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Canary in the old growth

The search for an ecosystem's vital signs


In the early 20th century, George Burrell and other chemists with the Bureau of Mines tested canaries to see if they could reliably signal dangerous levels of carbon monoxide in coal mines. And, as was the way of science at the time, the men also cheerfully gassed themselves, recording how much carbon monoxide it took to produce a walloping headache or leave a man disoriented for days. The canaries looked ill before the men felt ill, making them a useful tool to gauge the quality of mine air. They were the first "indicator species," creatures monitored to determine the health of an environment.

But decades later, when "canary in the coal mine" had become a cliche and the question was not the effects of underground blasting, but aboveground clearcuts, the issue became thornier. How do you take the pulse of a forest? Can you look at one bird species, check its population, its breeding success, the extent of its territory, and learn something meaningful about a patch of old growth or a stand of lowland conifers?

Under the 1982 guidelines for the National Forest Management Act, the Forest Service was supposed to use indicator species to determine if activities such as logging were damaging its lands. The ideal indicator would be dependent on a specific habitat. By tracking its population, land managers could get a glimpse of the health of the habitat and the other animals that relied on it. The northern spotted owl was linked to Northwestern old growth, the Merriam's wild turkey to piñon-juniper forests, the mountain quail to chaparral. Some forests used five indicator species, all birds. Others, like the Klamath National Forest in California and Oregon, used dozens, ranging from the tailed frog to the northern water shrew.

From the beginning, some researchers were skeptical about this approach. These days, when even threatened and endangered species rarely receive the monitoring they need, tracking indicators is a significant expense. (Monitoring just one indicator in western Montana's Lolo National Forest -- the flammulated owl -- costs almost $30,000 a year.) Often scientists have only scraps of data about many indicator species, and baseline information about historical population numbers is usually absent. The kinds of studies Burrell did in his laboratory no longer exist. It's frustratingly inexact.

But indicator species, along with a requirement that managers maintain viable populations of native vertebrates, made the 1982 rule a powerful tool for environmental groups seeking to stop forest plans they believed to be flawed. The courts have repeatedly determined that the rule demands wildlife surveys, and the Forest Service has repeatedly said it doesn't have the time or money. In 2002, the Utah Environmental Congress was able to stop a salvage logging project on the Manti-La Sal National Forest, because the Forest Service hadn't surveyed for blue grouse for at least 10 years. In 2006, a judge halted a grazing plan for Idaho's Sawtooth National Forest because of insufficient monitoring of two indicator species, pileated woodpeckers and bulltrout.

Now, in the face of tight budgets and mounting criticism from foresters and managers, the Forest Service wants to abandon indicator species. The method's critics celebrate the decision and see it as a chance to find sounder alternatives. But environmentalists and some wildlife biologists worry that animals will take a huge hit.

In theory, indicators represent two things: changes in habitat over time, and the status of other animal species. But in practice, the problems become apparent. How much can a butterfly, for instance, reveal about the life of a mammal? If a bird that winters in South America fails to nest in Washington state, does that say something concrete about the Northwestern landscape?

Consider the northern goshawk. The raptor is used as an indicator species for old-growth Douglas-fir in the Northern Rockies. The goshawk usually doesn't nest in dead trees, though, so it doesn't reveal much about the status of the flammulated owl or the great gray owl, which do. In some areas of the goshawk's range, it can also nest in lodgepole pines and aspen. So the absence of goshawks in a given stand of Douglas-fir doesn't say anything definite about the state of the habitat.

Or take the sage grouse, often selected as an indicator for sagebrush habitat. Idaho biologist John Connelly recommends a 15 to 25 percent canopy cover of sagebrush for sage grouse breeding habitat. But historically, the average sagebrush canopy may have been much less dense because of fire. Should managers aim to re-create the original landscape, before fire suppression became the norm? Or should they simply try for one that provides the best homes for sage grouse?

In the 1990s, scientists and forest managers began to look for management techniques based on preserving the whole ecosystem, with all of its functions, over a significant period of time, rather than tailoring the forest to meet the needs of one chosen creature.

"If we want to know what the condition of our forests is, why don't we just measure that?"  asks one longtime biologist with the Forest Service, who doesn't want his name used. "Why measure it through a surrogate when we can measure it directly?" If you want to know the condition of a stream, take the water temperature and test the water quality. If you want to know the condition of a stand of trees, look at the age and diameter and canopy closure and the number of non-native species. And manage for specific future landscape goals -- for instance, that the forest should be 20 percent old growth 50 years from now -- providing a wide variety of habitats able to withstand the inevitable disturbances caused by fire, insects and global warming.

The idea makes intuitive sense, but there's little consensus about what "ecosystem management" looks like or how to gauge its success or failure. Some definitions are based on specific, measurable targets. Some stress "a planning timeline of centuries." And others, written by the timber industry, focus on human needs as key ecosystem components.

Last April, the Forest Service released its latest rewrite of the indicator species rule, touting "ecosystem management" and confirming conservationists' fears that the agency planned to water down wildlife protection. The 2008 version scraps requirements for monitoring indicator species and maintaining native species viability, saying they aren't feasible. A coalition of environmental groups promptly sued, asking for a return to the 1982 rule. A hearing is scheduled this month. According to Taylor McKinnon, public-lands program director for the Center for Biological Diversity, which is one of the parties to the lawsuit, indicator species, along with the viability requirement and the monitoring they demand, help hold the Forest Service accountable for the state of the forests.

"It's the hard measure for the maintenance of ecological sustainability on the national forests," McKinnon says. "There's no guarantee that this ecosystem management is going to happen. ... The Forest Service record is not one that lends itself to discretion on these issues. We need standards."

The hope behind indicator species was that they provided a shortcut to keeping tabs on every plant and animal. But there may be no shortcuts. Scott Mills, a professor at the University of Montana forestry school and author of the textbook Conservation of Wildlife Populations, calls ecosystem management as put forward in the new rule "a hopeful platitude that there's an easy fix." For Mills, wild animals are not a surrogate for the health of the forest; they are the health of the forest. 

"What we really want to know is are the creatures on that landscape doing OK," he says. Mills advocates tracking a suite of "focal species," ranging from the commercially and politically important to those that rely on a particular habitat niche. It would be expensive and time-consuming, but, he adds, "Is there any other way to monitor the health of an intact ecosystem? No."