Invasive Alien plants can threaten water supply

Invasive Alien plants can threaten water supply

Subject: Environment

Section: Space  

Context: The study predicted that clearing catchment areas fully infested with mature invasive alien trees can increase streamflow by between 15.1% and 29.5%.

Alien species and water Supply

• To find out how much alien trees threaten water supply, a hydrological study was conducted. The researchers set up the most fine-scale, detailed models possible to try and estimate how alien trees affect stream flow in four small mountain catchments above some of Cape Town’s major dams.
• The models predicted that clearing catchment areas fully infested with mature invasive alien trees can increase stream flow by between 15.1% and 29.5%.
• The study also found that stream flow gains from clearing alien trees from rivers were almost twice as high as clearing the alien trees from the surrounding land. That’s because alien trees in rivers have access to an almost endless water supply and so use more.

What are invasive Alien Species (IAS):

• An alien species is a species introduced outside its normal distribution.
• An alien species becomes ‘invasive’ when they are introduced deliberately or accidentally outside their natural areas, where they out-compete the native species and upset the ecological balance.
• Invasive alien species (IAS) are animals, plants or other organisms that are introduced into places outside their natural range, negatively impacting native biodiversity, ecosystem services or human well-being.
• The most common characteristics of invasive species are
  • rapid reproduction and growth,
  • high dispersal ability,
  • ability to survive on various food types, and in a wide range of environmental conditions and
  • the ability to adapt physiologically to new conditions, called phenotypic plasticity.
• The alien invasive species are non-native to an ecosystem. They may cause economic or environmental harm or even adversely affect human health.
• IAS are the most common threat to amphibians, reptiles and mammals on The IUCN Red List; they may lead to changes in the structure and composition of ecosystems detrimentally affecting ecosystem services, human economy and well being. IAS are such a problem that Aichi Biodiversity Target 9 and one clause of UN Sustainable Development Goal 15 – Life on Land specifically address the issue.