More than 30 years ago, wilderness areas – natural areas that have not been considerably modified by humans – were identified as priorities of conservation and protection actions. Only recently has there been a push to define how to measure wilderness, with a focus on intact habitats.
Currently, there is no common definition of intactness. Past assessments, which focused on mapping human influence on habitat intactness, created maps of anthropogenic impact that independently estimated that between 20% and 40% of the planet’s terrestrial surface remains free from major human disturbance (such as human settlements, roads, and light and noise pollution).
In the new study, Plumptre and colleagues took a different approach. Instead of focusing on human impact, they made a scoping of Key Biodiversity Areas (KBA) Criterion C sites, which states that an intact ecological community has the full complement of species known to occur in a particular site in their natural abundances (ie no known loss of animals in that area), relative to a regionally appropriate benchmark. As a benchmark, the authors chose the year 1500 CE, as this is the baseline date for assessing species extinctions within the IUCN Red List of Threatened Species. In addition to habitat intactness, the authors also assessed faunal intactness (ie, without any loss of animal species) and functional intactness (no loss of animal densities below a level that would affect the healthy functioning of an ecosystem).
The authors explored how applying these 3 measures of intactness reduces the number of sites that might qualify under KBA Criterion C. They found that only between 2% an 3% of Earth’s terrestrial surface qualifies if Criterion C is defined as sites which are functionally intact, 10 times lower than previously estimated. Worryingly, only 11% of the measured sites are covered by protected areas. Many of the identified areas coincide with territories managed by indigenous communities, who play a crucial role in maintaining them.
However, there is hope. The authors say that up to 20% of the planet’s land surface could be restored to faunal intactness through reintroductions of only a few species into remaining intact habitat.
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Source: EurekAlert!
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