Douglas-fir beetle lipid levels in relation to tree physical characteristics

The relationship of Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, brood adult lipid levels and position of development along infested tree boles was investigated. In addition, the effects of phloem and bark thickness on brood adult lipid levels were also tested. There were no significant differences (P > 0.05) in brood adult lipid levels in relation to bole position, phloem thickness, or bark thickness found in this study. Numbers of attacks, larval mines, brood adults, and parasitoid cocoons did not differ significantly by tree bole position. Results from this study suggest Douglas-fir beetle does not benefit, in the form of increased lipid levels, from oviposition at different bole positions

The effects of mechanical and chemical site preparation on ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and lodgepole pine (Pinus contorta Dougl. ex Loud.) performance, associated vegetation, and soil properties in southcentral Oregon eight years after planting

The effects of six alternative site preparation treatments were compared at three different sites in southcentral Oregon. Treatments included a logged-only control, ripping, brushblading, disking, chemical, and chemical followed by disking. Subplots containing ponderosa pine bareroot (2+0) and containerized (1+0) and lodgepole pine containerized (1+0) seedlings were also included in the experiment. The study involved the remeasurement of the plots eight growing seasons after establishment. The treatments were evaluated based on changes in selected soil chemical and physical properties, the response of non-conifer vegetation, and the survival and growth of the planted pines. Soil samples were analyzed for total N, total S, total C, and extractable phosphorus. Bulk density was also determined for each sample. In general, the brushblade and chemical/disk treatments caused the greatest reduction in nutrient levels and the greatest increase in bulk density compared to the control arid other treatments. The greatest differences in the amount of non-conifer vegetation among site preparation treatments were observed at the low elevation site (East Aspen), which supported an established shrub community prior to treatment. Total aboveground biomass of shrubs was highest on the control plot. Ripping had the second highest shrub biomass, followed by the disk, brushblade, chemical, and chemical/disk treatments. Plant communities at the higher elevation sites (Swede Cabin and Camp Nine) were primarily composed of grass, sedge, and forb species with scattered shrubs. In general, the control and rip plots had the highest canopy coverage of herbaceous vegetation at these sites, followed by the brushblade, disk, chemical/disk, and chemical treatments. Pine survival was satisfactory for all treatments except the rip and control plots at East Aspen and Swede Cabin. Survival was low for all treatments at Camp Nine. The greatest differences in conifer height growth among site preparation treatments occurred at East Aspen. At this site, the chemical/disk and chemical treatments resulted in a substantial increase in height growth compared to the control. Disking, brushblading, and ripping also increased height growth, but to a lesser extent. All of the treatments except ripping were equally effective at Swede Cabin in increasing height growth compared to the control. At Camp Nine, the effect of treatments with respect to height growth was the same as that at East Aspen, although the magnitude of the differences was less. The results of this study indicate the importance of controlling competing vegetation in order to achieve maximum survival and early growth of planted pines in southcentral Oregon

Pathogenicity to Douglas-fir of Ophiostoma pseudotsugae and Leptographium abietinum, fungi associated with the Douglas-fir beetle

Pole-size Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were inoculated with two fungi (Ophiostoma pseudotsugae (Rumb.) von Arx and Leptographium abietinum (Peck) Wingf.) associated with the Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) to evaluate their pathogenicity. Pruning the lowermost 30% of the live crown had no effect on host tree defenses. Inoculation with O. pseudotsugae produced significantly longer lesions in the phloem and resulted in a significantly greater percentage of necrotic phloem than inoculation with L. abietinum. The percentage of occluded sapwood was also greater following O. pseudotsugae inoculations, but the difference was not statistically significant. Individual lesion lengths declined significantly with increasing inoculation density, but the total percentage of necrotic phloem increased significantly. Both fungi appeared to be better adapted to grow in sapwood than in phloem. None of the inoculated trees were dead after 5 months, but some were chlorotic with less than 30% functional sapwood within the inoculation band. The results suggest that these fungi may assist the Douglas-fir beetle in overcoming the defenses of live trees.Keywords: fungal pathogenicity, Ophiostoma pseudotsugae, Leptographium abietinum, Douglas-fir beetle (Dendroctonus pseudotsugae), host defenses, Douglas-fir (Pseudotsuga menziesii), prunin

Pathogenicity to western larch (Larix occidentalis) of two fungi, Ophiostoma oseudotsugae and Leptoaraghium abietinum, associated with the douglas-fir beetle (Coleoptera: Scolytidae) in Eastern Oregon, U.S.A.

Pole-sized, live western larch Larix occidentalis Nutt.) were inoculated with Ophiostoma pseudotsugae(Rumb.) von Arx or Leptographium abietinum (Peck) Wingf., two blue stain fungi associated with the Douglas-fir beetle (Dendroctonous pseudotsugae Hopkins), to assess their pathogenicity. Inoculation with O. pseudotsugae resulted in a significantly greater percentage of necrotic phloem compared to inoculations with L. abietinum. The percentage of occluded sapwood was significantly greater after L. abietinum inoculations compared to O. pseudotsugae inoculations. Percentages of necrotic phloem and occluded sapwood were positively correlated with inoculation density. In the inoculation band, all trees had greater than 60% functional sapwood four months after inoculation. The results suggest that western larch can successfully limit colonization by Q. pseudotsugae and L. abietinum. The inability of the fungi to thrive in live western larch may be a factor in the consistent failure of Douglas-fir beetle brood to survive in live western larch

Estimating aboveground biomass of shrubs and young ponderosa and lodgepole pines in southcentral Oregon

Regression equations for estimating the aboveground biomass (ovendry weight) of individual plants of 10 shrub and 2 pine species were developed from data collected in south central Oregon. All include a single independent variable and were generated from logarithmically transformed data. Total aboveground biomass of each shrub species is predicted from canopy breadth or volume (length x width x height). Total aboveground and bole-only biomass of ponderosa and lodgepole pines (<3.5 m tall) are predicted from stem diameter, diameter squared times height, or total height. Equations for ponderosa pine were found to be site--specific for the three sampling locations. All of the regression equations are most appropriate for predicting plant biomass in the first 8 years after severe disturbance of forest sites in south central Oregon