surviving past glaciations in more than one refugium, although differentiation was much less marked, presumably due to the greater dispersal of cpDNA via pollen.
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2008
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2009
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2006
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2008
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2008
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Esta Circular Técnica tem como objetivo auxiliar na correta identificação de A. gossypii e de seus danos no meloeiro, além de fornecer informações básicas para o seu manejo.
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1998
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Ciclo biológico da vespa-da-madeira; Como identificar a vespa-da-madeira; Como identificar árvores atacadas; Danos provocados pela praga; Medidas preventivas; Manejo florestal; Quarentena; Monitoramento para detecção precoce - instalação de árvores-armadilha; Medidas a serem adotadas após a detecção da praga; Mapeamento das áreas atacadas pela vespa-da-madeira; Amostragem sequencial; Controle biológico; Utilização do nematóide Beddingia siridicola; Utilização de insetos parasitóides; Avaliação da eficiência dos agentes de controle biológico.
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2015
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© 2015 Published by Elsevier B.V.Tree growth resources and the efficiency of resource-use for biomass production determine the productivity of forest ecosystems. In nutrient-limited forests, nitrogen (N)-fertilization increases foliage [N], which may increase photosynthetic rates, leaf area index (L), and thus light interception (I
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La producción mundial de maíz en general tiene carácter de ser un producto commodity, con grandes volúmenes, precios altos y homogéneos. Pero en Perú hoy en día surge la necesidad de competir globalmente, con productos especiality, con pocos volúmenes y altamente diferenciados. Dicha estrategia es aplicada por el Perú con el Maíz Blanco Gigante, presentando ventaja comparativa a nivel de otras variedades de maíz, al poseer características únicas en relación al lugar de origen y prácticas culturales que se han mantenido en su cultivo a través del tiempo. Es por ello que se da reconocimiento y certificación como DO en el año 2005, como Maíz Blanco Gigante del Cusco, presentando tendencias de exportación a partir de dicho año. La investigación se enfoca al estudio de la situación actual del MBGC como DO bajo la Nueva Economía Institucional (NEI). Los resultados del estudio indican que la conexión institucional presenta desatinos, los organismos que dieron inicio al proceso de la DO se encuentran descoordinados, con ausencia de medidas de control. Ello ha ocasionado un débil enforcement en las reglas de juego y por ende en el marco institucional, afectando la imagen, posicionamiento y falencias a nivel de la cadena del MBGC. Se recomienda definir políticas y estrategias de uso de la DO, con miras a establecer mesas de diálogo sobre la participación (promoción, normativa y/o fiscalizadora), de los entes públicos como INDECOPI, Gobierno Regional, Gobierno Local con respecto a la DO del MBGC y sus características particulares como bien público a fin de dinamizar las inversiones, comercio y mantener la ventaja competitiva.
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p.17-27
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Pollen, microscopic charcoal, palaeohydrological and dendrochronological analyses are applied to a radiocarbon and tephrochronologically dated mid Holocene (ca. 8500–3000 cal B.P.) peat sequence with abundant fossil Pinus (pine) wood. The Pinus populations on peat fluctuated considerably over the period in question. Colonisation by Pinus from ca. 7900–7600 cal B.P. appears to have had no specific environmental trigger; it was probably determined by the rate of migration from particular populations. The second phase, at ca. 5000–4400 cal B.P., was facilitated by anthropogenic interference that reduced competition from other trees. The pollen record shows two Pinus declines. The first at ca. 6200–5500 cal B.P. was caused by a series of rapid and frequent climatic shifts. The second, the so-called pine decline, was very gradual (ca. 4200–3300 cal B.P.) at Loch Farlary and may not have been related to climate change as is often supposed. Low intensity but sustained grazing pressures were more important. Throughout the mid Holocene, the frequency and intensity of burning in these open Pinus–Calluna woods were probably highly sensitive to hydrological (climatic) change. Axe marks on several trees are related to the mid to late Bronze Age, i.e., long after the trees had died.
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Confirmation de la présence do Lonicero-Pinetum thalictretosum, climacique dans les Pyrénées aragonaises sur substrats calcaires. Il s’y développe, á l’étage supraméditerranéen, dans des conditions climatiques méditerranéo-continentales mais relativement xérothermiques.