bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors influencing the enlargement of trunk cankers of Phytophthoracinnamomi in red oak
Authors: Robin Cécile , Desprez-Loustau Marie-Laure , Delatour Claude
Published: February 2008

Development of cankers on red oak (Quercusrubra L.) caused by Phytophthoracinnamomi Rands was studied with dendrochronological techniques. Factors of variation among lesions were investigated. Lesion parameters proved to vary with the particular tree to which the lesion belonged. A discriminant factorial analysis and principal component analysis showed that this tree susceptibility was made up of two components. The first accounted for root infection and wound healing. The second concerned susceptibility to vertical spread of the pathogen in bark tissues. Relationships between (i) tree susceptibility and (ii) tree age and vigor were studied. From the occurrence of the first lesion at the collar, number and severity of lesions increased with time, following an exponential and logistic curve, respectively. A comparison of ring widths in infected and healthy trees showed that the disease had no detrimental effect on tree growth. However, annual necrosis length was positively correlated with the annual radial tree growth. The observed differences among trees could not be explained by the effects of time and vigor only. Temperature and drought were analyzed to determine their effect on lesion development. No direct effect of drought on this disease could be shown. The low cold hardiness of P. cinnamomi in the trunk was determined.
Seasonal variation in nitrate reductase activity in needles of high-elevation red spruce trees
Authors: Tjoelker M.G. , McLaughlin S.B. , DiCosty R.J. , Lindberg S.E. , Norby R.J.
Published: February 2008

To assess seasonal and site variation in foliar nitrate reductase activity and its utility as a biochemical marker for the uptake of nitrogen oxide pollutants in high-elevation forests, we measured nitrate reductase activity in current-year needles of red spruce (Picearubens Sarg.) saplings at two high-elevation stands (1935 and 1720 m) in the Great Smoky Mountains, North Carolina. Measurements spanned two growing seasons between September 1987 and September 1988. Nitrate reductase activity peaked near 60 nmol•g−1•h−1 at both sites in September and October 1987 and August 1988 and declined 80% in November 1987 and 65% in September 1988. Although nitrate reductase activity was 30% greater in saplings at the higher site relative to the lower site in September and October 1987, activity dropped to approximately 10 nmol•g−1•h−1 at both sites in November 1987. No differences among sites were evident the following year. Comparing deposition of nitric acid vapor at a nearby site to nitrate reductase activity suggests that needle nitrate reductase activity is not an unequivocal marker for foliar uptake of nitrogen oxides during air pollutant episodes. The changes in soil nitrate levels in this system provide preliminary evidence that foliar nitrate assimilation may, in part, include nitrate taken up from the soil, as the highest activity occurred during periods of higher A-horizon nitrate concentrations in 1988. These measurements of nitrate reductase activity suggest that red spruce are capable of assimilating nitrate in foliage in the field and that the nitrate assimilation capacity varies throughout the year.
Synomones of two sympatric species deter attack by the pine engraver, Ipspini (Coleoptera: Scolytidae)
Authors: Borden J.H. , Devlin D.R. , Miller D.R.
Published: February 2008

The capture of pine engravers, Ipspini (Say), in ipdienol-baited, multiple-funnel traps in British Columbia was significantly reduced when devices releasing ipsenol or verbenone were placed in the traps. These results suggest that ipsenol and verbenone are synomones released by Ipslatidens (LeC.) and the mountain pine beetle, Dendroctonusponderosae Hopk., respectively. When verbenone and ipsenol were released together from five stations 2 m apart on felled trees, at 50 and 1.5 mg per day per tree, respectively, there was a 66.7% reduction in the number of logs attacked and a 98.8% reduction in attack density. The same treatment caused a 74.1% reduction in attack density on standing trees surrounded by a 4 × 4 grid of 16 release devices at 5- m centres. The antiaggregant composition of verbenone plus ipsenol has considerable operational potential for use in precommercial thinnings and in areas where standing pines are of high value; e.g., in rural subdivisions, shelterbelts, and recreational forests.
Hardening and dehardening of shoots and roots of containerized black spruce and white spruce seedlings under short and long days
Authors: Blgras Francine J. , D'aoust André L.
Published: February 2008

Containerized black spruce (Piceamariana (Mill.) B.S.P.) and white spruce (Piceaglauca (Moench) Voss) seedlings that were 120 days old were acclimated under short-day (8-h photoperiod) and long-day (16-h photoperiod) conditions at 10 °C for 12 h and 5 °C for 12 h for 28 days. Afterwards, they were exposed to 3 °C (8-h photoperiod) for 21 days and to 0 °C (without light) for 28 days. Finally, seedlings were dehardened at 10 °C (14-h photoperiod) for 21 days. Hardening of needles, excised stem parts, and whole seedlings was increased by short-day treatment, whereas roots hardened only in response to lowering of temperature. Whole seedlings and needles exposed to the short-day treatment dehardened earlier, whereas roots dehardened only in response to temperature changes. Bud formation was not influenced by photoperiod treatment, but seedlings exposed to the short-day treatment had an earlier bud break. No significant difference was observed between photoperiod treatments for water, sugar, and mineral content of shoots and roots prior to or during dehardening.
Embryogenesis from protoplasts of haploid European larch
Authors: Aderkas Patrick Von
Published: February 2008

Haploid megagametophyte-derived lines of European larch (Larixdecidua Mill.) displaying different degrees of embryogenicity had their protoplasts isolated and cultured. Embryoids were produced from two lines. Colonies of dividing cells but no embryoids were produced from the third, least embryogenic, line. The isolation procedure consisted of preplasmolysis in 0.44 M mannitol for 1 h, followed by enzyme digestion of the cell walls using cellulase and Macerozyme. The released protoplasts were separated from the digestion mixture by screening through cheesecloth and Nitex meshes and by differential gradient centrifugation. The protoplasts were plated in modified half-strength LM medium solidified with agarose. At the end of 1 week the agarose was suspended in a regeneration medium that had lower osmolarity. Osmotic levels were progressively lowered over a period lasting 3 weeks. An alternative method for osmotic reduction was used in which protoplasts were transferred directly from regeneration to maintenance medium. In either method, regeneration of protoplasts occurred in agarose. Regenerated embryoids underwent limited development in suspension, so maturation was completed by plating them onto semisolid half-strength LM medium, and they were raised in the dark for another month. Development from single protoplasts is described, and time-lapse illustrations of colony development from multinucleate protoplasts (coenocytes) are also included.
Soil temperature, nitrogen mineralization, and carbon source–sink relationships in boreal forests
Authors: Bonan Gordon B. , Cleve Keith Van
Published: February 2008

Boreal forests contain large quantities of soil carbon, prompting concern that climatic warming may stimulate decomposition and accentuate increasing atmospheric CO2 concentrations. While soil warming increases decomposition rates, the accompanying increase in nutrient mineralization may promote tree growth in these nutrient-poor soils and thereby compensate for the increased carbon loss during decomposition. We used a model of production and decomposition to test this hypothesis. In black spruce (Piceamariana (Mill.) B.S.P.), white spruce (Piceaglauca (Moench) Voss), and paper birch (Betulapapyrifera Marsh.) forests, decomposition increased with the soil warming caused by a 5 °C increase in air temperature. However, increased nitrogen mineralization promoted tree growth, offsetting the increased carbon loss during decomposition. In the black spruce forest, increased tree production was maintained for the 25 years of simulation. Whether this can be maintained indefinitely is unknown. In the birch forest, tree production decreased to prewarming levels after about 10 years. Our analyses examined only the consequences of belowground feedbacks that affect ecosystem carbon uptake with climatic warming. These analyses highlight the importance of interactions among net primary production, decomposition, and nitrogen mineralization in determining the response of forest ecosystems to climatic change.
Seasonal patterns of biomass accumulation and carbon allocation in Pinustaeda seedlings exposed to ozone, acidic precipitation, and reduced soil Mg
Authors: Edwards G.S. , Friend A.L. , O'Neill E.G. , Tomlinson P.T.
Published: February 2008

Seasonal patterns of biomass accumulation and carbon allocation were determined for 1-year-old loblolly pine (Pinustaeda L.) seedlings grown in soil having either 15 or 35 μg Mg•g−1 and exposed to subambient, ambient, or twice ambient levels of ozone (O3) and simulated rainfall at pH 3.8 or 5.2 in open-top chambers. Seedlings were harvested during the 1988 dormancy period, immediately prior to bud break in 1989, during the first and third foliar growth flushes of 1989, and at the end of the 1989 growing season. At each harvest, biomass of individual seedling components was determined for all seedlings, and 14C allocation among components was determined on a subset of seedlings. Seedlings exposed to twice ambient O3 exhibited a delay in fine-root production at the beginning of the 1989 growing season and reduced coarse-root biomass at the end of the 1989 growing season. Acidic precipitation and soil Mg treatments did not significantly affect biomass at any harvest date, nor were any treatment interactions observed. Biomass accumulation and carbon allocation were strongly affected by plant phenological stage, with maximum root allocation immediately prior to bud break and maximum shoot allocation at the end of the growing season. Seedlings exposed to twice ambient levels of O3 exhibited increased total respirational losses, decreased foliar retention, and slightly reduced export of initial 14C label to stem and roots compared with seedlings exposed to subambient O3; however, these trends were not statistically significant.
The response of Chamaecyparisnootkatensis stecklings to seven nutrient regimes
Authors: Hawkins B.J.
Published: February 2008

Yellow cypress (Chamaecyparisnootkatensis (D. Don) Spach) stecklings (rooted cuttings) of two clones from each of three provenances representing northern and southern Vancouver Island and the lower mainland, British Columbia, were grown in inert rooting medium and fertilized with seven nutrient solutions. The stecklings were compared for their growth and photosynthetic responses to (i) deficiencies of nitrogen, phosphorus, and potassium separately, or a deficiency of all three macronutrients; (ii) nutrients supplied in excess; and (iii) nutrients supplied at constant or exponentially increasing rates. One clone from the northern Vancouver Island provenance was consistently more productive than the others, having the greatest total dry weight and highest net photosynthetic rate in all nutrient treatments. The "complete" nutrient mix supplied in exponentially increasing volumes provided maximum response in growth and photosynthesis for all clones. This response was not significantly better than that of stecklings that received the complete solution at a constant rate of addition; however, stecklings supplied at a constant rate were less efficient in their uptake of macronutrients. Deficiency of nitrogen resulted in the greatest reduction in steckling growth. Phosphorus deficiency resulted in the greatest reduction in stomatal and mesophyll conductances, and therefore assimilation rate. Provided the proportions of individual mineral elements were balanced, plants subject to very low levels of nutrition survived and continued to photosynthesize. Nutrients provided in excess resulted in luxury consumption, and eventually led to plant death. This study demonstrates the potential for using nutritional testing in clonal screening trials to reveal high productivity or deficiency-susceptible clones.
A simple method for extracting plant phenolic compounds
Authors: Sauvesty A. , Page F. , Huot J.
Published: February 2008

Quantitative estimation of phenolic compounds in plant tissues remains uncertain, mainly because those substances are unstable and easily degradable. In this research we have developed and tested a new method for extracting phenolic compounds from sugar maple (Acersaccharum Marsh.) leaves. The research involved three steps: (i) various procedures currently used for extraction of phenolic compounds were tested with five pure phenolic acids; (ii) the extraction solvent, the procedure for dissolving the phenolic compounds, the temperature, and the duration of the treatment were tested on maple leaves; (iii) two methods that were found equally efficient for litter maple leaves were tested on maple leaves collected in June, on barley leaves, and on four pure phenolic acids. Based on those tests, the dissolution of phenolic compounds in 50% aqueous ethanol (v/v) at 40 °C for 3 h appeared to be the most reliable and the least destructive method. We also recommend the use of Polyclar AT, a resin that retains phenolics in solution, to assess the amount of reductive nonphenolic substances present in the plant material analyzed.
Growth trends and stand dynamics in natural loblolly pine in the southeastern United States
Authors: Van Deusen Paul C.
Published: February 2008

A number of recent studies have shown reduced stand-level and individual-tree growth in natural loblolly pine (Pinustaeda L.) stands in the southeastern United States. This study uses increment cores from dominant and codominant trees to determine if individual-tree growth has changed from 1915 to 1985. The cores are grouped for comparison by first sorting on the basis of median stand age and then further sorting these groups of cores by individual-tree age. These trees experienced increasing basal area increments from the mid-1940s into the mid-1970s, after which growth rates returned to preincrease levels. These data support recent findings of growth reductions, but also indicate previously unreported growth increases preceding the growth decreases. These and supplemental permanent plot data suggest that stand dynamics is a viable hypothesis for explaining these growth trends.
Relationships between weather patterns, Sitka spruce (Piceasitchensis) stress, and possible tip weevil (Pissodesstrobi) infestation levels
Authors: Warkentin Dennis L. , Overhulser D.L. , Gara R.I. , Hinckley T.M.
Published: February 2008

Vapor pressure deficit (VPD) regimes were determined for Sitka spruce (Piceasitchensis (Bong.) Carr.) plantations growing in coastal and inland sites of the Olympic Peninsula of Washington State. Relationships between VPD regimes on patterns of stomatal conductance, stem hydration, and xylem pressure potential were examined in Sitka spruce saplings growing on these two sites. These patterns and VPD regimes were analyzed in relation to areas known to sustain either low or high infestation levels of the tip weevil (Pissodesstrobi (Peck) (Coleoptera: Curculionidae)). High VPD regimes of inland Sitka spruce plantations were frequently observed in the summers and were associated with clear days and on-shore breezes; in synchrony with high VPD regimes, the trees of these areas exhibited water stress and decreased photosynthesis. In turn, these factors might contribute to lowered host defenses against tip weevil attacks. Coastal sites generally experienced lower VPD regimes and, consequently, infrequent water stress and stomatal closure, and spruces growing near the coast were mostly associated with low tip weevil attack.
An 802-year tree-ring chronology from the Quebec boreal forest
Authors: Archambault Sylvain , Bergeron Yves
Published: February 2008

On the rocky shores and islands of Lake Duparquet, in the southwestern Quebec boreal forest, Thujaoccidentalis L. reaches ages in excess of 800 years. Annual ring widths from 38 trees were used to develop an 802-year chronology (1186–1987) standardized by polynomial regressions. Excellent cross dating, correlation with a shorter chronology located 14 km inland, and 33.6% common variance in a chronology subsample all point to the existence of a climatic signal. After autoregressive modeling to obtain a serially random residual chronology, correlation and response functions were used to identify the growth–climate relationship. The resulting model reduced 19.2% of the chronology variance. Precipitation in June as well as low temperature in June or July seemed to have a positive influence on growth. Likewise, a drought index was closely related to growth, indicating that the chronology could be used to estimate past drought conditions. Moisture deficits are thus inferred for the 13th century as well as during the Little Ice Age (17th century to late 19th century). Since the end of the latter period, precipitation seems to have followed an upward trend.
Taxonomic patterns and inheritance of chloroplast DNA variation in a survey of Pinusechinata, Pinuselliottii, Pinuspalustris, and Pinustaeda
Authors: Wagner D.B. , Nance W.L. , Nelson C.D. , Li T. , Patel R.N. , Govindaraju D.R.
Published: February 2008

We used 20 heterologous probes (representing approximately 78% of the Pinuscontorta Dougl. chloroplast genome) and 16 endonucleases to examine chloroplast DNA restriction fragments from four Pinus L. species of the southeastern United States. Three variable markers, separated from each other by at least 20 kilobase pairs, were detected in a preliminary screening of two samples from each of the four southern pine species. Restriction fragments of these three markers were paternally inherited in controlled matings, as would be expected of chloroplast DNA genotypes of conifers. Eight chloroplast DNA haplotypes were identified by joint analysis of the three markers in a geographic survey of 215 individuals. The taxonomic distribution of these eight haplotypes placed the four southern pines in the following three groups: (i) Pinusechinata Mill.–Pinuspalustris Mill., (ii) Pinuselliottii Engelm., and (iii)Pinustaeda L. Little intraspecific variation was evident in the geographic survey, but one of the three chloroplast DNA markers was clearly polymorphic in P. elliottii.
The effects of summer shoot production on height growth components of seedlings of California red and white fir
Authors: Hallgren Stephen W. , Helms John A.
Published: February 2008

Morphogenesis of the terminal shoot was studied in 2-year-old seedlings of California red fir (Abiesmagnifica A. Murr.) and two elevational sources of white fir (Abiesconcolor (Gord. & Glend.) Lindl.). Seedlings were either watered or left unwatered during the growing season in order to produce different shoot morphologies and seedlings with and without a summer shoot. Under favorable soil moisture, the frequency of summer shoot production was 32, 53, and 82% for red fir and high- and low-elevation white fir, respectively. Drought from mid-May to mid-September reduced summer shoot production to less than 1% in both species. Spring shoot morphology was not an indicator of capacity to produce a summer shoot. Rate of primordium production was directly related to apical dome diameter. However, when the normal spring increase in apical dome diameter was arrested by summer shoot elongation, the rate of primordium production appeared to be unaffected. Although the apical and subapical meristems were active at the same time, they did not appear to be antagonistic. The major effects of producing a summer shoot were as follows: (i) elongation of 60–120% more intemodes in the current growing season, (ii) production of 15–40% more needle primordia in the overwintering bud, (iii) production of 30–60% more primordia annually, and (iv) increase in the percentage of total primordium production that developed into needles from 60% to 75–80%.
Growth and foliar nutrient status of sugar maple: incidence of forest decline and reaction to fertilization
Authors: Ouimet R. , Fortin J.-M.
Published: February 2008

Typical decline symptoms have become common observations in the deciduous forest of southern Quebec. In 1988, sugar maple (Acersaccharum Marsh.) trees exhibiting various degrees of foliage loss were studied in 21 mature stands scattered throughout the province of Quebec in order to determine the impact of forest decline on the stands' growth and nutritional status. Results showed the following: (i) large variations in foliar concentrations existed between sites and sampling year, (ii) damaged trees were K deficient, (iii) stem radial growth over 5 years (1983–1988) and the 1987–1988 foliar K concentration decreased in a linear fashion as visual estimation of crown foliage loss increased, (iv) radial growth reduction averaged 27 and 54% for trees having a percentage of foliage loss of 6–25 and 25–50%, respectively. We tested the following hypothesis: improvement of foliar status by diagnostic fertilization in declining trees that have a deficiency in K leads to enhanced tree vigor that can be measured as increased stem growth. Beneficial fertilization effects occurred very rapidly, beginning in the year of treatment. Fertilization caused a 50% increase in stem radial growth compared with unfertilized trees in the 2 years following treatment application. This response was accompanied by increased foliar N, K, and Ca levels, and decreased P concentration, compared with control trees. The results suggest that poor growth and vigor of sugar maple on these sites are related to impaired foliar nutrition in K, and that a rapid revival of declining sugar maple characterized by a K deficiency can be produced in the short term by proper fertilization.
Empirical relationships between temperature and nitrogen availability across North American forests
Authors: Yin Xiwei
Published: February 2008

Published data were analyzed to examine whether nitrogen (N) availability varies along macroclimatic gradients in North America. Extractable N produced during 8-week aerobic laboratory incubation was used as an index of potential net N mineralization. Mean extractable N during the growing season in the forest floor plus top mineral soil was used as an index of the available N pool. Using multiple regression, potential net N mineralization was shown to increase with available N and with litter-fall N (R2 = 0.722). Available N increased with increasing total soil N and with decreasing mean January and July air temperatures (R2 = 0.770). These relationships appeared to hold also for deciduous and coniferous forests separately across regions. Results suggest that net N mineralization output under uniform temperature and moisture conditions can be generally expressed by variations of N input (litter fall) and the available soil N pool, and that the available soil N pool is predictable along a temperature gradient at a regional scale.
Changes in the pattern of genetic variability over time in American sycamore and the implication for early selection
Authors: Greene T.A. , Lowe W.J.
Published: February 2008

Height, volume, and stem canker symptom data were collected at ages 3, 5, 7, 10, 13, and 15 years in three genetic tests of American sycamore (Platanusoccidentalis L.) planted in Texas and Louisiana. Five provenances from Texas, Arkansas, and Louisiana were represented in the tests. Data were subjected to analysis of variance; heritabilities, coefficients of genetic prediction, and variance components were calculated. Provenance had no significant effect on height and volume; however, northern provenances tended to be more susceptible to stem canker. Significant family effects occurred for height and volume at all ages, and family heritabilities were moderate to high for all traits. Coefficients of genetic prediction between age 3 height and age 15 volume and canker rating were large and positive, suggesting that early selection to improve 15-year volume and canker resistance in sycamore would be possible. Over the course of this study, the additive variance for height and volume growth gradually increased. The variance attributed to the plantation x family interaction was generally small and nonsignificant. Changes in height and volume individual tree heritabilities over time were due to changes in the magnitude of the between-plot and within-plot error terms and their impact on phenotypic variance. This appeared to be caused by differential timing and severity of stem canker infection in the tests.
Keys for soil moisture regime evaluation for northwestern Quebec
Authors: Brais Suzanne , Camiré Claude
Published: February 2008

Soil moisture regime is an important component of forest land classification at the local level, and in Quebec, it is a criterion for many decisions concerning forestry activities. To facilitate consistent evaluation of soil moisture regime, dichotomous keys were developed for the Abitibi–Temiscamingue region of northwestern Quebec using topographic and edaphic variables and a nonparametric discriminant classification procedure. Probability of correctly classifying a new observation ranges between 63 and 71%, whereas 98–99% of the observations are classified in their moisture class of origin or in an adjacent class.
Comparison of point-3P and modified point-list sampling for inventory of mature native hardwood forest in southeastern New South Wales
Authors: Wood Geoffrey B. , Wiant Jr. Harry V.
Published: February 2008

A modified form of point-list sampling is described for a forest inventory; apart from a preliminary reconnaissance survey, this sampling method requires a single visit to the field and ensures that the desired size of the second-stage sample is obtained. Results achieved in applying the method for inventory of 68 ha of mature hardwood forest in southeastern New South Wales are compared with those derived from a conventional point-3P (also known as point-Poisson) inventory of the area using an identical first-stage sample design. The total volume estimates for the two inventories were comparable. The precision of the point-3P inventory was slightly better (8.7% SE compared with 9.0%) but the cost was greater because 9 more than the desired number of trees (38) were selected in the second-stage sample. The advantages of modified point-list sampling are discussed and estimation formulae are presented.
Influence of fuelwood trees on sodic soils
Authors: Garg V.K. , Jain R.K.
Published: February 2008

The persistent acute fuelwood shortage problem in India has necessitated having tree plantations on waste lands to obtain renewable energy. Fuelwood production screening trials initiated in 1981 at the Biomass Research Centre in Banthra, India (of the National Botanical Research Institute, Lucknow, India), identified babul, Acacianilotica (L.) Willd. ex Delile, and mesquite, Prosopisjuliflora (Swartz) DC, to be the most promising and suitable leguminous trees in terms of biomass production on sodic sites. A study was carried out to assess soil enrichment due to the growth of these fuelwood trees planted a decade past on sodic soil that had had no other amendments. Results showed preferential nutrient accumulation and greater reduction in soil pH (from 9.5 to 7.9) and exchangeable sodium (from 30 to 8%) at the P. juliflora plantation compared with at the A. nilotica plantation. There was also a reduction in surface soil (0–15 cm) bulk density, but an enhancement in porosity and water holding capacity, making soil more friable. The P. juliflora plantation produced markedly more leaf litter (6.1 t•ha−1•year−1) than the A. nilotica plantation (5.7 t•ha−1•year−1). Both the species had fibrous lateral root systems on the surface in the sodic soil. However, the penetration and spread of roots were almost 2-fold greater in P. juliflora than in A. nilotica. Thus, the potential magnitude of changes in soil properties was related to the distribution of roots and amount of litter falling on the soil surface. Prosopisjuliflora appeared to be better than A. nilotica under adverse sodic soil conditions in establishing an enlarged plant-litter nutrient cycle relationship. This study also provides an assessment of soil amelioration by leguminous trees under short-rotation forestry practices.
Effect of heat and its timing within a polyhouse on flowering in potted Douglas-fir trees
Authors: Ross Stephen D.
Published: February 2008

Female and male flowering in potted Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) rooted cuttings treated with gibberellin A4/7, with and without naphthaleneacetic acid, were inhibited by heat treatment in a closed polyhouse with a temperature regimen of 28:15 °C (day:night) relative to the flowering achieved in an open-sided polyhouse with near-ambient temperatures. The effect was greater for an early heat treatment (from vegetative bud burst to end of shoot elongation), which bracketed cone-bud differentiation, than for a following late heat treatment of similar duration. Effects of the early plus late heat treatments were additive. It was not the objective of this study to determine the optimal temperature regimen for flowering. However, other than possibly in locations where low temperatures prevail during cone-bud differentiation in spring, heat treatment within a polyhouse appears to be neither a necessary nor desirable adjunct to gibberellin A4/7 for promotion of flowering in potted Douglas-fir.
Changes in drought resistance and root growth capacity of container seedlings in response to nursery drought, nitrogen, and potassium treatments
Authors: Driessche R. van den
Published: February 2008

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), lodgepole pine (Pinuscontorta Dougl.), and white spruce (Piceaglauca (Moench) Voss) seedlings, each represented by two seed lots, were grown in Styroblock containers in a greenhouse and plastic shelter house from February 1989 to January 1990. The seedlings were exposed to two nitrogen (N) treatments and three potassium (K) treatments arranged factorially within three drought treatments. After winter storage, seedlings from a complete set of treatments were planted into hygric, mesic, and xeric sand beds during 12–14 March. Increasing nursery drought stress increased survival of Douglas-fir and lodgepole pine after planting, and high N treatment level increased survival of lodgepole pine and white spruce. Under xeric conditions, combined nursery drought and high N treatments increased survival of lodgepole pine by 33%, indicating the importance of nursery cultural regime for stock quality. Increase in nursery drought decreased seedling size relatively little, but increase in N increased seedling size one season after planting. A positive relationship between shoot/root ratio and survival in lodgepole pine and white spruce indicated that increase in N increased both shoot growth and drought resistance over the N range investigated. Only Douglas-fir showed an interaction between drought and N treatment and a small response in both survival and dry weight to K. Root growth capacity, measured at the time of planting, showed an approximate doubling in all species due to high N treatment, and was also increased in white spruce by drought stress. Survival and root growth capacity were poorly correlated, but dry-weight growth in sand beds was well correlated with root growth capacity. Shoot dry weight and percent N in shoots measured after nursery growth were correlated with root growth capacity. Manipulation of root growth capacity by changing nursery treatment was apparently possible without altering resistance to drought stress after planting.
Influence of taxonomic relatedness and medium composition on meristematic nodule and adventitious shoot formation in nine pine species
Authors: Bergmann Ben A. , Stomp Anne-Marie
Published: February 2008

Embryos of Pinusechinata Mill., Pinustaeda L., Pinusserotina Michx., Pinuseldarica Medwed., Pinuscaribaea Morelet, Pinusoocarpa Scheide, Pinustecunumanii (Schwd.) Equiluz & Perry, Pinusstrobus L., and Pinusradiata D. Don were cultured following the protocol for Pinusradiata to determine if a perpetual meristem culture could be produced. Two subsequent experiments were done that included modifications to the medium's mineral composition, strength (modified LePoivre and Murashige and Skoog at half-strength and full strength), cytokinin concentration (1.0, 2.5, and 5.0 mg/L benzyladenine), and auxin concentration (0 and 0.1 mg/L indolebutyric acid). Pines in subsection Australes performed poorly in culture relative to those species in subsection Oocarpae. Pinusradiata and Pinuseldarica were the only species to produce long-term subculturable meristematic tissue, although shoots were obtained with seven of the species. Half-strength modified LePoivre medium containing 2.5 mg/L benzyladenine but no auxin gave the best results with most species. Significant differences in shoot production were found among Pinusoocarpa provenances.
Ozone effects on the growth of grafted mature and juvenile red spruce
Authors: Rebbeck Joanne , Jensen Keith F. , Greenwood Michael S.
Published: February 2008

Grafted juvenile and mature scions of red spruce (Picearubens Sarg.) were grown in open-top chambers at a low-elevation site in central Maine to determine if developmental age of tissue affects response to oxidant pollution. After 18 weeks of ozone exposure, grafted red spruce showed little or no growth response to ozone. No significant ozone effect on biomass production was measured, although there were significant differences between juvenile and mature scions. At the final harvest, juvenile scion stem, stem needles, branches, branch needles, and roots had 60, 18, 74, 73, and 35% more dry weight, respectively, than mature scions. Despite the observed differences in growth and biomass production, the two graft types did not differ in their responses to ozone, suggesting that tissue age may not be a factor in ozone-tolerant woody species such as red spruce. It does not preclude the importance of assessing the influence of age on other woody species' response to air pollution. This type of information is critical for extrapolation of seedling data to field conditions with mature trees.
Ponderosa pine needle length: an early indicator of release treatment effectiveness
Authors: McDonald Philip M. , Skinner Carl N. , Fiddler Gary O.
Published: February 2008

Growth responses of ponderosa pine seedlings range from fast to slow after release and often demonstrate the effectiveness of the prescribed treatments. Although several morphological parameters have heen identified as being sensitive to competition, no link to future growth and treatment effectiveness has been made. Shrubs and grasses in four 1- to 3-year-old ponderosa pine (Pinusponderosa Dougl. ex Laws. var. ponderosa) plantations in northern California were treated by several manual and chemical release techniques that resulted in differing amounts of competition to ponderosa pine seedlings. Differing amounts of competition in turn affected pine growth and led to a wide range of stem heights, diameters, and needle lengths. Correlation coefficients indicated that 1-year-old needles, measured 2–4 years after treatment, were positively associated with pine height and diameter up to 7 years after treatment and potentially beyond. Consequently, length of 1-year-old needles may provide a useful early indication of longer term treatment effectiveness.
Shoot-tip respiration of 1st-year interior and coastal Douglas-fir seedlings during bud development
Authors: Fielder Peter , Owens John N.
Published: February 2008

Respiration rates of shoot tips of 1st year (1-0) Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings of one interior and one coastal seed lot were measured using a polarographic Clark-type oxygen probe. Total respiration of shoot tips was high in August and early September (32 nmol O2•mg−1•h−1), the period of most rapid bud development, decreased to between 8 and 16 nmol O2•mg−1•h−1 in the later stage of bud development, and was between 8 and 12 nmol O2•mg−1•h−1 when bud development was complete. Bud development in the interior seed lot was in advance of that in the coastal seed lot, so the basal rate of respiration was reached earlier. However, differences in shoot-tip respiration between seed lots became smaller towards the later stages of bud development. Oxygen consumption increased gradually from February through March in the coastal seed lot but not in the interior seed lot. The capacity of the alternative pathway was determined by the addition of inhibitors of respiration, potassium cyanide (2 mM) and salicylhydroxamic acid (3 mM). The capacity of the alternative pathway did not vary throughout the dormant period and was always less than 10% of total respiration. Respiration rate during bud development is discussed, and it is concluded that this technique may be useful as a test to assess bud dormancy status.
Fine-root distribution of coniferous plantations in relation to site in southern Buenos Aires, Argentina
Authors: Ares Adrián , Peinemann Norman
Published: February 2008

A study was conducted to determine the amounts and vertical distribution of fine roots <2 mm as a function of site quality in a temperate, hilly zone of Argentina. Fine roots were sampled in autumn from 0.2-ha plots established in 12 coniferous plantations of Pinushalepensis Mill., Pinusradiata D. Don, Cedrusdeodara (D. Don) G. Don, and Cupressussempervirens L.f. horizontalis, located in Sierra de la Ventana, southern Buenos Aires. Generally, root density was found to be higher under low-growth stands. The distance from a tree sometimes had an effect on root density, but no clear pattern within stands could be observed. Root density commonly decreased with depth, but slight irregularities in some profiles were observed. Site quality and soil type influenced root distribution. Belowground biomass up to a depth of 50 cm ranged from 1600 to 9800 kg•ha−1 in high-growth stands and from 5400 to 40 700 kg•ha−1 in low-growth stands. Soil organic matter content provided the best correlation with root density. A possible practical implication would be the use of indices related to vertical distribution of organic matter, among other variables, as complementary estimators of effective depth of rooting. The results strongly suggest that trees maintain a large fine-root system in poor sites at the expense of aboveground growth.
Growth response to elevated CO2 in seedlings of four co-occurring birch species
Authors: Rochefort L. , Bazzaz F.A.
Published: February 2008

Seedlings of four birch species were examined to evaluate the presence and extent of phylogenetic constraints on the response of species to global CO2 change. The species differ in their habitat preferences and their successional status. Seedlings were grown for 3 months at near ambient (380 μL•L−1) and double (690 μL•L−1) CO2 concentrations in glasshouses. We found the following: (i) yellow birch (Betulaalleghaniensis Britton) was the only species whose survival differed among CO2 treatments. Survival was slightly increased by elevated CO2. (ii) All growth parameters considered in all four species were significantly stimulated by enriched CO2 conditions, but the magnitude of response was different among species. The most shade-intolerant, fast-growing species (grey birch; Betulapopulifolia Marsh.) took greater advantage of the elevated CO2 resource than the more shade-tolerant, later successional species (e.g., yellow birch). (iii) Patterns of allocation, shoot architecture, and leaf nitrogen content were affected differently by CO2 concentrations for the different species, (iv) The presence and identity of a neighbor did not influence the magnitude or pattern of response to CO2 in birches of a given community. Our results suggest that congeneric species might be more similar in their response to global CO2 in comparison to unrelated species of the same ecosystem that had been studied by others, despite the fact that these closely related birch species differ in their habitat preferences and successional status.
Some hydrological effects of peatland drainage in Alberta's boreal forest
Authors: Hillman G.R.
Published: February 2008

Ninety hectares in a treed fen in north central Alberta were drained to improve growth of stagnant black spruce (Piceamariana (Mill.) B.S.P.) and tamarack (Larixlaricina (Du Roi) K. Koch) stands. Installation of 30-, 40-, 50-, and 60-m ditch spacings resulted in a lowering of the average water table by 79, 66, 56, and 73 cm, respectively. The results and the groundwater level criteria used (drainage norm, 40 cm; flood duration limit, 14 days) indicated that the 50-m ditch spacing was hydrologically the most appropriate one for this area. Given the relatively high hydraulic conductivity of the area, it is believed the 30-m spacing was too narrow and resulted in an excessively low average water table. The 60-m spacing was also overeffective, but in this case, overeffectiveness was attributed more to "edge effects" i.e., to site factors such as the proximity to uplands and the small size of upstream source areas, than to the distance between ditches. The results illustrate the importance, for ditch network design purposes, of taking into account hydrologic conditions both within and well beyond the boundaries of an area proposed to be drained. Peat subsidence after drainage appeared to be related to the average drop in water table level and amounted to about 5 cm•a−1.
Factors controlling denitrification rates in upland and swamp forests
Authors: Merrill Amy G. , Zak Donald R.
Published: February 2008

Spatial patterns of denitrification and temporal variation in the factors controlling this process were studied in three forested ecosystems in northern Lower Michigan. Two forest stands were randomly located within each of two well-drained upland forests (sugar maple–red oak/Maianthemum and sugar maple–basswood/Osmorhiza ecosystems) and one swamp ecosystem (silver maple–red maple/Osmunda ecosystem). Potential N mineralization, nitrification, and microbial respiration were measured in each forest stand using a 33-week laboratory incubation. Factors controlling denitrification were investigated in each ecosystem by treating soil samples with factorial combinations of NO3−, C, and Ar (anaerobic conditions). We also investigated the separate production of N2 and N2O during denitrification, and the factors controlling these fluxes, in a different experiment. Seasonal patterns of denitrification were quantified using an intact soil core method. Potential nitrification and microbial respiration were consistently highest in the swamp forest and lowest in the sugar maple–red oak/Maianthemum ecosystem (582 vs. 3 μg NO3−-N•g−1 and 5275 vs. 1254 μg CO2-C•g−1, respectively). Nitrate availability was the most important factor controlling denitrification in the swamp ecosystem, whereas increased soil water content resulted in the greatest response in the upland forests. Although NO3− significantly increased denitrification in the upland ecosystems, water additions elicited an even greater response. In addition, N2O production in the upland forests accounted for 70 to 90% of the total gaseous N loss; N2O accounted for only 25% of this loss in the swamp forest. Mean denitrification (intact soil cores) in the sugar maple–red oak/Maianthemum ecosystem (12 μg N2O-N•m−2•d−1) was significantly lower than rates measured in the sugar maple–bass-wood/Osmorhiza and silver maple–red maple/Osmunda ecosystems (24 and 39 μg N2O-N•m−2•d−1, respectively). Denitrification reached a maximum during June and July in the sugar maple–basswood/Osmorhiza ecosystem, whereas peaks occurred in May and September in the silver maple–red maple/Osmunda ecosystem. Denitrification in the sugar maple–red oak/Maianthemum forest was variable throughout the year and consistently low. Although variability was high, results suggest that denitrification and the factors controlling this process can be predicted using the spatial distribution of ecosystems.
Comparisons of seasonal changes in photosynthetic capacity, pigments, and carbohydrates of healthy sapling and mature red spruce and of declining and healthy red spruce
Authors: Amundson R.G. , Hadley J.L. , Fincher J.F. , Fellows S. , Alscher R.G.
Published: February 2008

To determine whether healthy sapling and mature red spruce (Picearubens Sarg.) or healthy and declining mature red spruce were physiologically similar, photosynthetic capacity, pigments, and carbohydrates of the three or four most current age-classes of foliage were measured through one growing season. Foliar nutrients were measured once in September. The healthy trees were located at low pollution deposition sites near Howland (mature trees) or Millinocket (saplings), Maine, while the trees in decline were located at a high pollution deposition site at 1100 m on Whiteface Mountain, New York (mature trees). The seasonal time courses of all variables were similar regardless of tree age or vigor. For healthy trees, photosynthetic capacity and foliar nitrogen were positively correlated and declined with age of foliage. For trees in decline, photosynthetic capacity was not correlated with nitrogen and nitrogen did not decline in older foliage. Calcium and magnesium were low in current-year foliage from trees in decline, as were total soluble sugars and raffinose. The nutrient imbalances, lack of correlation between nitrogen and photosynthetic capacity, and low foliar carbohydrates indicate that the trees in decline are physiologically impaired. The low levels of total soluble sugars and raffinose also indicate that current-year foliage of trees in decline may have reduced cold tolerance and thus should predispose that foliage to winter damage.
Effects of fertilization on the nutrition and growth of a slow-growing Engelmann spruce plantation in south central British Columbia
Authors: Brockley R.P.
Published: February 2008

A study was undertaken to investigate the effects of ground and foliar fertilizer applications on the growth of a 15-year-old Engelmann spruce (Piceaengelmannii Parry) plantation in the south central interior of British Columbia. The site had been broadcast burned prior to plantation establishment, and poor growth performance and pretreatment foliar analyses indicated that multiple nutrient deficiencies were likely growth limiting. Fertilization has had a very strong positive influence on height increment and branch elongation. Although growth responses were minimal in the 1st year after treatment, cumulative increases in height increment over the next 2 years averaged 41 cm (range 28–48 cm) greater than those recorded in unfertilized trees. In relative terms, these responses averaged 102% (range 90–120%). Improvements in branch increment over this 2-year period also averaged 102% (range 85–115%). Results indicate that the majority of the growth response has been due to improved nitrogen nutrition. Combined ground applications of nitrogen and a "complete mix" fertilizer were no better than nitrogen alone in stimulating tree growth. The effectiveness of 2% ferrous sulphate and sodium sulphate sprays was probably adversely affected by foliar scorching following spray application. However, despite foliar burning, results indicate that trees may respond favourably to iron applications if accompanied by ground applications of nitrogen and other deficient nutrients (likely sulphur). Because the study design did not allow distinction of cause and effect, with respect to the consequences of the prior broadcast burn, it cannot be stated conclusively that burning is responsible for inadequate stand nutrition and poor tree growth on this site. However, when combined with evidence of impaired nutrition following slash burning from other studies, it may be safely inferred that burning will exacerbate existing nutritional problems and that fertilization under these conditions may at least temporarily improve plantation performance.