Global areas of low human impact (‘Low Impact Areas’) and fragmentation of the natural world

Habitat loss and fragmentation due to human activities is the leading
cause of the loss of biodiversity and ecosystem services. protected areas
are the primary response to this challenge and are
the cornerstone of biodiversity conservation efforts. Roughly 15%
of land is currently protected although there is momentum to dramatically
raise protected area targets towards 50%. But, how much land remains in a
natural state? We answer this critical question by using open-access,
frequently updated data sets on terrestrial human impacts to create a new
categorical map of global human influence (‘Low Impact Areas’) at a 1
km2 resolution. We found that 56% of the terrestrial surface,
minus permanent ice and snow, currently has low human impact.
This suggests that increased protected area targets could be met in areas
minimally impacted by people, although there is substantial variation
across ecoregions and biomes. While habitat loss is well documented,
habitat fragmentation and differences infragmentation rates between biomes
has received little attention. Low impact Areas uniquely
enabled us to calculate global fragmentation rates across biomes,
and we compared these to an idealized globe with no human-caused
fragmentation. The land in Low Impact Areas is heavily fragmented,
compromised by reduced patch size and core area, and exposed to edge
effects. Tropical dry forests and temperate grasslands are the
world’s most impacted biomes. We demonstrate that when
habitatfragmentation is considered in addition to habitat loss, the
world’s species, ecosystems and associated services are in worse
condition than previously reported.