Africa's savannahs may all change into forests before the turn of the century due to excess CO2 in the atmosphere
A study suggests that some of Africa's savannahs - large areas sparse vegetation other than grass - may become forests by the end of the century.
Research from The Biodiversity and Climate Research Centre and the Goethe University Frankfurt suggests that a build-up of carbon dioxide in the soil will force an increase of tree cover throughout Africa.
When CO2 in the air and soil reaches a certain density, it forces trees to increase their size and foliage, meaning the open-sky savannahs may end up with a tree canopy.
The savannahs may change to forests within 100 years, according to new research which believes CO2 may lead to rapid tree growth
Because each site has an individual 'threshold', it is likely that separate savannahs will begin to change at different times, by many of them will switch before 2100, according to the researchers.
According to Science Daily, experimental studies show that plants do not show a large response to CO2 fertilisation.
But Steven Higgins, lead author of the study, said: 'Most of these studies were conducted in northern ecosystems or on commercially important species.
'In fact, only one experimental study has investigated how savanna plants will respond to changing CO2 concentrations and this study showed that savanna trees were essentially CO2 starved under pre-industrial CO2 concentrations, and that their growth really starts taking off at the CO2 concentrations we are currently experiencing.'
The savannahs of Africa are generally grassland with some trees - but they may be forests within 100 years.
Some theorists call this abrupt switch a 'catastrophic regime shift', where a big switchover happens rapidly. These are normally caused by small changes in the area's regulation systems, but the small changes have a 'butterfly effect', where large-scale processes are set into motion.
The study found that locations where the temperature rise associated with climate change occurs rapidly, for example in the center of southern Africa, will switch to forests later as there is a high rate of temperature increase, which means the savanna grasses can remain competitive for longer.
This means that areas will adjust over differing time-scales, which will reduce shocks to the biosphere. While the changes will be a 'catastrophic regime change' for the area, when the change is averaged over the area, it will be smoother and more gradual..
Higgins said: 'While this may seem reassuring, we have to bear in mind that these changes are still rapid when viewed on geological time scales.'
Source: Daily Mail (29 June 2012)