Climate change may restrict dryland forest regeneration in the 21st century.

The persistence and geographic expansion of dryland forests in the 21st century will be influenced by how climate change supports the demographic processes associated with tree regeneration. Yet, the way that climate change may alter regeneration is unclear. We developed a quantitative framework that estimates forest regeneration potential (RP) as a function of key environmental conditions for ponderosa pine, a key dryland forest species. We integrated meteorological data and climate projections for 47 ponderosa pine forest sites across the western United States, and evaluated RP using an ecosystem water balance model. Our primary goal was to contrast conditions supporting regeneration among historical, mid-21st century and late-21st century time frames. Future climatic conditions supported 50% higher RP in 2020-2059 relative to 1910-2014. As temperatures increased more substantially in 2060-2099, seedling survival decreased, RP declined by 50%, and the frequency of years with very low RP increased from 25% to 58%. Thus, climate change may initially support higher RP and increase the likelihood of successful regeneration events, yet will ultimately reduce average RP and the frequency of years with moderate climate support of regeneration. Our results suggest that climate change alone may begin to restrict the persistence and expansion of dryland forests by limiting seedling survival in the late 21st century.

Continuing education needs as perceived by dietetic practitioners.

Educational needs of dietitians were identified by 232 practitioners in Ohio by means of a self-administered questionnaire. Three major knowledge areas--managerial science, nutritional care science, and behavioral, communicative, and socio-cultural science--were covered in 109 questions. The respondents perceived a need for more professional knowledge than for behavioral, communicative, and socio-cultural sciences. Greater need was expressed for skills in technical and human ability than for skills in conceptual ability, and generally for nutritional knowledge rather than application. The findings could form the basis for continuing education programs.

Assessing achievement for minimum academic competency. I. Instrument development.

Test instruments for evaluating The American Dietetic Association's Minimum Academic Competencies were developed and tested for four major instructional areas--food, nutrition, nutrition in disease, and management--relevant to professional sciences for general dietetics. The study consisted of four steps: Development of objectives or test criteria; determination of mastery performance standards; test instrument development; and test administration and evaluation. This paper describes procedures used in developing and testing two forms of a criterion-referenced test instrument, which was then administered to determine academic competency of students in dietetics. Salient findings of the test results and evaluation are reported.

Assessing achievement for minimal academic competency. II. Validity and reliability.

Research was undertaken to develop, administer, and evaluate two forms of a criterion-referenced test instrument for measuring the competency status of students graduating from undergraduate programs in general dietetics. Involved in the evaluation of the final forms were 186 students graduating from fourteen college or university programs. Results are reported on the content validity, concurrent validity, reliability, and summary and individual test-item statistics. It is concluded that the test forms need further refinement and development and that the use of criterion-referenced evaluation tools to measure academic competency of students graduating in dietetics is needed.

Transpiration and whole-tree conductance in ponderosa pine trees of different heights.

Changes in leaf physiology with tree age and size could alter forest growth, water yield, and carbon fluxes. We measured tree water flux (Q) for 14 ponderosa pine trees in two size classes (12 m tall and ∼40 years old, and 36 m tall and ∼ 290 years old) to determine if transpiration (E) and whole-tree conductance (g t) differed between the two sizes of trees. For both size classes, E was approximately equal to Q measured 2 m above the ground: Q was most highly correlated with current, not lagged, water vapor pressure deficit, and night Q was <12% of total daily flux. E for days 165-195 and 240-260 averaged 0.97 mmol m-2 (leaf area, projected) s-1 for the 12-m trees and 0.57 mmol m-2 (leaf area) s-1 for the 36-m trees. When photosynthetically active radiation (I P) exceeded the light saturation for photosynthesis in ponderosa pine (900 µmol m-2 (ground) s-1), differences in E were more pronounced: 2.4 mmol m-2 (leaf area) s-1 for the 12-m trees and 1.2 mmol m-2 s-1 for the 36-m trees, yielding g t of 140 mmol m-2 (leaf area) s-1 for the 12-m trees and 72 mmol m-2 s-1 for the 36-m trees. Extrapolated to forests with leaf area index =1, the 36-m trees would transpire 117 mm between 1 June and 31 August compared to 170 mm for the 12-m trees, a difference of 15% of average annual precipitation. Lower g t in the taller trees also likely lowers photosynthesis during the growing season.

Micronema granuloma in the gingiva of a horse.

A well-circumscribed proliferative mass was protruding from the body of the mandible of a 4-year-old Appaloosa gelding. The mass was uniformly firm and was ulcerated on the dorsal surface. The horse was euthanatized due to extensive involvement of the jaw and difficulty in eating. Microscopically, the mass consisted of numerous discrete microgranulomas separated by bands of abundant fibrous connective tissue containing lymphocytes, plasma cells, and histiocytic macrophages. Numerous rhabditiform nematodes were in the microgranulomas as well as in the surrounding connective tissue. The nematodes were identified as Micronema species.

A simple, battery-operated, temperature-controlled cuvette for respiration measurements.

We designed a simple, portable, battery-operated, temperature-controlled cuvette to measure respiration of small samples of plant tissue in the field. The cuvette is built around a peltier cell and is controlled with a data logger. The cuvette maintained sample temperature within 0.5 degrees C over a temperature range of 5 to 45 degrees C and operated for 6-8 h from a 12 V 105 ampere-hour "deep-cycle" battery. Based on measurements with this cuvette, we found that, at 15 degrees C, CO(2) efflux from dark respiration of white pine (Pinus strobus L.) foliage was 40% greater during the day than at night.

Foliage, fine-root, woody-tissue and stand respiration in Pinus radiata in relation to nitrogen status.

We measured respiration of 20-year-old Pinus radiata D. Don trees growing in control (C), irrigated (I), and irrigated + fertilized (IL) stands in the Biology of Forest Growth experimental plantation near Canberra, Australia. Respiration was measured on fully expanded foliage, live branches, boles, and fine and coarse roots to determine the relationship between CO(2) efflux, tissue temperature, and biomass or nitrogen (N) content of individual tissues. Efflux of CO(2) from foliage (dark respiration at night) and fine roots was linearly related to biomass and N content, but N was a better predictor of CO(2) efflux than biomass. Respiration (assumed to be maintenance) per unit N at 15 degrees C and a CO(2) concentration of 400 micro mol mol(-1) was 1.71 micro mol s(-1) mol(-1) N for foliage and 11.2 micro mol s(-1) mol(-1) N for fine roots. Efflux of CO(2) from stems, coarse roots and branches was linearly related to sapwood volume (stems) or total volume (branches + coarse roots) and growth, with rates for maintenance respiration at 15 degrees C ranging from 18 to 104 micro mol m(-3) s(-1). Among woody components, branches in the upper canopy and small diameter coarse roots had the highest respiration rates. Stem maintenance respiration per unit sapwood volume did not differ among treatments. Annual C flux was estimated by summing (1) dry matter production and respiration of aboveground components, (2) annual soil CO(2) efflux minus aboveground litterfall, and (3) the annual increment in coarse root biomass. Annual C flux was 24.4, 25.3 and 34.4 Mg ha(-1) year(-1) for the C, I and IL treatments, respectively. Total belowground C allocation, estimated as the sum of (2) and (3) above, was equal to the sum of root respiration and estimated root production in the IL treatment, whereas in the nutrient-limited C and I treatments, total belowground C allocation was greater than the sum of root respiration and estimated root production, suggesting higher fine root turnover or increased allocation to mycorrhizae and root exudation. Carbon use efficiency, the ratio of net primary production to assimilation, was similar among treatments for aboveground tissues (0.43-0.50). Therefore, the proportion of assimilation used for construction and maintenance respiration on an annual basis was also similar among treatments.