It was a sunny summer's day in Whitehorse, with tourists wandering along Main Street in sandals and shorts.

But there, in the Environment Canada truck, were four of us in long pants, heavy boots, windproof jackets, carrying daypacks crammed with fleece pullovers, gloves, and woolly hats.

We were heading for the high plateau at the top of the Wolf Creek Research Basin, just a few kilometres away, to measure plants. With the wind blowing in from the ice fields of the coastal mountains, it's cold there, even under the summer sun.

In 1998, researchers from Environment Canada and the Yukon government established a site for the International Tundra Experiment, or ITEX, in the alpine tundra above Wolf Creek (see Your Yukon Column 87).

Every summer, they carefully record details about selected plants in small test plots staked out on the plateau. Some of the plots are left open to the elements; others are protected by small, open-topped greenhouses that raise the temperature by a degree or two.

The same pattern of open plots and warmed plots has been reproduced at ITEX sites around the circumpolar north since the program began in 1990. More than a dozen countries are now involved.

There are several sites in Canada, from the high Arctic to the alpine tundra of the Yukon. Their purpose is to research the responses of arctic tundra plants and ecosystems to predicted global climate change.

The tundra, whether on arctic islands or in the high reaches of the St. Elias Mountains, is a tough place to live, and small changes can make big differences to tundra species.

Reaching the Wolf Creek site involves a 40-minute drive up a steep, rutted road that tests the suspension of the truck and the nerves of the driver. Well above treeline, we parked the truck next to a ground squirrel colony and dug the packs out of the truck box.

The ITEX site is a kilometre or so away from the road. We pulled on the extra clothing, clipped bear spray on a belt, and set out, clambering over the tussocks and frost boils of the plateau.

The site is barely visible until you reach it, marked only by the small hexagonal enclosures that surround some of the plots, and by the old frames of a greenhouse design that didn't work. It actually seemed to lower the ground temperature, much to the researchers' surprise.

Once there, we broke into two teams. Val Loewen of Yukon Environment and Pippa McNeil of Environment Canada counted the number of flowers in each of the metre-square plots. Environment Canada biologist Joan Eamer and I recorded the details of specific marked plants.

At Wolf Creek, researchers are tracking the growth of four species of plants: Salix arctica (arctic willow), Dryas octopetala (white dryad), Polygonum viviparum (alpine bistort), and Lupinus arcticus (lupine).

The first three are part of the list of plants identified for monitoring by the international program.

"They're chosen because they're species that are really widespread around the circumpolar north," says Eamer.

Lupines are a local addition, simply because they are so abundant in the Yukon, and provide useful local information.

Measuring and recording details like length of leaf, length of annual growth, and other factors is not difficult -- just time-consuming. The hardest part is finding the right plants.

Specific plants within each plot are marked by small metal tags attached to wire. However, over the course of winter and spring, the tags get pressed down by snow and overtaken by new growth.

After five hours of searching, measuring and recording, we had completed five plots. The flower counters, with no tags to search for, had tallies for all of the plots. That left one more day's field work this season to complete the measurements, Eamer estimated.

Because the growth of tundra plants varies so much from year to year, this kind of minute observation over a period of many years is the only way to separate the effects of long-term temperature change from the other variables.

A few more years of patient measurement will likely be required to before the Wolf Creek ITEX plots yield information about the effects of climate change on the fragile alpine tundra.

For more information about ITEX, go to www.taiga.net/canttex/index.html. For information about the Wolf Creek Research Basin, go to www.taiga.net/wolfcreek/index.html.