An increase in land dominated by young second-growth Douglas-fir forests in the Pacific Northwest has coincided with heightened concerns over loss of old-growth habitat. In search of options for managing young forests to provide late-successional forest structures, the Young Stand Thinning and Diversity Study was designed to test the effectiveness of modified thinning in acceleration of late-successional structural characteristics. Thinning treatments included: a control, a light thin (typical of standard commercial thins), a heavy thin (densities lower than typically prescribed), and a light thin with gaps (stands thinned lightly with the addition of 0.2 hectare patch cuts evenly spaced throughout the stand). Early response (maximum of 5–7 years post-treatment) of overstory vegetation was examined. Average growth of Douglas-fir increased in all thinned stands, but growth of the largest Douglas-fir trees was only accelerated in the heavy thin. After thinning, the canopy of all thinned treatments was initially more open than the control, but after 5–7 years the light thin was no longer significantly different from the control. The light with gaps thin had the highest variation in overstory canopy cover. Differentiation of vertical canopy structure among treatments was not evident. There was no difference in mortality among any of the treatments for most species tested; those that did had highest mortality in the control. Our results indicate that thinning can be effective in hastening development of some, but not all late-successional attributes, but such acceleration is not equivalent among the different thinning treatments.

We analyzed environmental relationships of the Siskiyou Mountains salamander, comparing attributes at the landscape, macro- and micro-environmental scales, and the three scales combined, to determine which attributes best predicted salamander presence. Separate analyses were conducted for sites on the north and south sides of the Siskiyou Mountains which basically divide Oregon and California. We sampled 239 randomly selected sites (163 north and 76 south of the Siskiyou Crest), each in ≥ 5 ha of relatively homogeneous forest or post-forest (clearcut) habitat, 75 m from edge, in 7×7 m plots with ≥ 25 % rock cover. Measured attributes at the landscape, macro-, and micro-environmental scales totaled 230 independent variables. Subsets of 122 (North Slope) and 97 (South Slope) variables were used in hierarchical, exploratory, best subsets logistic regression, to determine the best predictors of salamander presence. We tested three analysis strategies: 1) linear relationships only; 2) linear, quadratic, and logistic relationships; and 3) linear, quadratic, and logistic relationships, and interactions among the covariates. The best models of salamander presence consisted of combined landscape, macro- and micro-environmental scale variables; included linear, quadratic, and pseudo-threshold (i.e., log) forms, and included interactions between variables. These models showed positive relationships of salamander presence with site conditions and plant assemblages characterizing old, less disturbed forest with closed canopy, moist, relatively warm microclimates, deep litter, and cobble and boulder-sized rock substrates. Our results suggest that mature to late-seral-forest attributes provide optimal habitat for the Siskiyou Mountains salamander. Stands of mature and older forests evenly distributed and interconnected across the geographical range of this species would likely best insure its long-term viability.

Invasive alien plants frequently possess greater seed banks than native species in disturbed areas, but native disturbance-adapted species may also possess large seed banks. We analyzed seed banks of ten sites with varying grazing histories in a shrub-steppe ecosystem dominated by antelope bitterbrush (Purshia tridentata) in the Okanagan valley in British Columbia, Canada. Overall effects of grazing on seed banks were overshadowed by site-specific differences, but canonical correspondence analysis (CCA) showed that the composition of the seed bank was significantly affected by bare soil which was positively correlated with grazing. Other factors affecting seed bank composition included litter, cover of spikemosses (Selaginella), shrub cover and microbiotic crust cover. The seed bank of the invasive herb diffuse knapweed (Centaurea diffusa) was largest at two of the three most heavily grazed sites. Cheatgrass (Bromus tectorum), another invasive species, exhibited large seed banks at all sites regardless of grazing history. Native species such as sand dropseed (Sporobolus cryptandrus) and Douglas' knotweed (Polygonum douglasii) had substantial seed banks (> 1500 seeds m⁻²). Planting sand dropseed, Douglas' knotweed, needle-and-thread grass (Hesperostipa comata) or their ecological equivalents could aid in the restoration of arid ecosystems because of their adaptation to disturbance and persistence of seeds in the soil.

The effects of benthic microalgae on sediment nutrient fluxes were investigated at three sites across the intertidal zone of lower Yaquina Bay. Study sites were selected where microalage were present but where seagrass and mud shrimp were absent. Sediment columns were collected seasonally from one to three stations from September 1999 through August 2000 to determine the seasonal and spatial range in benthic fluxes. Collected sediments were carried to the nearby laboratory for light and dark incubation experiments. Nitrate fluxes ranged from −122 to −4 μmol N m⁻² hr⁻¹, whereas ammonia fluxes ranged from −52 to 101 μmol N m⁻² hr⁻¹. The ranges for orthophosphate and silicate were −7.4 to 12 μmol P m⁻² hr⁻¹ and −93 to 283 μmol Si m⁻² hr⁻¹. The sediments were always a net sink for nitrate. Nitrate uptake rates were highest during the warmest month (August) and lowest during the coldest months (November and January). Nitrate fluxes were not statistically different for light and dark conditions. Ammonium was generally released from sediments into the water column in the dark, whereas it was taken up in the light. The sediments were a net sink for all tested nutrients under light conditions, whereas all nutrients except nitrate were released into the water column in the dark, indicating that ammonia, orthophosphate and silicate were utilized by benthic microalgae at the sediment-water interface in the light.

Information about the sensitivity of lodgepole pine to climate will allow forest managers to maximize growth, better understand how carbon sequestration changes over time, and better model and predict future ecosystem responses to climate change. We examined the effects of climatic variability during the 20th century on the growth of lodgepole pine along an elevation gradient in the North Cascades National Park, Washington. Multivariate analysis and correlation analysis were used to simplify growth patterns and identify climate-growth relations. Mid-elevation chronologies correlated negatively with growing season maximum temperature and positively with growing season precipitation. By contrast, high-elevation chronologies correlated positively with annual temperatures and winter Pacific Decadal Oscillation index. Projected increases in summer temperatures will likely cause greater soil moisture stress in many forested ecosystems and the potential of extended summer drought periods over decades may significantly alter spatial patterns of productivity, thus impacting carbon storage. The productivity of lodgepole pine likely will decrease at sites with shallow, excessively drained soils, south and west facing aspects, and steep slopes, but increase at high-elevation sites.

This paper summarizes a pilot study conducted in spring 2005 that documents, for the first time, eulachon, Thaleichthys pacificus, in the Elwha River. General morophometrics of the Elwha eulachon are comparable to those found in other northwest systems. Eulachon abundance in the Elwha appears much lower than in other northwest rivers with documented eulachon runs. Theories for fish presence in the Elwha include straying, and reestablishment of a remnant stock. The local historic observations of eulachon in the Elwha (but not other Olympic Peninsula rivers) up until the mid 1970's, combined with the severely degraded habitat of the lower Elwha River, indicate that the Elwha eulachon are a remnant population. Upcoming dam removals will restore riverine sediment processes, including delivery of sand gravel size material suitable for eulachon spawning to the now severely sediment starved lower river. Dam removals are therefore anticipated to have restoration benefit to eulachon and may play a role in regional restoration of severely depleted northwest eulachon stocks.