Engelmann spruce (Picea engelmannii Parry ex Engelm.) exhibits cone crop periodicity, producing seed in a cyclic pattern. Variation in seed production has been noted between individuals of a population, but synchronization on a large scale is common. The theory that ultimately these periodic large cone crops have resulted from the selective pressures of seed and cone predators, referred to as the predator satiation hypothesis, is considered. Assuming predator pressures have operated over evolutionary time to select for periodic synchrony, associations between seed and cone predators and cone crop production levels were anticipated. These potential consequences of predator satiation were examined. Long-term data from 1948 to 1970 of Engelmann spruce cone production levels and small mammal populations, estimated from trappings, were analyzed for positive associations. Three small mammal categories, mice (Peromyscus spp.), chipmunks (Eutamias spp.) and red squirrels (Tamiasciurus hudsonicus) were examined. Only the correlation coefficient between population indices for mice and cone crop production was found to be significant. Engelmann spruce cones were collected throughout the summer of a year of low cone production. The impacts and timing of insect infestation were determined in developing cones. The major insects found were western spruce budworm (Choristoneura occidentalis (Freeman) (Lepidoptera: Torticidae)), fir coneworm (Dioryctria abietvorella (Grote) (Lepidoptera: Pyralidae)), and spruce seed moth (Laspeyresia youngana (Kearfott) (Lepidoptera: Olethreutidae)). Insects reduced the survival of cones to 11.48 cones out of 100. The high percentage of seeds and cones lost to insect predation supported previous studies of a similar nature. Both studies examined the potential consequences of the predator satiation hypothesis which has been suggested as an adaptive mechanism for trees to avoid seed and cone predation.

Relationships between jack pine dwarf mistletoe (Arceuthobium americanum Nutt. ex Engelm.) and Armillaria root disease (Armillaria ostoyae (Romagn.) Herink) were examined to determine how these two disease agents contribute to jack pine (Pinus banksiana Lamb.) decline and mortality in the Belair Provincial Forest, Manitoba, Canada. The incidence and extent of Armillaria root disease was strongly related to tree vigor. Dwarf mistletoe infection did not affect either the incidence of Armillaria or the mean percentage of root system colonization within vigorous, declining, and dead classes of trees. However, field observations and other analyses indicate that dwarf mistletoe was primary responsible for jack pine decline and mortality. In dwarf mistletoe mortality centers, Armillaria appeared to act opportunistically, extensively colonizing only the stressed trees. Analysis of distributions of percent Armillaria colonization revealed that rapid root system colonization occurred just prior to, or at the time of tree death.

Biomass of roots in the top 6 inches of soil profile was measured . This weight was then used in a stepwise multiple regression to test correlations between root biomass and above ground merisurational parameters. Total biomass of all roots was 9822 ± 2810 pounds per acre oven dry. Spruce roots weighed 4417 ± 997 pounds per acre; of this spruce roots less than 0.125 inch diameter weighed 2023 ± 347 pounds per acre and biomass of spruce roots greater than 0.125 inch diameter was 2394 ± 8S3 pounds per acre. Total fir roots weighed Sl56 ± 2687 pounds per acre; of this roots less than 0.125 inch totaled 869 ± 181 pounds per acre and biomass of fir roots greater than 0.125 inch diameter was 4287 ± 2653 pounds per acre. Low r2 (0.11 to 0 .17) values were found and the parameters which showed the greatest predictive value were (dbh)2, dbh, basal area, (basal area)2, and height. The sampling design involved the pairing of trees over 4 inches diameter. Point density expressed as basal area was not useful in relating to root biomass with this sampling design.

A significant question currently facing environmental managers is how to accurately and efficiently quantify forest diversity and resources. Numerous studies have demonstrated the use of modern spatial analytical tools , such as geographical information systems (GIS), remote sensing devices, and statistical models for predicting the distribution of dominant vegetation cover types. This study examines the ability of generalized additive models (GAMs) to delineate structural diversity in forested ecosystems (specifically the Uinta Mountain Range in Utah) using GIS tools and satellite spectral data, and analyzes the effect of including different forms of satellite data in model construction (i.e., Landsat thematic mapper (TM), advanced very high resolution radiometer (AVHRR), and the GAP Analysis TM-classified map). Based on the assumption that vegetation composition, as well as structural diversity, is a function of environmental gradients, temperature, precipitation, elevation, aspect, slope, and geology were included as independent environmental variables. Probability surface maps were generated for presence of forest , presence of lodgepole pine, basal area of forest trees, percent cover of shrubs, and density of snags. The maps were validated using an independent set of field data collected from the Evanston Ranger District within the Uinta Mountain Range . In general, the models tended to underpredict at large numbers and overpredict at locations that were sampled as having no forest cover. The models predicting the presence of forest and lodgepole pine were 88% and 80% accurate, respectively, within the Evanston Ranger District and an average of 62% of the predictions of basal area, shrub cover , and snag density fell within an approximate 15% deviation from the field validation values . The addition of TM spectral data and the GAP Analysis TM-classified data were found to contribute significantly to the models' predictions, with some contribution from AVHRR data. The methods used in this study provide a systematic approach for delineating structural features within forest habitats, thus offering an efficient spatial tool for making management decisions.

Forty-three and 54 Ferruginous hawk (Buteo regalis) pairs were found occupying territories in northern Utah and southeastern Idaho during 1972 and 1973, respectively. Of these 38 and 27 nesting pairs laid eggs. Nesting success was 77.1 percent in 1972 and 74.6 percent in 1973. for successful nests, an average of 2.9 and 2.6 young hatched and 2.7 and 2.3 young fledged during the respective years. This population is reproductively comparable to others in Utah and Colorado. Analysis of prey items collected from the nests indicated that black-tailed jack-rabbits (Lepus californicus) constitute 86 percent of the biomass (by weight) of three major prey species consumed by ferruginous hawks in this area. Jackrabbit density may be a major determinant of the number of young produced in a given year. Weight gained by the nestlings showed a marked sexual dimorphism. Female fledgelings weighed up to 1.43 times as much as males. Criteria were developed for sexing ferruginous hawks by measuring the diameter of the hallux. Mortality of 17 birds from the study area was recorded, of which 47 percent were immature birds. A total of 108 fledglings were banded and marked with color-coded patagial wing markers. Band reports of five (10 percent) of these birds were received. Utah juniper (Juniperus osteosperma) provided nest sites for 96.0 percent of the nests while three percent were built on the ground. Plant community types were determined at 63 nesting sites from aerial photographs. Dominant vegetation around nest sites were desert shrub types and crested wheatgrass (Agropyron cristatum) seedings. The possible impact of land management practices on ferruginous hawks is discussed.

A field experiment tested the effectiveness of carbaryl and two pyrethroid insecticides, cyfluthrin and esfenvalerate, in protecting high-value Engelmann spruce trees from attack by Dendroctonus rufipennis Kirby. Carbaryl suspension at the 2% registered rate and a reduced rate of 1 % were both effective in protecting Engelmann spruce from attack by D. rufipennis through two pheromone baiting periods and 24 months following insecticide application . Cyfluthrin at 0.025% rate and esfenvalerate at 0.025 and 0.05% rates provided effective protection through one pheromone baiting and 12 months following insecticide application. Only cyfluthrin at 0.008% rate was judged ineffective protection 12 months following insecticide application. A laboratory evaluation utilizing a 32-h bioassay on D. rufipennis adults determined all three insecticides were toxic by contact. Carbaryl and piperonyl butoxide bioassays testing synergism were inconclusive. The methodology presented provides a means for forest land managers to quantify insecticide toxicity and monitor for resistance development.

Fire occurrence and behavior were determined by collecting and analyzing fuel , weather , and fire history ii data. Fuel plots were used to measure average fuel loading by vegetation type and integrated with weather to make worst - case fire behavior prediction s . A fire history was developed using oakbrush (Quercus qaffibelli Nutt . ) sprouts to determine age and the Global Positioning System (GPS) for mapping the burned areas . Average fuel loading was highest in the oakbrush fuel type with 16.8 t/ha , then juniper (Juniperus ost eosoerma Torrey ) with 6 . 72 t/ha , and the lowest was in sagebrush (Artemisia triden~at a Nutt. ) with 4 . 93 t/ha . Fire behavior predictions were similar for all fuel types. The fire rotation for the study area was calculated to be 30 years. The fire history showed the most hectares burned were in the oakbrush fuel type due to fuel loading and horizontal continuity. Prescribed burns and negative fuel breaks were suggested as management alternatives. The effect of fire on deer mouse (Peromyscus maniculatus) density in oakbrush was determined by using a trapping web design with distance sampling techniques . Webs were set in four pairs with one web of each pair being in 7- year- old burned oakbrush and the other web in unburned oakbrush. Variables such as shrub height and litter depth were recorded in order to reduce variance . Trapping occurred in June 1994 with each web set for two consecutive nights using 80 Museum Special snap traps spaced 6 m apart on eight lines . Density estimates were determined by using a computer program called DI STANCE and then analyzed using analysis of variance with a randomized block design . No significant differences between deer mouse densities were detected between burned and unburned oakbrush. Although litter depth and shrub height were both significantly less in burned sites, it did not affect deer mouse density . The conclusion from these result s was that after 7 years oakbrush had recovered to a point that the effect of fire on deer mouse density was negligible.

This dissertation describes the development and analysis of a new forest dynamics model. The NORTHern Woodland Dynamics Simulator (NORTHWDS) was designed to spatially model forest pattern and process for the northern Lake States, and to incorporate multiple spatial scales. While ecologically detailed, this stand table-based model is sufficiently parsimonious to be able to simulate 100s to 1000s of hectares for centuries. Processes like tree regeneration, growth, and mortality, herbaceous and shrubby competition, biogeochemistry, carbon cycling, edge effects, and climatic influences are incorporated in NORTHWDS. Wind disturbance and white-tailed deer browsing were also included to help forecast stand and landscape dynamics under managed and unmanaged scenarios. Preliminary results suggest that NORTHWDS can reliably predict long-term forest ecosystem responses to succession and disturbance. NORTHWDS was also applied to test the effectiveness of a managing-for-old-growth strategy, with results indicating that this type of management can provide improvements over traditional even- and uneven-aged harvest systems in desirable old-growth attributes like aboveground live biomass and coarse woody debris patterns. The results of the NORTHWDS developmental and application chapters were then synthesized to produce a new conceptual approach to landscape simulation that incorporated space, multiple scales, and a hierarchical design. A user's guide, the source code, and model defaults complete this dissertation.

It was the purpose of this study to examine an assumption basic to the forest habitat type classification system. Included in each habitat type is all land capable of supporting a single climax plant community type. In practice, land is grouped based on species camposition, relative abundance, and successional trends of the vegetation supported by the land. Land units of the same habitat type are assumed to represent similar environments. No previous critical evaluation of this assumption has been done. Land in the study area had been previously classified under the habitat type system. Relationships between vegetation and environment were studied in the Abies lasiocarpa/Pedicularis racemosa, Abies lasiocarpa/Osmorhiza chilensis, Abies lasiocarpa/Berberis repens, Pseudotsuga menziesii/Physocarpus malvaceus, Pseudotsuga menziesii/Berberis repens, and Pseudotsuga menziesii/Cercocarpus ledifolius habitat types. Environmental variables potentially important in determining the vegetation characteristics defining the habitat types were measured over two summers (1977 and 1978) in stands representative of these types. These measurements showed these habitat types to occupy significantly different environments for most environmentalvariables studied. Environments were more variable between than withinthe habitat types. Two-dimensional direct gradient analyses for single and multiple environmental variables were compared to ordination results to find which of the environmental variables measured might determine the vegetation gradients indicated by the ordination. Gradients of elevation, maximum and minimum air temperature, and estimated annual incident solar radiation did not correlate well with ordination axes. Best correlation, 0.78 and 0.74 respectively, resulted for summer soil temperature measured at 50 em for one ordination axis and, for the second ordination axis, a linear combination of soil moisture percentage at 20 em, estimated percent volume of coarse rock fragments in the soil, and available soil water storage capacity estimated from soil texture class and percent rock. These temperature and moisture variables are felt to be important through their influence on plant moisture stress. Direct measurement of predawn plant moisture stress on conifer saplings did not differentiate between habitat types. Results were highly variable. This was attributed to morphological and microhabitat influences such as disease, rooting pattern and shading which may obscure larger scale environmental differences between stands. It is hypothesized that vegetation in these habitat types responds to environmental gradients that determine the availability of soil moisture to plant roots to meet transpirational demand and atmospheric influences on that demand. Hypotheses of the relationships of the habitat types to these environmental gradients were developed. It is tentatively concluded that the habitat type classification system is effective in stratifying the physical environment in terms of environmental factors which are physiologically meaningful to the vegetation characteristics defining the habitat type classes.

A comprehensive fuel load assessment of all plant communities in Bryce Canyon National Park is provided. Fuel loads by community type are pooled into "fuel type associations" based on similarity in predicted fire behavior, and the fuel type associations are mapped throughout the Park. For each fuel type association, a series of fire behavior simulations is presented describing expected rates of spread and intensities for typical conditions in each month of the fire season and for a worst-case scenario. These fire behavior predictions provide guidelines for writing prescribed burning prescriptions or for quickly assessing the need for possible fire suppression and the amount of effort required to suppress particular fires.