A scientific network intended originally for the high Arctic is expanding into the southern Yukon.

This summer, scientists from Environment Canada and from the Habitat division of Yukon Renewable Resources will set up ITEX plots in the high alpine section of the Wolf Creek Research Basin near Whitehorse.

ITEX is an acronym for the International Tundra Experiment, which was established in 1990 by an international group of tundra ecologists. Their goal was to discover what effects global warming might have on the northern environment.

The idea was to set up a network of sites in such a way that data could be exchanged among the sites, says Jill Johnstone of Environment Canada. Setting up comparative research sites means information can be applied across a broader geographical range.

"You can start extrapolating from pinprick research sites to global change," she says.

As far as possible, ITEX sites look at the same key species of northern plants, use the same techniques for conducting vegetation inventories, and follow common protocols for recording information. This makes it easier to compare information gathered at sites as far apart as Finland and Alaska, says Johnstone.

The ITEX site in the Wolf Creek Research Basin is a long way from the Arctic tundra, but high alpine vegetation is very similar to tundra vegetation. Alpine ITEX sites are already in operation in the Ruby Range of Kluane and at Niwot Ridge in Colorado.

One common ITEX protocol involves monitoring one-metre-square patches of vegetation. The locations of the plots, or quadrats, are marked permanently so that they can be located again several years later.

Once a plot is laid out, the vegetation within the quadrat is mapped in detail. A grid is placed over the plot and gradually moved down to ground level. As plants appear at the level of the grid, they are identified and marked, producing a three-dimensional vegetation map of the quadrat.

It takes two people about two hours to map a quadrat, with one person identifying plants and the other writing the information down, says Johnstone. If the plants are unusual and hard to identify, it might take much longer.

Once a quadrat has been marked and mapped, scientists can come back to it years later and see what changes have occurred in the type and mix of plants.

There are two distinct approaches to ITEX sites, she says. Some of the sites involve simply monitoring the changes in vegetation over a period of years.

At other sites, small open-topped greenhouses are used to increase the temperature by a couple of degrees, which is approximately the level of warming predicted by most climate change models for northern regions. The changes in vegetation in the warmed plots are compared to control plots in the same area.

Initially, the plots at Wolf Creek will involve monitoring both vegetation and snow cover. Eventually, the researchers hope to manipulate the temperature and snow depth on some plots to examine the effects of temperature change and snow drifting.

"Most ITEX sites started in 1992 to 1994, so we're coming in pretty late," says Johnstone. "Many sites have already explored the effects of annual change."

Rather than repeat that research, the Wolf Creek ITEX project will concentrate on long-term effects of increased temperatures, she says. Temperature drives many processes in the ecosystem, she explains, including such things as plant growth rates, soil moisture levels, and the availability of nutrients for plant growth. A key part of the study will be examining how changes in vegetation caused by warming could affect grazing animals such as ground squirrels and caribou.

"When it comes down to it, what's really important to figure out is the long-term effects of change," says Johnstone.

For more information about ITEX and the Wolf Creek Research Basin, contact Environment Canada in Whitehorse, or check out the Wolf Creek web site at www.taiga.net/wolfcreek.