Treesearch

After an intense stand-replacement fire in south-central Oregon, 1-y-old (1+0) bareroot seedlings of antelope bitterbrush (Purshia tridentata (Pursh) DC. [Rosaceae]) were outplanted over a 4-y period. Paired-plots were established to examine the benefits of protecting the plants from damage due to animal browsing with Vexar mesh tubing. In the first growing season, height growth in the protected plots was 18.4 cm (7.4 in) compared with 15.6 cm (6.3 in) in the unprotected plots. Survival was also higher in the protected plots (70% as compared with 62%). Larger plants had greater survival...

Bayesian belief and decision networks are relatively new modeling methods that are especially well suited to adaptive-management applications, but they appear not to have been widely used in adaptive management to date. Bayesian belief networks (BBNs) can serve many purposes for practioners of adaptive management, from illustrating system relations conceptually to calculating joint probabilities of decision options and predicting outcomes of management policies. We describe the nature and capabilities of BBNs, discuss their applications to various steps in the adaptive-management process,...

We provide practical guidelines for developing, testing, and revising Bayesian belief networks (BBNs). Primary steps in this process include creating influence diagrams of the hypothesized "causal web" of key factors affecting a species or ecological outcome of interest; developing a first, alpha-level BBN model from the influence diagram; revising the model after expert review; testing and calibrating the model with case files to create a beta-level model; and updating the model structure and conditional probabilities with new validation data, creating the final-application gamma-level...

Pruning trials in young alder stands were sampled to evaluate response to pruning. Effects of pruning (1) live branches on different dates, and (2) dead branches with or without damaging the branch collar were assessed on trees pruned in 3- and 6-year-old plantations, respectively. Six years after pruning, stem sections were collected and dissected in the longitudinal-radial plane to expose the center of the stem and branch stub. Ring counts and linear measurements were made for various boundaries or points, including time of pruning, stub length, defect, and beginning of clear wood...

The need for effective communication in the management and planning of forested landscapes has led to a substantial increase in the use of visual information. Using forest plots from California, Oregon, and Washington, and a survey of 183 natural resource professionals in these states, we examined the use of computer-generated images to convey information about forest characteristics. Age and density (basal area (BA)) were underestimated for large, old, dense forest and overestimated for small, young, open forest. Although accuracy of responses for density, tree size, and age of forest...

This study examined thinning effects on overstory and understory development for 8 years after treatment. Three 30- to 33-year-old Oregon Coast Range plantations were partitioned into four overstory treatments: (1) unthinned (~550 trees/ha) (2) light thin (~250 trees/ha), (3) moderate thin (~150 trees/ha), and (4) heavy thin (~75 trees/ha). Two understory treatments were implemented within each overstory treatment: (1) underplanted with Douglas-fir and western hemlock and (2) not underplanted. Overstory trees responded to thinning through increased stem growth, crown expansion, and...

We explored the association between Van Dyke's salamander (Plethodon vandykei) and hydrologic condition, geomorphology, and vegetation structure in headwall seeps in the Cascade Range of Washington State. We modeled occurrence of P. vandykei at three site scales: between seeps, within seeps, and between microhabitat sites. We ranked a priori models using Bayesian information criterion (BIC). Using logistic regression, with presence and absence as the response, we found best approximating models for the occurrence of P. vandykei at the three site scales is predicted by hydrological and...

Spring systems on the west slope of the Oregon High Cascades exhibit complex relationships among modern topography, lava flow geometries, and groundwater flow patterns. Seven cold springs were continuously monitored for discharge and temperature in the 2004 water year, and they were periodically sampled for ?18O, ?D, tritium, and dissolved noble gases. Anomalously high unit discharges suggest that topographically defined watersheds may not correspond to aquifer boundaries, and oxygen isotope data reveal that mean recharge elevations for the springs are coincident with extensive Holocene...

We determined the axial and radial xylem tension gradients in trunks of young Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees. Axial specific conductivity (ks-a) and sap flux density (Js) were measured at four consecutive depths within the sapwood at a stem height of 1 m. By definition, at a given position in the bole, Js is a function not only of ks-a, but also of the driving force for water movement. The Js:ks-a ratio was therefore used to estimate axial tension gradients and the radial gradients at a stem height of 1 m were calculated from the differences in axial tension...

The first Ensatina nests are described for Oregon. Fourteen nests were found during implementation of a forest density management project, seven before and seven after harvest. Nest detections are presented relative to search effort, salamander capture rates, and downed wood availability.