Natural History

What is the Greater North Cascades Ecosystem?

Diablo-Ross-NOCAThe Greater North Cascades Ecosystem (GNCE) is one of the finest expressions on the North American continent of nature's beauty and diversity. The Ecosystem ranges from shell-studded tidewater bays along Puget Sound to one of the world's densest ancient forests, an enclosed damp world of towering trees and green of every hue. These ancient lowland forests give way with increasing elevation to colder, sparser montane forests, which at their upper limits are reduced to twisted, dwarf timberline trees, and finally to the land above all trees, where dazzling meadows of alpine wildflowers emerge from snow for only a few weeks a year.

The North Cascades are rugged mountains, with precipitous crags climbing high above deep dark valleys. Their dominant characteristics are water, ice, jagged peaks, near-vertical cirque headwalls and steep glacial valleys. Indeed, the North Cascades contain most of the glaciers of the United States outside of Alaska. These are steep mountains--often ascending more than 5,000 feet from valley to summit. This amazing elevational gradient makes other mountains seem gentle by comparison. From the Cascade Crest, a stark world of sheer rock walls, glaciers, and permanent snowfields, the Ecosystem stretches eastward into the rainshadow forests of spruce and pine, until finally reaching the airy light of the vast sagebrush steppe. This land of Raven and Salmon, Bear and Wolf, remains  a realm of insistent beauty and enormous ecological diversity, one of the wildest intact ecosystems remaining in the world.

The GNCE stretches eastward from Puget Sound  to the Okanogan and Columbia Rivers, and from Snoqualmie Pass northward to the Fraser and Thompson Rivers. This spectacular region of coastal plain, rich lowland valleys, dense forests, spectacular mountain peaks, and arid shrub-steppe habitats encompasses approximately 28,000 square miles. The close proximity of the moist marine ecosystem of Puget Sound to the west and the dry continental Rocky Mountains to the east is essential to an understanding of the GNCE. The mutual influence of the maritime weather system and the mountains  provides the climatic framework for ecological diversity throughout the region. Drainages west of the Cascade Crest flow directly to saltwater; drainages to the east flow to the Columbia River before ultimately making their passages to the sea.  

Elevations in the GNCE range from sea-level at Puget Sound to 10,778 feet at Mount Baker. It is characteristic of the North Cascades that these two vastly different places are separated by only 30 miles. The highest peaks are the only two volcanoes in the region: Mount Baker and Glacier Peak (10,541 feet).  The highest non-volcanic peaks range from 8,000 to 9,500 feet.

The largest watercourse in the GNCE is the Columbia River, which gathers together all the waters of the eastern slope and empties directly into the Pacific Ocean along the Washington-Oregon border. Watersheds west of the crest drain directly into the inland marine waters of Puget Sound and the Strait of Georgia. The largest of these west-slope rivers are the Skagit and the Fraser, the latter of which, with the Thompson River, is the only river to bisect the North Cascades, and thus serve as a low corridor connecting its dramatically different east and west sides.

The American portion of the GNCE comprises one of the most intact wildlands in the contiguous United States. The heart of this area lies under public management as North Cascades National Park,  Ross Lake and Lake Chelan National Recreation Areas, Mount Baker-Snoqualmie, Okanogan, and Wenatchee National Forests, and the Glacier Peak, Pasayten, Mount Baker, Chelan-Sawtooth, Boulder River, Noisy-Diobsud, Alpine Lakes, and Henry M. Jackson Wilderness Areas. North of the international border much of the land is designated as Manning and Cathedral Provincial Parks, the Skagit and Cascade Recreation Areas, and in Provincial (Crown) Forests.

Excerpted from Tidewater to Timberline: Natural History of the Greater North Cascades Ecosystem by Thomas L. Fleischner and Saul Weisberg (link to download the full essay in sidebar).