Saturday, June 30, 2012

Great Sand Dunes National Park

The fires raging in Colorado are reminding many of us of similar recent events on our home turf, and we feel great empathy for the current trauma there. Colorado was my home for many years during childhood, college years and young adulthood, and the scent of pine and the rush of mountain streams still take me home. Let's look for a bit at some of Colorado's natural jewels, starting with the Great Sand Dunes.

Dunefield of Great Sand Dunes National Park (Photos by Narca)

Hidden away in the San Luis Valley of Colorado are the sculpted sands of the tallest dunefield in North America: Great Sand Dunes National Park and Preserve. A recent scouting trip allowed me to explore this newest national park, in the fine company of our friend Jim.

Gnarly bark of a Rocky Mountain Juniper (Juniperus scopulorum)

The dune ecosystem is far more complex than I had realized. Cradled against the 14,000-foot Sangre de Cristo Mountains, the park's life zones range from alpine tundra above treeline, down through subalpine spruce forest, montane forest, pinyon-juniper woodland, the dunefield itself, the sand sheet and grassland surrounding the dunes, on down to the lowest elevations, which feature alkaline flats or "sabkha", and the riparian corridors and wetlands associated with seasonal creeks.

Sand dunes, we learned at the Gray Ranch in New Mexico, are a sponge for absorbing precipitation. Beneath the dunes, any impervious layer of rock or clay traps the water, so that trees can establish at lower elevations if their roots can reach water. Imagine what aquifer underlies the Great Sand Dunes!

Creeks flow into the dunes from the towering Sangre de Cristos––mainly Medano and Sand Creeks. These creeks are shallow, surging, and seasonal. Children and adults delight in playing in the cool waters. In this extreme year of drought and heat, very few wet spots are showing at the surface in late June. But at a slightly lower elevation, the waters sponged up by the dunes are still being released slowly, feeding the wetlands where American Avocets and Killdeer breed.

The dunefield at dusk

The sand sheet with its grasslands surrounds the dunefield. In this region vegetation has stabilized old dunes, so that they no longer shift and now support thriving grasses and shrubs like Rabbitbrush (a fantastic magnet for butterflies and other insects when it blooms).

This trip, we camp at Pinyon Flats, as shadows grow long on the dunes. Smoke from the distant Little Sand Fire, burning to the northwest of Pagosa Springs, blurs the western mountains but doesn't quite reach us here.

Next morning, we find Clark's Nutcrackers and bright flowers along shady Montville Nature Trail. By all reports the winter has been exceedingly dry, and certainly the Sangre de Cristos don't carry their usual mantle of snow and ice––what was there has mostly melted. Yet I am used to desert conditions, and am surprised to find a fine variety of wildflowers and busy insects, in so dry a year.

Wyoming Paintbrush (Castilleja linariifolia)

Quaking Aspen (Populus tremuloides)

After hiking the nature trail, we drive to the Point of No Return and explore the nearby dunes. The whisk marks of kangaroo rats' tails and the miniature tractor-prints of big beetles pattern the sand.

Vesper Sparrows and Green-tailed Towhees both find the region much to their liking. They are at the peak of nesting season, and the air rings with their songs.

A hefty Vesper Sparrow on territory

A Green-tailed Towhee throws every ounce of strength into broadcasting his song.

Even in the grassland near the dunes, flowers still manage to bloom, beautifully.

Hall's Penstemon (Penstemon hallii)

In wetter years, Prairie Sunflowers (Helianthus petiolaris) carpet the grassland. Now only a scattered few are blooming.

Scarlet Gaura (Gaura coccinea) is a familiar, widespread species.

Rocky Mountain Beeplant (Cleome serrulata) is spectacular!

This native Wavyleaf Thistle (Cirsium undulatum) is irresistible to insects.

A night-blooming Cutleaf Evening Primrose (Oenothera coronopifolia) hasn't yet faded with the coming of day.

Insects also catch our eye, including this lovely dragonfly.

OK, Doug and Bob, this one is for you!
And indeed, Doug Danforth tells me this is a female Variegated Meadowhawk (Sympetrum corruptum)––thanks, Doug!

An endemic tiger beetle roams the dunes, but seeing that gorgeous insect will have to wait till the next trip!

Dark, heavy sand grains of magnetite form patterns on the dune.

Another fantasy dances in my mind: imagine spending the night up on those dunes, when they are flooded in moonlight, or dark with a field of stars blazing overhead. We talk to one young couple who did just that. They say that sand is in all their gear and clothes, but how worth it for the experience!

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