About the Forest
About the Forest
Andrews Lookout Creek Watershed - WSLOOK
Andrews Experimental Forest (HJA)
Watershed above the Lookout Creek gaging station
Bounding Coordinates (decimal degrees):
Slope (%): 40.28
Aspect (degrees): 267
The watershed is approximately 25% patch-cut from 1948 to present. GIS estimated percent harvest: 23.1%
Soils developed in these parent materials are mainly Inceptisols with local areas of Alfisols and Spodosols.
Lower elevations of the Forest are underlain mainly by Oligocene-lower Miocene volcanic rocks composed of mudflow, ash flow, and stream deposits. In higher areas bedrock is composed of andesite lava flows of Miocene age and of younger High Cascade rocks. Stream erosion, a variety of types of landslides, and glaciation have created a deeply dissected, locally steep landscape.
Gauged watershed area: 6242 ha (USGS original survey = 24.1 square miles)) The Lookout Creek watershed comprises the entire Andrews Forest. All other Andrews watersheds are nested within the gaged portion of Lookout Creek with the exception of Watersheds 1 (which is in the drainage below the Lookout gage) and 9 and 10 which are directly adjacent to the Lookout drainage.
When it was established in 1948, the Andrews was covered with virgin forest. Before timber cutting began in 1950, about 65% of the Andrews Forest was in old-growth forest (400-500 years old) and the remainder was largely in stands developed after wildfires in the mid-1800s to early 1900s. Clearcutting and shelterwood cuttings over about 30% of the Andrews Forest have created young plantation forests varying in composition , stocking level, and age. Old-growth forest stands with dominant trees over 400 years old still cover about 40 percent of the total area. Mature stands (100 to 140 years old) originating from wildfire cover about 20 percent. Pre-treatment vegetation: A limited determination of stand basal area was made in old_growth (>400 yrs. old) using a cruising prism. Observed range of basal area measured was 70-140 m2/ha in Pseudotsuga stands and 70-84 m2/ha in Tsuga-Pseudotsuga. Succession description: Lower elevation forest are dominated by Douglas-fir, western hemlock, and western redcedar. Upper elevation forests contain noble fir, Pacific silver fir, Douglas-fir, and western hemlock. Low- and mid-elevation forests in this area are among the tallest and most productive in the world. Average heights are in excess of 75 m and a typical stand stores in excess of 600 megagrams of carbon per ha. These forests are also noteworthy for the large amounts of fine and coarse woody debris they contain. As elevation increases, Douglas- fir and western red cedar decline in importance and western hemlock is gradually replaced by Pacific silver fir. Non-forest habitats include wet and dry meadows, rock cliffs, and talus slopes.
Typically, snow begins falling in November with peak snow water equivalent storage estimated to occur in Feb-April. Mean annual maximum varies from 375-1000 mm water equiv. At highest elevation. Transient snow zone with 25% precip falling as snow at lowest elevations. Mean annual precipitation: 2200-2600 mm Mean annual radiation: 10.5 - 13.5 Megajoules per square meter per day