“If you can't measure it, you can't manage it” is, as with all such well-worn phrases, only partly true. But to adapt another such maxim, while we might be able to make progress without measurement, we do need proof to satisfy everyone else.
The use and popularity of Google Earth has grown tremendously since its launch, and it has a range of uses from mapping and viewing mountain bike routes to monitoring chimpanzee forest habitat. However, Google Earth had no formal recognition or guidelines for its use in the field of invasion science, despite the fact that many scientists and managers use it on a regular basis.
Alien trees offer several benefits to the people of South Africa, often as welcoming features of gardens, parks and streets, and as sources of food and timber. Despite the benefits gained from alien trees, a small number of these trees can become invasive and can cause harm to the ecosystems they invade.
Scale-area curves have been used in conservation science as an affordable means of identifying shrinking populations that need protection. Invasions are the result of populations of invasive species that are spreading and becoming dominant in areas to which they have been introduced.
Freshwater fish invasions are a major source of environmental homogenisation around the world; unique species assemblages are increasingly being overwhelmed by large numbers of introduced species. While active human-mediated introductions contribute to this process, there are also many passive pathways of fish introductions.
