Wednesday, 4 January 2012

On the benefits of forests: Regulation of surface temperature

Forest, Amazon Basin. Copyright Bolivian Ministry of Culture
Acerca de los beneficios de los bosques: Regulación de la temperatura de la superficie

...forests are fundamental to regulate surface temperatures; they should be considered to have the potential to become powerful countermeasures against the adverse potential impacts of climate change.

Trees are fundamental elements of our ecosystems. Yesterday, The Guardian published a press article on it, where they collect the opinion of the French botanist Francis Hallé. The botanist points out the benefits of trees along the following phrases:
1. "The history of our zoological species can be found in the life of a tree", and let´s not forget "the underground activity, the size and strength of the roots, and the many species that live in symbiosis with it".

2. "trees silently elude their enemies by developing an arsenal of chemicals"; they produce "molecules to keep mice and insects at bay and in doing so provide man with, e.g., taxol, an efficient anti-cancer drug",

3. "the oxygen that allows us to live" is produced by the arboreal photosynthesis, which simultaneously is "our best ally in the fight against global warming", why? because woods store "quantities of carbon dioxide, responsible for greenhouse gases, and between 20% and 50% of matter produced by the tree, including wood, roots, leaves and fruit, is composed of CO2. When trees breathe they clean the atmosphere and retain CO2 and urban pollutants such as heavy metals, lead, manganese, industrial soot and nitrous oxide". "The UN believes that tree planting could offset 15% of carbon emissions in the first half of the 21st century", the article says.

4. trees "humidify and cool the atmosphere by evaporation and transpiration". "A wooded area of 50 square meters brings the temperature down by 3.5C and increases the humidity by 50%". Moreover, "Urban trees are vital in preserving the soil, containing floods, providing energy and producing healthy foodstuffs. They make cities cooler and more pleasant", adds Julien Custot, FAO adviser.

The two latter are one of the most amazing benefits of forests to the preservation of the hydro-environmental system that gives us shelter. Would you like a proof? I will give you one by demonstrating how fundamental forests are to regulate surface temperatures; they should be considered to have the potential to become powerful countermeasure against the adverse potential impacts of climate change. Let me share with you one of the findings of my research (Soria, 2010) where I used remotely sensed imagery to investigate the impacts of global warming in mountains.

Copyright Soria (2010).
The findings are summarized in the graph above. Each line shows the trends of historic remotely sensed images of surface temperature taken at different altitudes along a tropical forest downstream the Andes in Bolivia, and show how dramatic the increase in surface temperature has been in the last 30 years. At high elevations, where bare soil is characteristic (the tree line is at about 3600m above sea level), the increase in surface temperature has been up to 0.174C per year, whereas at lower elevations, the trends in temperature have been relatively stagnant. The time span shown is 1984-2008 (time scale in years). What about the uncertainties? The data has not yet been measured on site (limited funds), therefore the ciphers are merely indicative; the enormous increase in 0.385C per year is incredibly high because such points were once covered by glaciers/ice/snow; it is possible that the uncertainties at sites not covered by forests are higher than those at forest-covered sites, because of the noise introduced to the signal by the brightness reflected by the bare soil. Besides that, the results are still interesting, demonstrating the priceless value of forest in our ecosystems.

- The contribution of trees to our lives: it is time to take stock, by
- Streamflow and runoff responses to climate change in high elevation watersheds, by F. Soria (2010), Phd Thesis.

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