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Technology allows educators to convey information more flexibly and visually. How to access and make use of technological teaching tools is the challenge facing educators. HortBase provides the framework for educators to create and access educational chunks. How to make use of the information in HortBase in distance teaching is a three-step process. 1) Before assembling the teaching material, the educator must decide on who the target audience is and what information to convey. Audiences on campus have higher expectations of how they learn, as they are used to live teaching and guidance, and often do not have a clear idea of what they want to learn. Off-campus audiences have lower expectations and are more focused on the information they want. 2) The educator then decides how much of the information to convert into digital form individually and how much to draw from elsewhere. Pieces of digitized information can be created by scanning existing images into the computer or created on computer with authoring-illustrating programs. Once digitized, images can be manipulated to get the desired look. This is a very time-consuming step, so much effort can be saved by taking created “chunks” from HortBase. 3) Finally, what medium and tools to use must be decided. Course content can be presented with slide-show software that incorporates digitized slides, drawings, animations, and video footage with text. Lectures can then be output to videotape or broadcast over an analog rework. Alternatively, the digitized information can be incorporated into interactive packages for CD-ROM or the World Wide Web.

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Supplemental watering of shade trees in field production nurseries is needed, even in summer-rainfall climates, to achieve maximum growth. Scheduling the timing and amount of supplemental watering makes more efficient use of financial and water resources while maintaining maximum growth. Methods of scheduling supplemental watering based on uniform canopy and rooting in production agriculture must be modified, however, for shade trees in a production setting. Nursery trees are non-uniform in canopy and rooting compared to an agricultural crop. Applying the water budget method can be effective with sprinkler systems if tree water loss and rooting depth can be properly estimated. A measure of reference evapotranspiration and a species-specific multiplier are typically used to estimate water loss. Since species diversity in a field nursery is quite high, however, estimates of both tree transpiration and rooting depth must necessarily be simplified assumptions less accurate than for a uniform agricultural crop. If supplemental water is to be applied with drip irrigation, estimates of tree transpiration and soil water depletion need to be converted to volume units with information on total tree leaf area.

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Growth and water relations of Kentucky coffee tree [Gymnocladus dioica (L.) K. Koch] whips in translucent tubelike shelters were investigated. In a container study, 1.2-m-high shelters were placed over whips following transplanting, then diurnal microclimate, water relations, and water use were measured. Shelter air temperature and vapor pressure were substantially higher, and solar radiation was 70% lower, than ambient conditions. Sheltered trees responded with nearly three-times higher stomatrd conductance than nonsheltered trees. However, due to substantially lower boundary layer conductance created by the shelter, normalized water use was 40910 lower. In a second experiment, same-sized shelters were placed on whips following spring transplanting in the field. Predawn and midday leaf water potentials and midday stomatal conductance (g,) were monitored periodically through the season, and growth was measured in late summer. Midday gs was also much higher in field-grown trees with shelters than in those without. Sheltered trees in the field had four times greater terminal shoot elongation but 40% less stem diameter growth. Attenuated radiation in the shelters and lower specific leaf area of sheltered trees indicated shade acclimation. Shelters can improve height and reduce water loss during establishment in a field nursery, but they do not allow for sufficient trunk growth.

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Shade acclimation response of Emerald Queen Norway maple street trees to variable urban irradiance levels was investigated. Specific leaf area, trunk growth, and crown density were measured from trees in 13 sites ranging from urban canyons in the business core to open exposures in residential areas of Seattle, Wash. Percentage of potential seasonal input of global shortwave radiation for each site was modeled based on the azimuth and elevation angles of the surrounding horizon topography. Building height in the business core reduced estimated irradiance to a range of 27% to 90% of that for an unobstructed horizon topography, while those outside the business core had 90% to 95% irradiance. As estimated potential irradiance decreased, growth of these maple street trees exhibited responses characteristic of shade acclimation in a dose-response pattern. Specific leaf area increased and trunk growth and crown density decreased to acclimated levels at -70% of potential irradiance. These acclimation responses did not degrade the function of the trees in their urban-canyon locations. Their foliage was healthy, and reduced crown density was not apparent since there were no full-sun-grown trees for comparison.

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Changes in foliage temperature with environmental conditions were investigated for use in detecting water stress and scheduling irrigations of woody nursery plants. Midday leaf-minus-air temperature (Tl-Ta) and vapor pressure deficit (VPD) were monitored seasonally for container-grown shrubs--prostrate juniper, upright juniper and dwarf red-stem dogwood--at open and closed spacings. There was an inverse relationship between Tl-Ta and VPD for all species and spacings but with substantial scatter. Slopes for openand closed-spaced shrubs were not significantly different for any species. As container moisture and predawn leaf water potential declined during a dry-down cycle Tl-Ta increased significantly over well-watered levels for open-spaced plants and closed-spaced dogwood. In a field experiment Tl-Ta and VPD were monitored in young London plane, flowering pear, and redbud with-and-without irrigation. Only irrigated London plane Tl-Ta was inversely related to VPD. Leaves coated with petroleum jelly, however, had Tl-Ta levels consistently greater than uncoated leaves in all species, and non-irrigated Tl-Ta rose to those levels during a mid-summer drought. These results suggest that irrigation of container shrubs can be timed to increases in Tl-Ta with VPD, while comparing coated and non-coated Tl-Ta may be more successful for irrigated field production.

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We investigated water loss of shade trees over turf and asphalt in an arid and humid climate for Russian olive and silver maple. Total daily tree water loss, and dawn-to-dusk stomatal conductance (gs) and leaf temperature (Tl), as well as air temperature, surface temperature, and vapor pressure deficit, were measured in Logan, Utah, and Stillwater, Okla., in early and mid-summer. Midday air temperatures in mid-summer were similar at both locations, 30 to 35 °C. Comparable vapor pressure deficits (VPD, kPa) were much higher in Logan, 3.5–5.0, than Stillwater, 2–2.5. Differences in humidity and air temperature between asphalt and turf were negligible at both Stillwater and Logan. Midday surface temperatures for asphalt and turf averaged 34 and 50 °C, respectively, in Logan, but were 10 °C higher for both surfaces in Oklahoma. The effect of higher longwave radiation from hotter surfaces on stomatal conductance and water loss of trees over asphalt in Stillwater was not consistently different for either species from those over turf. However, at Logan, Tl of trees over asphalt were consistently 2 to 4 °C higher and gs was 10% to 20% lower than those over turf. Stomatal closure for trees over asphalt resulted in water loss that was the same or slightly lower as trees over turf. The effect of paved surfaces on tree water loss appears to be more pronounced in an arid than a humid climate. The combined effect of higher VPD in an arid region and greater longwave radiation from hotter paved surfaces induces stomatal closure that limits water loss, and likely photosynthesis. By contrast, in humid regions, increased tree radiation interception over asphalt does not appear to trigger stomatal closure due to lower VPD.

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We developed two courses, sustainable landscaping and landscape water conservation, to meet time-constrained students on campus and place-bound students off campus. Lecture material consisting of text, slides, drawings, and some video were assembled digitally using presentation software. Each course was broken into nine to10 units by topic matter, and each unit consisted of 50 to 100 individual “slides” containing visuals, text, and audio narration. The lecture material was then packaged for student consumption onto videotape and CD-ROM, and on the Web (without audio) and as hard copy. Students taking the course received a course reader of the lecture material in hard copy and CD format. Contact with the instructor was through e-mail and a threaded newsgroup on the Web. All testing was with take-home quizzes and an exam. These courses had 700 to 800 slides averaging 1 min of narration per slide, equaling 12 to 14 h of audio. Assembly time for 1 h of narration, or about 60 slides, was 20 to 30 h. These courses are taught live in a classroom, where the presentation time is doubled compared to audio narration, alternate years, and have been available every term on an arranged basis. Survey results of 40 students to date taking the course on an arranged basis, obtaining lecture material mainly through CD-ROM, showed that by a 6:1 margin, their learning experience was overall positive. However, by a 19:1 margin, students would have preferred to have taken the course with live classroom instruction. Developing digital courses such as these is only feasible if a faculty member has unequivocal and ample administrative and financial support, and is only cost-effective if there is sufficient student demand outside of conventional scheduling.

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In this symposium we will explore the unique capabilities, differences, and requirements of authoring and distributing information as electronic media rather than as the printed page. What is meant by “authoring for the interested learner”? How can the information base be constructed to be “inquiry driven”? Can information be developed as concise answers, chunks, or electronically digitized information packages to be used to support decisions on specific questions? What is meant by “authoring once” for use across alternative media platforms (WWW, CD-ROM, printed page) and for linkage (use) into alternative documents? How can we get groups of educators to collaborate on a “global information system”? Can we establish effective national “peer review” systems for educational information? What can we do with the current electronic information technology? What would we like to be able to do? These and other questions will be discussed by educators from diverse disciplines, ranging through library information science, education, communications, horticulture, and crop and soil science. We invite you to join us in developing this symposium (subjects, speakers) by checking its evolution under the “symposia” link at http://www.forages.css.orst.edu/AAAS-PD/ and sending your ideas by e-mail to the moderators or individual speakers.

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As populations become increasingly urbanized, landscape water conservation becomes more important. Landscape water consumption can increase municipal water use up to 4-fold during the growing season, and account for half the total yearly water use. Landscape water conservation is important in decreasing peak summer water demand to reduce the strain on delivery systems, and to reduce total demand so that development of new sources can be forestalled. Potential water savings from existing landscapes can be estimated by comparing historical usage gleaned from water meter readings to plant water needs estimated from reference evapotranspiration. Estimating water needs for turf is straightforward because of the few species involved and the uniformity of turf landscapes. Estimating water needs of woody plants is more difficult because of the heterogeneity of woody plants and how they are used, and woody plants respond to evaporative demand differently than turfgrass. Many woody plants will actually use less water as reference evapotranspiration increases due to stomatal closure induced by high leaf-air vapor pressure gradients. Landscape water is then conserved by either applying water more effectively in scheduling when and how long to irrigate based on estimating water use again from reference evapotranspiration, or by replacing areas in turfgrass with plants more-adapted to the existing conditions. Encouraging water conservation by end users is the final and largest challenge. Automated irrigation systems makes wasting water easy, while conserving water takes more effort. Education is the key to successful landscape water conservation.

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Technology allows educators to convey information be conveyed more flexibly and visually. How to access and make use of technological teaching tools is the challenge facing educators. HortBase provides the framework for educators to create and access educational chunks. How to make use of the information in HortBase in distance teaching is a three-step process. 1) Before assembling the teaching material, the educator must decide on who the target audience is and what information to convey. Audiences on campus have higher expectations of how they learn, as they are used to live teaching and guidance, and often do not have a clear idea of what they want to learn. Off-campus audiences have lower expectations and are more focused on the information they want. 2) The educator then decides how much of the information to bring into digital form oneself and what to draw from elsewhere. Pieces of digitized information can be created by scanning existing images into the computer or created on computer with drawing programs. Once digitized images can be manipulated to get the desired look. This is a very time-consuming step, so much effort can be saved by taking created “chunks” from HortBase. 3) Finally, what medium and tools to use must be decided. Course content can be presented with slide-show software that incorporates digitized slides, drawing, animations, video footage with text. Lectures can then be outputted to videotape or broadcast via over an analog network. Alternatively, the digitized information can be incorporated into interactive packages for CD-ROM or the World Wide Web.

Free access