Groundwater depletion could 'damage woodlands'

Woodlands around the world could be at risk due to the over-extraction of groundwater, according to scientists at Australia's National centre for Groundwater Research and Training (NCGRT). Even if forests and woodlands are in countries that have wetter climates, extracting large amounts of groundwater can result in trees dying due to the lack of water available for them to drink.

According to the research, trees that live in areas with wetter climes could be more at risk of groundwater over-extraction as they are more sensitive to changes in water demands. Professor Derek Eamus, of NCGRT and the University Technology of Sydney (UTS), said that trees in wetter climates could be less likely to survive than those in semi-dry environments because of their increased sensitivity to water stress.

Estimations currently suggest that around 1,000 cubic kilometers of groundwater are extracted each year from around the world. Many regions suffer from water shortages as the amount of water they remove from the ground is more than rain can replenish, leaving reserves in short supply. 

If areas tend to have heavy rainfall their water tables are quite shallow as they are replenished on a regular basis. These water tables are used to feed forests and woodlands and so if groundwater extraction has left them depleted, the trees and plants in these areas will suffer. In comparison to trees in dryer areas, those that are from wetter environments are unable to cope with low water supplies. 

Dr Sepideh Zolfaghar, one of the researchers within the study, said: "[The trees have] grown in an environment where water supply is continuous and plentiful, so they haven't evolved to cope with droughts. Trees in dry areas, in comparison, have developed drought resistance and are more resilient." 

The continued depletion of groundwater sources around the world could lead to the mass death of trees in woodland environments, which could be detrimental to air quality as they help to absorb carbon dioxide from the atmosphere.