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California coast live oaks ( Quercus agrifolia Nee) have suffered large losses from sudden oak death, caused by the introduced oomycete Phytophthora ramorum . Infected mature coast live oaks exhibit cankers on the main stem that produce a viscous sap-derived exudate, referred to as bleeding. Subsequent attacks by ambrosia and bark beetles, followed by the activity of fungi introduced by these insects, have led to mortality levels greater than 50% since the mid-1990s. Despite an infection rate of 5% year −1 , asymptomatic trees still persist in many heavily infected stands after more than 15 years of exposure to the pathogen. We hypothesized that varying responses to P. ramorum , including apparent recovery from infections, reflected phenotypic differences in susceptibility. In this study we evaluated the relationship between the early development of symptoms in mature trees that were experimentally inoculated with P. ramorum and long-term survival. A logit model showed that external canker lengths measured 9 months following inoculation predicted survival 7 years later. We defined resistance to P. ramorum in the surviving trees as absence or cessation of bleeding after the 7 years of the study and absence of beetle attacks on bleeding trees. Probability of resistance was also predicted by external canker length measured 9 months after inoculation. Canker length distribution was consistent with quantitative resistance to P. ramorum . The role of plant chemistry in resistance was examined by quantifying soluble phenolics in phloem methanol extracts prepared from the surviving trees. A logistic regression model found that expression of resistance was associated with four phenolic compounds; ellagic acid and a partially characterized ellagic acid derivative, and two chromatographic peaks that represent two uncharacterized phenolic compounds. Ellagic acid and a crude methanol extract from coast live oak phloem (total phenolics) were fungistatic when assayed in vitro at physiologically relevant levels and total phenolics were fungicidal at the highest concentration tested. The association of certain phenolics with resistance may facilitate the use of biomarkers in minimally invasive assays to predict the response of trees to P. ramorum , thereby increasing the options for managing threatened forests.

In interior Alaska, increased use of mechanical fuel reduction treatments, increased interests in the use of wood energy systems as alternatives to fossil fuels, and elevated populations of northern spruce engraver, Ips perturbatus (Eichhoff), have raised concerns regarding the impact of this bark beetle to forest resources. We conducted a large-scale field study in 2009−2011 (Study 1) to determine the effects of slash scoring (mechanical by chainsaw versus none), slash distribution (scattered versus decked), and cutting date (spring versus fall) on I. perturbatus colonization of and reproductive performance in white spruce, Picea glauca (Moench) Voss, slash, and to determine the effects of resulting treatments on adjacent levels of tree mortality caused by I. perturbatus. Unfortunately, attack densities were lower than expected, and did not provide for a very robust examination of the effects of these treatments. As a result, we reproduced several aspects of Study 1 in a second study (2011) using a baited design. Higher levels of I. perturbatus attack and emergence occurred on dispersed logs. Attack densities were highest in the dispersed, unscored treatment, and ∼70% higher than observed in the decked, scored treatment. The scoring of dispersed logs significantly reduced attack densities by ∼28%, but had no effect in decked treatments or on levels of emergence in either treatment. Higher levels of attack and emergence were observed on the tops of logs as compared to the bottoms of logs. Brood production (i.e., defined here as emergence/attacks) was also greater on the tops of logs compared to the bottoms of logs, suggesting the tops of logs are not only more attractive to I. perturbatus, but confer some advantage to brood development. Lower levels of attack and emergence occurred on small diameter logs. Higher levels of attack and emergence were observed on logs in a shaded fuelbreak (i.e., a more open condition of lower tree density) compared to the adjacent forest. Overall, our research suggests that unlike other works on Ips spp. in the western USA that promote the desiccation of slash to minimize colonization and brood production, I. perturbatus appears regulated by the apparency and accessibility of host material. This finding highlights the importance of developing management guidelines based on local science. A third study found two semiochemicals, trans-conophthorin and verbenone, reduced colonization of slash by I. perturbatus, and therefore holds promise as a tool for managing I. perturbatus populations. The implications of these and other results to the management of I. perturbatus in interior Alaska are discussed.

A critical component of a growth and yield simulator is an estimate of mortality rates. The mortality models presented here are developed from long-term permanent plots in provinces from throughout the geographic range of ponderosa pine in the United States extending from the Black Hills of South Dakota to the Pacific Coast. The study had two objectives: estimation of the probability of a tree survival for the next 5 years and the probability of a tree surviving longer than a given time period (survival trend) for a given set of covariates. The probability of a tree surviving for the next 5 years was estimated using a logistic model regressed on 18 covariates measured 5 years before the last measurement period with 15 smoothing variables (S1–S15) for spatial effects of latitude and longitude surface. The fitted model showed that the probability of survival increased with increasing diameter at breast height (DBH), DBH periodic annual increment (PAIDBH) and increasing plot basal area/number of trees per hectare (PBAH/TPH), and decreased with increasing average of the 5 tallest trees in the plot (AVGHT5) when other selected covariates were included in the model. The probability of a tree surviving longer than a given time period was estimated by fitting the Cox Proportional Hazard model to the last observed survival period regressed on 13 covariates measured at the first measurement period. This probability also increased with increasing DBH and PAIDBH, and decreased with increasing AVGHT5. The Akaike’s Information Criterion (AIC) and graphs of partial residuals were used in the selection of covariates included in the models.

Sudden oak death, caused byPhytophthora ramorum, is widely established in mesic forests of coastal central and northern California. In 2000, we placed 18 plots in two Marin County sites to monitor dis- ease progression in coast live oaks (Quercus agrifolia), California black oaks (Q. kelloggii), and tanoaks (Lithocarpus densiflorus), the species that are most consistently killed by the pathogen in these areas. Through early 2008, the numbers of newly infected trees increased for all species. The infection rate for trees that were asymptomatic in 2000 was 5.0%y "1 for coast live oaks, 4.1%y "1 for black oaks and

The fisher (Martes pennanti) is a forest mustelid endemic to North America that has experienced range reductions in Pacific states that have led to their listing under the Endangered Species Act as warranted but precluded by higher priorities. The viability of the southern Sierra Nevada fisher population is of particular concern due to its reduced historical range, isolated nature, and low genetic variability. We located resting structures of radio-collared fishers in the southern Sierra Nevada and compared resting and available habitat to examine selection for specific features of resting sites. Resting structures provide protection from predators and unfavorable weather and are believed to be the most limiting habitat element across fisher home ranges. Resting structures were found primarily in live trees (76%) and snags (15%). Trees used by fishers for resting were among the largest available and frequently had mistletoe infestations. Ponderosa pines (Pinus ponderosa) were used more often than expected and incense cedars (Calocedrus decurrens) less than expected. Snags were also large and in fairly advanced stages of decay. Habitat at fisher resting sites had higher canopy cover, greater basal area of snags and hardwoods, and smaller and more variable tree sizes compared to random sites. Resting sites were also found on steeper slopes and closer to streams. Canopy cover was consistently the most important variable distinguishing rest and random sites. In western North America, fishers are generally associated with late-successional forests, but changes in these forests due to logging and fire suppression have resulted in a transition to forest stands characterized by fewer large trees and more small stems. These conditions are consistent with our finding that the large rest structures were surrounded by smaller than average trees. Management practices that support the growth and retention of greater numbers of large trees and snags, while maintaining a minimum of 61% (based on moosehorn) or 56% (generated via Forest Vegetation Simulator) canopy cover and a complex horizontal and vertical forest structure, can improve and provide for future fisher habitat.

We tested a new formulation of verbenone, an antiaggregation pheromone of the mountain pine beetle (Dendroctonus ponderosae Hopkins) (Coleoptera: Curculionidae: Scolytinae), for area-wide protection of lodgepole pine (Pinus contorta Douglas ex Loudon) stands in the western United States. Helicopter applications of verbenone-releasing laminated flakes were made at the rate of 370 g of active ingredient/ha to two sites, one in California and one in Idaho, during summer 2005. Each site consisted of five 20.23-ha treated plots and five matching 20.23-ha untreated plots. We assessed D. ponderosae flight into study plots using traps baited with aggregation pheromones and we tallied D. ponderosae attack rates on P. contorta trees in treated and control plots before and after application. There were no significant differences between numbers of D. ponderosae trapped on treated and control plots. However, a significantly smaller proportion of P. contorta trees was attacked in treated plots than in control plots at both sites; the attack rate in untreated stands was roughly three times that of treated stands in both California and Idaho, even at this low application rate. Furthermore, attack rate in 2004 was a significant explanatory variable for the response in 2005 regardless of treatment in both California and Idaho. There was no significant treatment effect at either site on attraction of Temnochila chlorodia (Coleoptera: Trogositidae) Mannerheim, a key predator of D. ponderosae, to the prey aggregation pheromone.

We tested methylcyclohexenone (MCH), an anti-aggregation pheromone for the Douglas-fir beetle (Dendroctonus pseudotsugae), for protection of Douglas-fir (Pseudotsuga menziesii) stands by applying MCH-releasing polymer flakes by helicopter twice during summer 2006 to five 4.05-ha plots in the State of Washington, USA. Five similar plots served as untreated controls. We assessed D. pseudotsugae flight into study plots using baited pheromone traps, and tallied D. pseudotsugae attack rates on all P. menziesii trees in 2005 and 2006. We also measured stand basal area and incorporated that as an explanatory variable in the analysis. Significantly fewer D. pseudotsugae were trapped in treated plots than in control plots, and significantly fewer P. menziesii trees were attacked in treated plots than in control plots. The attack rate in untreated stands was nearly 10 times that of treated plots, and stands with higher basal area were significantly more likely to be attacked by D. pseudotsugae than were stands of lower basal area. Attack rates in 2006 and 2005 were significantly correlated, regardless of treatment.

Sudden oak death (SOD), caused by Phytophthora ramorum, is killing oaks and tanoaks in the Coast Ranges of California, from Monterey County to Humboldt County. In March 2000, 20 disease progression plots were established in Marin County, California, to characterize the progress of disease symptoms, and to determine the fidelity of the association of three or more bark and ambrosia beetle species (Coleoptera: Scolytidae) with diseased oaks and tanoaks. Symptoms of sudden oak death and signs of associated organisms were recorded from coast live oaks (Quercus agrifolia), California black oaks (Q. kelloggii), valley oaks (Q. lobata), and tanoaks (Lithocarpus densiflorus), four times per year, from March 2000 through March 2003. Symptoms and signs in Q. agrifolia progressed from bleeding, to infestation by scolytid beetles, to the development of fruiting structures of the fungus Hypoxylon thouarsianum. Mortality of symptomatic trees increased from 2000 to 2003 as follows: Q. agrifolia (n = 668), 5.8‐17.4%; Q. kelloggii (n = 53), 3.8‐9.4%; and L. densiflorus (n = 164), 8.3‐22.2%. All 31 Q. lobata remained asymptomatic. From 2000 to 2003, bleeding trees were 25.0‐23.6% of living Q. agrifolia, 15.5‐25.0% of Q. kelloggii, and 39.0‐62.4% of L. densiflorus. Scolytid beetles colonized more than 95% of the living symptomatic Q. agrifolia that subsequently died. Same-symptom cohorts were followed from March 2000 through March 2003. In the asymptomatic Q. agrifolia cohort, 12.0% developed bleeding by 2003. For the bleeding only cohort, 22.7% of Q. agrifolia died, but 73.5% of the beetle-colonized bleeding cohort died. Bleeding developed in 40.9% of the initially asymptomatic L. densiflorus cohort. By 2003, 24.6% of the initially bleeding L. densiflorus cohort had died. Both Weibull and Cox Proportional Hazards regression were