At first glance it looks like a piece of artwork, someone's psychedelic dream perhaps. Fingers of emerald green lace across the paper, while patterns of hot pink, intense blue and lime green create a mosaic of colour.

But in fact, this is not just a free-form riot of colour, it is a map; more specifically the Southern Lakes Earth Cover Field Map. Generated from a satellite image, it shows 3.8 million hectares of land in the Whitehorse area.

The vivid colours represent a slice of reality, indicating rock and ice, water and trees; shrubs and wetlands. The problem is, it is not an exact slice.

"You cannot map reality. It is just too hard," says Val Loewen, a vegetation specialist with the Yukon Department of Renewable Resources.

Loewen is one of the people making sure that biologists and resource managers can squeeze as much information out of this map as possible. Then it can be used to pinpoint areas with good habitat for caribou, moose and other wildlife, protecting that habitat when necessary.

But right now, it is estimated that the map is around 80 percent accurate, and it stands as a good example of both the advantages and pitfalls of new technology.

Generated through a joint project with Ducks Unlimited, the groundwork for this map was laid on August 1, 1999, when a Landsat satellite -- orbiting 705 kilometres above the Earth -- snapped a cloud-free shot of this 185 by 175 kilometre section of land.

In the days before cartographers began to work with satellite images, they made maps from aerial photographs, spending countless hours staring through stereoscopes. Much of the accuracy of these maps depended upon the talents of the individual mappers.

Satellite image maps are less expensive to make than ones from aerial photographs as computers do much of the work. The problem is, to a computer dealing with a stream of data, sometimes a dry area with shrub birch and lichen can look identical to a wet tussock meadow.

Remote sensing instruments on board the satellite gather the information for the images, and they "see" nothing but reflected light. Many different wavelengths of light hit the earth and then bounce back into space, where they are recorded by the satellite passing overhead.

The satellite measures the light in seven discrete portions or bands of the electromagnetic spectrum, and an enhanced image is made with this information. The mapmakers can choose the particular band of light that is best at showing certain features; infrared wavelengths, for example, are usually used for vegetation.

After that, the real work of building a map begins, and this is where human expertise comes back into play. The first step is to pick out coloured areas that look like they show "a big chunk of the same thing." Then it is time for humans to head out into the field, and figure out what the colours on the map really mean.

"The whole effort involves taking samples of vegetation, rock, ice, snow and then going back and telling the computer 'This is rock and this is snow,' and then matching it with a reflective value. But when you get into the vegetation it gets tougher," says Loewen.

You have different kinds of trees, with different ages, canopies and understories, and that will all affect reflective values."

They checked almost 500 sites for the project, but Loewen says that number is not particularly high since there were so many different types of vegetation to separate out.

Around wetlands, for example, the vegetation tends to grow in long thin bands that do not show up distinctly on a satellite image. Instead the computer can mush the different reflective values around the wetland together, producing a mixed value that could look like something else entirely.

"So they get all confused values and that confusion might look like a totally different vegetation type," she says.

This is not the Yukon's first satellite mapping project. Since the early 1990s maps have been produced for the range of the Porcupine Caribou Herd, the northern Richardson Mountains and the coastal plain, and work is now underway on a map for the region around the Bonnet Plume River.

For the Southern Lakes project, the expertise of Ducks Unlimited (DU) was an advantage as this group has been mapping areas of the boreal forest in Alaska since 1988. DU is particularly interested in finding out as much as possible about boreal forest wetlands in the area.

The Canadian Wildlife Service also helped with the project, surveying waterfowl on a sample of wetlands in the area. The Yukon Energy Corporation and the Fish and Wildlife Enhancement Trust pitched in money as well.

As well as their lower cost, one of the big advantages of the digital satellite image maps is that certain types of habitat can be quantified. For example, caribou depend upon pine forests where lichens grow, and the computer can tell you exactly how much of that habitat exists in a certain area. Then that information can be used to guide development in the region.

"It is good to have the hard numbers; good to be able to say only 5 percent of the area is pine-lichen habitat so we need to protect that," says Loewen.

And, this job will become easier as technology improves, and computers are better able to tell one type of habitat from another.

For more information, contact Val Loewen at 667-5281 or Marcus Waterreus, a habitat technician in the department, at 667-3739.