{"id":140789,"date":"2012-07-10T13:06:03","date_gmt":"2012-07-10T12:06:03","guid":{"rendered":"http:\/\/www.madrimasd.org\/blogs\/universo\/?p=140789"},"modified":"2012-07-10T13:06:03","modified_gmt":"2012-07-10T12:06:03","slug":"deposiciones-de-nitrogeno-en-los-suelos-de-los-bosques-tropicales-otro-reto-para-la-mantener-la-biodiversidad","status":"publish","type":"post","link":"https:\/\/www.madrimasd.org\/blogs\/universo\/2012\/07\/10\/140789","title":{"rendered":"Deposiciones de nitr\u00f3geno en los suelos de los bosques tropicales: Otro reto para la Mantener la biodiversidad"},"content":{"rendered":"

Mediante la sobrefertilizaci\u00f3n y otras pr\u00e1cticas industriales hemos ido incrementando la concentraci\u00f3n de<\/strong> <\/span>nitr\u00f3geno reactivo<\/a> en la atm\u00f3sfera<\/strong>, incidiendo sobre el calentamiento de la \u00faltima<\/strong><\/span>. Tal proceso, \u201cno parece aumentar la asimilaci\u00f3n del carbono atmosf\u00e9rico<\/strong><\/span>\u201d, como la ciencia presupon\u00eda. Muy por el contrario, la incorporaci\u00f3n del nitr\u00f3geno al suelo termina por alterar la composici\u00f3n de las comunidades microbianas que alberga, la qu\u00edmica del medio ed\u00e1fico y la composici\u00f3n de los ecosistemas<\/strong><\/span>. Finalmente, mientras el \u00f3xido nitroso retorna a la atm\u00f3sfera, las plantas asociadas a las especies de microorganismos que lo fijan,\u00a0u otras especies de bacterias que lo hacen libremente, se encuentran en desventaja competitiva, pudiendo terminar por extinguirse<\/strong><\/span>. A \u00a0larga, cuando bajen tales deposiciones los ecosistemas afectados padecer\u00e1n m\u00e1s dificultades con vistas a obtener esta mol\u00e9cula de forma bioasimilable<\/strong><\/span>. Como ya os narramos en otro post, tal alteraci\u00f3n perniciosa del ciclo del nitr\u00f3geno, ha sido bien documentada en los bosques, prados y pastos bajo clima templado<\/strong><\/span>. \u00a0La noticia de hoy nos da cuenta que lo mismo parece estar ocurriendo en los bosques tropicales<\/strong> <\/span>de Panam\u00e1, Brasil y el SE asi\u00e1tico. \u00a0Se trata de una fertilizaci\u00f3n contaminante que puede terminar por hacer desaparecer numerosas especies arb\u00f3reas tropicales fijadoras de este elemento<\/strong><\/span>, como las fab\u00e1ceas<\/a>. Y mientras tanto, nuestra sociedad industrial persiste en seguir incrementando sus concentraciones en la atm\u00f3sfera. Ya sabemos sobradamente que la contaminaci\u00f3n emitida por los pa\u00edses industrializados perjudica la biodiversidad a miles de kil\u00f3metros de distancia. Y as\u00ed, actualmente, los suelos tropicales pueden haber triplicado las emisiones de<\/strong><\/span>\u00a0\u00a0nitr\u00f3geno reactivo<\/a> a la atm\u00f3sfera<\/strong><\/span>, fomentando el cambio clim\u00e1tico. \u00bfOtra forma de bioterrorismo industrial?<\/strong><\/span><\/p>\n

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

\"bosque-fertilizado-por-nitogeno-sciende-daily-tropical-forest-in-panama-credit-alfredo-maiquez\"<\/p>\n

Deposici\u00f3n de nitr\u00f3geno en el suelo y p\u00e9rdida de biodiversidad de los bosques tropicales (Panam\u00e1). Fuente ScienceDaily Credito: Alfredo Maiquez<\/a><\/p>\n

<\/p>\n

Post Precedente sobre el tema<\/strong><\/span>:<\/p>\n

Suelos Forestales, Nitr\u00f3geno Reactivo y Cambio Clim\u00e1tico<\/a><\/p>\n

Tropical Forests Fertilized by Nitrogen Air Pollution, Scientists Find<\/a><\/h3>\n

ScienceDaily (<\/strong>Nov. 3, 2011<\/strong>)<\/strong> <\/span>\u2014 Scientists braved ticks and a tiger to discover how human activities have perturbed the nitrogen cycle in tropical forests<\/strong>. Studies at two remote Smithsonian Institution Global Earth Observatory sites in Panama and Thailand<\/strong> show the first evidence of long-term effects of nitrogen pollution in tropical trees.<\/strong><\/p>\n

\u00abAir pollution is fertilizing tropical forests with one of the most important nutrients for growth<\/strong>,\u00bb said S. Joseph Wright, staff scientist at the Smithsonian Tropical Research Institute in Panama. \u00abWe compared nitrogen in leaves from dried specimens collected in 1968 with nitrogen in samples of new leaves collected in 2007. Leaf nitrogen concentration and the proportion of heavy to light nitrogen isotopes increased in the last 40 years, just as they did in another experiment when we applied fertilizer to the forest floor<\/strong>.\u00bb<\/p>\n

Nitrogen is an element created in stars under high temperatures and pressures. Under normal conditions, it is a colorless, odorless gas that does not readily react with other substances. Air consists of more than 75% nitrogen. But nitrogen also plays a big role in life as an essential component of proteins<\/strong>. When nitrogen gas is zapped by lightning, or absorbed by soil bacteria called \u00abnitrogen fixers,\u00bb<\/strong> it is converted into other \u00abactive\u00bb forms that can be used by animals and plants. Humans fix nitrogen by the Haber process, which converts nitrogen gas into ammonia — now a principal ingredient in fertilizers. Today, nitrogen fixation by humans has approximately doubled the amount of reactive nitrogen emitted.<\/strong><\/p>\n

Nitrogen comes in two forms or isotopes<\/strong>: atoms that have the same number of protons but different numbers of neutrons. In the case of nitrogen, the isotopes are 14N and 15N, although only about one in 300 nitrogen atoms is the heavier form. Imagine nitrogen in the ecosystem like a bowl of popcorn. Normally the ratio of popped (light) to unpopped (heavy) kernels stays the same, but when someone starts to eat the popcorn, the lighter, popped kernels get used up first, increasing the ratio of heavy to light kernels (or 15N\/14N<\/strong> in the case of the ecosystem). Light nitrogen is lost through nitrate leaching and as gases such as N2<\/sub>, and various forms of nitrous oxides or \u00abnoxides,\u00bb some of which can be important greenhouse gases<\/strong>. In the fertilization study in <\/strong>Panama<\/strong>, mentioned earlier, N2<\/sub>O emissions were tripled<\/strong>.<\/p>\n

\u00abTree rings provide a handy timeline for measuring changes in wood nitrogen content<\/strong>,\u00bb said Peter Hietz from the Institute of Botany at the University of Natural Resources and Life Sciences in Vienna, who faced down a tiger when sampling trees in a monsoon forest on the Thailand-Myanmar border<\/strong>. \u00abWe find that over the last century, there’s an increase in the heavier form of nitrogen over the lighter form, which tells us that there is more nitrogen going into this system and higher losses<\/strong>. We also got the same result<\/strong> in an earlier study of tree rings in Brazilian rainforests<\/strong>, so it looks like nitrogen fixed by humans now affects some of the most remote areas in the world<\/strong>.\u00bb<\/p>\n

\u00abThe results have a number of important implications,\u00bb said Ben Turner, staff scientist at STRI. \u00abThe most obvious is for trees in the bean family (Fabaceae), a major group in tropical forests that fix their own nitrogen in association with soil bacteria<\/strong>. Increased nitrogen from outside could take away their competitive advantage and make them less common, changing the composition of tree communities<\/strong>.\u00bb<\/p>\n

\u00abThere are also implications for global change <\/strong>models, which are beginning to include nitrogen availability as a factor affecting the response of plants to increasing atmospheric carbon dioxide concentrations<\/strong>,\u00bb said Turner. \u00abMost models assume that higher nitrogen equals more plant growth, which would remove carbon from the atmosphere and offset future warming. However a challenge for the models is that there is no evidence that trees are growing faster<\/strong> in <\/strong>Panama<\/strong>, despite the long-term increases in nitrogen deposition and atmospheric carbon dioxide<\/strong>.\u00bb<\/p>\n

Decades of atmospheric nitrogen deposition have caused major changes in the plants and soils of temperate forests in the U.S. and Europe<\/strong>. Whether tropical forests will face similar consequences is an important question for future research.<\/p>\n","protected":false},"excerpt":{"rendered":"

Mediante la sobrefertilizaci\u00f3n y otras pr\u00e1cticas industriales hemos ido incrementando la concentraci\u00f3n de nitr\u00f3geno reactivo en la atm\u00f3sfera, incidiendo sobre el calentamiento de la \u00faltima. Tal proceso, \u201cno parece aumentar la asimilaci\u00f3n del carbono atmosf\u00e9rico\u201d, como la ciencia presupon\u00eda. Muy por el contrario, la incorporaci\u00f3n del nitr\u00f3geno al suelo termina por alterar la composici\u00f3n de las comunidades microbianas que alberga, la qu\u00edmica del medio ed\u00e1fico y la composici\u00f3n de los ecosistemas. Finalmente, mientras el \u00f3xido nitroso retorna a la atm\u00f3sfera, las plantas asociadas a las especies de microorganismos que lo fijan,\u00a0u otras especies de bacterias que lo hacen libremente, se\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":[596,594,618,613,589,600,595],"tags":[46737,47182,47183,47185,47184],"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\/140789"}],"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=140789"}],"version-history":[{"count":6,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/140789\/revisions"}],"predecessor-version":[{"id":142430,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/140789\/revisions\/142430"}],"wp:attachment":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/media?parent=140789"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/categories?post=140789"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/tags?post=140789"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}