Evaluation of mixed-effects models for predicting Douglas-fir mortality

We examined the performance of several generalized linear fixed- and mixed-effects individual-tree mortality models for Douglas-fir stands in the Pacific Northwest. The mixed-effects models accounted for sampling and study design overdispersion. Inclusion of a random intercept term reduced model bias by 88% relative to the fixed-effects model; however, model discrimination did not substantially differ. An uninformed version of the mixed model that used only its fixed effects parameters produced predicted mortality values that exceeded the fixed-effects model bias by 31%. Overall, we did not find compelling evidence to suggest that the mixed models fit our data better than the fixed-effects model. In particular, the mixed models produced fixed-effects parameter estimates that predicted unreasonably high mortality rates for trees approaching 1 m in diameter at breast height.Keywords: Douglas-fir, Mortality, Generalized linear model, Mixed mode

Patch colonization dynamics in Carolina chickadees (Poecile carolinensis) in a fragmented landscape: a manipulative study

Habitat and landscape features that influence the rate of interpatch movement and colonization may determine the likelihood that a species will persist in fragmented landscapes. We simulated patch extinction by removing Carolina Chickadees (Poecile carolinensis) from woodland fragments in an Ohio agricultural landscape in January 2002. We then monitored the woodlands to determine their dates of reoccupation and subsequent use for breeding by the birds. All woodlots were eventually reoccupied, regardless of size or degree of isolation, but woodlots in less-forested landscapes connected to other woodland by habitat corridors were reoccupied sooner than unconnected woodlots. Reoccupation was more likely to occur during periods of mild wind chill. Following reoccupation, individual Carolina Chickadees were more often temporarily absent from smaller woodlots, which suggests that they may have used woodlots that insufficiently met foraging or breeding requirements. Carolina Chickadees were more likely to remain to breed in larger woodlots. Results indicate that habitat connectivity may affect the tendency of this species to move through a fragmented landscape. Habitat corridors may be important management tools for maintaining movement of animals between patches.Las características del hábitat y del paisaje que influencian la tasa de movimiento y colonización entre parches puede determinar la probabilidad de que una especie determinada persista en pasajes fragmentados. Simulamos la extinción en parches mediante la remoción de individuos de Poecile carolinensis en fragmentos de bosque en un paisaje agrícola en Ohio en enero del 2002. Posteriormente monitoreamos los fragmentos para determinar las fechas de reocupación y el uso posterior para reproducción por parte de las aves. Todos los fragmentos fueron reocupados eventualmente, independientemente de su tamaño o grado de aislamiento, pero los fragmentos que se encontraban en paisajes con menor cobertura de bosque pero conectados por corredores a otros fragmentos fueron reocupados antes que los fragmentos no conectados. La reocupación fue más probable durante periodos con vientos moderados fríos. Posterior a la reocupación, en fragmentos pequeños los individuos de P. carolinensis presentaron más ausencias temporales, lo que sugiere que éstos usaron fragmentos que no cumplían los requerimientos mínimos para el forrajeo o la reproducción. Los individuos de P. carolinensis tuvieron una mayor probabilidad de continuar reproduciéndose en los fragmentos de mayor tamaño. Los resultados de este estudio indican que la conectividad del hábitat puede afectar la tendencia de esta especie a moverse a través de un paisaje fragmentado. Los corredores de hábitat pueden ser herramientas de manejo importantes para mantener el movimiento de animales entre parches.Keywords: Fragmentation, Wind chill, Corridor, Carolina Chickadee, Colonization, Poecile carolinensi

Shade, light, and stream temperature responses to riparian thinning in second-growth redwood forests of northern California.

Resource managers in the Pacific Northwest (USA) actively thin second-growth forests to accelerate the development of late-successional conditions and seek to expand these restoration thinning treatments into riparian zones. Riparian forest thinning, however, may impact stream temperatures-a key water quality parameter often regulated to protect stream habitat and aquatic organisms. To better understand the effects of riparian thinning on shade, light, and stream temperature, we employed a manipulative field experiment following a replicated Before-After-Control-Impact (BACI) design in three watersheds in the redwood forests of northern California, USA. Thinning treatments were intended to reduce canopy closure or basal area within the riparian zone by up to 50% on both sides of the stream channel along a 100-200 m stream reach. We found that responses to thinning ranged widely depending on the intensity of thinning treatments. In the watersheds with more intensive treatments, thinning reduced shade, increased light, and altered stream thermal regimes in thinned and downstream reaches. Thinning shifted thermal regimes by increasing maximum temperatures, thermal variability, and the frequency and duration of elevated temperatures. These thermal responses occurred primarily during summer but also extended into spring and fall. Longitudinal profiles indicated that increases in temperature associated with thinning frequently persisted downstream, but downstream effects depended on the magnitude of upstream temperature increases. Model selection analyses indicated that local changes in shade as well as upstream thermal conditions and proximity to upstream treatments explained variation in stream temperature responses to thinning. In contrast, in the study watershed with less intensive thinning, smaller changes in shade and light resulted in minimal stream temperature responses. Collectively, our data shed new light on the stream thermal responses to riparian thinning. These results provide relevant information for managers considering thinning as a viable restoration strategy for second-growth riparian forests

Stream temperature change detection for state and private forests in the Oregon Coast Range

Oregon’s forested coastal watersheds support important cold-water fisheries of salmon and steelhead (Oncorhynchus spp.) as well as forestry-dependent local economies. Riparian timber harvest restrictions in Oregon and elsewhere are designed to protect stream habitat characteristics while enabling upland timber harvest. We present an assessment of riparian leave tree rule effectiveness at protecting streams from temperature increases in the Oregon Coast Range. We evaluated temperature responses to timber harvest at 33 privately owned and state forest sites with Oregon’s water quality temperature antidegradation standard, the Protecting Cold Water (PCW) criterion. At each site we evaluated stream temperature patterns before and after harvest upstream, within, and downstream of harvest units. We developed a method for detecting stream temperature change between years that adhered as closely as possible to Oregon’s water quality rule language. The procedure provided an exceedance history across sites that allowed us to quantify background and treatment (timber harvest) PCW exceedance rates. For streams adjacent to harvested areas on privately owned lands, preharvest to postharvest year comparisons exhibited a 40% probability of exceedance. Sites managed according to the more stringent state forest riparian standards did not exhibit exceedance rates that differed from preharvest, control, or downstream rates (5%). These results will inform policy discussion regarding the sufficiency of Oregon’s forest practices regulation at protecting stream temperature. The analysis process itself may assist other states and countries in developing and evaluating their forest management and water quality antidegradation regulations.Keywords: Oregon Coast Range, Stream temperatur

GroomJeremy.FERM.ResponseWesternOregon.pdf

A replicated before–after-control-impact study was used to test effectiveness of Oregon’s (USA) riparian protection measures at minimizing increases in summer stream temperature associated with timber harvest. Sites were located on private and state forest land. Practices on private forests require riparian management areas around fish-bearing streams; state forest’s prescriptions are similar but wider. Overall we found no change in maximum temperatures for state forest streams while private sites increased preharvest to post-harvest on average by 0.7 °C with an observed range of response from -0.9 to 2.5 °C. The observed increases are less than changes observed with historic management practices. The observed changes in stream temperature were most strongly correlated with shade levels measured before and after harvest. Treatment reach length, stream gradient, and changes in the upstream reach stream temperature were additionally useful in explaining treatment reach temperature change. Our models indicated that maximum, mean, minimum, and diel fluctuations in summer stream temperature increased with a reduction in shade, longer treatment reaches, and low gradient. Shade was best predicted by riparian basal area and tree height. Findings suggest that riparian protection measures that maintain higher shade such as the state forests were more likely to maintain stream temperatures similar to control conditions

GroomJeremy.Ferm.ResponseWesternOregonFigures.pdf

A replicated before–after-control-impact study was used to test effectiveness of Oregon’s (USA) riparian protection measures at minimizing increases in summer stream temperature associated with timber harvest. Sites were located on private and state forest land. Practices on private forests require riparian management areas around fish-bearing streams; state forest’s prescriptions are similar but wider. Overall we found no change in maximum temperatures for state forest streams while private sites increased preharvest to post-harvest on average by 0.7 °C with an observed range of response from -0.9 to 2.5 °C. The observed increases are less than changes observed with historic management practices. The observed changes in stream temperature were most strongly correlated with shade levels measured before and after harvest. Treatment reach length, stream gradient, and changes in the upstream reach stream temperature were additionally useful in explaining treatment reach temperature change. Our models indicated that maximum, mean, minimum, and diel fluctuations in summer stream temperature increased with a reduction in shade, longer treatment reaches, and low gradient. Shade was best predicted by riparian basal area and tree height. Findings suggest that riparian protection measures that maintain higher shade such as the state forests were more likely to maintain stream temperatures similar to control conditions

Response of western Oregon stream temperatures to contemporary forest management

A replicated before–after-control-impact study was used to test effectiveness of Oregon’s (USA) riparian protection measures at minimizing increases in summer stream temperature associated with timber harvest. Sites were located on private and state forest land. Practices on private forests require riparian management areas around fish-bearing streams; state forest’s prescriptions are similar but wider. Overall we found no change in maximum temperatures for state forest streams while private sites increased preharvest to post-harvest on average by 0.7 °C with an observed range of response from -0.9 to 2.5 °C. The observed increases are less than changes observed with historic management practices. The observed changes in stream temperature were most strongly correlated with shade levels measured before and after harvest. Treatment reach length, stream gradient, and changes in the upstream reach stream temperature were additionally useful in explaining treatment reach temperature change. Our models indicated that maximum, mean, minimum, and diel fluctuations in summer stream temperature increased with a reduction in shade, longer treatment reaches, and low gradient. Shade was best predicted by riparian basal area and tree height. Findings suggest that riparian protection measures that maintain higher shade such as the state forests were more likely to maintain stream temperatures similar to control conditions.Keywords: Mixed-effects, Stream temperature, Riparian buffer, ShadeKeywords: Mixed-effects, Stream temperature, Riparian buffer, Shad

Same admission cardiac catheterization and cardiac surgery: is there an increased incidence of acute kidney injury?

BACKGROUND: Acute kidney injury (AKI) is predictive of increased long-term mortality after cardiac surgery. Patients often undergo surgery after cardiac catheterization during the same admission for reasons of instability and threatening anatomy as well as nonurgent reasons such as patient convenience. We hypothesized that patients undergoing cardiac catheterization and cardiac surgery during the same admission are more likely to develop AKI after cardiac surgery than patients for whom surgery is performed on a later admission. METHODS: We prospectively enrolled 668 nonemergent adult cardiac surgical cases. Patients having heart catheterization were divided into two groups: cardiac catheterization followed by cardiac surgery during the same hospital admission (same admission) or catheterization followed by surgery during a later admission (later admission). The AKI was defined by an increase in serum creatinine from baseline by 50% or greater or 0.3 (mg/dL) or greater. Univariable and multivariable logistic regression and propensity-matched analyses were conducted. RESULTS: The incidence of AKI was significantly higher in the patients who had same admission cardiac catheterization and surgery (50.2%) compared with patients who had surgery on a later admission (33.7%, p = 0.009). The adjusted odds ratio for surgery on a later admission was 1.54 (95% confidence interval: 1.11 to 2.13) suggesting a 54% increased risk of AKI. Propensity-matched results were similar with 1.58 (95% confidence interval: 1.13 to 2.22). CONCLUSIONS: When cardiac catheterization and cardiac surgery occur during the same hospitalization, there is an increased risk for postoperative AKI. After cardiac catheterization, discharge and readmission for nonurgent surgery should be considered as such an approach might reduce the risk of AKI

Microemboli from cardiopulmonary bypass are associated with a serum marker of brain injury.

An increasing number of reports surrounding neurologic injury in the setting of cardiac surgery has focused on utilizing biomarkers as intermediate outcomes. Previous research has associated cerebral microemboli and neurobehavioral deficits with biomarkers. A leading source of cerebral microemboli is the cardiopulmonary bypass (CPB) circuit. This present study seeks to identify a relationship between microemboli leaving the CPB circuit and a biomarker of neurologic injury. We enrolled 71 patients undergoing coronary artery bypass grafting at a single institution from October 14, 2004 through December 5, 2007. Microemboli were monitored using Power-M-Mode Doppler in the inflow and outflow of the CPB circuit. Blood was sampled before and within 48 hours after surgery. Neurologic injury was measured using S100beta (microg/L). Significant differences in post-operative S100beta relative to microemboli leaving the circuit were tested with analysis of variance and Kruskal-Wallis. Most patients had increased serum levels of S100beta (mean .25 microg/L, median .15 microg/L) following surgery. Terciles of microemboli measured in the outflow (indexed to the duration of time spent on CPB) were associated with elevated levels of S100beta (p = .03). Microemboli leaving the CPB circuit were associated with increases in postoperative S100beta levels. Efforts aimed at reducing microembolic load leaving the CPB circuit should be adopted to reduce brain injury