Filling the gaps.

How can we keep plants and animals off the endangered list? Put them on the map!

Imagine a vast, open Idaho field. Lots of sky, no houses, no people. Sound like an ideal bomb-testing site? The U.S. military thought so--until they checked with Michael Scott, a research biologist at the U.S. Fish and Wildlife Service. The site, which looked relatively lifeless at first glance, was actually rich in plant and animal species, Scott told them.

To make his case, Scott displayed a series of maps that could be stacked on top of each other using computer graphics. Each map revealed something different about the site. The first map, for instance, used green splotches to show the locations of all the major plant species in the area. Red blobs on the second map showed where all the animal species lived.

Next, Scott sandwiched the maps together to show where the plant and animal species overlapped. The dark swaths of color were enough to convince the military that if they went ahead with their tests, they'd be destroying a habitat teeming with life. End of case, but not the end of the story.

Now the question was how to prevent future threats from other people interested in using the land, such as housing developers. For that, the site would have to be designated a protected area.

That's where Scott's third map proved useful. Here, Scott used purple to show the parts of the site that were already protected as government-designated wilderness areas, for example.

When Scott layered the third map on top of the others, he found that things didn't quite add up. Many of the species (green and red) fell outside the protected areas (purple). To ensure the species' future, the gaps would have to be filled.

How? One way: Buy private land and add it to existing preserves. Or, connect the preserves using land bridges--areas where animals can safely pass from one region to the next.

SAGE REMARKS

The process of mapping species and their habitats, and using that information to make the best use of land, is called gap analysis. "Gap analysis makes people look at the big picture," Scott says. Instead of trying to save species one by one after they've become endangered, gap analysis attempts to protect a large variety of species before they ever near the brink. This strategy helps ensure that species common today are still plentiful 100 years from now, Scott says.

Twenty-two states are now using gap analysis programs to ensure the future preservation of their native species. California, a state with about 800 plant and animal species in peril, hopes to complete its gap maps next year.

One California habitat that may benefit from new preserves created through gap analysis is coastal sage scrub. "The scrub used to be common, but now it's a rare habitat type," explains biologists Peter Stine. "In Los Angeles, it's 70 to 90 percent gone." People tore it up and paved it over as they settled the West Coast. By analyzing maps of the area, Stine could see that the remaining scrub lies on private or military lands, areas that continue to be developed at the expense of sage scrub habitat.

As the sage vanishes, so do the animals that depend on it for survival. For example, the California gnatcatcher, a bird that nests in the scrub, is close to being endangered (see photo, p. 15). Efforts are now underway to figure out how to stop further destruction of its habitat.

BUILDING BRIDGES

Gap programs don't just set the stage to save species. They can also bridge gaps among people. For instance, conservation groups and developers are often bitter enemies when it comes to managing land. But gap maps can settle disputes long before the accusations, editorials, and lawsuits begin. How? The interested parties can set aside for protection lands that are the richest in species, and likewise, build on lands with the lowest concentration of species. Working side by side, the groups can not only save species, but lots of time and money, as well.

To show its commitment to conservation, the Hofmann company, a homebuilding firm, provided half the initial funds for California's gap program. With gap analysis, says company spokesman Dan Boatwright, we can look down the road and come up with solutions before problems ever develop.