Small habitats matter for biodiversity

With the planet’s biodiversity crisis putting up to half a million species at risk of extinction, conservationists aren’t sure whether to focus efforts and resources on protecting large, wild habitats or those that are fragmented and degraded.

An analysis published in the journal Proceedings of the National Academy of Sciences now reveals that both are important, identifying valuable habitats in untouched and human-dominated environments.

Habitats are key to saving species, says lead author Karel Mokany from Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO). 

“Averting this extinction crisis requires us to retain and protect high-value habitats for biodiversity,” he explains. “Habitat is where species live – without habitat, species go extinct.”

Biodiversity loss, in turn, has far-reaching impacts on ecosystems and human wellbeing.

Humans have left a hefty footprint on the planet, dominating more than half the world’s land area with cities, intensive agriculture, population density, roads and other means of transport, along with hunting and invasive species introduction. 

To identify high-value biodiversity habitats around the globe, Mokany’s team collaborated with the Wildlife Conservation Society to harness recent advances in large data streams, computing, biodiversity modelling and assessment.

This includes a newly developed global biodiversity assessment system called BILBI. 

“We combined global datasets on habitat condition and spatial biodiversity patterns to identify the value of habitat for retaining biodiversity,” Mokany says, “for every location on the land surface of the Earth.”

They define high-value habitats as “locations which are in better condition than more than half of the areas expected to have supported a similar assemblage of species, and, hence, they cover approximately half the land surface of the planet”.

This essentially means habitats that are in the best condition to sustain the greatest diversity of species, which naturally live in different environments.

The uniquely broad analysis included data for more than 400,000 species of plants, vertebrates and arthropods. 

It confirmed that large untouched areas are important for biodiversity conservation, while partly damaged, fragmented environments are also critical for sustaining species that have lost large chunks of their homes.

“While not obvious at the global scale,” the authors write, “most heavily impacted regions contain very small areas of high-value habitat that is important for biodiversity conservation.”

“Some places in good condition support suites of species that have suffered habitat loss/degradation across most of their range,” Mokany explains.

An example is tropical forests of southeast Asia, which have endured considerable degradation but still have unique biodiversity that can be preserved.

Having identified the most valuable habitats, the team found that only 18.6% are protected globally. Channelling efforts to the regions identified would help meet international biodiversity goals.

The finding is timely as the world’s nations gear up to adopt a new post-2020 biodiversity framework under the Convention on Biological Diversity, with the goal of “Living in harmony with nature” by 2050.

“It’s really important that these targets are well formulated and informed by the best available science,” says Mokany, to provide guidance “on which areas are critical to retain and protect if we are to avert the current species extinction crisis”.