Information on primary production, decomposition, hydrology, and element cycling was integrated in annual budgets of accumulation and flux among components of a mature Douglas—fir forest ecosystem. Annual N input in precipitation and dust was 2.0 kg/ha, and an estimated 2.8 kg/ha were fixed by cyanophycophilous lichens in the canopy. Annual N loss to groundwater was 1.5 kg/ha. N appeared to be accumulating in the ecosystem. An annual decrease of ~ 2.8 kg/ha in vegetation was offset by estimated increases of 5.0 kg/ha in fallen logs, and 2.8 kg/ha in soil organic matter. Microparticulate litterfall provided a large input of N to the forest floor (3.3 kg°ha—1°yr—1). Annual input of metallic cations in precipitation was only 545 eq/ha, whereas weathering input (net release of cations to solution from primary and secondary minerals) was estimated by difference at °9000 eq/ha. Total annual loss to groundwater was 9400 eq/ha and, because of little cation accumulation, loss almost exactly balanced input. Net transfers of P were small. Total annual input was 0.5 kg/ha, total loss was 0.7 kg/ha, and net accumulation was —0.2 kg/ha. Input of elements in precipitation and dryfall was small compared with that in the eastern United States. Water chemistry profiles showed that the biologically important elements N, P, and K increased in concentration as water passed through the canopy and litter layer but decreased as water passed through the rooted part of the mineral soil. In contrast, Na increased by a factor of 20 as water passed through the rooted soil. Concentrations of all elements except Mg were lower in the stream water than in solution at 2.0—m depth in the subsoil. At our site, unlike some eastern forests, Kjeldahl N (organic N plus NH4+) accounted for most of the measured N in solution. Nitrate levels were low, averaging @<20 mg/L NO3——N at all points in the profile. Titratable alkalinity dominated anion chemistry in the mineral soil, but in the upper parts of the water chemistry profile (precipitation, throughfall, and litter leachate) Cl— and SO4= together accounted for 30—40% of the negative charge. Total return to the forest floor in litterfall was greater than that reported for other Douglas—fir stands mainly because of plentiful microparticulate forms and coarse woody debris. Leaf fall accounted for less than half of the total litterfall input of N to the forest floor. Element accumulations in coarse woody debris almost cancelled the negative net annual increments in the living vegetation compartments. Overall cycling patterns show that only the biologically limiting element, N, was tightly conserved. For other elements, losses nearly equaled or even exceeded inputs. Redistribution from old to new foliage was also more important for N, P, and K than for Ca, Mg, and Na. Solution transport processes were important for all elements and dominated the cycling patterns of biologically less important elements such as Ca and Na. Vegetation absorbed metallic cations mainly from the mineral soil. However, much N and P w...

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Road building, clearcutting 25 percent of the watershed, and slash disposal by broadcast burning or by natural decomposition caused changes in water quality of two small streams in the Bull Run Watershed in Oregon, which supplies water to the Portland, Oregon, metropolitan area. Concentrations of suspended sediment increased slightly, primarily owing to construction of a permanent logging road that crossed streams. Changes in nutrient cycling occurred due to logging and slash disposal in both watersheds where cutting was done. NO3‐N concentrations, which increased most where logging residue was left to decompose naturally, increased more than sixfold and commonly exceeded 100 pg/i during the October‐June high‐flow season for seven years after logging. Where logging slash was broadcast burned, NO3‐N concentrations increased roughly fourfold, but rarely exceeded 50 μg/l, and increases had mostly disappeared six years after slash burning. Changes in outflows of cations and other anions were not apparent. Annual maximum stream temperatures increased 2–3°C after logging, but temperature increases had mostly disappeared within three years as vegetation regrowth shaded the streams.

Soil samples were collected from sites typical of six forest habitat types in the western Oregon Cascades to determine the variability in total N, C, and mineralizable N. Within each type, 20 samples of surface soil (0‐15 cm deep) were removed from around the outside perimeter of a 0.25‐ha plot. Averages of 23, 28, and 70 samples were needed to estimate the population mean of total N, C, and mineralizable N, respectively, with an accuracy of ±10% at a 95% probability. Variability was not reduced by reporting data on the basis of mass per area rather than concentration, but the method of reporting data affected the relative ranking of sites. Within‐site variability was not generally related to microsite differences in slope or coarse fragment content.

almost 3,000 feet of creekbed in experimental watershed 3 on the H. J. Andrews Experimental Forest near Blue River, Oreg. , was scoured to bedrock by a tumbling, churning mass of mud, rocks, and logs. Five thousand cubic yards of this debris accumulated in two log jams in the main channel. Another 100 cubic yards of sand, silt, and gravel were washed on downstream and almost filled a small catchment basin which had collected only 57 cubic yards since 1 956. Slides like this are not uncommon in the forested mountains of