Eucalyptus
Eucalypts draw a very large amount of water from the soil. They have been planted (or re-planted) in some places to lower the water table and reduce the amount of salt in the soil. Eucalypts have also been used as a way of reducing malaria by draining the soil in such places as Algeria, Sicily mainland Europe and California. Drainage removes swamps which provide a habitat for mosquito larvae, but such drainage can also destroy harmless habitats by accident.