THE disused quarry in Cheffois in western France doesn’t seem like it would be high on anyone’s conservation watchlist. A swampy marsh leads to a sinister-looking pit pond, guarded by a dense thicket and overhung by trees and shrubs. Above the pond, a staircase of rock walls stretches skywards, while mosses and ferns monopolise the dank, shady corners.
Although a far cry from classic nature havens like the Galapagos Islands, this somewhat uninspiring landscape could rival them in value. Not only is the quarry brimming with wildlife, including many rare and threatened species, but the secrets to its biodiversity could help save all life on our planet.
It is now widely accepted that Earth is experiencing a sixth mass extinction event. The United Nations estimates that about 1 million species are threatened, and many have already been lost to human activity. We can’t save everything, so how do we prioritise?
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Until now, the focus has been on biodiversity hotspots, locations with good habitats that support exceptional concentrations of different species. But maybe our efforts have been misguided. Instead of focusing on specific species or habitats, one of the best ways of putting the brakes on the current mass extinction may be to protect our planet’s rocks and soils: its geodiversity. They may not look like much, but neglected quarries and unloved scrubland may be key to ensuring the long-term survival of life on Earth.
This change in perspective emerged around a decade ago. Mark Anderson at a conservation charity in the US, was assessing which areas of landscape they should prioritise. “I realised that we were buying up land to protect the species living there now, but climate change impacts might mean this wouldn’t be the right place in the future,” says Anderson. That led to an epiphany. Instead of buying land with great biodiversity today, he decided to look for areas that would retain their diversity as the planet warmed.
“Unusual or contrasting geologies can stimulate evolutionary diversification”
His initial focus was on landscapes with a wide range of microclimates: places with nooks and crannies, slopes and hills, sunshine and shade, wet and dry. The thinking was that even if the climate of the region changed significantly, the local climate variability would be greater, giving species a greater chance of finding a suitable new habitat locally.
To test the idea, Anderson and his colleagues started tracking how species richness changed with landscape and climate variables across 14 US states and three Canadian provinces. They of species diversity in temperate climates could be explained by just four landscape features: number of rock types, latitude, elevation range and amount of chalk or lime bedrock. “We expected landscape to influence species diversity, but we were surprised by just how strong that link was,” says Anderson.
In retrospect, it makes good sense. Geology affects the chemical and physical properties of soil and water. As Anderson suspected, it also influences local climate via the topography it creates. The more geodiverse the underlying landscape, the greater the range of habitats and the more species a region can support. “It seems that unusual or contrasting geologies can stimulate evolutionary diversification,” says Anderson.
Changing focus to geodiversity could be beneficial in other ways. Collecting biodiversity data is time-consuming and expensive. Some of the most biodiverse areas in the world are almost certainly unrecognised and unprotected because no one has recorded what lives there. Geodiversity is easier to recognise, and getting easier all the time: Joseph Bailey, a geographer at York St John University, UK, has been working on a way to use satellite data to measure geodiversity automatically. By homing in on very geodiverse regions, we can pinpoint where our most biodiverse locations are likely to be and target our conservation efforts.
The strategy pioneered by Anderson has gradually gathered traction. He and his colleagues have now mapped geodiversity and estimated the resilience of the landscape across most of the US. The Rockies and desert areas of the south-west United States are the , which they hope to complete by the end of the year. Their work suggests that to give US wildlife the greatest chance of adapting to and surviving future climate change, around a quarter of the US landscape needs to have protected status. Thanks to the Nature Conservancy and a number of other agencies, 40 per cent of those resilient locations are already protected. Now, their focus is on the remaining 60 per cent.
Their wish list may seem surprising, with overworked farmland and dull chunks of prairie often ranking above pristine wilderness. But Anderson believes that if the land is in the right place and is underlain by the right mix of rocks, then these areas can have greater conservation value. Right at the top of the list are places that can provide corridors in the landscape, ensuring there is room for wildlife to move between habitats as the climate changes. “Our work has identified some really scary pinch points,” he says.
Disused quarries are another surprising poster child for the conservation movement. The range of gradients and variety of microclimates (hot south-facing slopes and cool, shady north-facing crannies) make for a massive range of ecological niches. A 2013 study of Cheffois found that it represents a beacon of biodiversity in an area where intensive farming practices have long threatened wildlife. Its multitude of different landforms supports 27 kinds of cricket alone, along with hundreds of plants, including rare mosses, ferns and rock-loving flowers.
The UK landscape is peppered with such sites, but many are being sold off as rubbish dumps. “The pressure to use old quarries as landfill sites is huge,” says John Faithfull at the University of Glasgow, UK. Some, such as Trearne quarry in Ayrshire, have already been stuffed full of rubbish, and others face uncertain futures. But there are success stories, too. Thanks to the campaigning efforts of geologists, two Scottish open-cast coal mines, Spireslack and Mainshill Wood, may soon become . Today, peregrine falcons nest on and hunt from Spireslack’s exposed cliffs, whilst curlews and lapwings relish the undisturbed moor and grassland nearby.
Geodiversity also applies underwater, as a recent Finnish study shows. “We found that the greater the geodiversity, the higher the aquatic plant species richness,” says Maija Toivanen from the University of Oulu.
Saving geodiversity on its own won’t save the planet. Bailey mapped plant species richness across the UK and compared it against geodiversity. He found that there was a very strong link between the two, but that there were inevitable exceptions to the rule: single geologies that bred a diversity of life. What’s more, there are also very geodiverse areas that are comparatively barren, such as high mountain environments that are rock-rich but fairly hostile places to live. “I see geodiversity as another string to the bow of conservation, rather than being something we should switch to completely,” says Bailey.
Even so, it is a string that has so far been underused. We have done a reasonable job of protecting majestic landscapes – lush islands, awe-inspiring coastlines and dramatic mountaintops – but the less photogenic pieces of land aren’t as well-loved. If we want to stop the mass extinction of life on our planet, we will need to fight it not only on the beaches and on the hills, but in the floodplains and the quarries too.
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