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Tesis sobre el tema "Pinus ponderosa"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 31 de enero de 2023

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1

Braun, David M. "Host colonization behavior of the mountain pine beetle (Dendroctonus ponderosae Hopkins) in thinned and unthinned stands of second-growth ponderosa pine (Pinus ponderosa Laws.) /". Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/5482.

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2

Parra, Jaque Carlos Alfonso. "Productividad de las plantaciones de pino ponderosa (Pinus ponderosa Dougl. ex Laws.) de la Comuna de Coyhique, Provincia de Coyhaique, XI Región". Tesis, Universidad de Chile, 2009. http://repositorio.uchile.cl/handle/2250/151537.

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Memoria para optar al Título Profesional de Ingeniero Forestal
Ecuaciones altura-diámetro, de volumen, determinación de calidad de sitio y elaboración de modelos de productividad son testeados para plantaciones de pino ponderosa (Pinus ponderosa Dougl. ex Laws.) no raleadas de la comuna de Coyhaique, provincia de Coyhaique, región de Aysén. Los datos para los ajustes se obtienen de 91 parcelas instaladas en todo el rango de edades, número de árboles por hectárea y distribución geográfica de las plantaciones de pino ponderosa. Seis ecuaciones H-D (dos lineales y cuatro no lineales) de las más ampliamente usadas en pino ponderosa, son ajustadas con un set de 1.378 datos H-D obtenidas de las 91 parcelas antes indicadas. Los modelos son ajustados para cada una de las 91 parcelas y comparados según error estándar de estimación. El siguiente modelo no lineal es el escogido porque convergió más eficientemente respecto a los otros modelos no lineales y tiene más flexibilidad que las funciones lineales, además tiene un bajo error estándar de estimación.

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3

Telewski, Frank W. "Ethylene Production By Different Age Class Ponderosa and Jeffery Pine Needles as Related to Ozone Exposure and Visible Injury". Springer-Verlag, 1992. http://hdl.handle.net/10150/303765.

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Author's manuscript for published article. See Additional Links field for link to published version.
Ethylene production by different needle age classes was characterized using a mercuric perchlorate traps in natural populations of two ponderosa pine varieties (Pinus ponderosa var. arizonica [Engelm] Shaw and var. ponderosa Dougl. ex Laws.) and Jeffery pine (Pinus leffrevi Grev. and Balf.). All ozone -exposed populations contained individuals which were symptomatic and asymptomatic with respect to visible ozone injury. Ethylene production of different needle age classes was also characterized in Pinus ponderosa var. ponderosa seedlings grown in open top ozone fumigation chambers. Older age class needles produce more ethylene than younger age class needles. Needles of both P. ponderosa var. ponderosa and P. jeffreyi exhibiting ozone injury in the field produced significantly (p >0.05) higher levels of ethylene than asymptomatic conspecifics. Seedlings exposed to highest treatment level of ozone in the fumigation study produced the highest levels of ethylene followed by fumigation with medium and low ozone concentrations and carbon filtered air. These data indicate that measurement of ethylene in conifer needles as a measure of stress needs to be calibrated for needle age class. It also suggests that the sensitivity of a tree to ozone injury may be regulated by the inherent ability of the individual to produce ethylene.

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4

Kernan, James T. "GIS analyses of paleo-fire regimes in ponderosa pine (Pinus ponderosa) forests extending spatial approaches in ecological interpretation /". Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10045.

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Thesis (Ph. D.)--West Virginia University, 2009.
Title from document title page. Document formatted into pages; contains xii, 174 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references.

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5

Woodall, C. W. "When Is One Core Per Tree Suffifcient To Characterize Stand Attributes? Results Of A Pinus Ponderosa Case Study". Tree-Ring Society, 2008. http://hdl.handle.net/10150/622568.

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Increment cores are invaluable for assessing tree attributes such as inside bark diameter, radial growth, and sapwood area. However, because trees accrue growth and sapwood unevenly around their pith, tree attributes derived from one increment core may not provide sufficient precision for forest management/research activities. To assess the variability in a tree’s inside bark radius, sapwood radius, and 10-year radial growth estimated by tree cores, two increment cores at 90 degree angles were collected from ponderosa pine (Pinus ponderosa) trees in eastern Montana (n = 2,156). Paired core measurements varied substantially with 13% mean difference for inside bark radius, 19% mean difference for sapwood radius, and 23% mean difference for estimates of radial increment. Furthermore, decreasing crown ratio, decreasing diameter, and increasing site slope were all found to increase differences in estimates derived from paired cores. Whether for management or research purposes, the number of cores that should collected per tree depend on a stand’s susceptibility to reaction wood, required measurement precision, and budgetary constraints.

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6

Rensing, Kim Howard. "Ultrastructure of the vascular cambium of Pinus ponderosa seedlings preserved by cryofixation and cryosubstitution". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0034/NQ65468.pdf.

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7

Insinna, Patrick. "Vergleichende Multiproxy-Untersuchungen zur Bioindikation von Pinus sylvestris L. und Pinus ponderosa DOUGL. ex P. et C. LAWS. in Brandenburg vor dem Hintergrund sich ändernder Klimabedingungen = Comparative multyproxy-investigations for bioindication on Pinus sylvestris L. and Pinus ponderosa DOUGL. ex P. et C. LAWS. in Brandenburg (Germany) against the background of a changing climate /". Bayreuth, 2007. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000252757.

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8

Donoso, Caro Manuel Alejandro. "Evaluación de Prácticas Silvícolas en Plantaciones de Pinus ponderosa (Dougl. Ex Laws) en la XI Región de Aysén". Tesis, Universidad de Chile, 2008. http://www.repositorio.uchile.cl/handle/2250/105002.

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9

Adams, Henry D., Greg A. Barron-Gafford, Rebecca L. Minor, Alfonso A. Gardea, Lisa Patrick Bentley, Darin J. Law, David D. Breshears, Nate G. McDowell y Travis E. Huxman. "Temperature response surfaces for mortality risk of tree species with future drought". IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/626267.

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Widespread, high levels of tree mortality, termed forest die-off, associated with drought and rising temperatures, are disrupting forests worldwide. Drought will likely become more frequent with climate change, but even without more frequent drought, higher temperatures can exacerbate tree water stress. The temperature sensitivity of drought-induced mortality of tree species has been evaluated experimentally for only single-step changes in temperature (ambient compared to ambient + increase) rather than as a response surface (multiple levels of temperature increase), which constrains our ability to relate changes in the driver with the biological response. Here we show that time-to-mortality during drought for seedlings of two western United States tree species, Pinus edulis (Engelm.) and Pinus ponderosa (Douglas ex C. Lawson), declined in continuous proportion with increasing temperature spanning a 7.7 degrees C increase. Although P. edulis outlived P. ponderosa at all temperatures, both species had similar relative declines in time-to-mortality as temperature increased (5.2% per degrees C for P. edulis; 5.8% per. C for P. ponderosa). When combined with the non-linear frequency distribution of drought duration-many more short droughts than long droughts-these findings point to a progressive increase in mortality events with global change due to warming alone and independent of additional changes in future drought frequency distributions. As such, dire future forest recruitment patterns are projected assuming the calculated 7-9 seedling mortality events per species by 2100 under business-as-usual warming occur, congruent with additional vulnerability predicted for adult trees from stressors like pathogens and pests. Our progressive projection for increased mortality events was driven primarily by the non-linear shape of the drought duration frequency distribution, a common climate feature of drought-affected regions. These results illustrate profound benefits for reducing emissions of carbon to the atmosphere from anthropogenic sources and slowing warming as rapidly as possible to maximize forest persistence.

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10

Biondi, Franco y Thomas W. Swetnam. "Box-Jenkins Models of Forest Interior Tree-Ring Chronologies". Tree-Ring Society, 1987. http://hdl.handle.net/10150/261796.

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Time domain properties of 23 tree-ring chronologies derived from a large sample of Douglas-fir and ponderosa pine trees growing in closed-canopy forests of Colorado and New Mexico were analyzed using Box-Jenkins models. A variety of statistical criteria were employed during the identification and validation stages for evaluating the performance of different significant models, and the "best" Box-Jenkins model and its immediate "competitor" were reported for each tree-ring chronology. All series were stationary, and only one was approximately a white noise series. Overall, the ARMA(1,1) model was judged the best for 11 series, and the second for 7 of the remaining 12 series. The AR(2) model was considered the best for 6 series, and the second for 4 of the remaining 17 series. No statistical evidence was found for moving average models, nor for models with more than three different parameters. However, both cyclical (or seasonal) models and third-order autoregressive models with a null second-order parameter were chosen for some series. Fitted models explained from 7 to 51% of the variance of the original ring-index series, with an average of about 22 %. All parameter estimates were positive, and they varied within a relatively small range. From a comparison of all employed criteria, Akaike's Information Criterion (AIC) was the one that performed best in identifying Box-Jenkins models for tree-ring chronologies. Possible distinctions were recognized that would separate the selected models according to species and /or standardization option. Among the 12 chronologies from Colorado sites, all derived using the same standardization option, most Douglas-fir series were best fitted by the ARMA(1,1) model, while most ponderosa pine series were best fitted by the AR(2) model, suggesting a difference in the biological persistence of the two species. On the other hand, most of New Mexico chronologies, developed using various standardization options, were best fitted by the ARMA(1,1) model, and no difference was found between Douglas-fir and ponderosa pine series. Also, models fitted to Colorado chronologies explained a lower amount of variance than those for New Mexico chronologies (averages of 17 versus 29% respectively), and cyclical models were mainly selected for New Mexico series. Although periodicities in Douglas-fir series were probably caused by western spruce budworm outbreaks, similar periodic patterns in ponderosa pine series were more difficult to explain because pine trees in the study area had not been defoliated by that insect. Compared to the original tree-ring chronologies, prewhitened series showed similar short-term growth patterns, reduced long-term growth fluctuations, lower standard deviations, and higher mean sensitivities. Also, cross-correlations between chronologies from the same area usually increased after prewhitening. Since the autocorrelation problem is crucial in analyzing the relationships between different time series, and in removing the biological persistence included in tree-ring chronologies, the Box-Jenkins approach should facilitate the analysis of the dynamic relationships between tree growth and environmental variables.

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11

Mazari, Hiriart Alicia. "Effect of cytokinins on tissue structure, plastid development and photosynthetic proteins in tissue culture of PINUS PONDEROSA dougl. cotyledons during organogenesis". Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/31131.

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The cytokinins, benzyladenine and 2-isopentenyl adenine, promoted the in vitro formation of meristematic centers which led to bud and shoot production on excised cotyledons of Pinus ponderosa Dougl. The organogenic response was dependent on the time of exposure to these growth regulators. Differences between meristematic, non-meristematic regions, and cotyledons cultured on growth regulator free medium, were observed by day 5 in culture. Plastids in newly meristematic cells showed poorly developed thylakoid membranes and some grana, whereas cells in non-meristematic tissues and non-cytokinin treated tissues had well developed inner membranes, more thylakoid membranes and grana than plastids of meristematic cells. A decline in total protein content was detected during the first days in culture. The decline was more rapid on growth regulator free than on cytokinin treated cotyledons. This trend contrasted with chloroplast markers (chlorophyll and 5 polypeptides associated with photosynthesis), which were present in lower concentrations in cytokinin treated cotyledons than in those cultured in growth regulator free medium. Both benzyladenine and 2-isopentenyl adenine were effective in inhibiting the accumulation of at least two photosynthetic polypeptides in cotyledons in the first 24 hours in culture. The ability of cotyledons to respond in this way to cytokinins was lost after only three days in culture in growth regulator free medium.
Science, Faculty of
Botany, Department of
Graduate

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12

Wright, William Edward. "Delta-deuterium and delta-oxygen-18 in mixed conifer systems in the United States southwest: The potential of delta-oxygen-18 in Pinus ponderosa tree rings as a natural environmental recorder". Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/263512.

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The North American Monsoon provides half of the annual precipitation in Tucson, Arizona. The other half occurs dominantly during the winter and early spring. Late spring is the transitional period to the monsoon and is characterized by high temperatures and low humidity. The reliability of this hyperarid period, the consistency of the timing of monsoon onset, and the recognition that certain high-elevation trees produce annual false latewood bands in response to this transitional period, were critical to the design of this dissertation research. I hypothesized that subannual environmental signals might be fixed in stable oxygen isotopes in cellulose from such trees. Existence of a long-term dataset of deltaD and delta18O from Tucson precipitation provided impetus for the collection of a companion dataset at a high-elevation site in the Santa Catalina Mountains north of Tucson. Trees were sampled near the precipitation collection site. The relations between the stable isotope ratios in the precipitation and in the tree cellulose were identified through extraction of water from bimonthly samples of nearby soil, tree stems and needles. Spatial consistency of the cellulose stable isotope signals was measured using tree samples from seven additional sites across the U.S. desert Southwest. Correlations between Tucson summer precipitation delta18O and both local and extra-regional environmental parameters resulted in the identification of the dominant monsoonal moisture source for the Tucson area. Similar correlations with the cellulose delta18O timeseries from the post-false latewood cellulose, supported the previous interpretations, and suggest long-term reconstructions may be possible. Correlations between the earliest cellulose delta18O division and extra-regional environmental parameters suggest environmental measures may be reconstructable for the cool season. Comparison of the high and low elevation precipitation deltaD and delta18O datasets yielded many baseline measures of precipitation stable-isotope dynamics in the U.S. desert Southwest. Comparison of the high-elevation precipitation stable isotope record with soil and stem water deltaD and delta 18O from nearby confirmed that local trees were using dominantly deeper soil water. I noted correlations between measured needle-water stable isotope values and values calculated using a leaf-water model, but systematic departures suggest an additional unmodeled process may operate in this system.

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13

Jamieson, Leia P. "Fire history of a pinyon-juniper/ponderosa pine ecosystem in the Intermountain West". abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1456404.

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14

Eager, Thomas James. "Investigation of Host Selection by Mountain Pine Beetle (Dendroctonus Ponderosae) Hopk. in Lodgepole Pine (Pinus Contorta) Dougl". DigitalCommons@USU, 1986. https://digitalcommons.usu.edu/etd/7300.

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Lodgepole pines Pinus contorta (Douglas) were treated by girdling to assess the response by an endemic population of mountain pine beetle Dendroctonus ponderosae (Hopkins) (Coleoptera: Scolytidae). Capture in 'sticky traps' indicated that the beetles were attracted while in flight towards the wounded trees. A significant difference in the landing rates of bark beetles between the treated and untreated trees indicated that the beetles were able to distinguish wounded from non-wounded trees while still in flight. Pressure chamber readings demonstrated that water stress developed in the girded trees when compared to the non-girdled trees.

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15

Dean, Diana K. "Host utilization by the mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae), in mixed stands of limber pine, Pinus flexilis James, and lodgepole pine, Pinus contorta latifolia Engelmann". Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1404342031&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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16

Bentz, Barbara Joan. "Management decision-making tools for mountain pine beetle (Dendroctonus ponderosae) (Coleoptera: Scolytidae) populations in lodgepole pine (Pinus contorta) stands". Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-135558/.

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17

Gross, Donovan. "Mountain Pine Beetle Fecundity and Offspring Size Differ Among Lodgepole Pine and Whitebark Pine Hosts". DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/34.

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Whitebark pine (Pinus albicaulis Engelmann) is a treeline species in the central Rocky Mountains. Its occupation of high elevations previously protected whitebark pine from long-term mountain pine beetle outbreaks. The mountain pine beetle, however, is currently reaching outbreaks of record magnitude in high-elevation whitebark pine. We used a factorial laboratory experiment to compare mountain pine beetle (Dendroctonus ponderosae Hopkins) life history characteristics between a typical host, lodgepole pine (Pinus contorta Engelmann), and whitebark pine. We tested the effects of natal host and brood host on beetle fecundity, offspring size, and brood sex-ratio. We reared mountain pine beetles from whitebark pine and from lodgepole pine, and infested half of them into their natal host and half into the other host. Fecundity was greater overall in lodgepole pine brood hosts. Among lodgepole brood hosts, beetles from whitebark pine had greater fecundity. Fecundity was also significantly related to phloem thickness, which was greater in lodgepole pine. Offspring were larger from whitebark brood hosts than from lodgepole, regardless of their parents’ natal host. Finally, sex-ratio was closer to 1:1 in lodgepole than in whitebark brood hosts. We conclude that host species affects life history of mountain pine beetle with consequences for individual beetle fitness.

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18

Eidson, Erika L. "Great Basin Bristlecone Pine Resistance to Mountain Pine Beetle: An Evaluation of Dendroctonus ponderosae Host Selection Behavior and Reproductive Success in Pinus longaeva". DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6324.

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Over the last two decades, mountain pine beetle (Dendroctonus ponderosae) populations reached epidemic levels across much of western North America, including high elevations where cool temperatures previously limited beetle persistence. Many high-elevation pine species are susceptible hosts and experienced high levels of mortality in recent outbreaks, but co-occurring Great Basin bristlecone pine (Pinus longaeva), the longest-living non-clonal organism, were not attacked. I assessed Great Basin bristlecone pine resistance to mountain pine beetle by evaluating mountain pine beetle host selection behavior and reproductive success in this species. To evaluate mountain pine beetle host selection preference for Great Basin bristlecone pine, I used no-choice 48-hour attack box experiments that confined pioneering female beetles onto pairs of living Great Basin bristlecone and limber pine (P. flexilis), a susceptible host tree species. To investigate the effect of induced tree defenses on host selection behavior, I repeated the tests on paired sections of Great Basin bristlecone and limber pines that had been recently cut, thereby removing their capacity for induced defensive reactions to an attack. Mountain pine beetles avoided Great Basin bristlecone pine relative to limber pine, suggesting that Great Basin bristlecone pine has a high level of resistance to mountain pine beetle due at least in part to stimuli that repel pioneering females from initiating attacks, even when induced defenses are compromised. To investigate mountain pine beetle reproductive success in Great Basin bristlecone pine, I compared the mating success, fecundity, and brood production of mountain pine beetle parents placed in cut Great Basin bristlecone pine bolts with that of mountain pine beetles placed in cut bolts of limber pine and lodgepole pine (P. contorta), two susceptible species. Initial reproductive development was similar in all three tree species, but nearly all brood in Great Basin bristlecone pine died before emerging. The extensive offspring mortality observed in Great Basin bristlecone pine may be a key evolutionary driver behind mountain pine beetle aversion to the species. These findings suggest that Great Basin bristlecone pine is a highly resistant species with low vulnerability to climate-driven increases in mountain pine beetle outbreaks at high elevations.

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19

"Assessing Ponderosa Pine (Pinus ponderosa) Suitable Habitat throughout Arizona in Response to Future Climate Models". Master's thesis, 2011. http://hdl.handle.net/2286/R.I.8916.

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abstract: The species distribution model DISTRIB was used to model and map potential suitable habitat of ponderosa pine throughout Arizona under current and six future climate scenarios. Importance Values for each climate scenario were estimated from 24 predictor variables consisting of climate, elevation, soil, and vegetation data within a 4 km grid cell. Two emission scenarios, (A2 (high concentration) and B1 (low concentration)) and three climate models (the Parallel Climate Model, the Geophysical Fluid Dynamics Laboratory, and the HadleyCM3) were used to capture the potential variability among future climates and provide a range of responses from ponderosa pine. Summary tables for federal and state managed lands show the potential change in suitable habitat under the different climate scenarios; while an analysis of three elevational regions explores the potential shift of habitat upslope. According to the climate scenarios, mean annual temperature in Arizona could increase by 3.5% while annual precipitation could decrease by 36% over this century. Results of the DISTRIB model indicate that in response to the projected changes in climate, suitable habitat for ponderosa pine could increase by 13% throughout the state under the HadleyCM3 high scenario or lose 1.1% under the average of the three low scenarios. However, the spatial variability of climate changes will result in gains and losses among the ecoregions and federally and state managed lands. Therefore, alternative practices may need to be considered to limit the loss of suitable habitat in areas identified by the models.
Dissertation/Thesis
M.S. Applied Biological Sciences 2011

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20

Vance, Nan C. "Physiology of drought stress in Pinus ponderosa (Dougl. ex Laws.) and the influence of low irradiance /". 1988. http://hdl.handle.net/1957/13502.

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21

Vera-Castillo, J. A. Gil. "The influence of antidesiccants on field performance and physiology of 2+0 ponderosa pine (Pinus ponderosa Dougl.) seedlings /". 1995. http://hdl.handle.net/1957/11205.

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22

Weber, John C. "Geographic variation in central Oregon ponderosa pine (Pinus ponderosa Laws.) : seed germination; seed, wing, and cone morphology; seed color /". 1988. http://hdl.handle.net/1957/6678.

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23

Weber, John C. 1948. "Geographic variation in central Oregon ponderosa pine (Pinus ponderosa Laws.) : seed germination; seed, wing, and cone morphology; seed color". Thesis, 1988. http://hdl.handle.net/1957/6678.

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Geographic variation was investigated among 225 locations from five geographically disjunct regions in central Oregon. Characters included: germination speed and uniformity in two test environments differing in stratification period and incubation temperature; weight, three dimensions and three 'angles' of seeds; weight and three dimensions of wings; cone length and scale weight; the relative cover of 14 colors on the seed coat; and three sets of principal components (germination, morphology, color). The major objectives were to investigate: (1) the distribution of character variation within and among locations; (2) correlations among characters; (3) clinal relationships with several location variables (latitude, longitude, elevation, slope/aspect, soil characteristics, associated conifers); and (4) if the three major regions differed in the distribution of variation, correlations among characters, clinal relationships, and character means. In general, the major conclusions are: (1) much of the variation in all characters occurs within locations; (2) variation among locations is greater, and clines are steeper in germination than in morphological characters; (3) regions differ in several seed colors and morphological characters, and in several correlations among germination and morphological characters; (4) the Deschutes region has greater location-related variation, steeper clines, and stronger correlations between germination and morphological characters than do the two major regions farther east of the Cascade Mountain Range; (5) local aspect accounts for much of the variation in germination and morphological characters; (6) soil characteristics account for more variation in morphological than germination characters. Variation patterns are mainly interpreted as adaptive responses to the length of the growing season, which is strongly limited by summer drought in central Oregon. In general, drier locations appear to favor trees with faster and more uniform germination, and with longer, heavier seeds but shorter wings and cones. Seed colors are also correlated with several location variables. Effects of seed predators on seed size, shape and color are also considered.
Graduation date: 1989

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24

Hutten, Martin A. B. "Performance of Pinus ponderosa seedlings in clearcuts, patch cuts and undisturbed forests on lavas /". 1998. http://hdl.handle.net/1957/10873.

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25

Slayton, Jessica Dominique. "Separating the Effects of Wildfires from Climate in Growth of Ponderosa Pine (Pinus ponderosa Douglas ex. C. Lawson), Central Idaho, U.S.A". 2010. http://trace.tennessee.edu/utk_gradthes/833.

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Scientists use climate proxies, such as tree rings, to extend the climate record back in time, adding to the growing body of knowledge of past climate change. Tree rings provide a high-resolution proxy of climate. Many of the reconstructed climate records for the western U.S. use ponderosa pine (Pinus ponderosa Douglas ex. C. Lawson), a fire-adapted species that grows in areas prone to frequent fires. Such a disturbance as fire can introduce noise to climate reconstructions by causing growth releases or suppression following a fire event. My objective was to determine whether fire damage causes a quantifiable change in growth patterns of affected trees and whether the affected trees experience the changes in the same way. Increment cores and cross-sections were collected from living and dead ponderosa pine trees in Payette National Forest, central Idaho, U.S.A. One chronology was developed from a stand of ponderosa pine showing no evidence of frequent fire while two chronologies, one from cores collected mostly from trees without visible fire damage and one from cross-sections of fire-scarred trees, snags, and stumps, were developed from a separate cluster of three subsites affected by frequent fire. The mean fire-free interval for all fire subsites was 7.38 years. The mid-1600s to mid-1900s were characterized by nearly continuous fire activity at the fire subsites. The results from superposed epoch analysis (SEA) showed that tree growth is significantly lower than average the year of a fire event. The fire site chronologies showed slightly suppressed growth for 3 years after a fire. Significantly (p < 0.05) below average growth occurred after large fires in the fire site cross-section chronology. The difference chronologies indicated that fire does not cause a systematic change in tree growth and any added signal is comparable to other noise in the chronologies. Analyses using the computer program OUTBREAK showed that some fire years appeared to be followed by growth suppressions while others are not, regardless of fire size. Analyses of the chronologies and the fire history of the subsites indicated that no statistically significant systematic signal is introduced into the tree-growth patterns by fire events.

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26

Ross, Darrell W. "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 /". 1985. http://hdl.handle.net/1957/10386.

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27

Shea, Ronald W. "Effects of prescribed fire and silvicultural activities on fuel mass and nitrogen redistribution in Pinus ponderosa ecosystems of central Oregon /". 1993. http://hdl.handle.net/1957/13612.

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28

Rother, Monica Tyson. "Influences of Climate and Anthropogenic Disturbances on Wildfire Regimes of the Zuni Mountains, New Mexico, U.S.A". 2010. http://trace.tennessee.edu/utk_gradthes/745.

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This research examined the fire history of ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) forests in northwestern New Mexico. The study area included three sites in the Zuni Mountains of Cibola National Forest and one site along the boundary of El Malpais National Monument. I crossdated over 800 fire scars on 75 samples to reconstruct spatial and temporal characteristics of historic wildfire regimes. The Weibull Median Interval, Weibull Modal Interval, and Mean Fire Interval ranged from five to eight years across all sites and percent-scarred classes (all fires, 10% scarred, and 25% scarred) and indicated that low-severity wildfires occurred frequently in the study area during the period 1700 to 1880. Wildfires were historically driven by climatic variability. Superposed Epoch Analyses revealed that wetter conditions typically occurred one to three years prior to a fire event and were followed by drought during the fire year. No relationship was found between the Pacific Decadal Oscillation (PDO) and wildfire occurrence. These findings implied that shorter-term fluxes between wet and dry conditions, rather than longer-term climatic variability, were historically most conducive to fire occurrence. Fire frequency decreased suddenly in the late 19th century across the study area, and results indicated that fire has been absent at all sites since the 1920s. Anthropogenic disturbances including livestock grazing, timber harvesting, and fire suppression likely explain observed differences between historic and contemporary wildfire regimes in the Zuni Mountains.This research has important implications for forest management. In ponderosa pine forests of the southwestern United States, land managers often aim to restore historic ecological conditions. The reintroduction of a frequent, low-severity wildfire regime might restore some ecological patterns and processes, but given the strong legacy of human disturbances and the influences of human-induced climate change, a complete return to historic conditions may be neither possible nor desired.

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Sexton, Timothy Ogden. "Ecological effects of post-wildfire management activities (salvage-logging and grass-seeding) on vegetation composition, diversity, biomass, and growth and survival of Pinus ponderosa and Purshia tridentata /". 1998. http://hdl.handle.net/1957/9596.

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Hughes, Josie. "Patterns and Processes in Forest Insect Population Dynamics". Thesis, 2012. http://hdl.handle.net/1807/34060.

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This dissertation is concerned with effects dispersal and forest structure on forest insect population dynamics, and with identifying generating processes by comparing observed patterns to model predictions. In chapter 2, we investigated effects of changing forest landscape patterns on integro-difference models of host-parasitoid population dynamics. We demonstrated that removing habitat can increase herbivore density when herbivores don't disperse far, and parasitoids disperse further, due to differences in dispersal success between trophic levels. This is a novel potential explanation for why forest fragmentation increases the duration of forest tent caterpillar outbreaks. To better understand spatial model behaviour, we proposed a new local variation of the dispersal success approximation. The approximation successfully predicts effects of habitat loss and fragmentation on realistically complex landscapes, except when outbreak cycle amplitude is very large. Local dispersal success is useful in part because parameters can be estimated from widely available habitat data. In chapter 3, we investigated how well a discretized integro-difference model of mountain pine beetle population dynamics predicted the occurrence of new infestations in British Columbia. We found that a model with a large dispersal kernel, and high emigration from new, low severity infestations yielded the best predictions. However, we do not believe this to be convincing evidence that many beetles disperse from new, low severity infestations. Rather, we argued that differences in habitat quality, detection errors, and Moran effects can all confound dispersal patterns, making it difficult to infer dispersal parameters from observed infestation patterns. Nonetheless, predicting infestation risk is useful, and large kernels improve predictions. In chapter 4, we used generalized linear mixed models to characterize spatial and temporal variation in the propensity of jack pine trees to produce pollen cones, and account for confounding effects on the relationship between pollen cone production and previous defoliation by jack pine budworm. We found effects of stand age, and synchronous variation in pollen cone production among years. Accounting for background patterns in pollen cone production clarified that pollen cone production declines in with previous defoliation, as expected.

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