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Heather Lake Trail—December 2004

Winter is a good time to study structure. Gone are those distracting flowers with their sexual parts and tempting adornments. Whether it is the bones of deciduous trees and shrubs, or the bones of the forest, the Heather Lake Trail on the side of Mount Pilchuck has plenty to offer students of structure.

Begin the hike along a stream and note bud arrangement (opposite or alternate), bud scales, petiole scars, branches, and bark color and texture to identify the deciduous woody plants that thrive in this moist open environment. Don’t forget to include forensic evidence such as old leaves, stipules, and fruits. After a mile of second-growth western hemlock (Tsuga heterophylla) forest, the trail enters old-growth. How can we tell when a forest is old-growth? Structure!

First notice big old live trees. Really big western redcedar (Thuja plicata) and big western hemlock beckon. These big live trees are important primary producers, provide habitat for epiphytes and animals, store nutrients, modify the environment of the forest interior, and influence disturbance regimes. Also notice standing dead trees. Snags provide habitat such as perches and cavities, food and habitat for decomposers, let light into the forest, and influence disturbance regimes. Horizontal dead trees also create openings, and when decomposed enough to hold moisture, can become nurse logs. Nurse logs create habitat for primary producers, critters, including amphibians, food for decomposers, nutrients for the forest when decomposed, and influence disturbance regimes. In addition to individual structural elements, note the complex overall structure of the old-growth forest compared to the second-growth. The old-growth forest has complex multi-layered vertical structure, with ground vegetation, a shrub layer, understory canopy, and overstory canopy, and complex horizontal structure with openings created by dead wood that let light in.

Much of the understory canopy in the old-growth forest is young trees. Most of the young trees here are western hemlock, indicating the trail enters old-growth in the lowland Western Hemlock Zone. Note an increasing abundance of young Pacific silver fir (Abies amabilis) as the trail gains elevation and enters the montane Pacific Silver Fir Zone. Temperature, precipitation, and the interaction between the two are the main environmental controls on zone boundaries. Though precipitation amounts in the two zones are similar, the lower winter temperatures of the higher elevation montane forest means more of the precipitation falls as snow so less is available for plant use. This shorter growing season favors Pacific silver fir. Vegetation responds continuously to changing climate. Old western hemlock and western redcedar in the Silver Fir Zone may reflect warmer conditions hundreds of years ago.
As the trail enters the lake basin notice old and young mountain hemlock (Tsuga mertensiana). Cold air and snow slide into the north-facing basin resulting in deep, long-lasting snow pack. Mountain hemlock withstands the heavy snow and even shorter growing season better than Pacific silver fir. In this case, topography and aspect, rather than just elevation, affect temperature and form of precipitation and result in a very low elevation (about 2500’) Mountain Hemlock Zone.

Heather Lake sits in a glacial cirque. Expect snow and the possibility of avalanches tumbling down the cirque walls. Unless avalanche danger is low, do not walk around the lake. Stand at the outlet and study landscape patterns around the lake instead. The cirque is a mosaic of forested and non-forested communities. Areas of high disturbance, such as snow and rock slides, high moisture, such as marshy lakeshore and the lake itself, and high snow accumulation such as the south end of the lake are not forested. Scattered trees grow out of sheltered microclimates such as the lee side of large boulders, ledges, and the company of other trees.

Practice your twig identification over lunch. Look for willows (Salix sp.) with their single bud scales (like a mitten without the thumb) at the outlet. The capsules of copperbush (Elliottia pyroliflorus) resemble miniature peeled tangerines. Pioneers salmonberry (Rubus spectabilis) and Sitka alder (Alnus sinuata) fill the avalanche chutes.

Bring the 10 essentials, extra warm layers, rain gear, good boots, a thermos, and ski poles to help negotiate the icy, snowy conditions near the lake. The moderate four mile round-trip hike can be treacherous during winter. Directions: Drive the Mountain Loop Highway east from Granite Falls to USFS Road # 42 (Mount Pilchuck Road) on your right at MP 12 and drive 1.4 miles to the trailhead.

Updated: July 3, 2016
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