In a first-of-its-kind study published in the research journal Ecology Letters, scientists from The Nature Conservancy and World Wildlife Fund recently posed a deceptively simple question:
Are we losing ground?

Conservancy scientist Jonathan Hoekstra, lead author of the study, reveals the surprising answer and sheds light on why it's the habitat that counts.

Are we losing ground? Conservationists often ask this question, but what they usually mean is, are we losing species? The answer, not surprisingly, is yes — especially in places rich in species, such as tropical rain forests.

But when my colleagues and I at The Nature Conservancy and World Wildlife Fund posed the question, we meant something else entirely. We wanted to know, quite literally, the extent to which we are losing ground — the lands and waters that support life on Earth. Are we protecting the habitats that species ultimately depend on?

To answer this question, we analyzed data for 13 major terrestrial habitat types, such as boreal forests, and tropical grasslands and savannas — distinct areas defined by climate, geology and ecology. For each habitat, we compared the amount of land that has been converted (to farmland, cities and the like) with the amount of habitat that has been protected. Our analysis marked the first time anyone had compared these two measures for the entire planet.

We found that land conversion exceeds land protection in many habitats. However, the worst cases are not the usual suspects, such as rain forests, but rather little considered habitats such as temperate grasslands. In fact, of the more than 300 terrestrial regions that may be in crisis, only about 50 percent are targeted for protection by major conservation organizations.

How did entire categories of habitat fall through the gaps? For some places, the habitat loss predated the rise of the conservation movement — it was gone before we had a chance to protect it. For others, though, people simply failed to recognize the problem. For a long time, conservation groups have set priorities according to where species are most concentrated or endangered. This, in turn, focused the lion's share of attention on species-rich places like tropical rain forests, at the expense of other habitats like grasslands and estuaries, which sustain fewer species but represent equally important ecological diversity.  

But humanity has the tools to maintain healthy grasslands and estuaries — and other neglected habitats. That doesn't mean conservationists should stop working in rain forests. Rather, those efforts must be combined with a strategic investment in habitats that contain the forgotten parts of the planet's diversity.

That's what the Conservancy is working on: My team is assembling the information that will enable the organization — and partners, governments and funders — to rebalance priorities and make informed choices about where resources are most needed. The Conservancy's mission to protect the diversity of life on Earth remains the same. What's different is that suddenly we can see, better than ever, which parts of that diversity need help now.

Terrestrial Habitats Protected vs. Converted View a larger graph © The Nature Conservancy

Are We Losing Our Lands?
The world is losing key terrestrial habitats, but not the ones you might think. In tropical rain forests, for example, land conversion exceeds habitat protection by a ratio of 2 to 1. We have protected only one acre of land for every two we have lost. That's worrisome.

But in Mediterranean habitats — dry scrublands such as those found around the Mediterranean Sea, along the central and southern coasts of California, and around the tip of South Africa — the disparity is 8 to 1. We have protected only one acre of land for every eight we have lost.

And in temperate grasslands — places like the Great Plains of the United States and the Argentine pampas — we have protected only one acre for every 10 we've lost. Half of such crisis ecoregions — those habitats classified as critically endangered, endangered and vulnerable — receive little or no conservation attention.

Marine and Freshwatrer Habitats Protected. View a larger graph © The Nature Conservancy

Are We Losing Our Waters?
The world's underwater habitats are suffering astonishing losses. Although scientists can't say precisely what percentage of each freshwater and marine habitat has been converted, the overall  trends are unmistakable.

More than half of the world's 292 major river systems have been substantially fragmented by dams, but few rivers receive any protective management. Nearly half of the world's coastal mangrove forests have been destroyed, and once-extensive shellfish beds in temperate estuaries are all but gone. Yet less than 2 percent of the world's coastal waters, where these habitats occur, have been afforded protection.