A roughly two-mile climb through spruce-hemlock forest or a five-minute "flight" over it in the tram brings you near the tree line on the Mount Roberts Trail.
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The most interesting part of the trail, in my book, is the part above the nature center, where the subalpine and alpine zones offer a dazzling array of biological diversity. The trail passes first through a nice stand of mountain hemlocks, many of which have trunks strongly curved by the weight of snow on them when they were smaller.
Above this grove, the subalpine mixture of open areas with clumps of alder, salmonberry, and a few stunted mountain hemlocks provides habitat for several kinds of birds. Robins, fox sparrows, Wilson's warblers, and dark-eyed juncos hang out in the brush and along the edges. Blue grouse ("hooter") families run around in open areas, gleaning insects and spiders from the low vegetation, and also feeding on buds, leaves, berries, and fallen seeds. The chicks stay with their mother for more than two months. They often become used to all the people walking up and down the trail and are therefore quite observable, but they are therefore also vulnerable to uncontrolled dogs and thoughtless humans. Black bears and deer sometimes cross the slopes and feed in the meadows. Marmot families emerge from their dens in summer, and the young ones wrestle and tumble in between feeding bouts.
Salmonberries are popular with bears and birds, as well as humans. They come in two colors, red and orange. Both colors are common around Juneau, but in other geographical areas one color or the other can predominate. People often think that the red ones taste better, and birds sometimes favor the red ones. The sugar content of the two color morphs is the same, blindfolded human test subjects cannot distinguish the color morphs by taste, and birds quickly learn that the orange ones are good, too. Although there is no difference in flavor, there is a difference in germination behavior of the enclosed seeds on different kinds of soil.
Some of the seemingly almost barren areas actually support a diverse community of small flowers. These are obviously very vulnerable to careless trampling, but a careful approach is sometimes feasible. Then, on your hands and knees, you might find the one-inch-tall moss-gentian with minuscule blue flowers, the uncommon frog orchid, and perhaps the mountain harebell with one blue flower that dwarfs the rest of the plant.
As you continue up the trail, the meadows in summer are full of many kinds of flowers of all colors. There's the small, pinkish alpine azalea, moss campion, and "pixie-eye" primrose, the larger yellow mountain heather, avens, and buttercups, the tall white Sitka valerian and yellow groundsels. Sky-blue broad-petaled gentians, lavender wild geraniums, and purple lupines add to the palette of color. Don't miss the white-flowered spotted saxifrage, white mountain heather, narcissus anemone, and partridgefoot. These flowers, and more, are illustrated in the booklet by Bob Armstrong and Marge Hermans, which is available at the nature center.
The alpine zone on Gold Ridge and Gastineau Peak is home to both willow and rock ptarmigan, and you may see families of them foraging for insects, buds, and berries. The willow ptarmigan is unusual among the grouse-like birds in that the male often stays with the female and their brood. The growing chicks stay with their parents for almost three months. There may be a few American pipits doing their aerial song display and perhaps a gray-crowned rosy finch, which favors the rocky areas. A great treat is the gang of nonbreeding ravens that play in the winds off the ridges, showing off their repertoire of flying skills.
Mary Willson is a retired ecology professor and a Trail Mix board member.
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