Happy Tramper

Walking the Forest Primeval: Thunder Creek to McAllister Creek, North Cascades

Our hiking group had turned to this creekside forest trail on a drippy Saturday, discouraged from the high country by late spring snows and poor weather.  As we drove through the foothills, the clouds blowing in from yet another Pacific weather system bunched above us as if snagged by the shaggy treetops, spitting moisture onto the windshield.   It was going to be a wet day, but raingear would overcome the elements, and we embraced the idea of a brisk, extended deep-forest hike accompanied by the tumbling snowmelt waters of Thunder Creek.  And this hike delivered far more than these superficial elements – yes, the thundering water was a constant accompaniment; and yes, the forest was deep and imposing.  But it was life in the full range of spatial scales that really left its mark in memory along this 12-mile ramble south from the Diablo Arm of Ross Lake deep in the North Cascades of Washington state.

From our first steps along the broad, soft trail you could almost hear carbon cycling all around us, life recycling life.   We were surrounded, enveloped by the great Northern Temperate Rainforest, one of the greatest repositories of biomass on the planet.   Life forms occupied every ecological niche.   Massive old conifers stood sentinel over younger trees which had waited decades for avalanche, windstorm or rockslide to open up enough sun and soil to take root on a fallen log and stump.   Huckleberry and salmonberry shrubs with their juvenile fruits already developing, rushed to reproduce in the short growing season.  Then, as we adjusted our eyes to smaller and smaller scales, even more diversity.  Tiny flowers stood solitary and in small groups – here a delicate purple lady-slipper, there a white-lavender trillium, over there a group of vivid yellow skunk cabbage flowers.   Ferns large and minute unfurled their lime-green fiddleheads, presenting a stark contrast from the dark brown forest floor.

The rolling ground and old logs and limbs were beshawled thickly with verdant mosses with their tiny lush fronds and minute fruiting bodies reaching out.   Bright orange spore sacs exclaimed their presence against the grey-blue background of staghorn lichens clinging to rocks and fallen from trees.  The occasional, vivid yellow and salmon pink mushrooms and white and orange icicle plants pushed up through the organic matter, feeding on living and dead roots unseen below, nature’s little vampire drama.  And unseen but ubiquitous, all the insects and bacteria chewing, absorbing, excreting, converting fallen organisms into new soil to start the cycle anew.  Even the human installations, puncheons and bridges, were being quickly reclaimed by the patient, inexorable barrage of life forms in their simple but extremely powerful drive to feed, respire, reproduce, occupy.  Hurry, hurry!  Time is short!  Claim your resources, replicate your genes!  Then, without fuss or rancor, contributing your organic compounds to the inexorable cycle.

The North Cascades are home to 700 glaciers, natural reservoirs of ice that store as much water as all of Washington’s lakes, rivers, and reservoirs combined.   The North Cascade glaciers release approximately 230 billion gallons of water during the summer, and many of these gallons tumbled across our path draining into Thunder Creek[1].  Nearly 15% of the Thunder Creek watershed is fed by glaciers, and over time, flow rates in the creek have increased as the local glaciers have receded.  In recent years an average of 900 to 1000 cubic feet per second pass along the creek in the spring, the equivalent of almost 6200 faucets running full tilt.   So the creek was a Presence all along the route, a Terrain Feature of its own right, crashing and tumbling just out of view and occasionally emerging through a break in the trees.


The Temperate Rainforest ecosystem around us, stretching from the Cascade crest to the coast from British Columbia to northern California, is unique among temperate forest regions of the world.  Elsewhere in similar environments and latitudes, deciduous hardwood forests dominate; and in fact prior to about 1.5 million years ago the forests west of the crest in Oregon and Washington were likewise dominated by hardwoods:   hickory, oak, sycamore, beech.  Then, according to paleobotanists, two major events occurred to fundamentally change the composition of the region’s forests.  The uplift of the Cascade mountain chain during the Pliocene (between 2 and 5 million years ago) fundamentally changed the region’s climate in unique ways – relatively warm winters, very dry summers – that gradually led the hardwoods to be replaced by the conifer communities familiar to us today[2].  Then, during the most recent ice age as recently as 10 to 15 thousand years ago, much of northern North America was buried under ice, and in the Pacific Northwest the ice pushed conifers into a few refugia along the southern extent of the glaciers and in a few unglaciated coastal areas (the western Olympic peninsula, Vancouver Island and the Queen Charlotte Islands).    Pollen records then document the re-spread of the great conifers from these refugia back northward along the Pacific coast, the Washington and Oregon Cascade westside and into the western Rocky Mountains during the Holocene (from 12 thousand years ago to the present)[3].  The intervening climate conditions and relatively limited disturbance allowed the massive evergreens and their rich associations to flourish.  In fact, the great temperate rain forests of the coastal Northwest foster a disproportionate share of the world’s biological production.   In large part due to cool temperatures and immense quantities of precipitation (as rain or fog), they accumulate and store more organic matter than any other forest type (including tropical rain forests) – as much as 200-750 tons of wood, tree foliage, plant matter, leaf litter, moss, and organic soil per acre[4].  That’s the equivalent of up to 65 double-axle dump trucks of carbon on every acre, busily cycling.

So beyond the tumble of Thunder Creek before us, through the shaggy boles of the big trees, the fog-draped hills formed a soft green-gray backdrop, and, beyond them, just a hint of the snowy crags of the North Cascades.   Coming around a corner, a reminder of the immense power of water in a great curve of the creek which now presented a 100-foot-tall naked eroded bank of soil with a few trees clinging with their rooty toes to the edge and many more tumbled down. 

Then our trail wound back into the forest, proceeding gently but steadily upward toward the headwall between the north-facing drainages of Thunder Creek and Park Creek and the south-facing drainages feeding the Stehekin River beyond.   But the headwall was 20-some miles beyond, a destination for parties with packs.    For us, a log-scramble across another tumbling tributary and another half-mile to our lunch spot on a sturdy bridge over McAllister Creek, before turning to make our way back the 6 miles to the trailhead through the dripping, breathing, cycling forest.  And a valuable reminder that, some days, the best experiences can be found by looking closely to see the forest among the trees.

[1] From Mauri S. Pelto,  North Cascades Glacier Project, http://www.nichols.edu/departments/glacier/glacier.htm.

[2] From Wareing and Franklin, 1979.  Evergreen Coniferous Forests of the Pacific Northwest.  SCIENCE, VOL. 204, 29 JUNE 1979

[3] S. J. Brunsfeld, J. Sullivan, D. E. Soltis and P. S. Soltis.  2001.  Comparative phylogeography of northwestern North America: a synthesis.  In (J. Silvertown and J. Antonovics, eds.) Integrating ecological and evolutionary processes in a spatial context. Pp. 319-339. Blackwell Science, Oxford.

[4] From America’s Rainforests – A Distance Learning Adventure.  http://rainforests.pwnet.org/4students/index.php

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