True Fir Research Articles

No Long-Term Impact of Carbaryl Treatment on Western Spruce Budworm Populations and Host Trees in the Malheur National Forest, Oregon

Abstract The effects of a single application of carbaryl on western spruce budworm (Choristoneura occidentalis Freeman) populations on the Malheur National Forest in northeastern Oregon were examined for 7 consecutive years beginning in 1983. Budworm control was evident only in the treatment year, 1983, and the next, 1984. There was little difference in the pattern of budworm population behavior between treated and untreated sites during the 7 yr study. Defoliation of Douglas-fir and true firs was reduced slightly by the carbaryl treatment, but did not translate into increased radial growth. On the contrary, there was a general decline in annual radial increment among host trees in both treated and untreated areas from 1980 to 1987, presumably because of chronic defoliation. For. Sci. 41(4):851-863.

Mapping and monitoring conifer mortality using remote sensing in the Lake Tahoe Basin

A prolonged drought in the western United States has resulted in alarming levels of mortality in conifer forests. Satellite remote sensing holds the potential for mapping and monitoring the effects of such environmental changes over large geographic areas in a timely manner. Results from the application of a forest canopy reflectance model using multitemporal Landsat TM imagery and field measurements, indicate conifer mortality can be effectively mapped and inventoried. The test area for this project is the Lake Tahoe Basin Management Unit in the Sierra Nevada of California. The Landsat TM images are from the summers of 1988 and 1991. The Li-Strahler canopy model estimates several forest stand parameters, including tree size and canopy cover for each conifer stand, from reflectance values in satellite imagery. The difference in cover estimates between the dates forms the basis for stratifying stands into mortality classes, which are used as both themes in a map and the basis of the field sampling design. Field measurements from 61 stands collected in the summer of 1992 indicate 15 % of the original timber volume in the true fir zone died between 1988 and 1992. The resulting low standard error of 11 % for this estimate indicates the utility of these mortality classes for detecting areas of high mortality. Also, the patterns in the estimated mean timber volume loss for each class follow the expected trends. The results of this project are immediately useful for fire hazard management, by providing both estimates of the degree of overall mortality and maps showing its location. They also indicate current remote sensing technology may be useful for monitoring the changes in vegetation that are expected to result from climate change.

Assessing Forest Health Conditions in Idaho with Forest Inventory Data

Periodic inventory measurements of forest characteristics published by the U.S. Forest Service are used to assess trends in forest conditions in Idaho. Forest species composition, measured by growing stock volume, has changed since 1952. Western white pine and ponderosa pine have declined by 60% and 40%, respectively. True firs (mostly grand fir) increased by 60% lodgepole pine by almost 40%, and Douglas-fir, the predominant species throughout the state, increased by 15%. Measurements of tree mortality across the state and region from 1952 to 1987 establish a baseline regional range for judging current conditions. Recent mortality data from some Idaho national forests are much higher than the upper limit of the baseline regional range. On the Boise and Payette National Forests in southwestern Idaho, annual mortality exceeds annual growth. Recent inventories of national forests in northern Idaho show mature stands have mortality well above the baseline regional range, which projects into a negative net gro...

Classification of cedar, aspen, and true fir trees as decayed versus sound

Trees are classed as decayed if there is structural damage as a result of internal decay and as sound otherwise. This classification is often performed on standing trees using tree and stand measurements to predict the class. For this study, three general rule systems were proposed and compared. Two different methods, discriminant analysis and classification-trees analysis, were used to derive the various rules. These rules were developed for three species, true fir (Abieslasiocarpa (Hook.) Nutt.), western red cedar (Thujaplicata Donn), and trembling aspen (Populustremuloides Michx.), growing in British Columbia (B.C.). The success of each of the three rules systems developed using each of the two analytical methods was evaluated using the misclassification error rates calculated for a reserved portion of the data available for each species (test data sets). The ease of using and interpreting the rules was also considered in the evaluation. The results indicated that the developed rules were reasonably accurate in predicting the class of trees in the test data sets. Results were more accurate for cedar and aspen than for fir. The use of classification-trees analysis to develop rules in recommended over the use of discriminant analysis. Misclassification error rates were similar for the two methods, but the dichotomous trees that result from classification-trees analysis are much easier to use and interpret.

Effects of a native forest pathogen, Phellinusweirii, on Douglas-fir forest composition in western Oregon

The fungal pathogen Phellinusweirii (Murrill) Gilbertson (Family: Hymenochaetaceae) causes extensive rot in the roots and bole of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and true firs, eventually leading to tree mortality. The native pathogen spreads slowly via root grafts and root contacts between conifers, leaving behind areas of tree mortality commonly called infection centers. This study determines (i) whether the slow, systematic removal of the Douglas-fir overstory by P. weirii changes the community composition of old-growth and mature forests, (ii) if composition is significantly affected, to what degree P. weirii influences the composition, (iii) what effects the disease has on individual populations, and (iv) whether vascular plant diversity is affected by disease presence. The herb, shrub, and tree strata were randomly sampled within and adjacent to six P. weirii infection centers located in the low-elevation Cascade and Coast ranges of western Oregon. Statistically significant (P ≤ 0.05) differences in species composition between infected and adjacent noninfected forest were found across all sites. Ordination techniques showed that the distance of vegetation to the infection center edge was a major factor underlying the forest community's structure. The average cover of all herbaceous species was higher inside infection centers as compared with outside, for all locations, though statistically significant at only two sites. In general, species differed in their responses to disease presence. Changes in diversity due to the presence of the root rot were statistically significant in three of the six cases (P ≤ 0.05) but the patterns of change differed from site to site. The removal of Douglas-fir overstory has strong effects on the plant community, but the specific patterns depend on the species and site involved.

Young True Fir Trees Response to Nitrogen Fertilization in Western Washington and Oregon

Young True Fir Trees Response to Nitrogen Fertilization in Western Washington and Oregon

Percent decay estimation using decayed wood area at breast or stump height

The estimation of tree percent decay is important for estimating the quantity and quality of wood available for timber products. Several different independent variables have been used to estimate the percent decay of standing trees, but often the resulting percent decay predictions are poor. Other independent variables are required for more precise prediction of percent decay. The objective of this study was to examine the use of percent decay area measured at breast or stump height as a possible variable for estimating tree percent decay. Data used in testing included one species group, true fir (Abies spp.), and two species, western red cedar (Thujaplicata Donn) and trembling aspen (Populustremuloides Michx.), from several zones of the province of British Columbia. The use of percent decay area at either breast or stump height resulted in substantial improvements in the estimation of percent decay for all species in all zones. As an alternative to the expensive task of measuring percent decay area on all trees, a sampling design is suggested and one possible design is illustrated.

Effects of Harvesting Season and Stump Size on Incidence of Annosus Root Disease of True Fir

Abstract A high frequency (89%) of annosus root disease caused by Heterobasidion annosum was found in true fir stumps cut 5 to 10 years earlier in northeastern Oregon. Neither season of harvesting nor stump size significantly affected the amount of stump decay which averaged 51%. Another root pathogen, possibly a species of Armillaria heretofore not recorded in Oregon, was often found in H. annosum-infected stumps. Additional surveys and research are recommended in true fir forests throughout western North America. West. J. Appl. For. 7(2):54-56.

Populations of Arboreal Spiders (Araneae) on Douglas-Firs and True Firs in the Interior Pacific Northwest

Population densities and relative abundances of spider families were estimated on Douglas-fir, Pseudotsugata menziessii var. glauca (Beissn.) Franco and true firs, Abies spp., in three geographical provinces of the interior Pacific Northwest: the Southern Cascades, the Northern Cascades, and the Blue Mountains. Mean densities, estimated by sampling tree foliage on lower branches in June 1981, were 9.96, 5.21, and 6.03 spiders per square meter of branch area for the three areas, respectively. Eleven families were represented in the sample. Over half of all individuals were hunting spiders of the families Salticidae and Philodromidae, of which several species are believed to be important predators of defoliating insects. The rest were web-spinners, mostly of the families Dictynidae, Araneidae, Linyphiidae, and Theridiidae. The relative abundance of families had a consistent statistical pattern in which their frequencies were apportioned according to a log series distribution. This suggests that arboreal spider communities of interior Pacific Northwest fir stands have a similar familial structure, probably determined by the branch and foliage characteristics of their habitat.

Long-Term Effect of Treating True Fir Stumps with Sodium Tetraborate to Control Losses from Heterobasidion annosum

Abstract Stump treatment with sodium tetraborate (borax) to control infection by Heterobasidion annosum and to reduce losses was tested in 10 true fir stands in California. These stands were thinned in 1978, 1979, or 1980, and borax was applied to stumps on 0.5 ha plots. Adjacent 0.5 ha plots were left untreated. Borax reduced stump surface infection but did not affect tree mortality between paired treated and untreated plots. The incidence of H. annosum increased for borax-treated stumps whose protected surfaces were removed 1 year earlier. The number of firs that died over the period of the study was positively correlated with the average age of the trees. Differences in mortality were not significant between treated and untreated plots West. J. Appl. For. 7(1):29-31

Survival of Sapling and Pole-Sized Conifers near True Fir Stumps with Annosus Root Disease in Northern California1

Abstract Mixed conifer saplings and small poles near 870 large, true fir (Abies spp.) stumps with annosus root disease caused by Heterobasidion annosum (Fr.) Bref. were studied in 1984 to evaluate mortality. Of 3035 trees adjacent to stumps, 24 were dead (0.8%), and none showed symptoms of annosus root disease. Of 1102 trees adjacent to 71 true fir stumps revisisted 3 and 6 years later, 31 were dead (2.8%), and none showed annosus symptoms. The rarity of annosus-caused conifer mortality associated with infected stumps could be due to variations in pathogenicity, host specificity of H. annosum isolates, decline of inoculum in roots of stumps, or to a combination of these factors. West. J. Appl. For. 6(4):102-105.

HOST ASSOCIATIONS IN SYMPATRIC POPULATIONS OF CHORISTONEURA OCCIDENTALIS FREEMAN AND C. RETINIANA (WALSINGHAM) (LEPIDOPTERA: TORTRICIDAE) IN SOUTH-CENTRAL OREGON AT HIGH POPULATION DENSITIES

Sympatric, synchronous populations of conifer-feeding Choristoneura (Lepidoptera: Tortricidae) occur in western North America (Powell 1980). Choristoneura occidentalis Freeman, the western spruce budworm, co-exists with C. retiniana, the Modoc budworm, in mixed stands of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, and true firs, Abies spp. Choristoneura occidentalis has brown larvae and a broad geographic distribution associated with one of its principle hosts, Douglas-fir (Stehr 1967). Larvae of C. retiniana are green and feed on true firs, particularly white fir, Abies concolor (Gord. & Glend.) Lindl. (Stehr 1967; Carolin et al. 1987).

Defense Mechanisms of Conifers

Cell-free extracts from Pinus ponderosa Lawson (ponderosa pine) and Pinus sylvestris L. (Scotch pine) wood exhibited high levels of monoterpene synthase (cyclase) activity, whereas bark extracts of these species contained no detectable activity, and they inhibited cyclase activity when added to extracts from wood, unless polyvinylpyrrolidone was included in the preparation. The molecular mass of the polyvinylpyrrolidone added was of little consequence; however, polyvinylpolypyrrolidone (a cross-linked insoluble form of the polymer) was ineffective in protecting enzyme activity. Based on these observations, methods were developed for the efficient extraction and assay of monoterpene cyclase activity from conifer stem (wood and bark) tissue. The level of monoterpene cyclase activity for a given conifer species was shown to correlate closely with the monoterpene content of the oleoresin and with the degree of anatomical complexity of the specialized resin-secreting structures. Cyclase activity and monoterpene content were lowest in the stems of species containing only isolated resin cells, such as western red cedar (Thuja plicata D. Don). Increasing levels of cyclase activity and oleoresin monoterpenes were observed in advancing from species with multicellular resin blisters (true firs [Abies]) to those with organized resin passages, such as western larch (Larix occidentalis Nutt.), Colorado blue spruce (Picea pungens Engelm.) and Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). The highest levels of cyclase activity and oleoresin monoterpenes were noted in Pinus species that contain the most highly developed resin duct systems. The relationship between biosynthetic capacity, as measured by cyclase activity, monoterpene content, and the degree of organization of the secretory structures for a given species, may reflect the total number of specialized resin-producing cells per unit mass of stem tissue.

Modelling disaggregated lumber demand and supply by constrained estimation techniques

Constrained estimation techniques were used to estimate a 12-equation demand and supply system for Douglas-fir and hemlock–fir (true fir) lumber by clear and common grades. Such techniques combine sample information with nonsample information and produce estimates with smaller variances than those based only on sample data. Conventional econometric estimation was compared with a quadratic programming technique with regression coefficients constrained to their a priori correct signs. A goal programming technique that minimized the sum of the absolute deviations was rejected because of its substantially different results and lack of information on the statistical properties of its estimates. The quadratic programming technique had the advantages of statistical efficiency, objectivity, and speed. The conventional estimation technique excluded fewer variables from the system and thus was less susceptible to omission of variables bias. Elasticity estimates for most key variables were similar. Quadratic programming versus conventional estimates of demand elasticity were, respectively, −0.95 and −0.88 for Douglas-fir clears, −2.83 and −2.91 for Douglas-fir commons, and −2.13 and −2.27 for all Douglas-fir; whereas supply elasticities for hemlock–fir commons were 1.35 and 1.37, and for all hemlock–fir, −1.76 and −1.42.

Growth resumption and performance of nonchilled Abies seedlings after their first winter

Survival, phenology, and growth of containerized noble fir (Abiesprocera Rehd.) and Shasta red fir (Abiesmagnifica A. Murr. var. shastensis Lemm.) seedlings were measured in response to dormancy induction chilling, and postplanting irrigation treatments. Temperature, photoperiod, and moisture were varied to induce dormancy. Seedlings were not chilled during the first winter, but received natural chilling during the second winter. In the first growing season (no winter chilling), terminal buds did not flush, but remained alive and inactive. Buds on lateral branches flushed and extended normally. In the second season (natural winter chilling), all terminal buds and lateral buds flushed. Dormancy induction treatment did not significantly affect budbreak, survival, or growth. However, postplanting drought simulation significantly reduced height, diameter, and aboveground biomass. The results demonstrate that the terminal buds of planted, nonchilled seedlings of these true fir species can remain inactive through an entire season and then resume growth once their chilling requirements are fulfilled.

Weather and Bird Populations in True Fir Forests of the Sierra Nevada, California

Bird communities were monitored in fir (Abies spp.) forests at 51 sites in the western Sierra Nevada during the breeding seasons of 1983, 1984 and 1985. The El Nino winter of 1982-83 had the greatest snowfall on record. The summers of 1984 and 1985 followed winters with moderate snowfalls. Bird species richness and average total count increased linearly from 1983 to 1985. The relative abundances of 12 common species increased from 1983 to 1985. Abundances of two common species did not differ among years. Twenty-eight uncommon species increased and four decreased in numbers from 1983 to 1985. Bird response patterns differed between lower-altitude white fir (A. concolor) forests and upper-altitude red fir (A. magnifica) forests. Bird numbers were similar in both habitats in 1983 but greater in white fir then in red fir in 1984 and 1985. Abundances of the common species increased in both habitats in both years, but abundances of uncommon species did not increase substantially in red fir until 1985. It was suggested that bird numbers were depressed in 1983, although not atypically so for fir forests, and that white fir and low-altitude forests might harbour 'source' populations for red fir 'sink' populations during periods of resource stress.

TOXICITY OF SMOKE FROM SPOROPHORES OF THE INDIAN PAINT FUNGUS AND WOOD FROM WESTERN HEMLOCK TO YELLOWFEVER MOSQUITOES

AbstractTo mitigate the effects of mosquitoes, settlers in the Revelstoke area of British Columbia reportedly burned the sporophores of the Indian paint fungus, Echinodontium tinctorium (Ell. & Ev.) Ell. & Ev., a pathogen of western hemlock, Tsuga heterophylla (Raf.) Sarg., and true firs, Abies spp. Larval and adult yellowfever mosquitoes, Aedes aegypti (L.), were exposed to aqueous extracts of smoke (smoke-waters) from E. tinctorium sporophores, and from western hemlock sapwood and heartwood. Smoke-waters were of approximately equal toxicity to larvae. Fungus smoke-water, but not sapwood or heartwood smoke-waters, lost 50% of its potency in 5 months. Vapors from fungus smoke-water were significantly more toxic to adult mosquitoes than those from sapwood or heartwood. Thus smoke from E. tinctorium sporophores and T. heterophylla wood apparently contain different water-soluble combustion products toxic to A. aegypti.

Comparison of Volume Growth Calculation Methods for Remeasured Horizontal Line Sampling

Abstract In remeasured horizontal line sampling, there is only one commonly used method for estimating yield. However, there are several methods for estimating growth. Five different methods of growth estimation, based on how a given classification of tree could be treated in the growth estimation, were tested on four species groups (true fir and spruce, cypress, pine, mixed softwood and hardwood) in Taiwan. The classical method (also called the Strand method, or the compatible method), where tree status was ignored, had significantly larger mean squared error of the estimators than the others. There was no interaction between species group and method. The other four methods were very similar in the precision of estimate. Based on the ease of gathering data, the revised Purdue method is recommended. If volume and growth need to be compatible, the variable diameter factor method should be used for remeasured horizontal line sampling. For. Sci. 33(4):1062-1067.

Pollen analysis of a late pliocene and early pleistocene section from the Gubik Formation of Arctic Alaska

A 14-m-thick section of marine and nonmarine sediments of the Gubik Formation of northern Alaska, exposed in bluffs near Ocean Point on the Colville River, has been studied by means of pollen analysis. Pollen from the marine sediments, of probable late Pliocene age, records a boreal forest of spruce and birch with minor amounts of alder in the adjacent terrestrial vegetation. Pine and perhaps true fir were probably at or near their northern limit here, but hemlocks and hardwoods were absent. The suggested environment for the Arctic Slope during the time represented by the marine sediments is similar to that of present-day Anchorage. Pollen floras from the overlying fluvial strata, of early or middle Pleistocene age, record predominantly herbaceous taxa indicating tundra conditions probably more severe than those of the present day. These deposits were most likely contemporaneous with glacial conditions in the Brooks Range to the south. Pollen of woody taxa (spruce, alder, birch, heaths) is rare through most of the section, although birch and alder percentages similar to those found in modern river sediments indicate an interstadial or interglacial warming in midsection. Inland climates during glacial episodes may have been similar to those of the present Arctic coast.

Impact of tephra deposition on growth in conifers: the year of the eruption

Seven sites ranging from 15 to 135 km from Mount St. Helens were selected to study the impact of air-fall tephra on the growth of Abiesamabilis (Dougl.) Forbes, A. procera Rehd., Pseudotsugamenziesii (Mirb.) Franco, Tsugaheterophylla (Raf.) Sarg., and T. mertensiana (Bong.) Carr. As tephra depth increased, there was a corresponding increase in visible foliar damage and associated decreases in diameter and height growth. Reduction in diameter growth was greater than reduction in height growth. The reduction in diameter growth approached 50% in both trees and saplings of A. amabilis. Growth reduction in true firs was greater than in associated species. This difference was related to their greater capacity for interception and retention of air-fall tephra. Damage to trees, and resulting growth reductions, were due to tephra coverage of both the foliage and the soil. Coverage of the foliage resulted in foliar damage, foliage abscission and reduction of total tree foliar area, and increased fine root mortality. Tephra coverage of the soil had the potential to restrict oxygen diffusion into the soil. However, soil oxygen concentrations less than 10% were measured only once over a 2-year period.