bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of nitrogen fertilization of white spruce (Piceaglauca) on the yellow-headed spruce sawfly (Pikonemaalaskansis)
Authors: Popp M. P. , Kulman H. M. , White E. H.
Published: May 2008

Fertilization with 224 and 448 kg Nha−1 applied to white spruce, Piceaglauca (Moench) Voss, as ammonium nitrate significantly increased concentrations of foliar N. Trees with 1.10 to 1.29% foliar N on July 3 had the highest average number of yellow-headed spruce sawfly, Pikonemaalaskansis (Rohwer), larvae per tree (final population) and the lowest percent mortality. This corresponded to trees receiving 224 kg N ha−1. Although not significantly, the final population increased, and the percent mortality decreased with increasing N concentrations up to 1.29% (July 3) (N-deficient trees). As foliar N concentrations, at the time of feeding, increased above 1.29% (N-sufficient trees), final population decreased and percent mortality increased. Therefore, indiscrimate use of fertilizers may increase insect numbers.
Nutritional concerns in selection of black cottonwood and hybrid clones for short rotation
Authors: Heilman Paul E. , Stettler R. F.
Published: May 2008

Nitrogen in leaf fall and in aboveground tissue of close-spaced 4-year-old clones of black cottonwood (Populustrichocarpa Torr. & Gray), Populustrichocarpa × Populusdeltoides Bartr. hybrids, and a 'Robusta' clone was determined. Phosphorus and calcium in the harvested material were also determined. Dry weight of leaf fall varied from 4.4 to 6.6 Mg ha−1 year−1 and it contained from 62 to 84 kg N ha−1. Estimated annual uptake of N in aboveground biomass and leaves ranged from 95 to 276 kg N ha−1 and was largely related to clonal productivity. Aboveground dry weight of woody biomass at the end of 4 years varied from 29 to 111 Mg ha−1 with the two trichocarpa × deltoides hybrids being the highest producers. Nutrients contained in aboveground woody biomass differed greatly among clones in this study, ranging from 95 to 420 kg N ha−1, 14 to 105 kg P ha−1, and 80 to 288 kg Ca ha−1. The N and P utilization efficiency of clones ranked as follows: black cottonwood > new hybrids > 'Robusta'. For Ca, the ranking was as follows: black cottonwood = new hybrids > 'Robusta'. From the standpoint of nutrient-use efficiency, as well as high yield, rooting of cuttings, sprouting after harvest, and other desirable features, black cottonwood offers clear advantages to be captured in breeding programs for short-rotation culture.
Influence of stratification on germination of Pinusleucodermis
Authors: Borghetti M. , Vendramin G. G. , Veneziano A. , Giannini R.
Published: May 2008

The influence of cold–moist stratification on germination of Pinusleucodermis Antoine seed collected at different altitudes in Calabria, Italy, was studied. Germination was significantly enhanced by stratification up to 40 days. Cumulative percent germination for nonstratified seeds was less than half of that for seeds stratified for 40 days. Cumulative percent germination was higher at 30:20 °C (8:16 h) thermoperiod than at a constant temperature of 20 °C. Germination was generally higher in seed lots from lower altitudes. A significant interaction was observed between stratification and temperature.
Foliage loss due to snow, wind, and winter drying damage: its effects on leaf biomass of some western conifer forests
Authors: Grier Charles C.
Published: May 2008

Damage to forest canopies by wind, snow, or winter desiccation significantly reduced stand leaf biomass and area below "steady-state" levels in several western coniferous forests. Leaf biomass of 12 different western conifer forests sampled for an average of 4 years was reduced by as much as 36.3, 34.5, and 42.2% by single wind damage, snow breakage, or winter desiccation events, respectively, during the sampling interval. Foliage loss exceeded annual foliage production as estimated from leaf litterfall in about half the stands where damage occurred. Production efficiency (Mg dry matter•ha−1•year−1•Mg−1 foliage) by remaining foliage appeared to increase after damage. Based on the data available, major canopy damage appears to occur at roughly 9- to 16-year intervals in western coniferous forests. However, this canopy damage is epidosic and unpredictable. Such damage adds an additional measure of uncertainty to forest productivity models.
Effect of inoculum concentration of Endocronartiumharknessii on the infection of lodgepole pine
Authors: Blenis P. V. , Pinnell H. D.
Published: May 2008

From each of three heavily infected Pinuscontorta (Engelm.) var. latifolia stands, cones were collected and bulked from at least five trees with few or no galls, and from at least five trees with many galls. Two additional seedlots were obtained from single, apparently resistant trees from two of the stands. Five levels of Endocronartiumharknessii spores (2, 7, 20, 60, and 180 mg) were applied per tray of 50 seedlings in four replicated experiments. The number of spores observed on 1 cm long stem sections was directly proportional to the number of spores applied. Differences in infection frequency between seedlots from heavily and lightly infected trees were significant, although not large, based on analysis of the four lowest inoculum concentrations. There was no interaction effect between inoculum concentration and infection frequency of the parent trees.
Litter dynamics in two Sierran mixed conifer forests. I. Litterfall and decomposition rates
Authors: Stohlgren Thomas J.
Published: May 2008

Litterfall was measured for 4 years and leaf litter decomposition rates were studied for 3.6 years in two mixed conifer forests (giant sequoia–fir and fir–pine) in the southern Sierra Nevada of California. The giant sequoia–fir forest (GS site) was dominated by giant sequoia (Sequoiadendrongiganteum (Lindl.) Buchh.), white fir (Abiesconcolor Lindl. & Gord.), and sugar pine (Pinuslambertiana Dougl.). The fir–pine forest (FP site) was dominated by white fir, sugar pine, and incense cedar (Calocedrusdecurrens (Torr.) Florin). Litterfall, including large woody debris <15.2 cm in diameter, at the GS site averaged 6364 kg•ha−1•year−1 compared with 4355 kg•ha−1•year−1 at the FP site. Compared with other temperate coniferous forests, annual variability in litterfall (as computed by the ratio of the annual maximum/minimum litterfall) was extremely high for the GS site (5.8:1) and moderately high for the FP site (3.4:1). In the GS site, leaf litter decomposition after 3.6 years was slowest for giant sequoia (28.2% mass loss), followed by sugar pine (34.3%) and white fir (45.1%). In the FP site, mass loss was slowest for sugar pine (40.0%), followed by white fir (45.1%), while incense cedar showed the greatest mass loss (56.9%) after 3.6 years. High litterfall rates of large woody debris (i.e., 2.5–15.2 cm diameter) and slow rates of leaf litter decomposition in the giant sequoia–fir forest type may result in higher litter accumulation rates than in the fir–pine type. Leaf litter times to 95% decay for the GS and FP sites were 30 and 27 years, respectively, if the initial 0.7-year period (a short period of rapid mass decay) was ignored in the calculation. A mass balance approach for total litterfall (<15.2 cm diameter) decomposition yielded lower decay constants than did the litterbag study and therefore longer times to 95% decay (57 years for the GS site and 62 years for the FP site).
Genotype × environment interaction in Norway spruce involving three levels of genetic control: seed source, clone mixture, and clone
Authors: Bentzer B. G. , Foster G. S. , Hellberg A. R. , Podzorski A. C.
Published: May 2008

A total of 913 Piceaabies (L.) Karst. clones was tested for height at ages 1 and 5 in two series on six and three locations, respectively, in Sweden. The genotype × environment interaction was studied for three levels of genetic control, i.e., seedling checklot, clone mixture, and clone. Stability of all three was estimated using regression coefficients. The alternative method, genetic correlation between locations, was also used to measure stability. Height differences among seedling checklots and among clones were substantial at age 5, while the variation among clone mixtures was not significant. Genotype × environment interaction was found to be significant for clones and accounted for an average of 2.1% of the total variance at age 5. No significant interaction was found between mixtures and locations. The genotype × environment interaction for seedling checklots was not significant and accounted for 0.5% of the total variation at age 5. The stability of seedling checklots at age 5 was high. For the clone mixtures, stability was found to be about average. Individual clones showed wide variation in stability. There was an apparent negative relationship between clone performance and stability. Genetic correlations indicated close agreement between locations in the ranking of clones for height growth.
Windstorm damage and microsite colonization in two Minnesota forests
Authors: Webb Sara L.
Published: May 2008

Scattered trees were uprooted, snapped, or bent during a 1983 windstorm in two northwestern Minnesota pine forests. I tested potential correlates (tree species, tree size, cause of damage) of damage type, and compared consequences of the uprooting, snapping, and bending of trees by assessing postdamage survival and by surveying formation and colonization of microsites (mounds, pits, stumps, and dead boles). Larger trees damaged directly by wind were usually snapped and killed in both study areas, regardless of tree species. Smaller trees damaged by falling neighbors were either (i) bent without sustaining mortality or forming microsites, a damage type prevalent among strong-wooded Acersaccharum and Ostryavirginiana in a Pinus–Acer study area, or (ii) uprooted, forming small mounds and pits, a damage type prevalent among weakwooded Abiesbalsamea and Picea spp. in a Pinus–Abies study area. Bent trees usually survived, at least for several years. However, uprooted and snapped trees were equally unlikely to survive their damage. Thus, uprooting and snapping were equally likely to result in dead bole formation. Windstorm-related microsites covered small proportions (6 and 18%) of the floor of the two forests, most as dead boles rather than as stumps, mounds, or pits. Microsites from uprooting, microsites from snapping, and background substrates did not differ in colonizing tree flora but did differ in density of colonists. The role of microsites varied with the autecology of tree species present. In the Pinus–Abies area, rotting wood of stumps and boles was the major establishment substrate for all regenerating tree species. In the Pinus–Acer area, Acersaccharum and A. rubrum were numerically dominant over other species on all substrates, with seedling densities highest away from microsites. Observed patterns of survival and tree regeneration indicate that uprooting and snapping of trees do not differ strongly in their consequences for either forest.
Pressure–volume analysis of leaves of Robiniapseudoacacia L. with the sap expression and free transpiration methods
Authors: Parker William C. , Pallardy Stephen G.
Published: May 2008

Leaf tissue water relations parameters of well-watered and drought-stressed black locust (Robiniapseudoacacia L.) seedlings were compared using the sap expression and free transpiration pressure–volume analysis techniques. Osmotic potentials at full tissue hydration and at the turgor loss point were higher using the sap expression method for well-watered but not for drought-stressed seedlings. These differences appeared to be related to the percentage of water left uncollected during the sap expression procedure. Osmotic adjustment in response to drought was detected by both methods. Leaf relative water content at the turgor loss point and the symplastic water fraction did not differ between methods. The relationship between bulk tissue elastic modulus (E) and turgor potential estimated by both techniques was not significantly different, although E values derived from sap expression curves for well-watered seedlings were generally higher at a given turgor potential.
Does the temperature response of rest break of woody plants change during the development?
Authors: Hänninen Heikki , Pelkonen Paavo
Published: May 2008

not available
Advances in Canadian forest research: an introduction
Authors: Brand David G.
Published: May 2008

not available
Physiological processes in plantation establishment and the development of specifications for forest planting stock
Authors: Burdett A. N.
Published: May 2008

Both the morphological and physiological characteristics of forest planting stock vary widely with nursery culture and environment. Through the control of environmentally determined variation in phenotype, stock can be adapted to both the stress of transplanting from nursery to forest site and the particular environmental conditions of the forest site. Evidence is discussed that indicates that the stress of transplanting is primarily water stress, resulting from (i) the confinement of roots to the planting hole, (ii) poor root–soil contact, and (iii) low root permeability. These deficiencies are overcome by root growth, which is thus a central process in plantation establishment. Root growth depends largely on current photosynthesis. Photosynthesis depends on the assimilation of carbon dioxide at the expense of lost water in transpiration. Transpiration is limited by water uptake and hence depends on root growth. Root growth and photosynthesis in newly planted trees are thus mutually dependent. Because of this relationship, plant water status immediately after planting, or as soon as conditions favorable to root growth occur, is a crucial factor in determining plantation establishment success. High plant tissue water status immediately after planting, or as soon as environmental conditions permit root growth, allows the onset of a positive cycle of root growth supported by photosynthesis and photosynthesis supported by root growth; whereas low tissue water potential immediately after planting can lead to the inhibition or root growth by a lack of photosynthesis and the inhibition of photosynthesis by a lack of root growth. Stock characteristics that enhance plant water status immediately after planting are reviewed and the scope for their control considered. Stock characteristics affecting adaptation to particular planting site conditions, or capable of affecting postestablishment plantation performance, are also discussed.
Artificial intelligence: a new tool for forest management
Authors: Kourtz Peter
Published: May 2008

Articicial intelligence is a new science that deals with the representation, automatic acquisition, and use of knowledge. Artificial intelligence programs attempt to emulate human thought processes such as deduction, inference, language, and visual recognition. The goal of artificial intelligence is to make computers more useful for reasoning, planning, acting, and communicating with humans. Development of artificial intelligence applications involves the integration of advanced computer science, psychology, and sometimes robotics. Of the subfields that artificial intelligence can be broken into, the one of most immediate interest to forest management is expert systems. Expert systems involve encoding knowledge usually derived from an expert in a narrow subject area and using this knowledge to mimic his decision making. The knowledge is represented usually in the form of facts and rules, involving symbols such as English words. At the core of these systems is a mechanism that automatically searches for and pieces together the facts and rules necessary to solve a specific problem. Small expert systems can be developed on common microcomputers using existing low-cost commercial expert shells. Shells are general expert systems empty of knowledge. The user merely defines the solution structure and adds the desired knowledge. Larger systems usually require integration with existing forestry data bases and models. Their development requires either the relatively expensive expert system development tool kits or the use of one of the artificial intelligence development languages such as lisp or PROLOG. Large systems are expensive to develop, require a high degree of skill in knowledge engineering and computer science, and can require years of testing and modification before they become operational. Expert systems have a major role in all aspects of Canadian forestry. They can be used in conjunction with conventional process models to add currently lacking expert knowledge or as pure knowledge-based systems to solve problems never before tackled. They can preserve and accumulate forestry knowledge by encoding it. Expert systems allow us to package our forestry knowlege into a transportable and saleable product. They are a means to ensure consistent application of policies and operational procedures. There is a sense of urgency associated with the integration of artificial intelligence tools into Canadian forestry. Canada must awaken to the potential of this technology. Such systems are essential to improve industrial efficiency. A possible spin-off will be a resource knowledge business that can market our forestry knowledge worldwide. If we act decisively, we can easily compete with other countries such as Japan to fill this niche. A consortium of resource companies, provincial resource agencies, universities, and federal government laboratories is required to advance this goal.
Ectomycorrhizae in reforestation
Authors: Kropp Bradley R. , Langlois Charles-Gilles
Published: May 2008

In view of the possible applications of ectomycorrhizae to forestry, this paper discusses the important functions of ectomycorrhizae, the conditions affecting their formation, and methods for the production and application of inoculum. A rationale for selecting appropriate ectomycorrhizal fungi and considerations in selecting sites where ectomycorrhizal seedlings should be planted are presented. Suggestions are also made on encouraging the use of ectomycorrhizal technology. A cost–benefit analysis of inoculation is done.
Advances in remote sensing technologies for forest surveys and management
Authors: Leckie Donald G.
Published: May 2008

Canadian forest management has had a long history of developing and implementing remote sensing technology and is a major user of remote sensing. Despite difficulties in developing and implementing new digital remote sensing techniques, several key developments in Canadian forest management and in remote sensing and computer technology make the development and implementation of new remote sensing techniques at this time feasible and appropriate. Integration of different remote sensing technologies, remote sensing data with other information sources through geographic information systems, and remote sensing interpretations with forest management systems and practices are critical. Current capabilities and new advances in remote sensing technology for forest survey (excluding forest damage assessment) are discussed. Satellite imagery is a cost-effective tool for broad forest type mapping. New satellite systems improve this capability, but their major impact will be in inventories for new clear-cut and burned areas. Advances in linear array imager technology and lidar systems may lead to development of an end to end inventory mapping system. This system would provide an alternative to aerial photography and current mapping methods and could revolutionize the way forests are inventoried. Imaging spectrometry is a new technology with applications in damage assessment, but as yet has limited potential for assisting in other forest surveys. Spaceborne imaging radar systems are being developed for the 1990s. These systems can produce imagery under cloudy conditions. Their major impact on forestry will be to provide an alternative to visible-infrared satellite data for inventory update.
Growth patterns of sugar maple seedlings and mature trees in healthy and in declining hardwood stands
Authors: Houle Gilles
Published: May 2008

Openings created in the forest canopy as a result of the decline of sugar maple (Acersaccharum Marsh.) may increase microsite heterogeneity and favor the growth of tree seedlings on the forest floor and possibly neighboring healthy trees because of resource release. To corroborate these hypotheses, I studied the growth of sugar maple seedlings and mature trees, and some microsite characteristics, in healthy and in declining hardwood stands. Sampling was carried out in 400-m2 quadrats in four stands of similar composition. In two of the stands, the trees showed no apparent symptoms of decline (healthy stands), but in the other two (declining stands), dieback had caused tree cover to be reduced by ≈25 to 30%. Photosynthetically active radiation below the canopy was significantly lower and less variable in the healthy than in the declining stands, under both cloudy and sunny conditions. In one of the declining stands, soil pH was higher and soil organic matter content was lower than in both healthy stands. Stem elongation of sugar maple seedlings did not differ among the stands prior to 1984, but following that date it was significantly higher and more variable among seedlings in the declining stands. Ring width of apparently healthy trees decreased markedly in the early 1980s and increased somewhat during the 1985–1987 period on the declining sites. Microsite heterogeneity and growth of tree seedlings on the forest floor were thus greater in the declining than in the healthy stands. Neighboring healthy trees did not necessarily respond to the opening of the canopy (as a result of dieback) by increased ring width; this possibly resulted from the hierarchical position within the canopy, the differential time of reaction, and the age and (or) the health status of each individual.
Spruce budworm defoliation and growth loss in young balsam fir: artificial defoliation of potted trees
Authors: Piene H. , Little C.H.A.
Published: May 2008

To simulate feeding by the spruce budworm (Choristoneurafumiferana Clem.), potted, 5-year-old balsam fir (Abiesbalsamea (L.) Mill.) trees were artificially defoliated at the peak of the sixth instar period in the first 1, 2, or 3 years of a 3-year experiment. This schedule allowed trees that were defoliated in the first 1 or 2 years to recover for 2 years and 1 year, respectively. Seven treatments were applied: 0, 33, 66, 90, or 100% of the current-year needles were manually removed, all current-year needles were clipped using scissors (clip treatment), or all current-year shoots were severed at their base (100+ treatment). The dry weights of stem axis, branch axes, and roots were measured at the end of the 3rd year, and current-year and total foliage weight, height growth, and specific volume increment were determined for each year of the experimental period. Needle removal decreased growth throughout the tree, the growth loss increasing with increasing intensity and frequency of defoliation. In the 1st year of defoliation, all treatments reduced specific volume increment, whereas only the 100+ treatment decreased height growth. In every defoliation year, specific volume increment, height growth (manifested in the year following the defoliation), and the final weights of stem axis, branch axes, and roots were generally related curvilinearly to total foliage weight. The 100% and 100+ treatments induced the sprouting of axillary and nodal buds that remained dormant in undefoliated trees. Retaining the defoliated shoot axes (100% treatment), compared with removing them (100+ treatment), increased specific volume increment. Retaining the needle base (clip treatment) prevented the apex necrosis that occurred in some shoots subjected to the 100% treatment. In trees allowed to recover, specific volume increment increased in the 1st year, the degree of recovery increasing with decreasing intensity and frequency of prior defoliation treatment. After 2 recovery years, specific volume increment and height growth were not affected by any previous defoliation treatment, and current-year foliage weight and stem axis weight were decreased only by the 100+ treatment; however, there was still an inhibitory effect of all treatments on the weights of total foliage, branch axes, and roots. The growth responses found in the present investigation were compared with those observed in balsam fir trees defoliated by the spruce budworm.
Respiration rates in forest soil organic horizon materials treated with simulated acid rain
Authors: Salonius P. O.
Published: May 2008

Organic soil materials from a spruce forest were submitted to simulated rain of pH 2.6, 3.6, 4.6, and 5.6. Marked decreases in soil microbial activity were found only with pH 2.6 rain, but responsiveness to increasing temperature was lower as rain of greater acidity was applied to the soil. Ammonium nitrogen mineralization rates were not affected by treatment of soil with acidified precipitation.
Comparison of a random search algorithm and mixed integer programming for solving area-based forest plans
Authors: Nelson John , Brodie J. Douglas
Published: May 2008

An area-based forest plan is formulated and solved by mixed integer programming and a random search algorithm. This is a computationally difficult problem because operational and environmental constraints require that harvest units and road projects be defined as strict binary variables. It was found that the random search algorithm could easily identify several solutions with objective function values within 10% of the true optimum. The best solution found was within 3% of the optimum. The random search algorithm is simple and can be readily implemented on the microcomputer. It is concluded that the random search algorithm is an effective technique for generating acceptable alternatives to complex area-based planning problems.
Leaf morphology and photosynthetic rate in birch seedlings and stump sprouts
Authors: Kauppi A. , Kiviniitty M. , Ferm A.
Published: May 2008

Comparisons were made of the leaves of sprout-origin and seed-origin shoots of Betulapubescens Ehrh. and B. pendula Roth grown under constant or varying temperatures. Particular attention was paid to leaf structure and other factors affecting the rate of photosynthesis. Differences in shoot growth, leaf size, mesophyll structure, and chlorophyll and nitrogen content were observed between the sprouts and seedlings of both species over the course of the growing season. Many of these differences were reflected in the photosynthesis measurements. The sprouts of both species appeared to show a better photosynthetic capacity in their first growing season than the seedlings, and they continued their height growth longer into the autumn. A distinct decline in the level of photosynthesis took place during the growing season. The results suggest that perhaps because of their higher chlorophyll and nitrogen content, young sprouts benefit more from the extremes of temperature at the beginning and end of the growing season than seedlings of the same age. The optimum temperature was the same for sprouts and seedlings of both species. Whether the superior photosynthetic capacity of sprouts compared with seedlings is maintained in later years remains to be resolved.
Soil nitrification as affected by N fertility and changes in forest floor C/N ratio in four forest soils
Authors: Miegroet H. Van , Johnson D. W. , Cole D. W.
Published: May 2008

Potential and actual nitrification were compared between a high and low N fertility Inceptisol in Washington State and between two Tennessee Ultisols to investigate the effect of soil N status and changes in forest floor C/N ratio on NO3-N production. Soil and soil solution data were collected (i) prior to treatment, (ii) after doubling the forest floor C/N ratio with sawdust, and (iii) after doubling the forest floor N content by adding urea N to each of the four forest types. Nitrate N production during aerobic soil incubation before and 1 year after treatment demonstrated significantly higher nitrification capacity of the N-rich Washington soil under alder, the stimulatory effect of N addition, and the suppressing effect of C on nitrification. Our study also indicated that the N fertility status was not as different between the Tennessee soils as originally assumed, that both soils in fact behaved similarly to the N-poor Washingon soil, and that these three soils should be considered in the same category of low N fertility sites. Nitrate concentrations in soil and soil solution samples collected in the field generally agreed with the laboratory findings, but differences in NO3− leaching between the untreated soils and between treatments were often less pronounced. Soil solution NO3− concentrations were <0.01 mmol/L in the two Tennessee soils and the N-poor Washington soil, and differed little between them. In soil that was N enriched by N-fixing alder, the average NO3− solution concentration was 0.4 mmol/L. Spring application of urea N caused an immediate and significant increase in NO3− solution concentration in all four soils, but the treatment effect subsided by the end of the 2nd year in all cases. Adding C to the forest floor did not further reduce already low NO3− solution levels in the two Tennessee soils and the N-poor Washington soil. This treatment did not cause a prolonged reduction in NO3− leaching from the N-rich Washington soil, and it was speculated that this was due to belowground N addition from the root system of the N-fixing alder at this site.
Constructing models for direct prediction of 5-year crown recession in southwestern Oregon Douglas-fir
Authors: Maguire Douglas A. , Hann David W.
Published: May 2008

Crown recession rates were estimated by branch mortality dating on 357 sectioned Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stems from temporary plots. Numerous nonlinear, logarithmic, and gamma-theory generalized linear models were developed for predicting 5-year crown recession across a range in tree, stand, and site conditions. Residual analyses and indices of fit demonstrated that a multiplicative model with lognormal errors was the most appropriate model form. The recommended logarithmic model predicts crown recession from current crown ratio, total height, breast height age, height growth, and crown competition factor. Data from southwestern Oregon indicate that within a given stand, trees with midsized crown ratios experience the most rapid crown recession.
Effects of low temperature, seed source, and seed age on germination of Chamaecyparislawsoniana
Authors: Zobel Donald B.
Published: May 2008

Seeds of Port Orford cedar (Chamaecyparislawsoniana (A. Murr.) Parl.) were collected throughout its natural range. Air-dried seeds were stored in glass bottles at −15 °C. Seeds from 35 sources were germinated fresh, after 3.6 and 10.7–11.7 years of storage. The oldest seeds were germinated on a temperature-gradient bar at ca. 5–20 °C. Initial germination capacity averaged 19–58% for nine collection areas and did not decrease with storage, germination in darkness, or a ca. 40-day period at suboptimal temperatures. Median rates of germination (1/days to 50% germination) decreased in darkness and at suboptimal temperatures. There was no consistent relationship between rate and capacity, nor evidence of a stratification effect. Estimates of the lower temperature limit for germination ranged from 9.6 to 14.0 °C (mean 12.6 °C). A temperature of 14.5–17.0 °C (mean 15.9 °C) was required to germinate half of the potentially germinable seeds. Seeds from coastal and low-elevation sites germinated fastest and responded most to rising temperatures. A high threshold for the lower temperature limit for germination may compensate for lack of dormancy and by causing late germination, contribute to the tree's limited distribution.
The influence of ultraviolet-B light and carbon dioxide enrichment on the growth and physiology of seedlings of three conifer species
Authors: Yakimchuk Roberta , Hoddinott John
Published: May 2008

Anthropogenic production of CO2 and stratospheric ozone depleting chemicals is altering the plant growth environment. Numerous studies have examined the influence of increasing CO2 and UV-B levels on plant growth and physiology, but few studies examine their interaction. Jack pine (Pinusbanksiana Lamb.), black spruce (Piceamariana (Mill.) B.S.R), and white spruce (Piceaglauca (Moench) Voss) were raised in growth rooms from seed for 16 weeks in air with either 350 or 700 μmol•mol−1 of CO2 in the presence or absence of supplemental UV-B irradiation. Classical and functional growth analyses were performed to identify treatment effects. Biomass production in all three species was increased by high CO2 levels while UV-B light reduced it. Shade-intolerant jack pine showed a greater production of UV-B absorbing pigments in UV-B light than did shade-tolerant spruce species. Overall, white spruce was the most sensitive species to both treatment factors. The relative magnitude of the effects in the three species caused by enhanced CO2 and UV-B levels indicate that future conifer seedling growth and competitive ability will be altered by the changing environment.
Effect of paclobutrazol on flower-bud production in Eucalyptusnitens espalier seed orchards
Authors: Moncur M.W. , Rasmussen G.F. , Hasan O.
Published: May 2008

Eucalyptusnitens (Dean & Maiden) Maiden grafts growing as espaliers at Ridgley, Tasmania, and Canberra, Australian Capital Territory, were treated with paclobutrazol as a single collar drench application. Umbel production was enhanced for 3 years at Ridgley and 2 years at Canberra. Canberra grafts were also treated by trunk injection, which proved effective only in the 1st year. Untreated grafts did not produce an appreciable number of umbels until year 3. Paclobutrazol reduced the level of endogenous gibberellins. Close association between gibberellin levels and increases in reproductive activity of E. nitens grafts suggests that the effects of paclobutrazol treatment may be mediated via a reduction in the rate of gibberellin biosynthesis.
Direct seeding of PinusSylvestris using microsite preparation and invigorated seed lots of different quality: 2-year results
Authors: Winsa Hans , Bergsten Urban
Published: May 2008

Direct seeding of Pinussylvestris L. is a regeneration method, with potential for development considering scarification, microsite preparation, seed invigoration, and seed quality. Three seed lots of different quality concerning seed weight, germination percent, and mean germination time were used on two sites in northern Sweden. Microsite preparation, 2 cm deep pyramidal indentations, of the mineral soil improved seedling emergence on the two sites by 48 and 62%, respectively, compared with seeding without preparation other than removal of the humus layer. Microsite preparation in combination with invigorated seed, i.e., seed incubated at 30% moisture content for 7 days at 15 °C, resulted in seedling emergence of about 85% for the highest and about 50% for the lowest seed quality at both sites. Noninvigorated seed, seeded without microsite preparation, reached about 55% for the highest and 22% at one and 43% at the other for the lowest seed quality. Without microsite preparation there was no, or a negative, effect of seed invigoration on seedling emergence. Seedling survival after the first winter improved significantly with better seed quality. Survival averaged 92 and 72% at the two sites, with frost heaving causing most mortality. Seedlings from invigorated and redried seed survived better than seedlings from untreated seed. Seedlings from the best seed quality had higher values in seedling height, about 35%, shoot length, about 60%, and needle length, about 30%, after two growing seasons than seedlings from lower seed qualities. Invigoration and microsite preparation had no effect on measured growth characteristics.
Somatic embryogenesis from immature and mature zygotic embryos and from cotyledons and needles of somatic plantlets of Larix
Authors: Lelu M.A. , Klimaszewska K. , Charest P.J.
Published: May 2008

Induction of embryonal masses was achieved from full-sib immature zygotic embryos of Larixdecidua Mill., Larix × eurolepis A. Henry, and Larix × leptoeuropaea, and it was found to be affected by the developmental stage of the embryos. Furthermore, the expiant response depended on a specific combination of parental trees used for production of seeds. For the first time, induction was successful in L. decidua with mature zygotic embryos. These embryos were isolated from one of the three seedlots tested and induction frequency was 5%. Mature somatic embryos of L. × leptoeuropaea expressed an initiation frequency of 83%. Cotyledons and needles of plantlets derived from somatic embryos of L. × leptoeuropaea were used as expiants to induce somatic embryogenesis at a frequency of 8 and 3%, respectively. A cytokinin pretreatment seemed to enhance the frequency of induction. Mature somatic embryos were obtained from embryonal masses derived from expiants of different ontogenic age. Future opportunities of research into the induction of embryonal masses from mature tree tissues are discussed.
Evaluation of eight forest fertilizer response estimators by means of a simulation study
Authors: McWilliams E.R.G. , Burk T.E.
Published: May 2008

Eight estimators of total fertilizer response (simple difference, ratio, covariance, and regression estimators) commonly used to determine the results of fertilization experiments were evaluated using a simulation study. An individual tree model based on equations developed for Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) was used to project the growth of fertilized and unfertilized plots under several different experimental conditions. The effects of number of plots, plot size, initial plot variability, stand age at the time of fertilization, length of response period, and differing growth responses to fertilization on the relative performance of the estimators were evaluated. Covariance and regression estimators provided the best estimates as long as there was sufficient data to determine model parameters. In almost all cases measures of growth were preferable to measures of yield. For the simple difference and ratio estimators strong linear relationships were observed between bias and pre-treatment differences in yield or growth between fertilized and unfertilized experimental units. Variability in growth response to fertilization did not influence the relative performance of the estimators. The more critical factor was the variability in unfertilized growth as this is what must be predicted in order to estimate fertilizer response.
Comparison of log volume estimates using formulae for log center of gravity and center of volume
Authors: Lynch Thomas B. , Wiant Jr. Harry V. , Patterson David W.
Published: May 2008

Formulae for estimating log center of gravity for logs of uniform density are presented that are based on frusta of simple solids of revolution. The center of gravity position for logs shaped as cones, paraboloids, paracones, neiloids, and logs having intermediate shapes can be estimated by using these formulae. A comparison of log volume estimates was made using the center of gravity and the center of volume locations as interlog positions for diameter measurements. The center of volume was found to be better than the center of gravity for log volume estimation. However, formulae for log center of gravity should be useful for engineering applications with logs of uniform density.
A comparison of forest canopy transmittance estimators
Authors: Smith E.R. , Riitters K.H.
Published: May 2008

Multiple sensors, and alternate statistical estimators, were tested for measuring canopy transmittance in four stands under a variety of sky conditions. On a given day, stand average transmittance estimates were insensitive to degree of synchronization of the sensors used to measure under-canopy and incoming radiation. In comparison to periodic measurement of incoming radiation with a single radiometer, the use of an additional sensor in the open does not automatically improve the estimates of stand average transmittance.
Nutrient concentration and acid–base status of leaf litter of tree species characteristic of the hardwood forest of southern Quebec
Authors: Côté Benoît , Fyles James W.
Published: May 2008

Leaf litter of 15 tree species characteristic of the deciduous and mixed forest of southern Quebec were analyzed for pH, directly titrable acids and bases in water extracts, ash bases, excess bases, excess ash bases, and for levels of N, P, K, Ca, and Mg. We hypothesized that many tree species typical of the climax of sugar maple (Acersaccharum Marsh.) dominated forest have leaf litter with a higher base status than sugar maple and red maple (Acerrubrum L.) leaf litter, and that the base status of leaf litter would be lower on wet sites. Mean differences among species were highly significant (p < 0.0001) for all variables related to acidity or bases, but the effect of drainage was not. Red and sugar maple leaf litter was very acid and low in N concentration. American beech (Fagusgrandifolia Ehrh.) and red oak (Quercusrubra L.) leaf litter was not very acidic but was low in nutrient concentrations. White pine (Pinusstrobus L.) was lowest in all nutrients and ash bases but was low in titrable acidity. Directly titrable bases in leaf litter extracts were correlated positively with leaf litter N and Mg, and ash bases were positively correlated with leaf litter Ca and Mg. Many species typical of the sugar maple climax may have better soil ameliorating potential than sugar and red maple.
Cone and seed morphology of western larch (Larixoccidentalis), alpine larch (Larixlyallii), and their hybrids
Authors: Carlson Clinton E. , Theroux Leon J.
Published: May 2008

not available
Rat aquaporin-5 4.3-kb 5′-flanking region differentially regulates expression in salivary gland and lung in vivo
Authors: Zhou Beiyun , Ann David K. , Flodby Per , Minoo Parviz , Liebler Janice M. , Crandall Edward D. , Borok Zea
Published: May 2008

We previously cloned a 4.3-kb genomic fragment encompassing 5′-flanking regulatory elements of rat aquaporin-5 ( Aqp5) that demonstrated preferential transcriptional activity in lung and salivary cells in vitro. To investigate the ability of Aqp5 regulatory elements to direct transgene expression in vivo, transgenic (TG) mice and rats were generated in which the 4.3-kb Aqp5 fragment directed the expression of enhanced green fluorescent protein (EGFP). RT-PCR revealed relative promoter specificity for the lung and salivary glands in TG mice. Immunofluorescence microscopy showed strong EGFP expression in salivary acinar cells but not in lung type I (AT1) cells, both known sites of endogenous AQP5 expression. Similar results were obtained in TG rats generated by lentiviral transgenesis. EGFP mRNA was detected in both salivary glands and lung. Robust EGFP fluorescence was observed in frozen sections of the rat salivary gland but not in the lung or other tested tissues. The percentage of EGFP-positive acinar cells was increased in parotid and submandibular glands of TG rats receiving a chronic injection of the β-adrenergic receptor agonist isoproterenol. EGFP-positive cells in the lung that were also reactive with the AT1-cell specific monoclonal antibody VIIIB2 were identified by flow cytometry. These findings demonstrate that the 4.3-kb Aqp5 promoter/enhancer directs strong cell-specific transgene expression in salivary gland and low-level AT1 cell-specific expression in the lung. While these Aqp5 regulatory elements should be useful for functional studies in salivary glands, additional upstream or intronic cis-active elements are likely required for robust expression in the lung.
Ouabain-induced stimulation of sodium-hydrogen exchange in rat optic nerve astrocytes
Authors: Mandal Amritlal , Delamere Nicholas A. , Shahidullah Mohammad
Published: May 2008

Sodium-dependent transporters are inhibited indirectly by the Na-K-ATPase inhibitor ouabain. Here we report stimulation of sodium-hydrogen exchange (NHE) in ouabain-treated cells. BCECF was used to measure cytoplasmic pH in cultured rat optic nerve astrocytes. Ammonium chloride was applied to acid load the cells. On removal of ammonium chloride, cytoplasmic pH fell abruptly, then gradually recovered toward baseline. Ouabain (1 μM) did not change cell sodium content, but the rate of pH recovery increased by 68%. Ouabain speeded pH recovery both in the presence and absence of bicarbonate. In bicarbonate-free medium, dimethylamiloride, an NHE inhibitor, eliminated the effect of 1 μM ouabain on pH recovery. Western blot analysis showed an NHE1 immunoreactive band but not NHE2, NHE3, or NHE4. Immunoprecipitation studies showed phosphorylation of NHE1 in cells treated with 1 μM ouabain. Ouabain evoked an increase of cAMP, and the effect of 1 μM ouabain on pH recovery was abolished by H-89, a protein kinase A inhibitor. 8-Bromoadenosine-cAMP increased the pH recovery rate, and this recovery was not further increased by ouabain. Although 1 μM ouabain did not alter cytoplasmic calcium concentration, it stimulated calcium entry after store depletion, a response abolished by 2-APB. Ouabain-induced stimulation of pH recovery was suppressed by inhibitors of capacitative calcium entry, SKF-96365, and 2-APB, as well as the cytoplasmic calcium chelator BAPTA. The cAMP increase in ouabain-treated cells was abolished by BAPTA and 2-APB. Taken together, the results are consistent with increased capacitative calcium entry and subsequent cAMP-PKA-dependent stimulation of NHE1 in ouabain-treated cells.
Electrophysiological properties and expression of the delayed rectifier potassium (ERG) channels in the heart of thermally acclimated rainbow trout
Authors: Hassinen M. , Haverinen J. , Vornanen M.
Published: May 2008

In ectotherms, compensatory changes in ion channel number and activity are needed to maintain proper cardiac function at variable temperatures. The rapid component of the delayed rectifier K+current ( IKr) is important for repolarization of cardiac action potential and, therefore, crucial for regulation of cellular excitability and heart rate. To examine temperature plasticity of cardiac IKr, we cloned the ether-à- go- go-related gene (ERG) channel and measured its electrophysiological properties in thermally acclimated rainbow trout ( Oncorhynchus mykiss; omERG). The present findings demonstrate a complete thermal compensation in the whole cell conductance of the atrial IKrin rainbow trout acclimated to 4°C (cold acclimation) and 18°C (warm acclimation). In situ hybridization indicates that transcripts of the omERG channel are present throughout the muscular tissue of the heart, and quantitative PCR shows increased expression of the omERG in cold-acclimated trout compared with warm-acclimated trout. In both acclimation groups, omERG expression is higher in atrium than ventricle. In addition, the omERG has some functional features that support IKractivity at low temperatures. Voltage dependence of steady-state activation is completely resistant to temperature changes, and steady-state inactivation and activation kinetics are little affected by temperatures below 11°C. Collectively, these findings suggest that high density of cardiac IKris achieved by cold-induced increase in the number of functional omERG channels and inherent insensitivity of the omERG to temperature below 11°C. These adaptations are probably important in maintaining high heart rates and proper excitability and contractility of trout cardiac myocytes in the cold.