Treesearch

This report highlights significant research findings and accomplishments of the Pacific Northwest Research Station during fiscal year 2018.

In the Pacific Northwest, clearcutting is the preferred method for harvesting wood products from Douglas-fir plantations because it’s economical and mimics a large-scale disturbance. Following a clearcut, Douglas-fir seedlings are planted throughout the recovering native plant community. Yet the newly planted seedlings and native plants aren’t the only vegetation claiming the open ground. Invasive plant species, such as Scotch broom and sweet vernalgrass, can also colonize the site and compete with the seedlings for water, nutrients, and light.Eradicating Scotch broom requires repeated...

A century of fire suppression across the Western United States has led to more crowded forests and increased competition for resources. Studies of forest thinning or stand conditions after mortality events have provided indirect evidence for how competition can promote drought stress and predispose forests to severe fire and/or bark beetle outbreaks. Here, we demonstrate linkages between fire deficits and increasing drought stress through analyses of annually resolved tree‐ring growth, fire scars, and carbon isotope discrimination (Δ13C) across a dry mixed‐conifer forest landscape. Fire...

The iso/anisohydry concept characterizes plants according to their water status regulation. Coexisting definitions and misconceptions have recently led to considerable criticism. Here, we discuss reasons for the misconceptions and propose a robust definition of iso/anisohydry using the leaf turgor loss point to integrate the complex interplay of plant hydraulic traits.

We discuss a recent paper which evaluated the hydrologic changes resulting from a pond-and-plug meadow restoration project in the Sierra Nevada Mountains of California. In the study, measurements of streamflow into and out of the meadow suggested late-summer baseflow increased as much as five-fold when compared with prerestoration conditions. However, the volume of streamflow attributed to the restored meadow (49,000–96,000 m3 over four months) would require that 2.5–4.8 m of saturated meadow soils drain during summer months. The groundwater data from this meadow record only 0.45 m of...

In this article we respond to a recent paper in which Rosenberg (2019) suggested that red tree voles (Arborimus longicaudus) were just as common as western redbacked voles (Myodes californicus) and implied that federal management agencies should consider dispensing with field surveys of red tree voles in favor of an unspecified adaptive management approach. Our primary purpose in writing this response is not to debate how management agencies should manage red tree voles. Our objective is to demonstrate that Rosenberg’s (2019) attempt to compare the distribution and relative abundance of...

Objectives - Determine whether patients who live in greener and more walkable neighbourhoods live longer, and take fewer opioids, following hip or knee arthroplasty. Design - Retrospective cohort study. Setting - Residential environment following surgery at one of 54 New Zealand hospitals. Participants - All people who received a total hip or knee arthroplasty at a publicly-funded hospital in New Zealand in 2006 and 2007 (7449 hip arthroplasties and 6558 knee arthroplasties). Primary and secondary outcome measure - Time to all-cause mortality and number of postsurgical opioid prescriptions....

Salt marsh habitats support a diverse array of estuarine species but are vulnerable to increased inundation resulting from sea-level rise. In order to characterize relationships between vegetation and elevation and inform assessments of risk to salt marsh communities from projected sea-level rise, we collected vegetation and elevation data at 42 salt marsh sites in Coos Bay Estuary, Oregon. For 1-m2 plots along transects from the bayside edge to the upland, we recorded height and percent cover of all plant species present. We determined plot location and elevation at 1-m intervals with a...

Fine particulate matter (PM2.5) is a well-established risk factor for public health. To support both health risk assessment and epidemiological studies, data are needed on spatial and temporal patterns of PM2.5 exposures. This review article surveys publicly available exposure datasets for surface PM2.5 mass concentrations over the contiguous U.S., summarizes their applications and limitations, and provides suggestions on future research needs. The complex landscape of satellite instruments, model capabilities, monitor networks, and data synthesis methods offers opportunities for research...

We quantified the sum of daily mean temperature above 0 °C and modeled incubation duration using water temperature data collected at 12 coho salmon (Oncorhynchus kisutch) spawning sites during two incubation periods with cool, snow dominant conditions and three incubation periods with anomalously warm, rain-transitional conditions, a proxy for a future climate scenario. Warmer water temperatures during warm–rain-transitional winters yielded a 58-day reduction in the median duration of egg incubation; however, the magnitude of change at individual sites varied widely and was controlled by...