{"id":137361,"date":"2010-12-27T10:46:11","date_gmt":"2010-12-27T09:46:11","guid":{"rendered":"http:\/\/www.madrimasd.org\/blogs\/universo\/?p=137361"},"modified":"2010-12-27T10:47:21","modified_gmt":"2010-12-27T09:47:21","slug":"arboles-rizosfera-y-absorcion-de-nutrientes-%c2%bfangiospermas-versus-gimnospermas","status":"publish","type":"post","link":"https:\/\/www.madrimasd.org\/blogs\/universo\/2010\/12\/27\/137361","title":{"rendered":"\u00c1rboles, Rizosfera y Absorci\u00f3n de Nutrientes: \u00bfAngiospermas versus Gimnospermas?"},"content":{"rendered":"

Aunque por la noticia que vamos a tratar no lo parezca, desde hace d\u00e9cadas la mayor parte de los estudios relacionados con el tema muestran que la abundancia y diversidad de especies es mayor en los suelos bajo fag\u00e1ceas (como robles y hayas) que en el caso de las con\u00edferas<\/span><\/strong>. Tambi\u00e9n ocurre lo mismo con la humificaci\u00f3n<\/span><\/strong> de la materia org\u00e1nica, por no hablar de grupos<\/span> tr\u00f3ficos<\/span><\/strong> de organismos y actividades enzim\u00e1ticas<\/span><\/strong>. Tanto es as\u00ed que cuando en una antigua nomenclatura se hablaba de <\/span>especies<\/span> mejorantes y acidificantes<\/span><\/strong> del medio ed\u00e1fico, se inclu\u00eda a las fag\u00e1ceas entre las primeras y a los pinos, abetos, etc. entre las segundas<\/span><\/strong>. La noticia de hoy nos ofrece el mismo patr\u00f3n pero<\/strong><\/span> desde una \u00f3ptica relativamente nueva. Se ha constatado (aunque se trata de un solo caso que deber\u00e1 ser corroborado) de que la diversidad y abundancia de las bacterias que alteran y descomponen los minerales primarios del suelo difiere en ambos casos, siendo mayor en robles y hayas que en abetos<\/span>.<\/strong> En otras palabras, las rizosferas de ambos grupos de plantas son diferentes<\/span><\/strong>. Y hasta donde yo se, las propiedades estructuradoras del humus<\/strong> <\/span>de los mencionados planifolios, tambi\u00e9n es superior a la de las confieras<\/span><\/strong>. Obviamente en suelos <\/span>de naturaleza \u00e1cida<\/span><\/strong>, disponer de una mayor cantidad de nutrientes<\/span><\/strong> debiera potenciar la supervivencia de los \u00e1rboles que lo consiguen. No obstante, en la naturaleza los procesos no suelen ser tan sencillos. Que diversas especies arb\u00f3reas atesoren comunidades rizosf\u00e9ricas dispares era de esperar<\/span><\/strong> (incluidas bacterias, y hongos), como tambi\u00e9n ocurre con la microfauna del suelo que sigue los mismos patrones<\/span><\/strong> que los aqu\u00ed apuntados. Decir, como apuntan los autores, que los sistemas radiculares de los \u00e1rboles \u201cseleccionan\u201d sus biocenosis ed\u00e1ficas no deja de ser un antropomorfismo aunque sirva como una met\u00e1fora<\/span><\/strong> aceptable en ocasiones como esta.<\/p>\n

\"rizosfera-y-toma-de-nutrientes-fuente-plant-physiology\"\u00a0<\/p>\n

Rizosfera y toma in situ nutrientes por las plantas. Fuente: Plant Physiology<\/a><\/p>\n

In Situ Mapping of Nutrient Uptake in the Rhizosphere Using Nanoscale Secondary Ion Mass Spectrometry, From Clode et al. 2009<\/a><\/p>\n

<\/p>\n

\u00a0Los estudios que yo realic\u00e9 antes y durante en mi tesis doctoral, tambi\u00e9n mostraban que la actividad biol\u00f3gica, biodiversidad de nematodos y humificaci\u00f3n bajo los robles (al menos aqu\u00ed en la Pen\u00ednsula Ib\u00e9rica) es m\u00e1s mayor que en el caso del haya, y la de esta que en los pinos<\/span><\/strong>. Una humificaci\u00f3n de la materia org\u00e1nica<\/span><\/strong> m\u00e1s adecuada (no entraremos aqu\u00ed en detalles t\u00e9cnicos) suele potenciar unas propiedades f\u00edsicas del suelo m\u00e1s favorables para el desarrollo de la vegetaci\u00f3n<\/span><\/strong>. Es decir, se puede ir m\u00e1s lejos.<\/p>\n

\u00a0Una de las cr\u00edticas que los ambientalistas ib\u00e9ricos han usado contra la repoblaci\u00f3n con con\u00edferas ha sido justamente esta: las con\u00edferas empobrecen y acidifican el suelo<\/span><\/strong> (al menos por estos lares y Europa en general). \u00a0<\/p>\n

\u00a0\"tiger_mottle_ferruginised-victorian-resources-online\"<\/p>\n

La actividad biol\u00f3gica del suelo en la rizosfera es tan intensa que suele dejar rastro en los perfiles miles de a\u00f1os despu\u00e9s (franjas y moteados, verticales, horizontales u\u00a0 oblicuos). Fuente: Victorian Resources Online<\/a><\/p>\n

\u00a0La \u00fanica novedad que detecto<\/span><\/strong> (a parte de algunos detalles instrumentales que desconozco) consiste en que los investigadores analizaron en sus test comparativos la alteraci\u00f3n de la biotita<\/span><\/strong>. Es decir que el estudio precisa que las comunidades ed\u00e1ficas de faner\u00f3gamas comentadas poseen un mayor potencial de meteorizar los minerales del suelo<\/strong> <\/span>(mientras anta\u00f1o tan hizo m\u00e1s \u00e9nfasis en la humificaci\u00f3n que en la alteraci\u00f3n biogeoqu\u00edmica de los minerales, o se consideraron ambas simult\u00e1neamente), o de producir protones, como tales investigadores especifican.<\/p>\n

\u00a0Como todos deb\u00e9is saber, las faner\u00f3gamas son una rama del \u00e1rbol evolutivo surgida con bastante posterioridad a las con\u00edferas<\/span><\/strong>. No debe pues extra\u00f1ar que atesoren algunos mecanismos de supervivencia m\u00e1s sofisticados.<\/p>\n

\u00a0No obstante, de la noticia pudiera desprenderse que las faner\u00f3gamas deber\u00edan desplazar a las con\u00edferas por \u201cse alimentan mejor\u201d. En determinadas circunstancias tal aserto es v\u00e1lido pero en otros no. La guerra entre unas y otras ocurre sobre y bajo el suelo<\/span><\/strong>. Por ejemplo, las con\u00edferas al acidificar el medio ed\u00e1fico, y empobrecerlo en microorganismos y nutrientes, generan un ambiente m\u00e1s hostil con vistas a que germinen, por ejemplo, robles y hayas. Del mismo modo, arden mejor bajo la acci\u00f3n del fuego (l\u00e9ase incendios forestales) atesorando a la postre un crecimiento m\u00e1s r\u00e1pido. Dicho de otro modo, pinos, abetos, etc., tambi\u00e9n posee sus mecanismos para competir. El que la naturaleza cribe a unos u a otros, depende de otros muchos factores<\/strong>.<\/span> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/p>\n

\u00a0Juan Jos\u00e9 Ib\u00e1\u00f1ez<\/span><\/strong><\/p>\n

\u00a0Some Trees ‘Farm’ Bacteria to Help Supply Nutrients<\/a><\/h3>\n

ScienceDaily (July 30, 2010)<\/span><\/strong> \u2014 Some trees growing in nutrient-poor forest soil may get what they need by cultivating specific root microbes to create compounds they require. These microbes are exceptionally efficient at turning inorganic minerals into nutrients that the trees can use<\/strong>.<\/p>\n

\u00a0\u00a0Researchers from France report their findings in the July 2010 issue of the journal Applied and Environmental Microbiology.<\/p>\n

\u00a0\u00abIn acidic forest soils, availability of inorganic nutrients is a tree-growth-limiting factor. A hypothesis to explain sustainable forest development proposes that tree roots select soil microbes involved in central biogeochemical processes, such as mineral weathering, that may contribute to nutrient mobilization and tree nutrition<\/strong>,\u00bb says St\u00e9phane Uroz, an author on the study.<\/p>\n

\u00a0Certain microbes are efficient at<\/strong> breaking down inorganic minerals into nutrients<\/strong>. This process, called mineral weathering, is especially important in acidic forest soils<\/strong> where tree growth can be limited by access to these nutrients. Mineral-weathering bacteria can release necessary nutrients such as iron from soil minerals<\/strong>. This gives trees with increased concentrations of mineral-weathering microbes an advantage over other trees<\/strong>.<\/p>\n

\u00a0Distinct impacts of the tree species on the soil bacterial community structure have been previously reported, suggesting that the composition and activity of soil bacterial communities depend on tree physiology and notably on its impact on the soil physicochemical properties and nutrient cycling<\/strong>. However, no study has ever addressed the question of the impact of tree species on the structure of forest soil bacterial communities involved in mineral weathering<\/strong>.<\/p>\n

\u00a0\u00abThis question regarding the impact of tree species on the functional diversity of the bacterial communities remains a major issue<\/strong> in forestry, especially in the context of today’s climate change, which will give rise to a shift in the spatial distribution of forest tree species,\u00bb says Uroz.<\/p>\n

\u00a0<\/strong>The researchers took soil samples from the root areas of beech, oak and Norway spruce trees and cultured them to determine the bacterial populations. <\/strong>They observed heightened levels of mineral-weathering bacteria in the samples near the roots of oak and beech trees compared to surrounding soil samples. This difference was not seen in the Norway spruce<\/strong> samples.<\/strong><\/p>\n

\u00a0\u00abOur results suggest that certain tree species have developed indirect strategies for mineral weathering in nutrient-poor soils<\/strong>, which lie in the selection of bacterial communities with efficient mineral weathering potentials<\/strong>,\u00bb says Uroz.<\/p>\n

\u00a0Story Source<\/span><\/strong>:<\/p>\n

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Society for Microbiology<\/a>, via EurekAlert!<\/a>, a service of AAAS.<\/p>\n

\u00a0Journal Reference<\/strong>:<\/span><\/p>\n

C. Calvaruso, M.-P. Turpault, E. Leclerc, J. Ranger, J. Garbaye, S. Uroz, P. Frey-Klett. Influence of Forest Trees on the Distribution of Mineral Weathering-Associated Bacterial Communities of the Scleroderma citrinum Mycorrhizosphere. Applied and Environmental Microbiology, 2010; 76 (14): 4780 DOI: 10.1128\/AEM.03040-09<\/a><\/p>\n

\u00a0Resumen del Art\u00edculo Original<\/span><\/strong><\/p>\n

Appl Environ Microbiol.<\/a> 2010 Jul;76(14):4780-7. Epub 2010 May 28.<\/p>\n

Influence of forest trees on the distribution of mineral weathering-associated bacterial communities of the Scleroderma citrinum mycorrhizosphere<\/strong>.<\/span><\/p>\n

Calvaruso C<\/a>, Turpault MP<\/a>, Leclerc E<\/a>, Ranger J<\/a>, Garbaye J<\/a>, Uroz S<\/a>, Frey-Klett P<\/a>.<\/p>\n

\u00a0Abstract<\/span><\/strong><\/p>\n

In acidic forest soils, availability of inorganic nutrients is a tree-growth-limiting factor. A hypothesis to explain sustainable forest development proposes that tree roots select soil microbes involved in central biogeochemical processes, such as mineral weathering, that may contribute to nutrient mobilization and tree nutrition<\/strong>. Here we showed, by combining soil analyses with cultivation-dependent analyses of the culturable bacterial communities associated with the widespread mycorrhizal fungus<\/strong> Scleroderma citrinum<\/em>, a significant enrichment of bacterial isolates with efficient mineral weathering potentials around the oak and beech mycorrhizal roots compared to bulk soil<\/strong>. Such a difference did not exist in the rhizosphere of Norway spruce<\/strong>. The mineral weathering ability of the bacterial isolates was assessed using a microplaque assay that measures the pH and the amount of iron released from biotite<\/strong>. Using this microplate assay, we demonstrated that the bacterial isolates harboring the most efficient mineral weathering potential belonged to the Burkholderia<\/em> genus. Notably, previous work revealed that oak and beech harbored very similar pHs in the 5- to 10-cm horizon in both rhizosphere and bulk soil environments. In the spruce rhizosphere, in contrast, the pH was significantly lower than that in bulk soil<\/strong>. Because the production of protons is one of the main mechanisms responsible for mineral weathering, our results suggest that certain tree species have developed indirect strategies for mineral weathering in nutrient-poor soils, which lie in the selection of bacterial communities with efficient mineral weathering potentials<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Aunque por la noticia que vamos a tratar no lo parezca, desde hace d\u00e9cadas la mayor parte de los estudios relacionados con el tema muestran que la abundancia y diversidad de especies es mayor en los suelos bajo fag\u00e1ceas (como robles y hayas) que en el caso de las con\u00edferas. Tambi\u00e9n ocurre lo mismo con la humificaci\u00f3n de la materia org\u00e1nica, por no hablar de grupos tr\u00f3ficos de organismos y actividades enzim\u00e1ticas. Tanto es as\u00ed que cuando en una antigua nomenclatura se hablaba de especies mejorantes y acidificantes del medio ed\u00e1fico, se inclu\u00eda a las fag\u00e1ceas entre las primeras y\u2026<\/p>\n","protected":false},"author":26,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0},"categories":[596,608,590,612,613,600],"tags":[2536,2537,2539,2538,46895],"blocksy_meta":{"styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":4}},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/137361"}],"collection":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/users\/26"}],"replies":[{"embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/comments?post=137361"}],"version-history":[{"count":7,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/137361\/revisions"}],"predecessor-version":[{"id":137749,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/137361\/revisions\/137749"}],"wp:attachment":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/media?parent=137361"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/categories?post=137361"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/tags?post=137361"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}