As we make our way down the mountain, the list of species lengthens. We see lustrous coppers, Edith's coppers, Mexican cloudywings, common-banded skippers, a Riding's satyr, a Becker's white and blues of various kinds: Shasta blues, Melissa blues, lupine blues, Boisduval's blues. We see them singly and in flocks, doing what blues like to do, which is to engage in an activity called "mud-puddling." (The term refers to their habit of alighting on patches of wet ground that contain dissolved salts and other nutrients.)

Tagging along with the butterfly team are Jeff Holmquist, another White Mountain Research Station scientist, and his wife, Jutta Schmidt-Gengenbach. Butterflies, Holmquist says, are big and showy, but there aren't that many of them. Ditto for the colorful dragonfly I spot on the wing, and the hunting wasp I see sipping nectar from a purple aster. More important, ecologically speaking, Holmquist says, is the army of far tinier creatures — flies, spiders, ants, beetles — that serve as herbivores, pollinators and predators.

While the butterfly-census takers (there are three this year) spread out, Holmquist and his wife execute a well-practiced sequence of maneuvers. First, Holmquist takes a net and sweeps it over a defined area precisely 50 times. He then stops to dump what he's collected into a plastic bag that Schmidt-Gengenbach holds open. At that point, he switches to a garden-variety leaf blower, which, he explains, can also be used like a vacuum cleaner. To block the noise, Holmquist puts on earmuffs while his wife positions a small mesh trap on the ground. Then he focuses on sucking up everything possible from beneath the tent-like enclosure. After he finishes, I peer into the collection bag and see grains of soil, wisps of grass and a fair number of creepy crawlies.

In recent years, Holmquist says, the density of small invertebrates in these high meadows has appeared to rise and fall in lockstep with precipitation shifts. "We're at the point where we think we see a pattern," he says. "But ask me again in a couple of decades." When it comes to ecologically available moisture, he notes, temperature is also a player. This spring, for example, was unusually cool and wet; throughout May, high elevations in the Whites were covered in snow. And then, Holmquist says, "Somehow a switch got thrown, and it got hot. It seems like August already, not mid-July."

A transient shift in the character of a season means nothing, of course, but a persistent shift would have cascading effects. If summers turn hotter, for example, then plants could be forced into premature senescence. Earlier spring warm-ups could lead them to green up and flower out of sync with their insect courtiers. And if snow melts too soon, both plants and animals could be exposed to outbreaks of severe cold. That's because snow is an excellent insulator, keeping near-ground temperatures from dipping much below 32 degrees Fahrenheit, which is downright toasty compared to the subzero readings for air temperatures found here in the winter.

An illustration of the importance of snow comes from a long-term study of willow leaf beetles that Smiley and his colleagues have been conducting in the Sierra. A reduction in snow cover, they think, may be responsible for the fact that these small, speckled herbivores have all but abandoned areas below 9,400 feet. The mechanism is probably two-fold, Smiley says, with snow protecting overwintering adults from drying out as well as from freezing. The process also works in reverse. This year — not coincidentally a year of late snow melt — a couple of beetles were observed in areas from which they were thought to have disappeared.

Rock. Bare Ground. Draba. Rock. Rock. I'm watching Jim and Catie Bishop, volunteers from the California Native Plant Society, walk a transect line defined by orange string held taut by Bob Westfall. At precise intervals, they stop to call out what they see. Seated on the ground, Connie Millar jots it all down on a worksheet. The exercise goes quickly because the plants here — including Draba oligosperma, a pretty yellow-flowered member of the mustard family — are outnumbered by non-living substrates, with islands of plants and leaf litter surrounded by talus and scree. It's like looking at a moonscape with flowers.

After two days in the field, the botanical teams conducting the survey have mastered their arcane GLORIA protocol. They're hoping to finish this, the last of three peaks, by mid-afternoon. At their feet, amid sharp shards of dolomite and quartzite, blooms a diminutive garden, and, all around, strands of multicolored string radiate out from this obscure 12,258-foot-high peak. Like a compass rose, the design marks the cardinal and ordinal directions. A short way down, the smallest survey plots, outlined in shiny white measuring-tape, are enclosed by larger lime-green diamonds, and around the diamonds, a yellow string wraps completely around the summit.

Working in pairs, the surveyors swing into action. In places, they fall to their hands and knees to count each plant individually. Elsewhere they meander around, recording a list of the species they see and making estimates of their abundance. In this way, a picture of what's present — and, just as important, what's absent — slowly comes into focus. Earlier in the week, at the first summit they tackled, the team took note of two limber pine seedlings at the tip of the south-facing green diamond. They checked their records: The seedlings were not present in 2005, when the peak was previously sampled.