THE WIND RIVER EXPERIMENTAL FOREST

LEO A. ISAAC, WILLIAM E. BULLARD.

An experimental forest is an outdoor laboratory, an area set aside for research in the reproduction, growing, and harvesting of forest crops. It covers 40 acres, or 20,000 acres, enough land so that one can conduct fundamental studies and extend the results to a commercial or pilot-plant scale. New findings and time-tested methods are tried out side by side, and the results compared as the forest develops and time passes.

One of these outdoor workshops the Wind River Experimental Forest in the Douglas-fir region is in the heart of the Cascade Mountains. It forms part of the upper reaches of a hanging valley that empties into the Columbia Gorge near Carson, Wash.

The Wind River locality is the cradle of forest research in the northwestern part of the United States. There, as early as 1910, some of the first cutting was done on a national forest. A year or two later the first Forest Service nursery was established, the first arboretum started, and the first natural area in the region was set aside there in 1925 to maintain in perpetuity virgin-forest conditions.

Early work in forest research was done in the nursery and on nearby Columbia National Forest land. Then, in 1932, some 10,000 acres surrounding this center was set aside as the Wind River Experimental Forest.

The tract is typical of a vast forested area at the middle elevations in the Cascade Mountains, where the soil and topography are such that the area will probably be kept forever in forest production and not diverted for grazing or other agricultural uses. It is a good timber-growing site not the best, but about equal to the average in the region. Physical features of the experimental forest are similar to those of the surrounding country. The underlying rocks are basalts, the peaks are old lava vents, and some lava flows are still exposed. The soils are mostly red-brown shot looms, very porous, heavily leached, and often containing a high percentage of broken rock. Elevations range from 1,000 to 3,500 feet above sea level. The climate, typical of the lower western slopes of the Cascade Mountains, is wet, except for the summer months. Rainfall averages 87 inches a year, of which 13 inches falls as snow. Nearly every night of the year relative humidity approaches 100 percent. Temperature extremes vary from below zero to over 100 F., and the frost-free season is short. During the dry, windy summers, the fire hazard is great. Forest trees grow well, but field crops do not.

The experimental forest consists of many age classes of timber grown up after old burns in the original forest and after some recent cuttings. There are approximately 4,000 acres of old-growth Douglas-fir and hemlock within the boundaries. An additional 2,500 acres of the area was burned by the great Yacolt forest fire of 1902. Part of that area now supports some small patches of old growth, some scattered large old-growth trees, and a wide variety of stands of natural regeneration some well-stocked stands that followed promptly after the burn, some partially stocked areas, and some areas consisting mostly of brush with occasional young trees growing in it. About 600 acres of this area was re-burned by the forest fires of 1927 and 1929; about 500 acres of that was promptly replanted and now supports a 20-year-old plantation of Douglas-fir, which will soon be large enough for the cultural-cutting operations. A few miles away from the main area lies a 3,500-acre watershed of 100-year-old Douglas-fir. The forest here is approaching maturity, and is representative of the vast, older second-growth stands in the region.

Timber types vary by age and composition. The young forest which seeded in naturally after the great fire of 1902 is mostly Douglas-fir, but there is a scattering of the western hemlock, western white pine, western redcedar, and balsam firs. Likewise, the 100-year-old stand is practically pure Douglas-fir, with hemlock and cedar beginning to show up in the understory. The old-growth forest is now in the process of transition from the intolerant even-aged Douglas-fir to the tolerant climax forest of hemlock and other shade-loving species. The Douglas-firs are old, but the other species are of all ages; in addition to hemlock, they include Pacific silver fir, grand fir, western white pine, western redcedar, and Pacific yew. Where the timber is of merchantable size, volumes range from 20,000 to 100,000 board feet an acre.

One of the important features of the experimental forest is the Wind River natural area. This block of 1,200 acres of the old-growth area was set aside to preserve in an undisturbed state for scientific observation and study an example of the virgin timber of the region. Most of the stand is Douglas-fir 300 to 460 years old; the largest trees are more than 6 feet in diameter and 200 feet tall. Parts of the stand are still practically pure even-aged Douglas-fir, while other parts are in various stages of transition from Douglas-fir to the climax forest of the shade-tolerant species. In places the Douglas-fir has entirely disappeared and hemlock is the dominant tree. This tract serves as an undisturbed check area for adjoining stands that are being placed under management. It is systematically covered with permanent sample plots on which timber growth, mortality, and other ecological changes are recorded.

MANY FOREST-RESEARCH PROJECTS have been completed on the experimental forest and many are under way. They vary from single observations or sample plots to commercial-size forest cutting operations. Early Douglas-fir nursery and planting techniques were worked out there, and many fundamental studies have been made that have shaped the silviculture of the region.

Seed of Douglas-fir and its associates, once thought to live years in the forest floor, was found to germinate or die mostly within a year after it falls. Forests that supposedly grew from this duff-stored seed following logging and slash burning were found to come from seed brought in considerable distances by the wind. Measurements of the seed flight of Douglas-fir and its associates, made by releasing seed at tree heights from a box kite over snow fields and also by catching the natural seed fall in seed traps, still stand as the most accurate and complete records ever made of tree-seed flight.

Fire studies made there on weather and fuel relationships, slash disposal, and so on have formed much of the background for the fire-protection system in this forest region.

Meteorological and biological studies that disclosed surface temperatures lethal to seedlings (both from heat and frost) and the seedling losses from excessive drought, lack of cover, competition, and rodent damage explained why seedlings came in thickly on some areas, while others refused to restock. These were supplemented by cone-crop records, which showed that several years elapsed between medium and heavy seed crops.