A process was developed by the New Brunswick Forest Gene Conservation Working Group to identify conservation needs for native tree species in New Brunswick. A multi-stakeholder, consensus-based, expert opinion process was employed to formulate a set of criteria and a rating system, which were then applied to identify tree species in New Brunswick requiring conservation attention at the genetic level. Known or presumed alien invasive insect or fungus species threaten three of these species: butternut (Juglans cinerea), American beech (Fagus grandifolia), and white elm (Ulmus americana). The fourth species, bur oak (Quercus macrocarpa)—with only a few remaining populations in the province—is threatened primarily by land development. Knowledge of the level, type, and pattern of genetic variability differs widely, depending on the species. Only American beech is naturally broadly distributed in the province. The distribution of the other three species is limited by their specific habitat requirements, and contributes to their vulnerability to new threats. Key words: American beech, bur oak, butternut, criteria, gene conservation, genetic variability, species status, threats, vulnerability, white elm

Guidelines were developed by the New Brunswick Forest Gene Conservation Working Group for conserving genetic resources of four native tree species in New Brunswick. Gene conservation guidelines for three of these species aim to maintain sufficient gene pools of known or putatively resistant stock to retain or develop the potential for restoration. Natural populations of American beech (Fagus grandifolia) are known to have genotypes resistant to the beech scale at low frequencies. Gene conservation approaches include in situ and ex situ measures, including resistance breeding. White elm (Ulmus americana) demonstrates a degree of resistance to Dutch elm disease (DED), and will benefit from a mixture of in situ and ex situ conservation measures. Resistance to butternut canker has not yet been demonstrated in populations of butternut (Juglans cinerea), but ex situ conservation of putatively resistant genotypes will be of increasing importance as the frequency of butternut canker escalates. Bur oak (Quercus macrocarpa), threatened by small population size, habitat loss, and ongoing development, requires primarily in situ conservation and restoration efforts. Key words: American beech, bur oak, butternut, disease resistance, ex situ, gene conservation guidelines, genetic resources, in situ, restoration, white elm

The effect on germination of soaking duration, moist-chilling time, and temperature was evaluated using five seed lots of Acer pensylvanicum L. Seeds were soaked for 0, 48, 72, or 96 h, then moist chilled at 4 °C for 16, 24, or 32 weeks. Two temperature regimes were used for germination: (i) 16 h dark at 5 °C : 8 h light at 15 °C (5:15 °C) and (ii) 16 h dark at 20 °C : 8 h light at 30 °C (20:30 °C). Soaking and chilling seeds significantly increased germination. Germination was highest at 5:15 °C, but the germination speed was slow. Germination at 20:30 °C was lower, but 94%–98% of ungerminated seeds appeared to be viable, suggesting that they were dormant. Overall results showed that soaking seeds for 48 h, moist chilling for 16 weeks, and germinating at 5:15 °C produced an average germination of 92%.

The National Tree Seed Centre has been collecting, storing and testing seed for over 35 years. During this time, a large database has been amassed which we use here to assess the potential of 15 species for long-term seed storage at -20degreesC. Seed moisture content and storage temperature are the two most important variables that impact seed longevity. The data show that seed stores well when moisture content is below 9%. For Picea glauca and Acer rubrum, for example, seed moisture contents exceeding 9% had a strong negative impact on storability. Survival curves for Betula alleghaniensis, Picea mariana, Pinus banksiana, Pinus resinosa and Populus grandidentata showed seed viability declined very little after 14 to 32 years in storage. As well, germination data from selected seed lots, 30 years old and older, of Picea glauca, P. mariana, P. rubens, P. sitchensis, Pinus banksiana, P. contorta vat. latifolia and P. resinosa indicate the functional storability (germination > 60%) of these species may be as great as 100 years when stored at -20degreesC with seed moisture contents less than 10%. Factors affecting storability, such as initial seed quality, seed moisture content and storage temperature are discussed.

Red spruce (Picea rubens Sarg.) has experienced a substantial decline across most of its range in eastern North America over the past century and probably also in the disjunct Ontario populations where it now occurs only in small isolated stands. Measurements of cone and seed traits from natural populations were used as indicators of the reproductive and genetic status of red spruce across the northern margins of its range in Canada. Cone and seed traits were quantified to provide reproductive benchmarks for assessing and monitoring population viability. Reduced fecundity and seedling height growth were observed in some of the smallest Ontario populations, suggesting some inbreeding depression in both vegetative and reproductive components of fitness. Nevertheless, the reproductive status of these small isolated Ontario populations compared favorably with the much larger, more extensive Maritime populations in Nova Scotia and New Brunswick. Significantly higher proportions of aborted (nonpollinated) seeds and lower proportions of filled seeds suggested poorer pollination conditions in the Maritimes in 1996. The proportion of empty seed, which was used to estimate inbreeding levels, was significantly and negatively related to seedling height growth. In the short-term, the Ontario populations, which probably represent relatively recent remnants of a broader past distribution, generally appeared to be quite resilient to the effects of small population size on fecundity and progeny fitness. In the longer term, continuing decline in population sizes and numbers may be expected to erode reproductive success and genetic diversity through the effects of inbreeding, genetic drift, and changes in mating behavior. The reproductive indicators described here have general validity for assessing and monitoring reproductive and genetic aspects of population viability in conifers.Key words: Picea rubens, reproductive success, reproductive fitness indicators, inbreeding, population viability, conservation.

Open-pollinated families represented in two series (1979 and 1980) of black spruce (Piceamariana (Mill.) B.S.P) seedling seed orchards and associated field tests were also established in retrospective greenhouse and nursery test environments. Height growth was assessed after varying numbers of growth cycles and compared with performance in the original field tests after 5, 10, and 15 years. The 1979 series consistently produced higher estimates of heritability throughout the 15 years in the field and 6 years in the retrospective nursery test. Phenotypic and genetic correlations among family means at the various field test sites were very strong for the 1979 series material, but generally much lower for the 1980 families. Correlations between performance in the field and retrospective nursery test environments were very strong and highly significant for the 1979 material, with genetic correlations in excess of 0.8. On the other hand, the 1980 material produced much lower correlations that were often not significant. In both cases, correlations with the nursery test environment appeared to peak at age 3 or 4 years. The accelerated greenhouse test environment produced very strong and highly significant correlations with field performance during all measurement intervals for the 1979 series, again with genetic correlations in excess of 0.8. The two accelerated tests of the 1980 material used differing growing regimes; one with artificially extended growing cycles, the other with compressed cycles. The extended-cycle regime produced highly significant phenotypic correlations with field performance in excess of 0.5 and genetic correlations above 0.6, while the compressed-cycle regime had weakly significant phenotypic correlations of about 0.33 and genetic correlations of about 0.4. The two test series present conflicting demonstrations of the impact of early selection. The 1979 series suggests that family selection can be done with a high degree of reliability after three or four accelerated cycles in a single nursery environment and that family rankings are reliable after only 5 years in the field tests, whereas the 1980 series suggests that longer test periods are required and that short-term nursery tests are only effective in identifying the very worst families. Reasons for this conflict and implications for operational breeding programs are discussed.

Although their designs appear simple and straightforward, notch filters for application in stochastic cooling systems are frequently difficult to construct with acceptable characteristics. Problems arise because the components are less than perfect, coaxial cables have loss plus dispersion and other necessary hardware has limitations. Usually it is the delay line, typically a high quality coaxial line, which is the source of most problems. Filter configurations have been produced in many styles. Their purpose is to provide a transmission coefficient with (nearly) zeroes at harmonically related frequencies over a large bandwidth. Specifics of the notch shape (and thus the phase) depend upon the particular filter design. Low dispersion of the notch distribution, that is, the deviation of notch frequencies from ideal, is often difficult to achieve. This is especially true as the operating bandwidths of cooling systems expand. The stochastic cooling systemns used in FNAL's TEV-I operate in the 12 and 2-4 GHz bands, but future systems at CERN'S ACOL or even an upgraded TEV-I will extend to 8 GHz. A filter developed at FNAL1 solves the dispersion problem by using a small superconducting coaxial cable as the long delay element. Laboratory measurements of its characteristics indicate it to have excellent parameters. Nevertheless it requires substantial support in the way of cryogenic and control equipment for its operation. This f ilter is the one chosen for use in the initial operation of the TeV-I pbar accumulation system.

The overall performance of slot couplers, at least for frequenciees below 2 GHz, can probably not match that of stripline based pickups. A measured, typical coupling at 2 GHz correesponds to about 6 to 7 ohms/slot-pair and produces about 8/sup 0/ phase shift/slot on the TEM line. Suppose a 12 to 14 slot array were constructed with these parameters. It would have a total 90/sup 0/ phase shift at about 1.7 GHz, and the coupling would be about 80 ohms at 2.0 GHz. Such an array would be 30 cm long. In a 10 m long straight section, one could place perhaps 25 such modules. After power adding, the net coupling would be about 80 x ..sqrt..25 = 400 ohms. This is 75% of the value which can be obtained by stripline structures (e.g. the FNAL Tevatron-I design). On the other hand, stripline structures may be difficult to construct for, let's say, a 4 to 8 GHz band. Slot coupled devices may then prove to be the more attractive choice. Slot couplers for these higher frequencies will be the subject of our R and D program at this time in the future.

Many hospital laboratories and departments now handle large quantities of radioactive nuclides—commonly ∼ 100 GBq (several curies) per day. Despite strict adherence to clearly defined safety procedures the risk of accidental contamination of skin cannot be entirely eliminated, particularly when high specific activities are used. For example many procedures require the administration of solutions containing 370 MBq (10 mCi) per ml of an isotope such as 99Tcm. A spill or spray of 0.1 μ1 would contain 37 kBq (1 μCi), which if spread over 1 cm2 of skin and left to decay would give a local absorbed dose of 3 cGy (rads) (calculated from the data of Henson (1972)). Even in departments which are not handling radioactive substances substantial risks to staff arise by contamination of the skin by drugs, many of which are sensitizing agents. Trace residues of these non-radioactive substances are difficult or impossible to measure accurately in vivo. The only satisfactory technique of assessing the effectiveness of decontaminating procedures is therefore to generalize from measurements made using γ ray emitting nuclides. We have compared soap and water with two detergents recommended for the removal of radioactive contamination from skin, and with a mildly abrasive skin cleanser. Three radioactive tracers were used, 99Tcm pertechnetate (because it is the commonest radionuclide used in large quantities), 123I sodium iodide and 51Cr in the form of chromic chloride. Both these latter can react chemically with proteins and may therefore become firmly attached to skin.