Tag : Phosphorus

Washington: Growth of the Amazon rainforest in our increasingly carbon-rich atmosphere could be limited by a lack of phosphorus in the soil, new research shows. Higher concentrations of carbon dioxide (CO2) cause plants to grow more quickly, meaning they store more carbon. This storage -- especially in huge forests like the Amazon -- helps to limit rising CO2 levels, slowing climate change. However, plants also need nutrients to grow, and the new study shows that the availability of a particular nutrient, phosphorus, could limit the Amazon's ability to increase productivity (growth rate) as CO2 rises. This could also make the rainforest less resilient to climate change, the researchers warn. The study, published in the journal Nature, was carried out by an international team led by Brazil's National Institute of Amazonian Research (INPA) and the University of Exeter. "Our results question the potential for current high rates of carbon uptake in Amazonia to be maintained" said lead author Hellen Fernanda Viana Cunha, from INPA. "About 60% of the Amazon basin is on old soils with low phosphorus content, but the role of phosphorus in controlling productivity was unclear because most fertilisation experiments in other parts of the world have been in more phosphorus-rich systems. "Our experiment, the Amazon Fertilisation Experiment (AFEX), examined the effects of adding phosphorus, nitrogen and base cations (other potentially key nutrients) in an old-growth, low-phosphorus area of the rainforest. "Only phosphorus led to increased productivity in the first two years of the experiment. "Having such rapid and strong responses to phosphorus, both above and below ground, is an indication that the whole system was functioning under seve ...