Graduation date: 1982

This thesis examines factors limiting understory herb presence and flowering in young second-growth Douglas-fir (Pseudotsuga menziesii) forests on the west side of the Cascade Mountains, Oregon, USA. I studied the belowground effects of canopy trees on understory herbs and shrubs in old-growth forests using trenched plots from which tree roots were excluded. Effects of tree density and stand age were tested by comparing the understory community composition of old-growth stands and pre-commercially thinned and unthinned young second-growth stands. I also examined the effect of conifer basal area on understory herb presence and flowering within one young second-growth watershed. In young stands, I focused on three groups of understory herb species: disturbance-responsive (release), forest generalist and old-growth associated. The effects of root trenching on vegetation and soil moisture were tested in closed-canopy and gap locations in two old-growth Douglas-fir (Pseudotsuga menziesii) forests. Ten years after installation, trenched plots averaged 92% total understory cover while untrenched plots averaged 47% cover. Trenched plots under closed canopies were moister than control plots throughout the growing season; the trenching effect on soil moisture became apparent in the generally wetter gaps only at the end of the growing season. Vegetation responses to trenching were concomitantly larger under closed canopies than in gaps. Stands that had been pre-commercially thinned 20 years earlier exhibited understory composition more similar to old growth than did unthinned stands. Thinned stands exhibited higher frequencies, abundances and density of flowering of old-growth associated herbs than did unthinned stands, but lower than did old-growth stands. Forest generalist and release species showed mixed responses to thinning. I used both general linear models and classification and regression tree models to explore the association of herb species presence and flowering with conifer basal area and abiotic variables. Both modeling approaches yielded similar biological insights. Flowering was more sensitive than presence to current stand basal area. Flowering of old-growth associated and release species was negatively correlated with conifer basal area. Linear models allowed clearer hypothesis tests, while tree-based models had greater explanatory power and provided information about interactions between variables. / Graduation date: 2004

The purpose of this study was to characterize glenohumeral joint laxity and stiffness using instrumented arthrometry. To evaluate the validity of an instrumented measurement system we compared cutaneous and bone-pinned measures of laxity and stiffness that replicate previously reported in vivo methodology. Characterization of capsular laxity was achieved through determination of the sagittal plane translational area at increasing levels of quantified force. Finally, a method for increasing the objectivity of the standard manual laxity examination was developed for the orthopaedic clinician to quantify humeral head translation and capsular volume in vivo. We hypothesized that: 1) cutaneous measures could accurately predict bone-pinned measures, 2) capsular laxity would increase with increasing levels of applied force, and 3) manual cutaneous, manual bone-pinned, and force-displacement bone-pinned measures of translation would be equal. Thirty fresh frozen cadaveric shoulder specimens (mean age=70��14 years) were tested. The shoulders were thawed and mounted to a custom-made shoulder-testing apparatus. Displacement was measured using an electromagnetic tracking system. Sensors were secured cutaneously and with bone-pins to the scapula and humerus. Force-displacement testing was performed using a load applicator and manual displacement testing utilized the anterior/posterior drawer and inferior sulcus tests. A comparison of cutaneous and bone-pinned measures of laxity and stiffness revealed good to excellent criterion validity (r=0.68 to 0.79). Examination of displacement measures at increasing levels of force revealed increasing capsular laxity with symmetric directional compliance. No significant difference was observed between anterior and posterior translation (0.4 mm, p=.55), with significant differences between inferior and anterior (4.6 mm, p<.0001) and between inferior and posterior (5.1 mm, p<.0001). A comparison of manual cutaneous to bone-pinned manual and kinetic measures of translation revealed a significant difference between methods (p=.0024) and between directions (p<.0001) with no significant interaction (p=.0948). Estimations of the force required to achieve clinical end-point suggest that greater force is required in the anterior (173 N) direction compared to posterior (123 N) and inferior (121 N). We have developed two new methods to measure glenohumeral joint kinematics and reported new information regarding normal kinematics of the glenohumeral joint. / Graduation date: 2001

The increase in tissue extensibility and joint range of motion through stretching has often been demonstrated. However, the existence of an optimal stretch duration has not been proven and the identification of an ideal number of repetitions of a stretch has received little attention in the literature. The purpose of this study was to examine and clarify the relationship of duration and number of repetitions of a stretch and their effect on changes in hamstring extensibility (HE) resulting from a stretching program. The HE of 33 subjects who were randomly assigned to a control group or one of three treatment groups was assessed before and after a three-week stretching program. The subjects in the three treatment groups stretched once a day, five times a week, and either once for 15 seconds (1 X 15), twice for 15 seconds (2 X 15), or once for 30 seconds (1 X 30). A repeated measures ANOVA showed no statistically significant effect for treatment group (P=0.181) or for treatment by pre- and post-treatment measurements (P=0.140), but indicated a significant difference between pre- and post-treatment measurements (P<0.001). The HE of the control group (which did not stretch) changed only slightly (0.9��, SD 5.7), the 1 X 15 and 1 X 30 groups improved more clearly (4.2��, SD 3.1 and 3.8��, SD 6.7, respectively), and the 2 X 15 group's HE increased the most (6.8��, SD 3.9). The results suggest that varying durations and repetitions of a stretch may influence the magnitude of improvement of HE. However, with the relatively low power (0.46) in the present study, no statistically significant difference between stretching protocols of 1 X 15 seconds, 2 X 15 seconds, and 1 X 30 seconds could be found. / Graduation date: 1997

No description available.

Black-faced Spoonbill (BFS), Platalea minor, numbers during the non-breeding season increased steadily from 1990 to 2004 in Taiwan. Numbers of the BFS in Taiwan accounted for more than 50% of the total population, with 96% of the BFS in southwestern Taiwan at the town of Chi-Ku and Tainan City. The percentage of adult BFS remained constant from 2000-2003. Relatively constant high survey counts, with similar ratios of adult to non-adult birds, suggested that the BFS has a healthy population. With the exception of avian botulism resulting in 73 BFS deaths in the 2002 winter, several other mortality factors were documented with no more than four birds lost in a year from 1849-2004. I counted numbers of BFS at the town of Chi-Ku and Tainan City almost daily during the winter months from September 1998 to May 2001. Although variable, overall population numbers increased sharply from September to October. From November to February, the BFS maintained a high, stable population-level. Migration began during March, and population numbers decreased from March to May. I used visual observations and radio-telemetry data to locate, count and monitor BFS during the day and night, respectively, and also to assess nocturnal habitat use. Information obtained through these methods showed that habitat use was not in direct proportion to its availability. Activity ranges obtained from radio tracking and visual observations showed an increase in activity range size by BFS just prior to migration with more of the study area used north of the core-roosting area. Sizes and weights of potential prey items were measured at fish ponds used by BFS. Available prey in fish ponds was dominated by fish prey less than 5 cm in length and at least 30 gm in size. Similar size classes of prey items were selected by a captive BFS. Biomass of prey in fish ponds around the primary roosting site declined sharply in the pre-migration stage (March-April), compared to the middle winter stage (November-February). I suggest that this low biomass of prey items may have stimulated the northward movement of BFS in the late stage of winter. In addition, the activity range expansion may have related to preparation for migration.

Reforesting harvested lands in southwestern Oregon has been difficult because of low rainfall, high evaporative demand, and competitive understory vegetation. Herbicides have been a preferred method to control competing vegetation but herbicide use on federal lands was curtailed in 1984. As a result, interest in livestock grazing as a vegetation control method has increased. I used prescribed cattle grazing from 1986-1990 to assess effects on reforestation. Treatments were established on a low-elevation (670 m) site to evaluate seedling survival and growth of Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco.) and ponderosa pine (Pinus ponderosa Dougl.). Treatments were: a) seeding of palatable forage species (SU); b) seeding with grazing (SG); c) no seeding with grazing (NG); and d) no seeding or grazing, with paper mulch applied on Douglas-fir only (PM/C). Year 5 mortality among treatments ranged from 57 to 87% for Douglas-fir and 11 to 25% for ponderosa pine. Porcupine girdling and late-spring frost were major causal factors in ponderosa pine and Douglas-fir mortality, respectively. Competition from understory vegetation, browsing, and trampling were only minor causal factors in seedling mortality. Cumulative growth of both species was best in NG. Severe browsing by cattle in year 2 on SG resulted in reduced year 3 relative growth for ponderosa pine. However, year 2 browsing did not reduce long-term relative growth. By year 5, relative growth for ponderosa pine was greatest in SG and lowest in SU. During years 1-3, soil moisture availability was not enhanced on the grazed vs. ungrazed treatments. However, by year 4, xylem potentials and soil moisture indicated seedlings in SG were less water-stressed than those in SU. Reduced water stress probably resulted from reductions in roots of orchardgrass (Dactylis glomerate L.) because of defoliation. Sampling with a root periscope indicated roots were reduced for defoliated (SG) plants compared with undefoliated (SU) plants. Leaf area and root growth reductions were apparent mechanisms permitting increased soil moisture availability. These results suggested that prescribed cattle grazing can facilitate reforestation. / Graduation date: 1992

Water potential, leaf conductance, growth, nitrogen content, and seedling survival of Wyoming Big Sagebrush (Artemisia tridentata ssp. wyomingensis) following defoliation of the herbaceous understory were assessed during two growing seasons. Precipitation was 107% and 63% of the long-term mean (283 mm) in 1989 and 1990, respectively, which presented an opportunity to study impacts during a drought and a non-drought year. Response of Artemisia was measured on a site seeded to Agropyron desertorum in the late 1960s, and a native site with Stipa thurberiana, Festuca idahoensis and Poa sandbergii in the understory. The two sites were analyzed as separate experiments. The dry year had a significant effect on plant water relations and growth of Artemisia on both sites. Pre-dawn water potentials averaged 1.23 MPa more negative on the seeded site and 1.22 MPa more negative on the native site in 1990 compared to the previous year. Mid-day water potential averaged 1.22 MPa more negative on the seeded site and 1.13 MPa more negative on the native site in 1990 compared to 1989. Morning leaf conductance in 1990 was 61% lower on the seeded site and 51% lower on the native site than in 1989. Mean afternoon leaf conductance in the drought year was 62% less on the seeded site and 63% less on the native site. Nitrogen content in current year's growth was reduced 29% on the seeded site and 18% on the native site from 1989 to 1990. Vegetative and reproductive shoot (stem plus leaves) weights were reduced by over 80% in 1990 compared to 1989. Other production variables showed similar reductions in the drought year. Nitrogen content was 11% greater in current year's growth from shrubs on control as opposed to defoliated plots on the native site in 1989. Shrubs on control plots had 8% heavier reproductive stems per unit of canopy, and 7% longer vegetative stems than shrubs on defoliated plots in 1989 on the seeded site. Shrubs on control plots had 18% fewer annual leaves per unit of vegetative shoot, but 12% more primary ephemeral leaves per vegetative shoot than shrubs on defoliated plots in 1990 on the seeded site. In 1990, shrubs on control plots on the seeded site had 11% more ephemeral leaves per vegetative shoot while shrubs on the control plots on the native site had 8% fewer ephemeral leaves per vegetative shoot. Large shrubs generally had more and heavier leaves, and longer and heavier stems than medium shrubs. Exceptions included large shrub lateral stems were 30% shorter than those of medium shrubs, and large shrubs had 37% fewer annual leaves per vegetative shoot than medium shrubs in 1989 on the seeded site. Drought had substantial negative impact on water relations and growth of Wyoming big sagebrush, while defoliation of understory vegetation had little effect. / Graduation date: 1993

El comportament hidrodinàmic de les aigües subterrànies en conques intramuntanyoses ve condicionat principalment per la geologia, i especialment pel context estructural i els materials sedimentaris que reomplen la conca. L'estudi d'aquestes àrees requereix un enfocament a gran escala per poder determinar les zones de recàrrega i descàrrega dels diferents sistemes de flux que conformen els recursos hídrics de la zona. Aquestes zones solen estar afectades per un fort desenvolupament humà que pot donar lloc a una modificació de la quantitat i la qualitat de l'aigua subterrània de diferents formes. En aquest sentit, en conques intramuntanyoses és un aspecte clau entendre la importància de la geologia i de les pressions humanes en el flux d'aigua subterrània per arribar a assolir una gestió correcta dels recursos hídrics, així com per assegurar llur disponibilitat a llarg termini. En aquesta tesi s'ha estudiat la depressió de la Selva com a un cas paradigmàtic on té lloc una important pressió sobre els recursos hídrics subterranis. Per tal d'estudiar el paper hidrogeològic que juguen les falles regionals en conques intramuntanyoses, en primer lloc, s'ha realitzat un model hidrogeològic conceptual a partir de la modelització del flux subterrani. Per fer&#8208;ho, s'ha dut a terme una simulació d'una zona de falla subjacent a una formació al&#8729;luvial, on la falla pot recarregar o drenar l'aqüífer al&#8729;luvial. S'han considerat diferents valors de permeabilitat per la zona muntanyosa, la zona de falla i els materials sedimentaris, així com diferents gruixos de falla i condicions de contorn. Els resultats mostren que es poden produir fluxos verticals ascendents i descendents a la part superior de la zona de falla degut a l'acció de la formació al&#8729;luvial, i fins i tot a través del sòcol, influenciant per tant la recàrrega dels materials sedimentaris de la depressió. En segon lloc, s'ha caracteritzat el sistema hidrogeològic de la depressió de la Selva mitjançant mesures del nivell piezomètric i dades hidroquímiques e isotòpiques (&#948;18O, &#948;D) al llarg de diverses campanyes de camp amb un doble objectiu: (i) caracteritzar un sistema hidrodinàmic on els elements tectònics juguen un paper important en la hidrodinàmica subterrània, i (ii) descriure la influència de l'explotació d'aigües subterrànies en la hidrodinàmica del sistema. Els resultats piezomètrics han posat de manifest la relació existent entre les formacions situades a les zones de muntanya que envolten la depressió i els materials sedimentaris que rebleixen aquesta. Les zones de falla tenen un efecte directe en la recarrega, permetent l'existència de fluxos verticals ascendents des del sòcol cap a diferents aqüífers sedimentaris. Les dades hidroquímiques i isotòpiques han validat aquestes observacions. En aquest sentit l'ió fluor (< 15 mg/l) i nitrat (< 217 mg/l) han estat usats com a traçadors dels fluxos profunds i superficials respectivament i han permès posar de manifest l'efecte dels bombejos en la distribució de les línies de flux. La composició isotòpica de la molècula de l'aigua (&#61540;18OH2O, &#61540;D) ha evidenciat canvis estacionals en les aigües captades pels pous posant de manifest l'existència de dos sistemes de flux: un sistema de flux regional amb llargs temps de trànsit i originat a les zones circumdants més elevades, i un sistema de flux local recarregat a la zona de la depressió. Els dos sistemes contribueixen de manera diferent als recursos hídrics que s'estan explotant, i la seva aportació específica defineix el potencial de la depressió per una explotació sostenible a llarg termini. S'han caracteritzat les aigües des d'un punt de vista hidroquímic a partir de la composició en elements majoritaris, minoritats i traça (fluor, brom, liti, TOC) i de dades isotòpiques (&#61540;18OH2O, &#61540;D, triti, &#61540;34SSO4, &#61540;18OSO4). Aquesta caracterització ha permès una descripció acurada dels processos geoquímics que defineixen les fàcies hidroquímiques de l'aigua subterrània al llarg de la depressió de la Selva. Així, s'han definit dos sistemes de flux regional i diferents qualitats de l'aigua associada a la recarrega local, i alhora s'ha corroborat el model hidrogeològic conceptual de la depressió de la Selva. Des d'un punt de vista regional, a la depressió de la Selva el control estructural defineix sistemes de flux locals, intermitjos i regionals, els quals son responsables de la hidrodinàmica a gran escala, fins al punt que aquests son responsables de la recuperació dels descensos del nivell piezomètric després del període de màxima extracció (estiu). A la zona d'estudi, l'origen de la recarrega, a escala regional, és atribuïda a la serralada Transversal, a la zona més septentrional de la conca, i a les Guilleries, especialment a la zona oest. Aquests sistemes hidrogeològics impliquen un flux vertical ascendent des del sòcol que recarrega els nivells aqüífers neògens de la depressió. Els sistemes de flux locals i intermitjos s'originen a la pròpia depressió o a les zones circumdants més properes, els quals estan menys afectats per les zones de falla. La pressió antròpica crea una barreja entre els diferents sistemes de flux modificant la qualitat de l'aigua al llarg de l'any. Els resultats d'aquest estudi mostren que en conques intramuntanyoses per obtenir una caracterització integrada del sistema hidrogeològic i el coneixement necessari per formular estratègies específiques cap a una gestió sostenible dels recursos hídrics, i en concret a la depressió de la Selva, és necessari: i) la utilització de diferents metodologies per abordar l'estudi d'aquests tipus de sistemes hidrogeològics. Així, en el present treball primerament s'aborda des de la caracterització de camp fins a la modelització numèrica passant per l'estudi de nivell piezomètrics i dades hidroquímiques e isotòpiques; ii) caracteritzar l'evolució piezomètrica de les diferents formacions geològiques juntament amb les característiques hidroquímiques/isotòpiques i els processos geoquímics relacionats que defineixen les mostres d'aigua, i per tant, cada un dels extrems de barreja de la recarrega (local, intermitja i regional) que participen en el conjunt del sistema de flux; iii) finalment, identificar les pressions humanes, fins i tot en els sistemes a més gran escala, com una verdadera alteració al comportament natural. Aquesta tesi defineix els sistema hidrogeològic de la depressió de la Selva com a exemple de funcionament hidrodinàmic sota pressions antròpiques aplicable a altres conques intramuntanyoses. Aquest coneixement és necessari per formular estratègies de gestió dels recursos hídrics des d'un punt de vista quantitatiu i qualitatiu, com a eina indispensable per satisfer la demanda lligada a una millora socioeconòmica sense produir un empitjorament de la qualitat ambiental a llarg termini. / Groundwater hydrodynamics in range&#8208;and&#8208;basin areas are essentially determined by their geology, including the tectonic structure and the basin sedimentary infilling. Their study requires a large&#8208;scale approach to determining the location of the recharge and discharge areas of each flow system providing the basin with water resources. Furthermore, most of these areas have undergone heavy human development that can modify groundwater quantity and/or quality in different ways. Understanding geological and human influences on groundwater flow in these areas is a key aspect in achieving an adequate water resources management and therefore its future availability. In this dissertation, the Selva Basin has been studied as a paradigmatic case of a range&#8208;and¬basin area with severe human pressure on its groundwater resources.A conceptual hydrogeological model emphasizing the role of the main fault zones has been developed and tested using numerical flow modeling as a first step. Groundwater flow has been simulated in a range&#8208;and&#8208;basin area affected by a significant fault zone, which may drain or recharge an overlying alluvial aquifer. Various hydraulic conductivity values for the range rocks, the fault¬zone, and the sedimentary infilling of the basin are considered, as well as different fault&#8208;zone widths and boundary conditions. The results show that upward and downward fluxes develop in the upper part of the fault zone controlled by the action of the alluvial aquifer, and even through the basement floor, which influence the recharge of the sedimentary infilling of the basin.Second, the Selva range&#8208;and&#8208;basin hydrogeological system is described using potentiometric, hydrochemical, and isotopic data (&#948;18O, &#948;D) taken from different field surveys, in order to achieve a twofold objective: (i) to describe a hydrogeological system in which tectonic elements play a significant role in the flow dynamics, and (ii) to show the influence of groundwater exploitation on the hydrodynamics of the system. Hydraulic head data indicate the relationships between the geological formations in the range areas and the sedimentary infill of the basin. In this context, fault zones and a fracture network have a direct effect on the recharge, and allow an upward vertical flow from the basement to the sedimentary aquifers. Hydrochemical and isotopic data support this observation. The use of fluoride (up to 15 mg/l) and nitrate (up to 217 mg/l) as tracers for the contribution of deep and shallow flow systems respectively provides a detailed portrait of the effects of pumping on the flowpath distribution. Isotopic data depict seasonal trends in groundwater captured by wells. Two distinct flow systems are differentiated: a regional, large&#8208;scale, long residence time system, originating in the surrounding ranges, and a local flow system constituted by infiltration in the lower areas of the basin. The two systems contribute differently to the resources that are withdrawn, and their specific contributions define the potential for sustainable future water exploitation in the basin. The final part of this hydrogeological study is a more specific description of the geochemical processes that determine the hydrochemical characteristics of groundwater across the Selva basin, based on the interpretation of major, minor and trace elements (such as fluoride, bromide, lithium, TOC, and their ratios to some major elements), and isotope data (&#61540;18OH2O, &#61540;D, tritium,&#61472;&#61540;34SSO4,&#61472;&#61540;18OSO4). It defines two different regional flow systems and different water qualities of local recharge anduses this specific data to corroborates the overall hydrogeologic conceptual model for the Selva range&#8208;and&#8208;basin area. From a methodological perspective, this chapter explores the use of minor elements and isotopes in the interpretation of regional scale system hydrodynamics. It also discusses their use as tracers of the distinct ground water flows originating in distinct recharge areas and influenced by an intricate tectonic setting. The results of this dissertation describe the flow system of the Selva basin. In this basin, structural control defines the local, intermediate and regional flow systems responsible for the large&#8208;scale hydrodynamics of the basin and, more importantly, the recovery of drawdown after the main withdrawal period (summer). The origin of the recharge of the large&#8208;scale, regional flow systems is assigned to the Transversal range on the northern side and to the Guilleries range, especially in the western part. These hydrogeological systems include a groundwater flow within the basement and an upward vertical recharge from the basement to the overlying Neogene sedimentary layers. The local and intermediate flow systems originate in the basin itself or in the less&#8208;elevated surrounding ranges, and the fault system has a minor effect on their flowpaths. Human development modifies the flow paths mixing the different flow systems and changing the water quality along the year seasons. From a broader point of view, this highlights the value of using different methodological insights in the study of these hydrogeological systems, as well as addressing the problem of water management in complex geological environments. First, it presents the outcome of various methodologies ranging from field work to numerical modeling, together with the analysis of hydraulic head, hydrochemical and isotopical data. Second, it shows the relevance of potentiometric evolution in different geological settings, and the treatment of the hydrochemical/isotopic features and related geochemical processes that define groundwater samples and therefore each of the recharge end&#8208;members (local, intermediate, and regional) that participate in the overall flow systems. Finally, it identifies the effect of human pressures even on large&#8208;scale flow systems, as true alterations of natural behavior. The recognition of these effects, together with an integrated characterization of the hydrogeological system, provides the necessary knowledge for formulating specific strategies for assessment focusing on sustainability of water resources management in these geological contexts. In specific terms, these strategies must be based on the importance of the groundwater flow terms in the water balance for a given hydrological basin. These terms are usually overlooked, yet they play an important role, especially when groundwater resources from deep confined (or leaky) aquifers are exploited. In the case of the Selva basin, identifying this contribution is fundamental in establishing potential future exploitation rates that further socio&#8208;economic developments may generate. This dissertation shows the scope of several approaches to describing this term in the water budget in range&#8208;and&#8208;basin areas in order to determine the availability of water resources therein, as a first essential step towards sustainability.

No description available.