premise: Ecosystem of Zambia's Victoria Falls is under serious threat from an invasive alien species (IAS) of weed called Lantana Camara, a conservationist has warned.
  The situation was very serious as the weed was killing off natural vegetation, Geoffrey Howard, eastern Africa regional program coordinator of International Union of Conservation of Nature (IUCN) was quoted by Saturday's The Post as saying.
  Lantana is regarded as one of the worst weeds because of its invasiveness, its potential to spread and its subsequent economic and environmental impact, according to Howard.
  The weed is a serious threat to biodiversity in several World Heritage-listed areas and poses a problem in gardens because it can cross-pollinate with weed varieties to create new, more resilient forms, he added.
  Howard said if left unattended to, the weed could become the dominant vegetation in the Victoria Falls area and that the other plant species were in danger of becoming extinct.
   Why was the public warned by the conservationist?
hypothesis: Ecosystem of Zambia's Victoria Falls is under serious threat