ALBERT

Description: Stand development of a subalpine forest in the Colorado Front Range following a ca. 15-ha blowdown was examined by analyzing tree population age structures and radial growth patterns. The stand studied was initiated by a fire at the start of the 18th century and was dominated by a dense population of lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) at the time of blowdown in 1973. Before the blowdown, the subcanopy was characterized by abundant subalpine fir (Abieslasiocarpa (Hook.) Nutt.) and scarce Engelmann spruce (Piceaengelmannii (Parry) Engelm.). Comparison with an adjacent control stand, affected only slightly by the blowdown, indicates that new seedling establishment following the blowdown was slight. Instead, the response was dominated by the release of the subcanopy fir and spruce, resulting in acceleration of the successional replacement of lodgepole pine by these shade-tolerant species. Given the 〉300 years required for an old-growth fir and spruce stand to develop following catastrophic fire, the likelihood of a major canopy disturbance in the form of blowdown and (or) lethal insect attack is high and should be explicitly incorporated into general explanations of stand development of subalpine forests in the southern Rocky Mountains.

Description: Analysis of the frequency of past moderate and high-intensity disturbances has been hindered in forests of complex age structure by methodological problems. A methodology is proposed for developing a disturbance chronology in such stands by identifying the probable date of canopy accession for each sample tree. Canopy accession dates are based on an evaluation of radial growth pattern and early growth rates of existing canopy trees. Canopy disturbance intensity is defined as the percentage of sample trees with canopy accession events in each decade. Rotation periods for disturbances of various intensities are calculated from the chronology. The method was evaluated using 893 increment cores from 70 plots in northern hardwood stands of western Upper Michigan. The estimated average disturbance rate for all plots and decades was 5.7–6.9% of land area per decade, with an implied average canopy tree residence time of 145–175 years. These estimates are similar to those obtained by on-site estimates of canopy tree residence time and studies in the literature on the rate of gap formation. Problems in radial increment analysis and possible solutions are discussed.

Description: A method for the production of multiple clonal plantlets of Pinuscaribaea var. hondurensis Morlet, P. oocarpa Schiede, and P. tecunumanii Equiluz and Perry (P. patula Schiede and Deppe ssp. tecunumanii (Equiluz and Perry) Styles) from juvenile sources is described. The procedure is based on the spontaneous production of axillary shoots following shoot elongation. Much interclonal variation exists with respect to expiant multiplication. The addition of activated charcoal (0.1%) stimulates shoot elongation, especially in recalcitrant clones of P. caribaea. Axillary bud initiation may be stimulated by 6-benzylaminopurine, but levels above 1 μM can result in failure of induced buds to form shoots. Rooting occurs at about 50% in nonsterile peat–perlite medium without auxin pretreatment. Rooted plantlets can be readily hardened and will grow normally in the glasshouse.

Description: Piceaglauca var. albertiana (S. Brown) Sarg. shoot phenology and water relation parameters were monitored monthly for 1 year. Seedlings were kept outdoors, well watered, and exposed to seasonal changes in temperature and day length. Changes in shoot water relation parameters corresponded with changes in phenology. During spring, shoot elongation, osmotic potential at saturation, and turgor loss point were least negative, −1.30 and −1.56 MPa, respectively, whereas bulk modulus of elasticity at full turgor was at its highest, 22 MPa. Both osmotic potential at saturation and turgor loss point were most negative, −2.01 and −2.73 MPa, respectively, during late winter just before bud break. Shoot dry weight fraction was at its lowest, 0.33 g dry wt./g shoot weight and maximum symplastic water per unit weight of shoot tissue was at its highest, 3.99 g H2O/g dry wt., during spring shoot elongation. Number of osmoles of solute per kilogram shoot dry weight was highest during spring and late summer shoot elongation phases, 1.03 and 0.91 osmol/kg dry wt., respectively. These data suggest that P. glauca seedlings do not adjust well to dry site conditions.

Description: Crown dimensions and sapwood area near crown base were measured on 189 Douglas-fir trees in southwestern Oregon. Sapwood areas were interpolated or extrapolated to crown base with a sapwood taper function. Various transformations of crown length and crown radius (as well as crown base stem diameter as a surrogate for crown diameter) were assessed for their ability to predict crown base sapwood area. Regression analyses indicated that no single untransformed variable was a good predictor of sapwood area at crown base, but that combinations representing conic surface area performed quite well. Given the consistently strong relationship between total leaf area and sapwood area at crown base, conic surface area should accurately reflect total leaf area and relative photosynthetic potential of the tree. Gross crown dimensions and crown base sapwood area prove complementary in a forest modeling context, owing to the structural appeal of the former and the physiological appeal of the latter.

Description: Pre- and post-harvest regeneration levels were compared for Abiesbalsamea (L.) Mill. –Betulapapyrifera Marsh. –Picea spp. forests in an area of the southern clay belt of northwestern Quebec. Results revealed abundant advance softwood regeneration (mean = 65 000 stems/ha), almost entirely of Abies prior to harvest. The survey following mechanical and manual whole-tree harvesting suggested a 92% reduction of softwood regeneration and a shift from softwood to a mixed or hardwood-shrub dominated regeneration. Ninety percent of softwood seedlings collected after harvest were pre-established. Destruction of advance regeneration was generally greater on fine-textured soils. Hierarchic cluster analysis of ecological types based on softwood, hardwood, and shrub tree regeneration data as variables, revealed nine groups that could serve as a basis for operational silvicultural decision making. In general, Salix spp. and Alnusrugosa (Du Roi) Spreng. are the major competitors on poorly drained sites; Betula sp., Acerspicatum Lam., and Prunuspensylvanica L.f. dominate on thin organic deposits and coarse deposits, whereas Populustremuloides Michx. and Acerspicatum dominate on fine-textured deposits. These findings suggest that a good understanding of physical site factors can provide useful information for harvesting and silvicultural planning.

Description: Height-growth patterns for jack pine (Pinusbanksiana Lamb.) were studied using stem analyses from dominant and codominant trees on 141 plots in north central Ontario. All plots were in natural, well-stocked, even-aged stands 50 years of age or older. Data from 32 of the 141 plots were randomly selected to confirm results, the remaining 109 plots were used for computing the curves. Height-growth curves were developed using a five-parameter Chapman–Richards nonlinear regression that expressed height as a function of age and site index. A site-index prediction equation was also computed using a similar model that expressed site index as a function of age and tree height. Estimated site index using height-growth curves based on the 109 computation plots agreed closely with site index observed from stem analyses on the 32 confirmation plots. Major results were as follows: (i) height-growth curves based on breast-height age were more accurate than curves based on total age; (ii) polymorphic height-growth patterns were related to site index, becoming more curvilinear as site index increased; (iii) average height-growth patterns were similar for jack pine growing on four glacial landforms: shallow and deep moraines, outwashed glacial sands, and lacustrine clays and silts; and (iv) height-growth patterns for ages less than 50 years were very similar to patterns of the commonly used Plonski curves for jack pine site classes in Ontario, but after 50 years, height growth was somewhat better for all sites than predicted by the Plonski curves.

Description: The use of principal components analysis to study tree stem profiles was critically analyzed during 1085 destructively sampled Douglas-fir trees and 1260 simulated trees with known geometric shapes. Interpretation about the meaning of each principal component is provided and contrasted with others in the forestry literature. Nearly identical results with both the destructively sampled and simulated trees, along with certain theoretical consideratons, indicate that the principal components are related to tree form as opposed to tree profile or taper. Therefore, principal components analysis is a useful analytical tool for stratifying trees into different form groups.

Description: Microplot and conventional plot trials were used to determine the nutritional status and required nutrient additions to bring young regenerations of western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western red cedar (Thujaplicata Donn ex D. Don) out of "check." The trees were growing on deep mor-humus Podzols invaded by dense salal (Gaultheriashallon). Salal removal by grubbing and application of Garlon was also tested. Foliar vector analysis, used for hemlock, identified a response to N and P that was confirmed by subsequent 3-year height growth response. Salal removal resulted in increased N uptake only in cedar. Cedar also responded to N and P additions, but vector analysis was not feasible owing to indeterminate growth. Foliar analysis values are compared with published data. It is suggested that salal competition or allelopathy may be the primary cause of inadequate N and P nutrition.

Description: Black spruce seedlings (Piceamariana Mill.) were exposed to either elevated (1000 ppm) or ambient (340 ppm) atmospheric CO2 levels at different stages of seedling development over a winter greenhouse production cycle. Seedlings germinated in early February and were placed in CO2 chambers for either 3 or 6 weeks during March, April, May, or August. Total seedling biomass increased under high CO2 conditions for the March, April, and May stages of development, but showed no significant response in August. The greater part of the CO2 response occurred during the second 3 weeks of exposure in March and April but during the first 3 weeks of exposure in May. In September, those seedlings exposed to CO2 in April and May had 30 and 14%, respectively, greater biomass than control seedlings, but seedlings from the other stages of development no longer had significant differences remaining from the CO2 treatment. This suggests that it could be very efficient to give a short well-timed CO2 pulse at the beginning of the production cycle in hopes of producing a size difference that is maintained throughout the remainder of the greenhouse production cycle under ambient levels of CO2. Short-term exposure to elevated CO2 also increased the ratio of shoot dry weight to total height for the March, April, and May stages of development. The ratio of total nonstructural carbohydrates to free amino acids was negatively correlated (r2 = 0.98) with the allocation of new growth between shoots and roots as measured by the allocation coefficient, k (milligrams shoot growth per milligrams root growth). As seedlings developed along their seasonal growth cycle, ratios of total nonstructural carbohydrates to free amino acids increased and the values for k decreased. The effect of CO2 enrichment on these two factors is discussed. Monitoring total nonstructural carbohydrate and free amino acid concentrations in foliage could have potential as a method to predict the percentage of carbon allocated to root systems of entire forest stands as well as of individual tree seedlings.

Description: Predation by curculionid larvae, tannic acid content, and germination were measured in acorns from individual trees of Quercusalba and Quercusrubra from two sites at the Meeman Biological Field Station, Shelby County, Tennessee, U.S.A. A crossed and nested analysis of variance design was used, and no significant differences were found among trees or between sites in percentages of acorns that were attacked nor in tannic acid contents. Quercusrubra acorns had significantly less predation and higher amounts of tannic acid than Q. alba acorns. Acorns of both species that were not attacked had significantly higher germination success (82% for Q. alba and 98% for Q. rubra) than acorns that were attacked. There was no significant relationship between amount of predation and tannic acid content for acorns from trees of either species. Tannic acid content appears to have an impact by reducing seed predation and may interact with seed crop size to increase annual germination success of trees.

Description: The acetylene reduction assay was used to estimate amounts of nitrogen fixed by Lupinusarcticus Wats. (1.97 kg•ha−1•year−1) and Shepherdiacanadensis (L.) Nutt. (0.78 kg•ha−1•year−1) in a regenerating lodgepole pine (Pinuscontorta Dougl.) stand in southern British Columbia. These amounts appear to be significant, as lodgepole pine ecosystems are generally highly deficient in nitrogen. Thinning of excessively dense pine stands may provide an added growth benefit by increasing nitrogen fixation activity of understory vegetation.

Description: Three indices of nitrogen (N) availability were compared in the field over a 1-year period in an old-growth and a young-growth mixed-conifer forest. The indices utilized were ion exchange resin (IER) bags, buried bags, and a core-IER method employing intact soil cores enclosed in tubes capped at both ends by IER bags. The results from all three methods indicated that in the surface mineral soil, N availability was higher in the young-growth stand than in the old-growth stand. However, seasonal patterns of N availability were generally not well correlated among the methods (correlation coefficients ranged from 0.32 to 0.62). For a given amount of net N mineralized in buried bags, more N accumulated on IER bags placed in the young-growth stand than in those placed in the old-growth stand. This was the result of greater net nitrification in the young-growth stand coupled with the greater mobility of [Formula: see text] relative to [Formula: see text] in soil. Ten-month estimates of net N mineralization measured by the core-IER and buried-bag methods were similar in the young-growth stand (about 42 mg•kg soil−1), but the core-IER estimate was almost twice that of the buried-bag estimate in the old-growth stand (31.7 and 16.8 mg•kg soil−1, respectively). The different sensitivities of the core-IER and buried-bag methods to changes in soil moisture and leaching probably account for much of the difference in their N availability estimates. Results from the core-IER method did reflect the effects of leaching; however, soil water content within the core did not follow changes in soil water content effectively. Because of the greater labor involved in using the core-IER method, its use may be most efficacious in high-precipitation environments, or when in-field soil incubations must be conducted for extended periods of time.

Description: The induction of the enzyme nitrate reductase in needles may be a prerequisite for the assimilation of foliar-absorbed nitrogen oxide pollutants by red spruce (Picearubens Sarg.) trees. To test for induction of nitrate reductase, 1-year-old red spruce seedlings were exposed to NO2, HNO3 vapor, or acid mist containing nitrate, and the activity of nitrate reductase in needles was measured. One day after exposure to NO2 (75 nL•L−1) began, nitrate reductase activity was three times greater than that of unexposed control plants. One day after exposure ended, the nitrate reductase activity returned to the control level. Older red spruce seedlings that had been excavated from a spruce–fir stand exhibited a similar pattern of response, but the level of nitrate reductase activity was much lower than that of the 1-year-old seedlings. Nitric acid vapor (75 nL•L−1) also induced nitrate reductase in red spruce needles, and the pattern of response was similar to that with NO2, except that the nitrate reductase activity did not return to control levels until 2 days after exposure ended. Exposure of seedlings to acid mist containing nitrate (pH 3.5 and 5.0) did not result in a change in nitrate reductase activity. These results indicate that red spruce is capable of assimilating NO2 and HNO3 vapor and that hypotheses of forest decline based on foliar assimilation of pollutant nitrogen oxides are tenable.

Description: From 1983 to 1987 a survey was made to determine the hosts and geographic distribution of the pinewood nematode Bursaphelenchusxylophilus (Steiner and Buhrer), the cause of pine wilt disease, in China. Samples (669) were obtained from dead and dying conifers in 18 provinces and in the federally administrated cities of Beijing and Shanghai. The nematode was only found in samples from Pinusthunbergii and P. massoniana in and around the cities of Nanjing and Zhenjiang (both in Jiansu Province). To determine the susceptibility of Chinese and exotic pines to the pinewood nematode, 15 pine species were inoculated with a Chinese isolate. The 2- to 5-year-old trees, growing at Qingdao (Shandong Province) and Hongjiang (Hunan Province), were inoculated in mid-August to mid-October 1985. The results showed that one pine (P. bungeana) was extremely susceptible to the pinewood nematode, seven were highly susceptible (P. yunnanensis, P. densiflora, P. armandii, P. kwangtungensis, P. elliottii, P. koraiensis, and P. thunbergii), four were moderately susceptible (P. taiwanensis, P. griffithii, P. fenzeliana, and P. sylvestris var. mongolica), and three were resistant (P. taeda, P. massoniana, and P. banksiana). The results are discussed in relation to the needs for quarantine and management of pine wilt disease in the People's Republic of China.

Description: Canadian fire control agencies use either simple interpolation methods or none at all in estimating fire danger between weather stations. We compare several methods of interpolation and use the fire weather index in the North Central Region of Ontario as a case study. Our work shows that the second order least square polynomial, the smoothed cubic spline, and the weighted interpolations had the lowest residual sum of squares in our verification scheme. These methods fit the observed data at both high and low fire weather index values. The highly variable nature of the spatial distribution of summer precipitation amount is the biggest problem in interpolating between stations. This factor leads to highly variable fire weather index fields that are the most difficult to interpolate. The use of radar and (or) satellite data could help resolve precipitation patterns with greater precision. These interpolation methods could easily be implemented by fire control agencies to gain a better understanding of fire danger in the region.

Description: A dendroecological study was carried out on 196 sites distributed throughout the whole natural range of silver fir (Abiesalba Miller) in the Vosges mountains of northeastern France. At each site, six dominant trees were bored to the pith. Stand age varied, intentionally, from 40 to 180 years. All tree rings were measured and crossdated; data were then standardized with reference to the mean curve ring width vs. cambial age. The growth indices obtained in this way were studied (setting aside the cambial age) and revealed a great increase in mean vigour from 1830 to 1930–1940 (+70%) and a slight decrease from 1930–1940 to the present (−10%). Using meteorological data from Strasbourg (monthly precipitation and temperature data available from 1881) and a stepwise multiple linear regression, a climatic model was created that explains 79% of the variance. This amount included not only the monthly parameters of years y (year of ring formation) and y − 1 in the model, but also the parameters of years y − 2 toy − 6. Thus, the notion of structural autocorrelation loses much of its credibility in comparison with the notion of climatic aftereffects. The statistical validation of the model distinguishes a calibration period (1881–1960) and a verification period (1961–1983). The model reconstructs the long-term trends satisfactorily, as well as periodic severe growth declines of silver fir in 1917–1923, 1943–1951, and 1976–1983. These phenomena are mainly explained by climatic factors. The possible aggravating role of air pollution is put forward, in particular, the role of the CO2 increases during the last century.

Description: Soil chemical properties were studied after a wildfire in stands of white spruce (Piceaglauca (Moench) Voss), black spruce (Piceamariana (Mill.) B.S.P.), paper birch (Betulapapyrifera Marsh.), and quaking aspen (Populustremuloides Michx.). Samples of the forest floor and surface 5 cm of mineral soil were collected from burned sites and unburned controls and analyzed soon after the fire. With the exception of soil pH, effects of the fire on soil chemistry differed among the four forest types. Generally, amounts of exchangeable K, Ca, and Mg did not appreciably increase in the forest floor and surface mineral soil except in heavily burned areas in white spruce and black spruce. Fire reduced amounts of N by about 50% in white spruce, aspen, and birch forest floors. In black spruce, quantities of N were slightly higher in heavily burned locations. Forest floor C:N ratios were substantially lower in heavily burned locations in white spruce and black spruce than in unburned controls. Burning did not have a marked influence on supplies of available P in the forest floor, except in heavily burned black spruce, where average amounts were 12.50 g/m2 versus only 0.46 g/m2 in the control. Burning caused more moderate gains in available P in surface mineral soils under aspen and white spruce. We concluded that fire caused marked short-term changes in soil chemistry in the four forest types. How long these changes will persist is unknown.

Description: The consequences for growth and phenology of early selection for height or its growth components were evaluated in 160 open-pollinated families of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) from southwestern Oregon. Seedlings from two inland and two coastal populations (40 families each) were grown for two growing seasons in a common garden. Predicted response to selection suggests that risk of low juvenile–mature correlation and maladaptation with early selection would be less in the inland than in the coastal region. A phenological event that influences a common growth pattern seems to account for the difference in response. Early bud set in the 1st year was genetically correlated with larger overwintering buds in seedlings from both inland and coastal regions. These larger buds yielded a large increment of predetermined growth in the 2nd year, followed by little or no free growth and early bud set. Seedlings with late bud set in the 1st year had the converse pattern. Inland seedlings set buds much earlier on the average than did coastal seedlings; hence seedlings from the two regions had different growth patterns. Risks that can attend early selection for height generally would be decreased in both regions by selecting for predetermined growth, but several qualifications are discussed.

Description: Nitrogen fertilization rate trials (0–672 kg/ha) were established in seven second-growth mixed deciduous forest stands in southern New York, on well to somewhat poorly drained soils typical of better hardwood sites, with no history of fire or cultivation. Basal-area growth over 20 years was determined from increment cores of dominant and codominant trees. Significant growth response occurred only for black cherry (Prunusserotina Ehrh.). Nitrogen additions of 168–336 kg/ha increased growth 21% over 5–10 years. Ten-year basal-area growth response of sugar maple (Acersaccharum Marsh.) and white ash (Fraxinusamericana L.) was less than in other fertilization studies. The lack of response is attributed to favorable nitrogen status of the soils, resulting from lack of disturbance over at least the last four decades and, possibly, atmospheric input of nitrogen.

Description: Cerrenaunicolor (Bull.: Fr.) Murr. (= Daedaleaunicolor) (Aphyllophorales, Polyporaceae) was found to cause a canker rot on two northern hardwood tree species, sugar maple (Acersaccharum Marsh.) and paper birch (Betulapapyrifera Marsh.). Pathogenicity of the fungus was determined by inoculation and examination of cankers 6 months, 1.5 years, and 2.5 years later. The two isolates used were found to differ in pathogenicity. Chemical and morphological barriers formed to compartmentalize the fungus. A zone of enhanced cell wall lignification and the formation of suberized impervious cells which composed the necrophylactic periderm in the host were observed. Xylem discoloration, callus formation, and periderm layers were more pronounced in maple than in birch. Cerrenaunicolor moved past host barriers via a mass of hyphae which annually penetrated weak points in the necrophylactic periderm and subsequently killed the adjacent cambium. Once past the necrophylactic periderm and into the xylem, C. unicolor was an aggressive decay organism which caused an extensive white rot. In naturally infected trees, columns of decay were two or three times longer than the cankers. Multiple zones of decayed and discolored wood were present in the xylem as a result of repeated attacks by the fungus.

Description: A series of microplot and conventional plot trials were used to determine the nutritional status and required nutrient additions to bring young chlorotic Sitka spruce (Piceasitchensis (Bong.) Carr) plantations out of "check." Check occurs on clear-cut and burned old-growth western red cedar (Thujaplicata Donn ex D. Don) and western hemlock (Tsugaheterophylla (Raf.) Sarg.) stands in the Coastal Western Hemlock biogeoclimatic zone growing on deep morhumus Podzols invaded by dense salal (Gaultheriashallon). Microplot trials identified the requirement for N and P. Checked trees responded to fertilization immediately with a 4- to 8-year temporary increase in leader length. Grubbing out of aboveground salal did not improve tree nutrition. There is a close parallel to "heather check" noted with Sitka spruce in British and Irish moorlands; a possible allelopathic effect of salal is suspected. It is concluded that one or more N and P additions are required to establish crown closure. Fertilized Sitka spruce show a high incidence of spruce weevil attack. The deficient and optimum foliar nutrient concentrations developed in Britain for the diagnosis of Sitka spruce appear to be applicable.

Description: Concentration ratios of aluminum to calcium, magnesium, and other divalent cations in increment cores obtained from red spruce and eastern hemlock trees growing in the Great Smoky Mountains National Park in Tennessee and North Carolina have increased in an unprecedented manner during the last 15–40 years. These trends, which also occur in other trees growing in eastern North America and Germany may reflect the mobilization of exchangeable aluminum by [Formula: see text] and [Formula: see text] deposition. The soil chemistry and plant physiology bases for this hypothesis are presented. Many of the spruce and hemlock cores from the Great Smoky Mountains also showed an inverse relationship between radial growth and aluminium:alcium ratios in the wood. Changes in the availability of soil cations, as recorded in tree rings, may provide an ecosystem-level method of evaluating the historical response of forest soils to atmospheric deposition.

Description: Nine-month-old seedlings of Cedrusatlantica Manetti and Pinusnigra Arn. ssp. Laricio var. Corsicana were transplanted in parallelepipedal containers permitting root growth observations (minirhizotrons) and in 6 L pots and were then transferred into two polyethylene tunnels in a greenhouse, where they were submitted to atmospheric CO2 concentrations of 350 (normal) and 800 μmol•mol−1 (enriched) for their 2nd growth year. At the end of the enrichment period, the biomass of the enriched plants was 66 (C. atlantica) and 30% (P. nigra) higher than those of the plants grown at normal CO2 concentrations. The root:shoot biomass ratio remained unaffected by enrichment in both species. Height and diameter growth were 20 (C. atlantica) and 10% (P. nigra) higher in the enriched treatment. At the end of the enrichment period, the CO2 assimilation rate was no longer stimulated in the enriched C. atlantica plants as compared with the normal treatment, but remained slightly stimulated in the P. nigra seedlings. The differential growth response to elevated CO2 appears to be related to the distinct genetic growth pattern of the two species, namely to their different patterns of root growth before bud break and during early aerial growth.

Description: Additions of 15N-labelled ammonium sulfate were used to evaluate the effects of burning at 2- and 4-year intervals during a 24-year period on nitrogen mineralization and immobilization in a loblolly pine (Pinustaeda L.) stand. Net N mineralization in 10-day laboratory incubations of Oe + Oa plus 0–10 cm mineral soil was greatest in the control (210 mg N/m2), intermediate for the 2 year interval burn treatment (87 mg N/m2), and lowest for the 4 year interval burn treatment (78 mg N/m2). Forest floor and mineral soil C/N ratios were greater for the burn treatments than for the control. All samples showed 〉95% immobilization of added 15N ammonium sulfate, the pattern being 2-year interval 〉4-year interval control. Both burning regimes appeared to increase N immobilization and decrease N availability on this very N-poor site.

Description: Matings of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) were performed to develop inbreeding levels with inbreeding coefficient (F) values from 0.0 to 0.75. A strong inverse linear relationship was found between filled seed per cone and F at values ≤0.5. The following mean filled seed per cone values were obtained: outcross (F = 0.0), 31.6; half-sib cross (F = 0.125), 21.3; full-sib cross (F = 0.25), 16.7; parent–offspring backcross (F = 0.25), 15.5; self (F = 0.5), 1.2; second generation self (F = 0.75), 0.03. Parental effects on filled seed per cone were large, accounting for about 50% of the total variation. The use of related clones in a seed orchard will result in less inbred seed than expected under total panmixia, owing to decreased filled seed production at all inbred levels. Also, breeding programs will require increased effort to obtain seed when mating designs include crosses between related trees.

Description: Floralturbation, the mixing of soil by the action of plants, is an important pedologic process in forested areas. The uprooting of trees, the most obvious form of floralturbation, is a natural process found in nearly all forested landscapes. The term uprooting is distinct from such terms as treethrow, treefall, and blowdown, which imply processes that may occur without soil disturbance, as in bole snap. Uprooting is exacerbated by shallow rooting, topographic exposure, weakened condition of the tree, certain cutting practices, and (or) low soil cohesion and shear strength. The root plate of an uprooted tree may deteriorate into a pit-mound pair, the size and shape of which depends on the characteristics of the root plate and the amount of backward displacement during uprooting. This paper (i) provides a synthesis of related terminology on the topics of treefall and uprooting, (ii) examines various lines of evidence for the widespread occurrence of uprooting, (iii) summarizes disturbance cycles for catastrophic uprooting events in different environments, (iv) discusses several examples of the economic import and scale of widespread uprooting events, and (v) reviews environmental factors and silvicultural practices that may lead to increased uprooting or can be used to minimize its likelihood.

Description: Spruce–fir ecosystem monitoring was initiated in 1985 in the southern Appalachians, United States, after reports of a red spruce (Picearubens Sarg.) decline in the northeast. Ice storms during the winter of 1986–1987 had a severe impact on spruce–fir forests in the Black Mountains of North Carolina, the location of Mount Mitchell, the highest peak in eastern North America. Mortality rates were higher for red spruce than for Fraser fir (Abiesfraseri (Pursh.) Poir.), 8.1 and 2.4%, respectively. Recent ice damage was apparent in 12.4% of surviving overstory stems, with red spruce having a 17% average decrease in height. Frequency of damage to stems tended to increase with increasing elevation. Little is known about the successional dynamics of southern high elevation montane second-growth forests. Our results suggest that ice storms may be an important cause of damage and mortality.

Description: A sequential decision plan based on Wald's sequential probability ratio test for the negative binomial distribution was derived for eastern hemlock looper (Lambdinafiscellariafiscellaria (Guen.)) egg populations in Newfoundland. An average sample number of not more than six midcrown branches was feasible, and both α and β error rates were defined. Monte Carlo simulation of operating characteristic and average sample number values for static and dynamic K of the negative binomial showed that Wald's sequential probability ratio test was acceptable. More eggs were found on midcrown balsam fir (Abiesbalsamea (L.) Mill.) branches than on other sampling substrates, such as ground mosses (mainly comprising Hylocomiumsplendens (Hedw.) B.S.G., Pleuroziumschreberi (Brid.) Mitt., and Ptiliumcrista-castrensis (Hedw.) De Not.), loose bark from paper birch (Betulapapyrifera Marsh.), and crown lichens (primarily Usnealongissima Ach.).

Description: Concentrations of extractable total phenols and tannins have been analyzed in the outer bark, inner bark, sapwood, and heart wood from logs of four conifer species, after 1 year on the ground. To estimate decay rates, initial tissue densities were compared with those after 1 and 2 years of decomposition. The four species studied, Pacific silver fir (Abiesamabilis Dougl. ex Forbs), western hemlock (Tsugaheterophylla (Raf.) Sarg.), Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), and western red cedar (Thujaplicata D. Don) represent a gradient of decay resistance. Within a species, outer bark contained the greatest quantities of extractable total phenols followed by inner bark, heart wood, and sapwood. Outer barks also had the highest extractable tannin concentrations. Woody tissues contained very low concentrations of tannin compared with the barks. Total phenol concentrations were highest in the heart wood of red cedar, the most resistant, and lowest in the heart wood of silver fir, the least resistant. There was no obvious relationship between tannins, in any tissues, and the resistance gradient. Density measurements indicated minimal decay in all tissues after 1 year. At 2 years, the inner barks of Douglas-fir, western hemlock, and silver fir had decreased significantly. In general, tissues with the highest extractable phenols appear to be decomposing most slowly.

Description: Douglas-fir seedlings were planted in cleared blocks within three adjacent vegetation types, whiteleaf manzanita, annual grass meadow, and an open stand of Oregon white oak, in southwest Oregon. Within subplots in each block, either pasteurized or unpasteurized soil from a nearby Pacific madrone stand was transferred to the planting holes of the seedlings; control seedlings received no madrone soil. Second-year survival averaged 92, 43, and 12% for seedlings planted on the manzanita, meadow, and oak sites, respectively. Growth differences generally paralleled survival differences. Added madrone soil, whether pasteurized or unpasteurized, did not influence survival, but growth of seedlings on the manzanita site was substantially increased by the addition of unpasteurized madrone soil. Unpasteurized madrone soil did not influence growth of seedlings in the meadow and the oak stand. Pasteurized madrone soil did not affect growth in any of the vegetation types. When added to the manzanita site, unpasteurized madrone soil nearly tripled the number of mycorrhizal root tips forming on seedlings and resulted in formation of a new mycorrhiza type not seen otherwise. As with growth, unpasteurized madrone soil had little or no effect in the other vegetation types. These results suggest that manzanita and madrone impose on soils a biological pattern that stimulates Douglas-fir growth and survival, and they add to the growing body of literature showing that root symbionts and rhizosphere organisms mediate interactions among plant species.

Description: A new procedure was developed for assessing the effects of drainage on tree ring growth. It uses both the predrainage growth of the drained site and the postdrainage growth on an adjacent undrained site as controls in estimating tree ring growth response following drainage. The procedure allows the calculation, on a yearly basis, of the net response of tree ring growth to peatland drainage. The new procedure was applied to black spruce on six peatlands in central Alberta; these sites were drained in 1966. The average age of trees on the sites ranged from 33 to 107 years at time of drainage. The response patterns were as follows: for the first 3 to 6 years following drainage, the tree ring growth did not increase in response to drainage. After that, the net increase in tree ring growth increased nearly linearly until reaching a maximum 13 to 19 years after drainage. The maximum net increases ranged from 76 to 766% of the projected growth of the trees if the sites had not been drained. The net increases fluctuated near the maximum value thereafter. The year to year fluctuations in tree ring index on the drained sites corresponded to the yearly fluctuations on the natural sites.

Description: Comprehensive sampling design including determination of the distribution, number of observations and specification of desired levels of precision is typically ignored in time studies of yarding operations. A computer-based data collection, processing, and analysis system was developed for time studies that permits improved sampling design. Data collection programs were written for continuous timing of yarding operations and downloaded on to hand-held computers equipped with real-time clocks. After each shift of observation, the time study data are uploaded to a portable microcomputer. The data are then processed through a series of programs that provide error checking, cataloging, and formatting in preparation for analysis. Data from three cable yarding operations were used in a study to assess the potential for sequential design and to determine precision levels obtainable from short-duration time studies. Confidence intervals were computed cumulatively and used to assess whether additional observation of a specific machine on a particular site was justified. The data collection, processing, and real-time analysis system shows promise as a technique for improving sampling design of time studies for timber harvesting operations through sequential analysis of the data.

Description: A grafted seed orchard of Acersaccharum Marsh, was established in Ohio in 1957 as part of a program of genetic improvement of sugar yield. During the 3rd decade, the orchard trees averaged 4.2% sap sugar. Although environmental sources of variance in sugar concentration were large, clonal differences were evident and generally consistent over the years; the clone × year interaction was negligible. Sap sugar concentration varied from year to year, but after an increase coinciding with early crown development in the 1st decade, there was no upward or downward trend with age. Inclusion of one seedling family in the orchard made it possible to obtain an approximation of within-family variance by comparison with within-clone variance. It was estimated to be about one-third of total family variance. The clone–family comparison also suggested that about 11% of total clonal variance was a rootstock effect. Sap tests over 3 years in a plantation of seed-orchard offspring showed that an initial thinning to an average 6.3 × 6.3 m spacing would leave trees with an average 4% sap sugar concentration. At final spacing the concentration would be higher. Only a few clones in the orchard produced medium or heavy crops of male or female flowers prior to age 27, but those from which seed was collected in early years averaged at least 4% sap sugar. All clones and the seedling family flowered by age 27.

Description: A linear correlation exists between long-term growth rates and calorimetrically measured metabolic heat rates in some clones of larch (Larixlaricina (Du Roi) K. Koch). The metabolic heat rate per gram of tissue was found to be highly variable among clones from different trees and reproducible for clones of the same tree. The ordering of metabolic rates for clones was shown to be independent of the physiological growth stage in which the measurements were made. Winter-hardened tissue was found to be immediately active on warming to room temperature.

Description: Basal-area increment and chemical composition of xylem wood were measured in three old-growth (ca. 75–100 years) white pine (Pinusstrobus L.) and three sugar maple (Acersaccharum) Marsh.) stands across a pH and SO4 gradient in precipitation in Wisconsin. In 1986 the volume-weighted mean pH and SO4 content of precipitation ranged from 4.5 to 5.0 and from 21 to 11 kg • ha−1, respectively, from southeastern to northwestern Wisconsin. With one exception (a white pine site at Point Beach in eastern Wisconsin), basal-area increment increased from the 1890s until the 1950s (sugar maple) or 1970s (white pine), then levelled off. Growth efficiency, estimated as the ratio of basal area to exposed crown area or crown volume for the 1980–1985 period, was similar for sugar maple across the gradient; however, growth efficiency of white pine was lower at Point Beach than at the two northern Wisconsin sites. Lead concentrations in xylem wood of both species have increased with time, except at Crotte Creek in northwestern Wisconsin, and Pb concentrations in xylem wood of both species were significantly greater in southeastern than in northwestern Wisconsin. Sulfur concentrations in xylem wood of white pine have increased since the 1960s at Point Beach and at one site in north central Wisconsin; S concentrations are significantly greater for both species in southeastern than in northern Wisconsin. Concentrations of Ca, Mg, and K in xylem wood of sugar maple have decreased over the past century. Whereas xylem wood concentrations of Mn and Zn generally show no age-related trends, Fe and P concentrations have increased markedly at all sites, particularly during the past decade. Although additional research is needed to determine the potential of dendrochemistry in evaluating the consequences of environmental pollution, the age- and site-related trends in chemical composition of xylem wood of white pine and sugar maple appear to be related to vehicular emissions (Pb), air pollution (S), migration along ray paths during conversion of sapwood into heartwood (P, Fe, Ca, K, Mg), and possibly reallocation of nutrients from the labile soil pool to perennial tree tissues during stand development (Ca, K, Mg).

Description: Seventy-five clones of Norway spruce (Piceaabies (L.) Karst.) were tested for height, diameter, and volume at two locations in southern Sweden. Total height was measured at seven ages from age 1 to 10 years, whereas diameter at breast height was measured and volume index calculated only at age 10. Clone effects were consistently significant for all traits, whereas clone × location interaction effects only showed significance for diameter at breast height at age 10, volume index, and height at age 3. Location effects for height were small and error effects large, up to age 6. Between ages 7 and 10, location effects increased considerably, while error effects decreased correspondingly. Clone-mean heritability for height remained stable from years 3 to 10, but was slightly higher at age 1. Genetic correlations between traits were generally large, which made efficient selection for height possible as early as age 4. The correlated response in volume index at age 10, when selecting for height at age 4 or later, was exceptionally good, and it provided gain estimates in volume that were as large as or larger than estimates from direct selection for volume index at age 10.

Description: The effects of mounding and soil scarification on microclimate, water relations, photosynthesis, and growth of planted Piceaengelmannii × glauca seedlings were evaluated over three growing seasons. Mounding increased soil temperatures by up to 40% at depths of 5 and 12 cm, but not at 30 cm, during periods of dry, clear weather. Scarification resulted in small increases in soil temperature only at the 5 cm depth. Soil water potential and soil water content were lower in mounds, but similar in scarified patches and controls from midsummer through fall. Transpiration, leaf conductance, and xylem pressure potentials were generally reduced by mounding and to a much lesser extent by scarification compared with controls. However, these responses were complicated by interactions with leaf to air vapor density differences and possibly by soil temperatures. Treatments had no significant effects on diurnal or light responses of photosynthesis. Mounding increased stem and needle weights during the first one-half of the growing season in the first 2 years after planting, but growth was reduced later in the season, probably as a result of increased water stress. Root growth in mounds was significantly greater than scarified patches and controls in all 3 years. Growth patterns for seedlings planted in scarified patches and control treatments were similar to each other. By the end of the third growing season after planting, seedlings in mound treatments had greater stem diameters and total seedling weight was more than double that of controls, but there was little difference in height. Seedlings in scarified patches were similar to controls in diameter and height, but had slightly greater total weights. Results suggest that the positive effects of improved soil temperatures and root growth in mound treatments were negated to a large extent by increased water stress in the first two seasons. By the third growing season, roots were beyond significant drying influence of the mound and their greater length and mass served to increase seedling biomass substantially.

Description: Anatomical characters of the early- and late-wood of individuals of a ring-porous oak (bur oak, Quercusmacrocarpa Michx.) growing in southeastern Nebraska display sensitivity to yearly variations in precipitation. Characteristics of the latewood increment (latewood vessel diameter and density) are closely related to ring width, with vessel diameter varying directly and vessel density varying inversely with ring width. Various analyses indicate that ring width appears to be a less direct climatic indicator than latewood vessel diameter in these trees. A regression equation incorporating latewood vessel diameter is used successfully to reconstruct precipitation over a 9-month period (October–June).

Description: The monoterpene α-pinene, a major component of the terpene composition of Pinus spp., has been reported to act as a host-produced kairomone for a variety of bark beetle species, including the mountain pine beetle, Dendroctonusponderosae Hopkins. However, our experiments indicate that α-pinene autoxidizes under normal temperature and atmospheric conditions to form significant quantities of trans-verbenol, an aggregation pheromone for many species of bark beetles. The quantities of α-pinene present in the resin that can flow from small wounds in pine trees appear to be sufficient to produce trans-verbenol at rates similar to those by female beetles that are actively synthesizing the compound.trans-Verbenol can then autoxidize rapidly to form verbenone, with the content of this compound reaching 8% within 13 weeks of exposure to air. Verbenone is often used by scolytids as an antiaggregation pheromone. Approximately 1.9% of the trans-verbenol and 2.7% of the verbenone found in Porapak Q aerations of phloem with boring spruce beetle, Dendroctonusrufipennis (Kirby), females, as well as 0.8% of the trans-verbenol and 0.8% of the verbenone found in aerations of phloem with boring D. ponderosae females, was due to the autoxidation of α-pinene and (or) the release of oxygenated compounds found in the phloem before bark beetle attack. The natural interconversion of α-pinene, trans-verbenol, and verbenone under ambient conditions suggests that many experiments involving the behavioral activity of these compounds require re-evaluation.

Description: The effect of the aggregation-inhibiting pheromone verbenone on mountain pine beetle attacks in lodgepole pine stands was assessed by affixing verbenone release devices on trees on a 10 × 10 m grid. In one experiment, aggregation to trees baited with an attractive combination of trans-verbenol, exo-brevicomin, and myrcene was reduced in verbenone-treated blocks compared with control blocks (attractive baits only). The mean number of trees with mass attacks (≥31.3 attacks/m2), mean percentage of available trees mass attacked, and mean total number of trees infested were reduced by 74.3, 66.7, and 58.5%, respectively. The ratio of 1987 attacks to 1986 attacks was reduced from 14.0 to 2.6. In a second experiment, using no attractive baits, verbenone caused similar but nonsignificant reductions. The mean number of trees with mass attacks, mean percentage of available trees mass attacked, and mean total number of trees infested were reduced by 75.2, 53.5, and 62.1%, respectively. The 1987 to 1986 attack ratio was reduced from 13.2 in control blocks to 0.2 in the verbenone-treated blocks, and the percentage of trees that were infested but not mass attacked was significantly increased, from 45.7% in the control blocks to 63.2% in the verbenone-treated blocks. We conclude that verbenone shows promise as a management tool for controlling the mountain pine beetle.

Description: The investigation of the structure of growth equations shows that most of them describe the growth decline by a negative exponential function. This decline can also be described by a power function. It was found that the equation based on this assumption is the best available model of diameter growth. Some applications of this equation are discussed.

Description: Periodic functions of Julian calendar dates were used to incorporate seasonal variation into logistic regression models designed to predict daily people-caused forest fire occurrence in the Northern Region of the province of Ontario. Three years of independent test data were used to evaluate predictions produced by the models.

Description: Data from 157 open-grown Sitka spruce (Piceasitchensis (Bong.) Carr.) and 102 western hemlock (Tsugaheterophylla (Raf.) Sarg.) at two locations in coastal Alaska and from 69 Sitka spruce on the Queen Charlotte Islands in British Columbia were used to develop height–diameter and crown width–diameter equations. Height–diameter relations for Sitka spruce were significantly different among all locations. Crown width–diameter relations were not significantly different. Common equations were fit to the spruce data and to the spruce and hemlock data independent of location and site index along the coast.

Description: Trees defoliated by the spruce budworm (Choristoneurafumiferana (Clem.)) for 1 to 4 years and subsequently protected rapidly regained foliar biomass. Three plots of 25- to 30-year-old balsam fir (Abiesbalsamga (L.) Mill.) trees, on the Cape Breton Highlands of Nova Scotia, were studied. Two major factors contributed to the rapid growth recovery rates: the ability to produce epicormic shoots, combined with increased retention of older age-classes of needles, and the development of new foliage at the expense of volume growth. A complete recovery of volume increment occurred after 2 years of extreme defoliation, but not after 4 years of severe defoliation. Epicormic shoot production was only associated with shoot and bud destruction and therefore, growth recovery was slow after partial defoliation of only current foliage. In all plots studied, there was a lag of 2 to 3 years between increased foliar biomass and significant increases in volume increment.

Description: Multiple-use management of forests often requires imposition of spatial constraints on the selection of units for harvest. To satisfy such constraints, harvest units must be treated as integral units. A biased sampling search technique is used to find integer solutions to operationally sized problems. Solutions found for the sample problems are within 8% of the upper bound of the corresponding linear programming solution and less than 4% below the upper bound on the true optimum as defined by a confidence interval estimator.

Description: Quantification of calcium carbonates in a light-colored matrix or disseminated calcium carbonates cannot be obtained directly from impregnated blocks by image analysis. A method that combined staining by alizarin red-S with digital image analysis made it possible to identify and quantify soil calcium carbonates including the disseminated form in thin sections. Best results were obtained under reflected light using a tungsten lamp source. Photographic filters did not improve the image quality of stained calcium carbonates. Key words: Image analysis, soil micromorphometry

Description: K deficiency was identified for the first time in British Columbia orchard soils. Greenhouse-grown apple seedlings responded to K in soils low in available K. MacSpur McIntosh (Malus domestica Borkh.) had increased leaf K (above deficiency) and improved initial fruiting after surface applications of KCl in an orchard with low soil K. Key words: Potassium deficiency, apple, leaf and soil potassium

Description: Growth chamber experiments were conducted to investigate the effect of size of fertilizer reaction zone, rate of added zinc and method of placement of added zinc on the dry matter yield, zinc concentration and zinc uptake of blackbeans grown on a calcareous soil. Relationships between zinc concentrations in the plant, zinc utilization by the plant and zinc concentration in the soil reaction zone were obtained. An equation was developed relating zinc utilization to zinc concentration in the fertilizer band, and a figure was derived showing how increasing the size of the fertilizer zone impacts upon the zinc concentration of the plant. The results indicate that inorganic zinc fertilizers must be mixed as uniformly as possible for maximum effectiveness. Key words: Zinc, placement, calcareous, soil, blackbean, Phaseolis vulgaris

Description: The development and function of the pollination mechanism is described for hemlock (Tsugaheterophylla (Raf.) Sarg.). Controlled pollinations at various stages following bud burst were used to define the period of maximum receptivity. Western hemlock has a pollination mechanism unlike that observed in other native conifers. The pollen grains were not taken into the micropyles; instead, the roughly sculptured pollen grains adhered to the long epicuticular wax covering the bracts. Seed cones became receptive to pollen soon after the bracts emerged from the bud scales and remained receptive until shortly before cone closure. Several days after the cones fully emerged beyond the bud scales, the ovuliferous scales elongated over the bracts, trapping the pollen between the bracts and scales. Several weeks after pollination, pollen germinated on the bracts and formed long pollen tubes which grew towards and into the micropyles.

Description: Aboveground biomass and production were determined for a 70-year-old mixed conifer forest of western larch (Larixoccidentalis Nutt.), lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.), and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) on the eastern slopes of the Cascade Range in Washington state. Live aboveground biomass, projected leaf area, and aboveground net primary production for the mixed conifer forest were 194 Mg•ha−1, 4.2 m−2•m−2, and 6.1 Mg•ha−1•year−1, respectively. Based on the few studies of montane forests on the eastern slope of the Cascades, aboveground biomass, leaf area index, and aboveground net primary production of these forests are more similar to those of montane coniferous forests in the Rocky Mountains than to those of similar forests located on the western slopes of the Cascades.

Description: Carbon content and indices of microbial biomass and activity were determined in 1985 in different soil horizons of two nitrogen-fertilized pine forests in Sweden. The Kroksbo site was fertilized in 1974 with 150 and 600 kg N•ha−1 using NH4NO3 or urea, while the Nissafors site was fertilized in 1977 and 1984 with 150 kg NH4NO3-N•ha−1 The absolute amount of C per square metre of forest floor increased in fertilizer treatments compared with the control (by 10–26%, depending on the site or fertilizer treatment). Respiration rate, ATP content, and microbial biomass C, measured with the substrate-induced respiration technique, decreased in all horizons when expressed per gram of C. The decrease was most evident with NH4NO3, and at the highest level of fertilization. However, on an area basis there were no differences between fertilizer and control treatments. A calculated increase in litter fall in the fertilized plots could not explain all the increase in the amount of C per square metre compared with the control. Decreased microbial activity per gram of C therefore appeared to be an important factor in the increase in C content in fertilized plots.

Description: Organic C, N, P, and S contents in soil are thought to be the result of interactions among soil-forming processes, which occur in all soils but to different degrees. To test this hypothesis, the effect of climate, vegetation and topography on the organic matter composition in cultivated soil profiles was examined along an environmental gradient, from semiarid to subhumid regions in Saskatchewan. This transect encompasses a narrow environmental gradient of decreasing evapotranspiration and increasing precipitation (350–450 mm). Representative catenas selected from Brown, Dark Brown, Black and Gray Luvisol soil zones showed changes in the quantity and composition of organic matter. Concentrations of organic C, N, P and S progressively increased from the Brown to the Black soils and then decreased substantially in the Gray soils. Nutrient concentrations also increased from the upper to the lower slope positions of the catenas and decreased with depth in the soil profile. However, the distribution of organic elements across the soil zones, relative to each other (i.e. C:N, C:P, or C:N:P:S ratios), did not follow the same trends as concentration of the individual elements. The most consistent trends were observed in the lower slope soils, where organic C:N (9.8 to 12.5:1), C:P (48 to 78:1) and C:N:P:S (68:6.9:1.4:1 to 145:11.6:1.8:1) ratios widened from the Brown to the Gray soils. Within any one catena, organic C:N:P:S ratios narrowed with depth in the soil profile, often showing a several-fold decrease relative to the C:N:P:S ratios of the surface horizons. This study demonstrates the value of recognizing integrative relationships among soil processes. It provides a mechanism for better understanding and explaining the patterns of distribution and behavior of various soil chemical, physical and biological properties. Key words: Catenary sequence, Chernozem, Luvisol, hierarchical relationships

Description: In an 8-yr experiment on an irrigated Dark Brown Chernozemic soil, four rates of N (0, 34, 67 and 101 kg ha−1), applied annually with 45 t ha−1 of manure containing softwood shavings (avg. of 46% dry wt) produced a linear yield response (from 3.5 with the check to 4.3 t ha−1 at the highest rate) of barley grain (Hordeum vulgare L. 'Galt'). There were large differences in yields among years, which could be attributed to weather factors, but there was no significant N × year response. Protein content increased linearly (from 11.2 to 13.5%), and both kernel weights and "test weights" (kg hL−1) decreased slightly but significantly with N applications. There was a pronounced "residual" effect of N rates on both grain yield (from 3.8 to 6.3 t ha−1) and protein content (from 10 to 13%) in the first year after applications of manure and N fertilizer ceased. These effects decreased rapidly and had practically disappeared by the end of the 3rd yr, although yields of all treatments remained high (about 5 t ha−1). Organic matter and N contents of the soil were increased by 70 and 41%, respectively, from the cumulative applications of shavings manure. It is concluded that application of manure containing large quantities of softwood shavings has a negligible effect on the N fertilizer requirements of the crop being grown. Beneficial residual effects of N fertilizer applied with the manure may result because of buildup of NO3-N throughout the soil profile, and likely also because of N release from readily mineralized organic compounds or microbial biomass. However, this effect was not reflected in soil tests for readily mineralizable N by NO3 incubation or KCl digestion methods and the effects were practically dissipated after 3 yr. The recovery of applied N fertilizer by the crops was high at all rates (61–79%), and essentially all of the N applied (fertilizer + manure) was accounted for by crop removal + increased soil N. Key words: Mineralizable-N soil tests, Chernozemic soil, repeated fertilizer applications, residual effects

Description: The objective of this study was to evaluate the Kelowna multiple element extractant and some EDTA and DTPA modifications for simultaneous determination of potassium and sodium in acid and calcareous soils. To that end, the relationships between K and Na concentrations extracted with 1 N NH4OAc and the Kelowna multiple element extractant (0.25 N HOAc + 0.015 N NH4F) were assessed. However, relationships between K and Na concentrations removed by the modified Kelowna multiple element extractants containing either EDTA or DTPA (KEDTA & KDTPA with NH4F; and AAEDTA & AADTPA without NH4F) were evaluated by comparing values against those obtained with the Kelowna extractant. Addition of these complexing agents was of interest because of their potential in enabling simultaneous extraction of available Zn. The procedures were evaluated by contrasting K and Na concentrations extracted from 100 Canadian soils — half which had pH values between 4.1 and 6.9 (H2O) and a second group with values between 7 and 9.6 — by means of graphing, regression and correlation techniques. Potassium and sodium concentrations removed by the Kelowna extractant ranged from 25 to 510 μg and from 10 to 1420 μg mL−1 soil, respectively. The Kelowna and its EDTA and DTPA modifications extracted K and Na as effectively from acid as calcareous soils. This conclusion was supported by the similar regression slopes obtained when relating concentrations of K and Na removed from these soil groups by the multiple element extractants against those removed by 1 N NH4OAc (r-values ≥ 0.97**). However, the new multiple element extractants removed an average of about 20% less K than 1 N NH4OAc from these soils, though similar Na levels. The lower K levels removed from the Kelowna extractant, or by one of its modifications, may require that soil test interpretation norms be adjusted to compensate for the lower values when using one of these to determine K-availability. A significant correlation was found between extracted Na levels and 1:2 vol/vol water-extract conductivities (r ≥ 0.83**) suggesting that "higher" Na levels may be soluble instead of exchangeable. Some Na test interpretations are discussed in the text. Key words: EDTA, DTPA

Description: Low recovery of recently added [Formula: see text] fertilizer as [Formula: see text] was observed in a Bainsville (Orthic Humic Gleysol) and a Dalhousie (Gleyed Eutric Brunisol) soil, whereas a Brookston (Orthic Humic Gleysol) and a Conestogo (Gleyed Melanic Brunisol) soil had a high recovery. The former two soils had higher vermiculite contents than the latter two soils. Therefore, [Formula: see text] fixation was believed to be responsible for the low recovery. Between 18 and 23% of added [Formula: see text] was fixed after 15 d in the Bainsville and Dalhousie soils whereas only 1–3% of added [Formula: see text] was fixed in the Brookston and Conestogo soils. Potassium pre-addition (with/without air drying) increased the apparent recovery in the Bainsville and Dalhousie soils but did not affect the actual recovery. Potassium pre-addition did not block subsequent [Formula: see text] fixation, rather it resulted in a release of native 14N. Gamma irradiation was used to inhibit biological activity. Between 1 and 7% of added 15N was immobilized in these soils after 15 d. Key words: Ammonium fixation, immobilization, vermiculites, 15N gamma radiation, potassium, native N, ammonium exchange

Description: Field experiments were conducted during 1982–1983 at two locations (Rimbey and Ellerslie) in north-central Alberta to determine the influence of date of application (mid-October, late October and spring), method of placement (incorporation, banding and nesting) and straw (0 and 3.4 t ha−1) on the recovery of 15N-labelled urea in plants and soil at harvest. The rate of N was 50 kg N ha−1. The recovery of 15N in mature barley plants at both locations was greater with spring application as compared to fall application, and greater with banding or nesting compared to incorporation. At Rimbey, the average recovery, in plants plus soil, of incorporated urea N was lower with October applications (43% for mid and 55% for late) as compared to spring application (89%). Banding or nesting increased the N recovery of October applications. With spring application, there was more immobilization of applied N when incorporated into soil as compared to band or nest placement. Also there was more immobilization of applied N when straw was added to the soil, but banding or nesting tended to overcome the immobilization effect of straw so that the plant N recovery was greater with banding or nesting as compared to incorporation. At the Ellerslie location, there was heavy rain with consequent saturated topsoil in late June and early July. Recovery of fall-applied N in plants was low, and even with nesting the recovery was only 13%. There was substantial immobilization of applied N at Ellerslie. With spring application, nesting overcame the large immobilization effect and produced normal recovery of applied N in the plants. Addition of straw resulted in more immobilization of applied urea N, particularly when urea was incorporated. The 15N recovery in plants plus soil of spring-applied N indicated N losses during the growing season and the losses were much greater at Ellerslie than at Rimbey. Key words: Band placement, fall application, immobilization of N, incorporation, 15N, N losses, nest placement, spring application

Description: The Ap horizons of two conservation tillage studies on Dark Brown Chernozemic soils in southern Alberta were sampled in 1986 following the fallow year. The first study, started in 1967, consisted of a wheat-fallow rotation under either no-till chemical fallow, blade-cultivate, or chemical fallow + blade-cultivate management. The second study, started in 1977, consisted of continuous winter wheat, winter wheat-barley-fallow, and winter wheat-fallow rotations under either no-till or conventional tillage management. Nine years of no-till continuous wheat and 19 yr of no-till in a wheat-fallow rotation both led to 40% of the dry aggregates being 〉 0.84 mm in diameter. The parameters selected helped to characterize differences in organic matter between soil tillage systems. Dehydrogenase and phosphatase activities were twice as high under no-till as under the blade-cultivate treatment. No-till also led to the largest monosaccharide accumulation in the soil. Carbohydrates, solvent-extractable organic matter, and chitin N were significantly higher in the 〉 0.84 mm diameter dry aggregates from the no-till treatment. The monosaccarides under the blade-cultivate regime were generally of microbial origin whereas those under the no-till regime were generally of plant origin. Key words: Water-stable aggregates, dry aggregates, enzyme activities, organic carbon, monosaccharides, fallow

Description: Linear equations were developed for converting electromagnetic induction readings (ECa) from EM38 meters to saturated paste electrical conductivity values (ECc). To correlate EM38 readings with measured ECe values, field sites representing a range of salinity conditions were sampled in 0.30-m increments to a depth of 1.5 m. Adapting a weighting procedure based on the EM38 meter's response to depth, ECe values were condensed into a single weighted value. The weighted ECe values were linearly correlated with temperature-corrected ECa readings. Equations were designed for soils of various textures under varying temperature and moisture conditions. For accurate ECa to ECe conversions, soil temperature correction of ECa is essential. When a frozen layer is present, EM38 readings are unreliable. EM38 horizontal and vertical modes show different ECa readings for the same depth-weighted ECe. Variability of ECa to ECe conversion was greater on coarse-textured than medium- or fine-textured soils. Available soil moisture should be above 30% for accurate ECe determinations from ECa readings. Key words: Salinity methods, soil salinity, saturated paste extract method, electromagnetic inductance meters, soil temperature

Description: A field experiment was conducted to examine the interaction of fertilizer placement and moisture level on barley (Hordeum vulgare 'Gait') utilization of urea-N during early growth. The 15N labelled urea (50 kg ha−1) was either deep-banded or broadcast-incorporated, and plant samples were taken from the two-leaf stage until anthesis, then again at maturity. Five moisture regimes were created using rain shelters, with 0, 10, 15, 20 and 25 mm water applied per week until anthesis. A natural precipitation treatment was also included. All barley plants were unsheltered from anthesis to maturity. Weekly fertilizer recoveries by the crop with no water additions were much less for broadcast-incorporated N than deep placement. The differences narrowed with increasing rates of water additions. Apparently, broadcast-incorporated fertilizer N remained in dry surface layers of the no-water treatment, and was positionally unavailable for absorption by the crop. Compared to deep-banded N, broadcast-incorporated N resulted in 37% less grain when drought stress occurred from seeding to anthesis. Broadcast-incorporated N was more susceptible to immobilization by the soil than was deep-banded N. Key words: Barley, drought stress, 15N-urea, fertilizer positional unavailability, N immobilization

Description: This research examined the effects of soil environment on the decomposition of cereal crop residues and stabilization of microbial products in the field. Microplots at semi-arid and subhumid field sites were amended with 14C-, 15N-labelled wheat straw and with 14C-labelled glucose plus 15N-labelled NH4NO3 and the fate of the residual C and N was monitored over 10 yr. Mineralization of C and N derived from wheat straw was greater at the site in the more moist environment in the short term (2 yr). In the long term (up to 10 yr), however, the residual C and N at this site decayed at a slightly slower rate, providing evidence of stabilization of organic material in chemically resistant forms, as compared to possible physical protection in the semi-arid clay-textured soil. The total recovery of labelled N was 22.5–24% in the harvested crops with 13.4–16% remaining in the surface soil by the end of the study. Mineralized labelled organic N was used with an efficiency ranging from 32 to 51%. However, after summer fallow the crop apparently used mineralized labelled N with an efficiency of only 7%. This study showed that moistness of the soil environment has a considerable effect on residue decomposition. Stabilization of humic material derived from residues relates more to the recalcitrance of microbial products and their interactions with soil mineral colloids than to the nature of the original residue. Key words: Mineralization rates, crop residues, microbial turnover, chemical recalcitrance, physical protection, plant N use-efficiency

Description: Sulfate sorption and desorption as a function of pH were measured for six podzolic horizons from two forested watersheds of the southern Laurentians. The results showed a rapid increase in sulfate sorption with decreasing pH to a maximum sorption capacity at pH values between 3.8 and 4.2 depending on the horizon considered. Below this pH retention decreased except for the Coniferous (Con) B horizon where sorption remained almost constant. This drop in the sorption capacity of the soils is related to the partial dissolution of Al, and possibly Fe, surface coatings. Levels of up to 15.9 mmol L−1 of total dissolved Al were measured at pH 3.0 for the Herminc (Her) B horizon. The amount of sorbed and total native sulfate and the maximum sorption during the experiment are positively correlated (R2 = 0.986, 0.982 and 0.800) with the oxalate extractable Al content of the soils. Except for the Con B horizon, amorphous plus crystalline Fe make up the bulk of the inorganic coatings in all six horizons. For the Con B horizon, which has the highest sorption capacity of the horizons tested, the composition of these coatings is dominated by Al materials. In all soils, the variations in sulfate sorption as a function of solution concentration are best described by the Gunary equation in the range of pH values tested. Key words: Sulfate, pH-dependent sorption, dissolution, Podzol

Description: The objective of this study was to compare the values, statistical characteristics and relationships of partition coefficients (Kd) computed from a short-term study of 54Mn sorption with those computed from DTPA extractions of soil Mn. Of particular interest were the frequency distributions, which must be very well known for use in stochastic modelling of environmental impacts. The study used 69 soils. Sorption of 54Mn, applied with stable 54Mn carrier, was measured after 24 h equilibration in suspension. The Kd for 54Mn was based on the single measurement of 54Mn in solution. Total soil Mn and DTPA + NaHCO3-extractable Mn were also measured and used to compute a Kd from two measurements. The frequency distributions of Kd values measured by either method were strongly skewed and conformed to lognormal, regardless of the statistical properties of the underlying measurements. The geometric mean Kd for 54Mn was 44 L kg−1 and was highest for high pH, high clay content and high organic matter content soils, as expected. The geometric mean Kd for DTPA-extractable Mn was 1070 L kg−1 and was not related in the same way to the soil properties. Clearly, the two Kd measurements were quite different. A significant correlation (r = 0.54, P 

Description: A tracer (15N) study using fallowed field microplots was conducted at Agassiz Research Station to examine the fate of applied N over an entire year. The tracer confirmed nontracer (difference between fertilized and control treatments) observations that applied N does not leach beyond the rooting zone (45 cm) during the growing season, despite the considerably more than average precipitation that occurred in July, but that all residual [Formula: see text] is leached over the winter. The tracer did, however, show that net immobilization of applied N occurred late in the fall resulting in 17% of the N recovered in the 75-cm profile 1 yr after application even though the nontracer method showed that none of the applied N remained. There was significant net mineralization of soil N over the summer (100 kg N ha−1 from early May to late August) and nitrification of the applied [Formula: see text] (120 kg ha−1) was essentially complete within 14 d of application. Tracer analyses suggested that 36% of the applied [Formula: see text] was immediately fixed by the clays but after 14 d in the field it decreased to less than 1%. The fixed [Formula: see text] remained at this level throughout the rest of the year. The apparent large decrease in fixed [Formula: see text] within the first 14 d may have been an analytical artifact which resulted when the initial soil was air dried. Negligible denitrification was observed during the growing season despite the soil remaining quite moist throughout most of the year. Delta 15N measurements of total N, fixed [Formula: see text] and extractable inorganic N fractions showed only enrichment of total N. The delta 15N results support the observation that denitrification tends to be low under Agassiz soil and weather conditions. Comparisons and contrasts to previously reported similar tracer studies in Ottawa were made. Key words: Leaching, clay fixation, N mineralization, N immobilization, nitrification, denitrification, delta 15N

Description: Ten soil properties, including texture, pH, available phosphorous, cation exchange capacity, exchangeable cations and organic carbon, were determined from the Ap horizons of 91 map units of two Montreal Lowlands counties. Multivariate analysis techniques were used to classify the soils into fertility groups. Nine fertility groups were derived from cluster analysis. Principal component analysis yielded two components which accounted for more that 75% of the variance. These principal components were related to soil texture and fertilizer management factors. They confirmed the grouping obtained by cluster analysis. Multiple discriminant analysis distinguished these fertility groups and allocated new soil mapping units to one of them using discriminant functions. Clay content, pH, exchangeable Ca and available P were selected as the more potent and significant variables in descriminating groups. This work demonstrated that multivariate analysis has considerable promise in deriving meaningful interpretive grouping from selected soil parameters. Key words: Fertility, interpretive grouping, soil quality, multivariate analysis

Description: Fertilizer P was applied annually (0, 15, 29 and 44 kg P ha−1 yr−1) for 26 yr to an acidic loam cropped to timothy (Phleum pratense L.). Some fertilizer P was translocated into the 30- to 45-cm depth of soil when 15 kg P ha−1 yr−1 was applied and into the 45- to 60-cm depth when 44 kg P ha−1 yr−1 was applied. The amount of P translocated increased with increasing rates of applied P. Key words: Fertilizer, phosphorus, leaching, translocation, movement

Description: Natural radionuclides of the uranium (U) and thorium (Th) decay series contribute to the radiation dose received by humans. In the context of U mining and refining, it is important to accurately assess the pathway for these radionuclides from soils to food plants. The Canadian Standards Association model of this pathway for dose estimation is based on the plant/soil concentration ratio (CR). In a controlled outdoor lysimeter setting, we measured CR values for experimentally applied U at 100 mg kg−1, 230Th at 8 kBq kg−1 and 210Pb (lead) at 20 kBq kg−1 using a sand, a loam, a clay and an organic soil in 12 soil and crop combinations. The overall geometric mean CR values were 0.013, 0.0022 and 0.0050 for U, 230Th and 210Pb, respectively. A second experiment using one soil and crop showed CR to be dependent on soil concentration for U, but not for Th and Pb. The final two experiments dealt with uptake of U, Th, Pb, Ra (radium), Cs (cesium), Po (polonium), and As (arsenic) from soils contaminated by a former Ra processing facility, both in a controlled lysimeter setting and in uncontrolled home-garden settings. The results generally agreed with those of the initial experiment, although the overall geometric mean CR for Th was higher at 0.02. Most of the recommended Th CR values for dose estimation are tenfold below those for U; our garden-setting results suggest they should be equal or higher. The effects on soil properties and crop type on CR values are discussed. Key words: Concentration ratio, uranium, thorium, lead

Description: Humic acid (HA) and alkali-insoluble residue fractions (Residue) were isolated from four types of peat from the Fraser River Delta area. The peat fractions were characterized with respect to sulphur forms and response to acid hydrolysis. Total S content of HA fractions ranged from 0.3 to 5.5% on an ash-free basis, with 69–83% in C-bonded S form. Nitrogen: sulphur ratios varied between 0.64 and 5.9. The highest S contents and lowest N:S ratios were associated with peats formed under the influence of brackish water. Similar patterns were observed for the Residue fractions. Only small proportions of S (7.9–17.3%) were recovered in soluble form from the peat fractions after acid hydrolysis, and hydrolysis was accompanied by S losses attributed to volatilization. On average 4% of the initial C-bonded S was recoverable in that form in the hydrolysates, whereas 46% of the initial organic sulphate appeared in the hydrolyzate in sulphate form. The low recovery of S in hydrolyzates indicated a correspondingly small contribution of S-amino acids to the C-bonded S fraction. The large proportions of sulphur and carbon resistant to hydrolysis indicated a rather high degree of chemical (and perhaps biological) stability. Key words: Sulphur forms, hydrolyzable-S, peat humic acid, gyttja, peat fractions

Description: Ground-penetrating radar (GPR) is a geophysical tool designed for subsurface probing of materials with contrasting dielectric properties. The applicability of this technique to locate agricultural drain tiles or tubes under some soil types and moisture conditions found in New Brunswick and Nova Scotia was evaluated. A method using GPR graphical outputs from adjacent, paired parallel traverses was developed to verify tile drain signatures. Over 50 drains, installed from 1 to 50 years ago, in soils developed in morainal till, glaciofluvial, and glaciomarine deposits were detected with the GPR system and confirmed by excavation. These included both clay and plastic drains. With experience, reliability was found to be close to 100%. The possibility of using the system for determining depth to the drain is also discussed briefly. Key words: Ground-penetrating radar, tube drain location, apparent dielectric constant, propagation time, electromagnetic wave, propagation velocity

Description: This study was conducted to compare the long-term (20 yr) effects of conventional tillage, minimum tillage and no-till on various soil-water related properties within the tilled layer (0–30 and 30–60 mm) and immediately below the tilled layer (90–120 mm) under a spring cereal-summerfallow rotation cropping system. Parameters measured included saturated hydraulic conductivity, saturation percentage, plant-available water-holding capacity, large pore porosity, bulk density, and infiltration rate of the soil. Tillage treatment effects on these soil properties in each of the four sampling periods were not significantly different. The confidence interval test showed some temporal changes in these soil physical properties, of which hydraulic conductivity was the most affected. In the summerfallow field, regardless of the previous cereal crops, the steady infiltration rate was significantly lower in the soil under conventional tillage than with that under no-till. The results indicate that the surface soil structure was most stable under no-till. In the fresh stubble field, the type of cereal crop had an effect on the infiltration rate of the soil. The mean infiltration rate was higher in the summerfallow field than in the fresh stubble field and also was higher in the fresh barley stubble than in the fresh wheat stubble. Except for infiltration rates, there is no significant advantage of one tillage method over the other with respect to the soil physical properties measured in this Brown Chernozemic clay loam soil. Key words: No-till, minimum tillage, hydraulic conductivity, bulk density, infiltration

Description: Long-term (8 yr) K+ fertilization experiments were started in 1983 on Jeddo clay loam, Smithville silt loam, Oneida loam, and Vineland sandy loam in the Niagara region of southern Ontario to study K+ exchange and fixation in relation to K+ uptake by grapes. Potassium fertilization at rates of 0, 100, 200, 400, and 600 kg K+ ha−1 was discontinued after 4 yr to record the build-up of soil K+ with fertilization and its decline after fertilization ceased. This paper reports the results on K+ exchange and fixation during the 4-yr K+ fertilization period. The clay mineralogy of the soils was similar with their clays containing mainly mica and smaller amounts of vermiculite, chlorite, quartz, and feldspars. There was a highly significant linear relationship between rates of applied K+ and K+ fractions of exchangeable cations for every soil in every year of K+ application. Exchangeable K+ concentrations in the coarse-textured Vineland soil increased sharply from the first to the second year of K+ application. However, there was no consistent increase of exchangeable K+ concentrations with time in the finer-textured soils for the first 2-4 years of K+ application. This was attributed mainly to K+ fixation. This interpretation was supported by chemical and X-ray evidence that showed reduced K+ fixation capacity and transformation of vermiculite to a mica-like mineral at the high rate of K+ application. Potassium exchange equilibria and standard Gibbs free energies for the exchange of (Ca2+ + Mg2+) by K+ were calculated using the theory of multiple ion exchange equilibria. Standard Gibbs free energy values for this exchange became more negative with increase in clay and vermiculite contents of the soils which was attributed to the strong adsorption of K+ in vermiculite and vermiculite-like minerals that were concentrated in the clay fraction. Clay content is therefore the dominant factor determining K+ exchangeability in the soils of the Niagara region of southern Ontario. Key words: soil mineralogy, vermiculite contents, potassium exchange equilibria, standard Gibbs free energy

Description: Air-drying decreased (〉 80%) microbial activity, microbial biomass carbon (MB-C) and sulfur (MB-S) levels of both native and cultivated soils. This resulted in a flush (~ 4 μg g−1) in the 0.01 M CaCl2 extractable SO4-S. Rewetting soils restored microbial activity and biomass contents to their original levels, but this led to immobilization of the SO4-S. Restoration of the MB-S levels was slower than MB-C levels. Thus, during drying and rewetting cycles, the MB-S pool acts as both a source and sink for the SO4-S pool in soil. Key words: Microbial activity, microbial biomass sulfur, extractable sulfate sulfur

Description: Impacts of silvicultural practices on soil structure were evaluated in hardwood plantations. On two different sites, four treatments (mechanical weed control, herbicide weed control, seeding of nitrogen-fixing companion species and a control) were undertaken, with and without earthworm introduction, according to a complete randomized block design. Treatments had significant effects on the water stability of soil aggregates, macroporosity and bulk density. Earthworm introduction significantly increased macroporosity in control plots while decreasing it in the three other treatments. Key words: Soil structure, silvicultural practices, earthworm, Lumbricus terrestris

Description: Rainfall simulation by sprinkler irrigation was used to evaluate the characteristics of sediment and runoff water from erosion plots on a Dark Brown Chernozemic soil near Lethbridge, Alberta. Replicated land treatments consisted of bare fallow, perennial alfalfa/wheat grass forage (Medicago sativa L./Agropyron riparium Scribn. & Smith) planted in rows parallel to the slope, barley (Hordeum vulgare L.) planted in rows parallel to the slope (barley-S) and barley on contour (barley-C). The eroded sediment from all four treatments was generally enriched in organic matter (OM), NH4-N, total N (TN), and PO4-P, but not in NO3-N or total P (TP). The sediment from the bare fallow treatment was enriched in silt-size particles and had the highest OM enrichment. Maximum NH4-N and TN enrichment occurred in the sediment from the barley-S treatment, and maximum PO4-P in that from the forage treatment. This selective removal of plant nutrients was attributed mainly to erosion processes and to cropping-induced differences in C:N:P ratios of organic complexes. The runoff water from all four treatments was enriched in NO3-N, TN, and PO4-P. For the three cropping treatments in this experiment, nutrient enrichment of the runoff water decreased from forage 〉 barley-S 〉 barley-C treatment. In general, more NO3-N was lost in the runoff water than in the sediment. Key words: Erosion, sediment quality, water quality, nutrient loss, nitrogen forms, phosphorus forms.

Description: Flax (Linum usitatissimum L.) was grown in two growth chamber experiments on a total of 16 Black Chernozemic soils varying in content of Mg, Ca, P, and Zn. On three of the soils, dry matter yield of flax increased in response to application of P. Phosphorus availability was greater with broadcast than with banded fertilizer applications. Increased yield in response to Zn application was observed on one-half of the soils. Applications of P that increased P level in the tissue above 0.46% led to consistent but nonsignificant decreases in yield and reduced the level of Zn in the tissue. Zinc fertilization increased Zn and decreased P level in the tissue. Yield response to P application was not strongly related to soil chemical parameters measured, but increased as tissue P level decreased and tissue Zn level increased. High levels of soil Mg and soil pH and high tissue levels of Mg and P were the factors most closely associated with a yield response to Zn applied with P. Key words: Flax, Linum usitatissimum, Ca, Zn, P, Mg, fertilizer placement

Description: Prairie farmers are interested in applying nitrogen (N) in the fall or winter to reduce fertilizer costs and allow a better distribution of labor and machinery use. Two studies were conducted in southwestern Saskatchewan to determine the consequences of applying N in late fall. In the laboratory, fertilizer N barely penetrated into the snow at constant subzero temperatures, but under freeze-thaw conditions, urea and ammonium nitrate descended 27 cm in 3 d. In the field, ammonium nitrate and urea were applied to snow-covered and bare microplots of grass sod and cereal stubble (1981–1982) and grass sod only (1985–1986). Nitrogen from ammonium nitrate penetrated deeper into the snow than N from urea. Nitrogen recovery in April 1982 was 55–59% from ammonium nitrate and 39–51% from urea, but was near 100% for both sources on bare soil treatments in April 1986. More N was recovered when fertilizer was applied to bare than to snow-covered soil, especially during 1985–1986 when all the applied fertilizer was blown off the snow-covered plots. Mineral N generally declined from fall to spring in all treatments, probably because of denitrification and immobilization. In 1985–1986, a period of extremely low temperatures in late fall resulted in no movement or transformation of N until after early December. By late January, periods of above-zero soil temperatures resulted in substantial mineralization of soil organic N, in the fertilized plots. This apparent priming effect was attributed to perturbations in the organic matter and microbial biomass due to fertilizer application and freezing and thawing. Following this period there was a general decrease in mineral N towards spring, as observed in 1981–1982. Producers must consider the benefits of using labor and equipment more efficiently and of lower fertilizer cost in the fall against the risk of large potential N losses over winter. Key words: Urea, ammonium nitrate, N recovery, frozen soils, fertilizing in winter

Description: Organic matter (OM) in the Bainsville and Melfort soils, and in coarse clay and medium silt fractions separated from these soils, was extracted under N2 with 0.5 M NaOH and unadjusted 0.1 M Na4P2O7 solutions. pH ranges of the soils and fractions in contact for 24 h with 0.5 M NaOH and 0.1 M Na4P2O7 solutions extended from 12.2 to 12.6 and 9.0 to 9.4, respectively. Slightly greater proportions of the soil-carbon were extracted by 0.5 M NaOH than by 0.1 M Na4P2O7 solution. The differences, however, did not appear to be significant and may vary from soil to soil. The efficiency of extraction and the characteristics of the extracted materials were assessed on humic acids (HAs), which were isolated from the extracts. From the Bainsville soil and fractions, 0.1 M Na4P2O7 solution extracted more high-molecular weight and more deeply colored HAs than did 0.5 M NaOH solution. But HAs extracted from the Melfort soil and fractions had similar molecular weights and colours. 13C NMR spectra showed that HAs extracted by 0.1 M Na4P2O7 solution tended to be more aromatic than HAs extracted by 0.5 M NaOH solution. Well defined solid-state 13C NMR spectra of HAs, containing up to 69.0% ash, could be recorded. Unadjusted 0.1 M Na4P2O7 solution under N2 was found to be an attractive alternative to 0.5 M NaOH solution as an extractant for soil OM. Key words: Humic acids, E4:E6 ratios, IR spectra, 13C NMR spectra, aromaticity

Description: The objective of this study was to determine the effect of adding either 0.001M EDTA or 0.005M DTPA on the amount of P removed from acid and calcareous soils by the Kelowna and 0.25M HO Ac extractants. These complexing agents were studied for possible simultaneous extraction and determination of available Zn. To achieve that end, P-concentrations removed by these solutions from a group of acid, calcareous, and combined soils were compared against reference values obtained with 0.5M NaHCO3 (Olsen et al.) and the Kelowna extractant (0.25M HOAc + 0.015M NH4F) by means of graphing, correlation and regression techniques. Of the 80 soils studied, 40 were acid with pH (H2O) values ranging from 4.2 to 6.9 and the remainder having higher values up to 9.3. Results indicated that additions of either 0.001M EDTA or 0.005M DTPA to the Kelowna solution increased average extracted P concentrations by about 20 and 60%, respectively. Values removed by either of the new KEDTA and KDTPA solutions were closely related to those extracted with 0.5M NaHCO3 and Kelowna solutions on acid and calcareous soils (r values ≥ 0.96**). As EDTA and DTPA increased extracted soil P, these were added at 0.001 and 0.005M as NH4 preparations to 0.25M HOAc (AADTPA & AAEDTA; without fluoride), respectively, for determining whether these complexing agents could supplant F for P extraction. These solutions removed proportionally related amounts (r ≈ 0.94**) of P from calcareous, compared to the Kelowna and 0.5M NaHCO3 solutions, but relationships were less precise for acid soils (r ≈ 0.76**). These results suggest that the AADTPA or AAEDTA solution should be evaluated further before adoption for routine P determination in multiple element extractions. Key words: Mehlich in, acid soils, calcareous soils

Description: A combination of field and laboratory procedures was used to estimate moisture-retention parameters of four coarse-textured soil series in southern Alberta. In situ field capacity moisture content was substantially higher than estimates based on conventional laboratory methods, resulting in significant underestimation of total available moisture. Moisture-retention capacity of all four soil series was found to be adequate for irrigation development. Empirical equations were developed to estimate the upper and lower limits of moisture retention on the basis of particle-size distribution, as determined by the Bouyoucos hydrometer method. Five alternative empirical methods were also evaluated for use in predicting moisture-retention parameters of coarse-textured soils. Equations presented by Rawls et al. (1982) were found to have the best relationship with southern Alberta data for both field capacity and wilting point. Key words: Coarse-textured soils, moisture-retention parameters, particle-size distribution, empirical models, irrigation suitability

Description: Application of N fertilizer in the fall as opposed to spring has been a controversial recommendation for cereal crops grown in Western Canada. Also, oilseed crops such as rapeseed may not respond to N in the same way as cereals. To investigate spring and fall application of N on barley and rapeseed, factorial split plot experiments were designed with three N treatments of 45, 90 and 134 kg N ha−1 and four P treatments of 0, 9.4, 18.8 and 28.2 kg P ha−1, as main plots. A control without fertilizer was included and the subplots were spring and fall times of broadcast application of ammonium nitrate fertilizer. Barley (Hordeum vulgare L.), cultivar Conquest and rapeseed (Brassica campestris L.) cultivar Arlo were seeded as the test crops over a 5-yr period and a 6-yr period, respectively, at separate sites on Melfort silty clay soil to determine the differences in yield and quality of grain between spring and fall applied N. In some years yield response to N fertilizer was greater when applied in the spring and in other years when applied in the fall, resulting in a significant time of N × year interaction effect on yield. However, on the average, there was no significant difference in yield of barley or rapeseed grain between fall and spring applied N, 3.51 vs. 3.59 and 1.39 vs. 1.41 t ha−1, respectively. Nitrogen and P fertilizer increased yield as much as 2.17 t of barley and 0.76 t of rapeseed ha−1 although the concentration of mineralized ammonium- and nitrate-N in the soil was rated medium according to provincial soil test standards. The difference in yield response of barley (Y, t ha−1) between spring and fall applied N among years was related to the rainfall (X, mm) in May by the equation:[Formula: see text]and for rapeseed:[Formula: see text]Because N was applied relatively late in the fall, the available soil N was medium and the conditions for N loss in these experiments minimal, differences in barley and rapeseed yield response to N fertilizer between spring and fall applied N were small. When P fertilizer was applied at a heavy rate, fall application of N produced a higher yield of rapeseed than spring application in all years. Key words: P, protein, rainfall, interaction, N, barley, rapeseed, time

Description: A greenhouse study was conducted on a fine sandy loam to determine the effect of adding different sources of Se on the Se concentration of forages and cereals. The three sources of Se were: NH4NO3 prills containing (i) 1.20% Se as sodium selenate, (ii) 1.02% Se as sodium selenite and (iii) urea prills containing 1.00% Se as sodium selenite. Application of 20 g Se ha−1 as sodium selenate (source i) produced Se concentrations of 1.02 and 1.05 mg kg−1 in timothy and 1.04 and 0.55 mg kg−1 in alfalfa in the two cuts, respectively, and 0.78 mg kg−1 in barley grain. This application rate of Se in the form of selenite resulted in 0.07–0.09 mg Se kg−1 in the two forages and barley grain. At similar application rates of Se, the ammonium nitrate doped with sodium selenate produced about 5–18 times more Se in the forages and barley than when doped with sodium selenite. Overall no significant difference was found in the plant Se concentration between ammonium nitrate or urea prills as the carrier for selenite. Key words: Sodium selenate and selenite doped NH4NO3, greenhouse, Se in forages and cereals

Description: In Kings County Nova Scotia, soils have developed over pre-Wisconsinan basaltic saprolite and basaltic and granitic till. The clay fraction of the soil developed on the saprolite is predominantly a trioctahedral smectite and apparently has not been significantly changed by post-Wisconsinan weathering. The clay fraction of the Aej horizon of the soil developed on granitic till is dominantly composed of dioctahedral layer silicates, mainly mica with some montmorillonite and vermiculite, and that developed on basaltic till by smectite and vermiculite. Key words: Basaltic saprolite, trioctahedral smectite, post-Wisconsinan weathering

Description: Recent work suggests that climate change will impact negatively on Canadian prairie wheat through more severe and frequent droughts and increased yield variability, and adaptive strategies have been called for to meet the coming change. However, previous studies have not determined if climate change has already affected wheat yields, nor has the entire prairie region been examined. Using a prairie wheat yield simulation model (PWYSM) at current (constant) technology, it is shown that the weather as it affects wheat, has had a zero trend over the 1900–1988 period. Also, there is no evidence that yield variability has recently increased. Prairie wheat yields therefore appear so far unconnected to the global warming trend this century, suggesting no current need to adapt to a changing climatic regime. Results also show that, at current technology, departures from mean weather may cause decade-long average yield fluctuations as large as ± 10% from the long-term mean, and climate change effects must be detected against this background fluctuation. Also, a 35% decline in actual wheat yields from the first to fourth decades of this century was not matched by deteriorating weather although weather contributed to the decline, and improved yields since 1940 are not explained by better weather. The study of Williams et al. (1988) concluded that a 1930s type dry spell would reduce Saskatchewan wheat yield by 20%, compared to the 1961–1979 mean That applied only to stubble-sown wheat. When adjusted here for the contribution of fallow-sown wheat, the reduction became 16.7%. With Alberta and Manitoba included, the yield reduction for the whole prairie became 13.8% — in good agreement with a 14.0% reduction obtained with the PWYSM. Yield reductions for Saskatchewan are larger than for the prairie as a whole. The reference period chosen also significantly affects findings, and, because the last decade has been relatively unfavourable, PWYSM results show that 1930s type weather would lower mean prairie wheat yield by only 11.0% relative to the 1979–1988 mean. Grain industry decision makers would more likely refer to the last decade than to a more distant period such as 1961–1979, and applying relative yield reductions to the 1979–1988 mean would result in substantial yield underestimates for drought scenarios. Reference periods must be carefully selected for consistent results. Key words: Climate change, wheat yield

Description: The percentage of soil material 〉 0.84 mm obtained by dry sieving is commonly used as an index of the wind erodibility of soils. Present sieving procedures do not account for the breakdown of friable aggregates during sieving so that results do not necessarily represent aggregation in the original sample. An equation was fitted to soil sieving data from a modified rapid rotary sieve. It successfully evaluated aggregate attrition during sieving for 397 out of 404 samples representing a wide variety of textures. Good reproducibility of results using the methodology was obtained for 45 paired soil samples. Results obtained employing the new method will relate more closely to field conditions allowing a better estimate of soil erodibility. Key words: Wind erosion, aggregate breakdown, sieving, soil erodibility, modified rapid rotary sieve

Description: Sieve loading in a modified rapid rotary sieve (MRRS) was investigated and data from the MRRS and a rotary sieve were compared; 1.5–2 kg sieve loadings gave the best precision. Correlation between the rotary sieve and the MRRS was 0.63; it improved to 0.79 when aggregate comminution in the MRRS was considered. Key words: Wind erosion, aggregate breakdown, sieving, modified rapid rotary sieve

Description: For 9 yr, subsurface return flow measurements from irrigated lysimeters containing "Macspur McIntosh" apple trees (Malus domestica Borkh.) on MM 111 rootstocks were collected. Water use with and without a grass cover crop was calculated as irrigation plus summer precipitation minus drainage. Drainages were consistently and significantly lower, and therefore water use higher, under grass than under bare soil but the differences were not large. The times of irrigation and drainage events were not closely linked. Drainage followed irrigation anywhere from a day to many days, stretching at times into weeks or months. By far the largest drainages, however, occurred during the irrigation season. Irrigation amounts provided most of the water for return flows with summer or winter precipitation contributing little to the drainage. At the higher irrigation levels the return flow quantities and calculated water use quantities clearly indicate that sprinkler design flow quantities are too high for the area and that improvements in irrigation efficiencies are possible. Key words: Drainage, irrigation, lysimeters, water use, apple trees

Description: A calcium-bound phosphate (PCa) chronofunction from a Vancouver Island soil chronosequence was compared mathematically with a chronofunction produced by leaching parent materials from the soil chronosequence with 0.3 M acetic acid for up to 24 wk in modified soxhlet extractors. The equivalent of approximately 13 yr of PCa weathering in the surface 10 cm of the chronosequence soils was achieved by one week of leaching in the soxhlets. After 24 wk of soxhlet leaching, the parent material samples lost approximately 20% of their original 220 g weight and resembled Ae horizon samples from the soil chronosequence. Equations derived from the change in elemental composition of the soxhlet-leached parent material samples were used with the elemental composition of the top 10 cm of the youngest soil (127 yr) in the chronosequence to predict the elemental composition of the top 10 cm of the oldest soil in the chronosequence (550 yr). The predictive equations were useful for elements such as Ca, Na, K, Al, Si and PCa, whereas the amount of Mg and Fe remaining in the soil chronosequence was overestimated, due to the inability of the acetic acid solution to attack ferro-magnesian minerals. An equation relating the weight of soil residues to soxhlet leaching time predicted that the chronosequence soils would experience a lowering landscape rate of 0.05 mm yr−1. The soxhlet leaching and field-time calibration technique described is considered by the authors to be useful for other applications, such as predicting loss of soil buffering constituents due to acid rain or predicting rates of release of elements from contaminated soils. Key words: Soil chronofunctions, soil chronosequence, soxhlet weathering, leaching

Description: Podzols formed in high-rainfall areas of south coastal B.C. often have layers of highly organic material at depth in the profile, and in many cases, “pipes” of similar material angling down through the profile. These materials have a greasy feel, few discernible mineral grains, occasional remnants of wood structure and a cellular nature. The horizontal layers, termed "root mats", range in thickness from 1 cm to 〉 30 cm, and are overlain by coarse-textured material of low organic matter content. Chemically this material is similar to surficial H horizons with respect to C:N and N:S ratios, but closely resembles Podzolic B horizons with respect to Fe content and humus fraction ratios. In contrast oxalate-extractable Al values are remarkably high, sometimes exceeding 10%. The majority of the root mats can be classified as organic (〉 17% organic C), either as H or O horizons. Those containing 〈 17% C meet the criteria for Bhf horizons. Key words: Root mat, root channel, oxalate-extractable Al, organic horizons

Description: We collected forest floor organic matter at two sites where exclosures had been established 12 years previously. The exclosures allowed examination of the effects of moose (Alcesalces) herbivory on the growth of balsam fir (Abiesbalsamea). The areas supported an understory with Kalmiaangustifolia, which has been shown to affect seedling growth of black spruce (Piceamariana). Balsam fir seedlings grown in the laboratory in soil from outside the exclosures showed a significant reduction in fresh weight of the primary root compared with plants grown in washed sand. Treatment soils also showed a previously known growth inhibition effect on roots of black spruce. Exclusion of moose browsing resulted in a higher density of balsam fir inside the exclosures, while Kalmia, which was not browsed, was more dense outside the exclosures. We postulate that moose browsing reduces the extent to which balsam fir shades Kalmia, and can result in a higher density of the latter species, with consequent inhibitory effects on regenerating coniferous species.

Description: The morphological and physiological response to water stress was studied in 2-year-old potted Italian alder (Alnuscordata Loisel.) seedlings. Leaf area, transpiration, stomatal conductance, and xylem water potential were measured during May 1987 on seedlings from five geographic sources grown (i) with soil water content close to field capacity and (ii) with a severe drought. Significant differences in leaf area were found, at the end of the experiment, between drought-stressed and well-watered plants. As drought progressed, plants displayed a reduction of xylem water potentials and a decrease in stomatal conductance. However, transpiration did not stop completely, and seedlings were not able to maintain a favourable internal water status. Osmotic potentials for the undiluted cell sap, estimated from pressure–volume curves, were between −0.9 and −1.3 MPa. In June 1988, a similar experiment was carried out using seedlings from only one geographic source. A simultaneous decrease of transpiration, xylem potential, and net photosynthesis was observed in seedlings subjected to the drought treatment. During both experiments, a recovery of physiological parameters was observed, after rewatering. Some differences between provenances were detected. The provenance from Corsica showed the greatest sensitivity to water stress; a seed source from the province of Avellino (Campania, south Italy) was able to maintain a more favourable internal water status, as drought progressed.

Description: This report describes the growth and wood density response of a coastal Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand on a poor site to thinning and nitrogen fertilization. The treatment plots were established in 1971 and 1972 at about 24 years of age. The effects of fertilization and thinning were evaluated 12 and 13 years after the initial treatments of the 1972 and 1971 plots, respectively, and 3 years after refertilization of the 1972 plots in 1981. Ring-width and ring-density data were obtained from pith to bark for all trees and were derived from computerized X-ray densitometry. Fertilization reduced ring density at breast height and 25% stem height by an average of 16% for a 3- to 4-year period after treatment, but not thereafter. Reductions in ring density resulted from decreases in the density of early wood and latewood, as well as from decreases in the percent of latewood. Effects were only pronounced in the lower half of the stem. Thinning resulted in a slight ring-density gain in the lower bole and a reduction in the top. The combined treatments had an intermediate effect on ring density. Ring density showed an increasing trend from pith to bark at all heights, except at the 75% height, and a decrease with increasing height in the bole. Fertilization and thinning both increased diameter growth, and their beneficial effects were still evident 13 years after treatments.

Description: In the rain shadow of the Andes in northern Patagonia, the evergreen beech Nothofagusdombeyi occurs in mixed stands with the xeric trees Austrocedruschilensis and (or) Nothofagusantarctica. In two old-growth stands (〉150 years old), size and age structures, treefall patterns, and regeneration responses to treefalls were examined. In the stand codominated by N. dombeyi and Austrocedrus, recruitment of both species occurs in small treefall gaps. The relative proportions of treefalls and potential successors in gaps imply that gap-phase regeneration is maintaining this stand in compositional equilibrium. In the second stand, N. antarctica was formerly a common canopy tree, but currently is not regenerating in treefall gaps; gaps are occupied instead by N. dombeyi. The successful regeneration of N. dombeyi in small treefall gaps in Patagonian forests contrasts with the dependence of this species on large-scale exogenous disturbance for its regeneration in lowland and montane Chilean rain forests. Small-scale gap-phase regeneration of N. dombeyi in Patagonian forests is successful because of (i) the lack of competing shade-tolerant tree species and (ii) the inability of understory bamboos to form dence understories in these relatively xeric habitats.

Description: A black and white video camera and an image analyzer were used to measure the length of oak roots from which soil had been washed. The image analyzer is an automated intersect counter which uses the same basis for length estimation as the modified line intersect method. The roots were arranged within a 13.5 × 19 cm rectangle on clear plastic sheets and photocopied (dry process), then the lengths of the photocopied root images were measured with the video system. Two measurements were made on each photocopy, with a 90° rotation of the photocopy made between the two measurements. The two measurements were summed to obtain an index of root length. The automated system tested had insufficient resolution to detect very fine roots (

Description: Concentrations of up to 14 elements were determined from increment cores by proton-induced X-ray emission for dated series of annual rings of plantation Liriodendrontulipifera L. All trees were treated in 1965 with 841, 224, and 280 kg/ha of elemental N, P, K, respectively, and with either 0, 1683, or 3366 kg/ha of elemental Ca applied as pulverized agricultural limestone. Intraring elemental concentrations were not significantly different between earlywood and late-wood. Statistical variability of proton-induced X-ray emission elemental determinations was greatest for Al, Si, Cl, Cu, and Zn; concentrations of P, K, Ca, Mn, and Sr were least variable. Estimated standard errors among cores within trees averaged less than those among trees on a uniform site. Element mobility was tested in xylem core samples taken in 1965 and 1986. Liming significantly increased P, S, K, Ca, and Zn and decreased Mn in pre-1965 xylem. Retroactive liming effects were not detected for Mg, Al, Fe, Sr, or Ba; liming responses of Si, Cl, and Cu were unclear. Significant differences in elemental concentration independent of liming were detected between the 1965 and 1986 sampling times for P, K, Ca, Mn, Zn, Sr, and Ba. Of these, differences in P, K, and Mn may be due largely to heartwood formation between sampling times. Exchangeable Ca and Mg, followed by pH, were the most important soil variables in significant regressions with xylem elemental concentrations; only weak relationships were found with foliar elemental concentrations. Concentrations of Al, Si, Fe, and Cu in L. tulipifera xylem could be useful biomonitors of soil chemical changes by virtue of their apparent immobility; other elements, particularly S and Sr, may also be useful. However, expected time trends, especially as they pertain to heartwood formation, should be taken into account for each element.

Description: Additions of 15N-labelled ammonium chloride were used to examine the role of microbial immobilization in long-term growth response of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantations to nitrogen fertilization. Soil samples were collected in the summer of 1986 from fertilized (448 or 470 kg N/ha) and nonfertilized plots at previously established N fertilization experiments near Shawnigan Lake, British Columbia, and the Wind River Experimental Forest near Carson, Washington. Douglas-fir on these sites were reported to still be responding to N fertilization after 12 and 18 years. Less than 2% of the added 15N was recovered as mineral N after a 14-day laboratory incubation of soil samples from the fertilized and nonfertilized plots. This indicates that gross mineralization could be over 50 times greater than net mineralization in these infertile soils if the remaining 98% of the added 15N was all biologically immobilized. Net mineralization was significantly greater (p ≤ 0.10) in soils from the fertilized plots than in those from the non-fertilized plots at the Wind River site. Though the current differences in N availability did not appear to be related to differences in microbial immobilization, such large rates of immobilization warrant closer scrutiny as a factor in long-term response to fertilization.

Description: Rooting percentage and root number in tissue-cultured Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) were influenced by the rooting substrate, the concentration of sucrose and boron in the rooting medium, shoot height, and shoot generation. Peat–perlite was a better substrate than agar, producing 70% compared with 0% rooted shoots, respectively. On peat–perlite, cell divisions were organized and were associated with tracheid nests, whereas on agar proliferation was unorganized and not restricted to the nests. A sucrose concentration of 4% was optimal for the production of nodular or rooted shoots. At 4% sucrose and 3 mg •L−1 boric acid, 100% of the shoots rooted, and the mean root number was 11. Rooting percentage and root number were significantly higher with shoots that were 3 cm tall than 2 or 1 cm tall shoots. Finally, it was found that shoot responses were more rapid in third and fourth generation shoots than in second generation shoots. At least 80% were rooted or nodular after 4 weeks, compared with only 36% from the second generation.

Description: Vitrification rates obtained from our inverted embryo system were significantly decreased by lowering the cytokinin concentrations in Brown and Lawrence medium containing 10 mM L-glutamine from 10 to 1 mg/L, or by replacing 10 mM L-glutamine with equimolar concentrations of Ca(NO3)2 or by adding 1 g/L Gelrite to the normal 10 g/L Difco–Bacto agar in the culture media. In all treatments, decreased vitrification was accompanied with decreased adventitious bud production. With reduced N6-benzylaminopurine, vitrification decreased from 77 to 29%, but bud production decreased from 61 to 17 buds per explant and mortality increased from 3 to 33%. Incorporation of Ca(NO3)2 into the media decreased vitrification from 87 to 21%, but the number of adventitious buds per embryo decreased from 75 to 42. Vitreous shoots were reverted to normal development with an 81% reversion frequency and a 6% mortality rate by culturing these shoots on Gresshof and Doy medium with one-half total nitrogen. Elongation of previously vitreous shoots was best when these shoots were cultured on Gresshof and Doy medium + 0.5 mg/L N6-benzylaminopurine for 2 weeks, followed by subculture on Gresshof of and Doy medium + 10 g/L charcoal.

Description: The potential allelopathic (phytotoxic or beneficial) effect of barley, oat, and wheat straw mulches was evaluated on growth, mineral nutrition, and mycorrhizal status of black spruce seedlings, under greenhouse conditions. The various straws did not affect spruce seedling height growth over a 2-month growth period. The newly formed fine roots of treated and control seedlings were mycorrhizal. Oat and wheat straw significantly enhanced foliar phosphorus content, as compared with the control. All treatments significantly depressed foliar manganese content, indicating that the straws could exert a detrimental effect on manganese uptake. Therefore, it is suggested that monitoring the status of manganese in planted spruce seedlings when using allelopathic cover straw mulches be used as a method for preventing the establishment of weed species.

Description: Two isolates of the pinewood nematode, Bursaphelenchusxylophilus (Steiner and Buhrer), from Canada (an r form from Ontario and an m form from Quebec) and one from Japan (an r form) were inoculated into Scots pine, Pinussylvestris L., western larch, Larixoccidentalis Nutt., and black spruce, Piceamariana (Mill.) B.S.P. to determine the pathogenicity of this nematode and to observe changes in its numbers as well as the effect it had on seedling water and tannin content. Attractiveness of water, ethyl ether, and ethyl acetate stem extracts of these conifers to the pinewood nematode was also determined. The r form of the pinewood nematode was pathogenic on all three conifers: the Japanese isolate killed more Scots pine and the Ontario isolate, more black spruce. The Quebec isolate was as pathogenic as the other two isolates to western larch, weakly pathogenic to black spruce, and nonpathogenic to Scots pine. In general, there was a positive relationship between nematode population buildup and seedling mortality. No clear relationship was found between the water content of seedling stems and changes in nematode populations. Tannin content of stems increased following inoculation with pinewood nematode, but whereas correlation values between tannin content and nematode numbers were positive and significant, they were small. Although all three isolates were attracted to all host extracts, regardless of solvent used, ethyl acetate extracts were generally more attractive. The Japanese and Ontario isolates, which originated from pines, showed no particular affinity for Scots pine extracts; however, the Ontario isolate, which was especially attracted to black spruce extracts, was also most pathogenic to black spruce.

Description: Gaseous nitrogen inputs due to asymbiotic nitrogen fixation and outputs due to biological denitrification were estimated for a mature mid-successional Pseudotsugamenziesii (Mirb.) Franco–Thujaplicata Donn–Tsugaheterophylla (Raf.) Sarg. forest in southwestern British Columbia. Forest floor material, mineral soil, decaying wood, foliage, and bark were incubated in an atmosphere of 10 kPa C2H2 to allow the simultaneous measurement of N2O production by denitrifying bacteria and C2H2 reduction by free-living bacteria and blue-green algae. Forest floor material accounted for 70% of an estimated total annual nitrogen fixation of 0.3 kg N•ha−1•year −1.•Relatively small amounts of nitrogen were fixed in mineral soil, decaying wood, and foliage, and no indication of nitrogen fixation activity in bark was detected. Some denitrification was found; it was essentially negligible, although possibly underestimated. The net gaseous nitrogen input into the mid-successional forests of the study area is likely to be