Location Name: Andrews Watershed 10 - WS10

Parent: Andrews Experimental Forest (HJA) - HJA

Site History:

100% clearcut in 1975. Clearcutting occured during the spring and summer of 1975, and a running skyline system yarded all logs and unmerchantable material >20 cm in diameter or >2.4 meters in length uphill to a single landing. A significant debris flow in Feb 1986 destroyed the gaging station. WS#9 is the control watershed for WS#10 GIS estimated percent harvest: 91.9%

Soils:

Soils are largely weathered to reddish brown latosols, in tuff and breccia parent materials. Although the parent rock may be weathered to great depths, soil horizonation is only weakly developed.(S1) Soils are approximately 130 cm deep and the parent material is commonly weathered to a depth of 3.7 meters over much of the watershed. Soils are classified as Typic Dystrochrepts (Inceptisols U.S. Dept. of Ag. 1960,1972) and range from gravelly silty clay loam to very gravelly clay loam. The <2-mm fractoin of these soils ranges from 20% to 50% clay and contains gravel amounting to 30%-50% of the soil volume. The forest floor ranges from 3-5 cm thick and is classified as a duff-mull.

Geology:

Soils are underlain by highly weathered volcanic tuffs and breccias.

Hydrology:

Gauged watershed area: 10.2 ha (original surveyed value used in rating equation calculations)

Vegetation:

The entire watershed is dominated by >450-year-old Douglas-fir stands. Four major plant community types were identified: Pseudotsuga-Castanopsis (xeric), Pseudotsuga-Rhododendron-Gaultheria (warm-mesic), Pseudotsuga-Rhododendron-Berberis (mesic), and Pseudotsuga-Acer-Polystichum (cool-moist). Patches of the old-growth forest, destroyed by fire and wind, have been replaced by younger age classes of Douglas-fir. Climax vegetation for the forest communities is, for the most part, Douglas-fir. Some hemlock is found near the streams. Understory vegetation includes golden chinkapin, Pacific rhododendron, salal, vine-maple, Oregon grape and sword fern.

Climate:

Typically, snow begins falling in November with peak snow water equivalent storage estimated to occur in Feb-April. Transient snow zone with <25% precip falling as snow at lowest elevations.