A new study performed by scientists at the Western Sydney University in Australia raised questions about the ability of trees to offset carbon emissions. It discovered that common trees could not store as much carbon as it had been thought before.
Thus, the scientists wondered if the solution to severe carbon emissions is indeed the planting of more trees. The research looked at the iconic forests of eucalyptus in Australia and found that they need certain nutrients in the soil to grow and absorb more carbon dioxide from the atmosphere.
Thus, the study is important for the many models used by the international climate agencies. These suggest the fact the rising rates of carbon dioxide in the air can fertilize the trees, provide a more abundant growth and a better capturing of the carbon dioxide from the atmosphere.
Professor David Ellsworth explained how important is climate change modelling, and the fact that people may much attention to the predictions on how much carbon can the trees store.
The data for these reports and models is taken mainly from temperate forests, where the quantity of nutrients is enough for the trees. Thus, the estimations do not account for the impact of a shortage of nutrients on the productivity of the forest.
Many tropical and sub-tropical forests have soils low on nutrients, therefore the estimations of the CO2 storage in these forests might be too high.
The research was conducted at the Hawkesbury Institute for the Environment of the Western University of Sydney. The institute hosts the only Free Air CO2 Experiment in the native woodlands. Here, large parts of eucalypt forests are exposed to elevated levels of CO2 at 550 ppm.
The researchers discovered that the photosynthesis levels increased by 19 percent at higher concentrations of CO2, but there was no increase in wood, stems, and leaves. The experiment was conducted over a period of three years.
However, there was an increase in trees when, besides the elevated CO2 levels, the researchers added phosphorus as a nutrient. Unfortunately, soils in Australia are quite old and withered, and they no longer contain the required nutrients.
The levels of carbon in the atmosphere are continuously rising and, in 30 to 50 years, they might cause drastic changes in our climate. At such rates, Australian forests might not be able to benefit from all the carbon in the atmosphere and help with its reduction.
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