ALBERT

Description: A nonlinear analytical model is developed to describe the relationship between average plant size (weight or volume) and stand density in single-aged, monospecific plant populations. The model gives estimates of the slope and intercept of the −3/2 power rule asymptote, the nature of the size–density trajectory, and such features as relative density at crown closure and the effects of soil type or site index. The model is tested by growing red alder (Alnusrubra Bong.) seedlings under greenhouse and lath house conditions at three initial spacings (8 × 8, 4 × 4, and 2 × 2 cm) and two soil types (river loam and alder forest soil) for 525 growth days. There are seven harvests, starting at crown closure. All size–density trajectories tend consistently towards the same single asymptote irrespective of initial spacing, soil type, or age. The asymptote slope and intercept are 1.46 and ca. 94 kg tree−1•m−2. The crown closure line is parallel to the asymptote at a relative density of 4.6 × 10−3. The model also adequately describes the size–density trajectories for 20–50-year-old red pines (Pinusresinosa Ait.) growing at six initial spacings. The asymptote slope and intercept are 1.6 and ca. 87 × 103 m3•tree−1•ha−1, respectively.

Description: Reduced levels of root activity were associated with winter injury to shoots of 1-year-old black spruce (Piceamariana (Mill.) B.S.P.) container seedlings.

Description: Three methods were compared for total sulphur analysis of tree foliage: magnesium nitrate ashing followed by turbidimetry, sodium hypobromite (NaOBr) oxidation followed by colorimetry, and an instrumental method using the Fisher S analyser, model 475. The latter method was found to be substantially better than the other methods with respect to accuracy and speed of analysis, and of satisfactory precision (average coefficient of variation (CV) was 2.5%). Dry ashing resulted in good precision (CV = 1.9%) but only recovered 76% of the reported total S in the United States National Bureau of Standards (NBS) orchard leaf standard. The NaOBr method recovered 88% of reported S from the NBS standard but showed poorer precision (CV = 4.5%). The Fisher analyser had the lowest operating cost per sample, largely owing to lower labour costs.

Description: The effects of fertilization and thinning of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) on the distribution of area increment along the bole were assessed using radial growth measurements 6 and 9 years after treatment. Within treatments, the average area increment per tree was linearly related to diameter at breast height, and this relationship was used to evaluate the effects of treatment on growth rate. Fertilization had the greatest effect on average area increment, and for a particular fertilization regime, thinning increased the response. Thinning modified the distribution of growth over the bole of all trees and increased butt flare, especially in smaller trees. The effect declined from the 4- to 6-year measurement period to the 7-to 9-year measurement period. Fertilization had no consistent effect on growth distribution. The regression methods used in this study provided a more sensitive measure of form changes than previous methods, were independent of size distribution, and facilitated extrapolations and evaluation of temporal trend.

Description: Organic content of the forest floor decreases for several years after clear-cutting, and then slowly recovers. Thickness, bulk density, organic matter, and nitrogen content of forest floors were measured for 13 northern hardwood stands in the White Mountains of New Hampshire. Stands ranged from 1 to about 100 years in age. Forest-floor thickness varied significantly with stand age, but bulk density, organic fraction, and nitrogen fraction were independent of age. Total organic content of the forest floor agreed very well with data from Covington's (W. W. Covington 1981. Ecology, 62: 41–48) study of the same area. Both studies indicated that mature forest floors have about 80 Mg organic matter•ha−1 and 1.9 Mg nitrogen•ha−1. Within 10 or 15 years after cutting, the organic matter content of the floor decreases to 50 Mg•ha−1, and its nitrogen content to 1.1 Mg•ha−1. The question whether the decrease is rapid and the minimum broad and flat, or if the decrease is gradual and the minimum sharp, cannot be answered. The subsequent increase to levels reached in mature forest requires about 50 years. Some of the initial decrease in organic matter and nitrogen content of the forest floor may be caused by organic decomposition and nitrogen leaching, but mechanical and chemical mixing of floor into mineral soil, during and after the harvest operation, may also be important. The difference is vital with respect to maintenance of long-term productivity.

Description: Straw was added over snow to smother ground vegetation (straw experiment) in sample plots in a 45-year-old jack pine (Pinusbanksiana Lamb.) stand in Quebec. Sample plots in the same stand were fertilized six times with N, P, and K in a 10-year period to maintain four foliar N regimes (optimum nutrition experiment). Smothering of ground vegetation with straw improved N nutrition and produced a sustained increase in tree growth. Sustained growth increases were obtained by repeated applications of 56 kg N/ha associated with 1.4% N foliar concentrations in current foliage. Gross volume increments of about 3 m3 • ha−1 • year−1 were sustained with these low applications. Repeated heavy N applications killed trees and reduced growth. Repeated additions of P and K with N did not produce appreciable differences in response from additions of N alone. Increment cores showed the annual development in growth as increasing over most of the 10-year period for low repeated N additions, and as increased and stable over the same period for the straw addition.

Description: In 4 different years' experiments with loblolly (Pinustaeda L.), slash (Pinuselliottiielliottii Engelm.), and longleaf (Pinuspalustris Mill.) pine, timing of gibberellin A4/7 (GA4/7) treatments was critical for optimal promotion of pollen conebuds. Two or three biweekly treatments given at strategic times were equivalent to six given from May to August. July to August applications best promoted pollen conebuds. Using the cationic surfactant Aromox C/12, aqueous foliar sprays of 200 mg/L of GA4/7 were more effective than ethanolic topical bud treatments for pollen conebud induction in slash pine. Addition of naphthaleneacetic acid enhanced the GA4/7 effect in loblolly pine but diminished it in slash and longleaf pine.

Description: Root and shoot biomass and mycorrhizal development were examined for white spruce (Piceaglauca (Moench) Voss) seedlings naturally regenerating in four floodplain communities in the boreal forest. Mean seedling biomass was highest in the open community and lowest in the spruce community. Seedlings growing in the open community had higher root:shoot ratios (0.50) compared with seedlings growing in the willow (0.34), alder (0.20), and spruce (0.24) communities. Essentially all short roots of spruce seedlings growing in all four communities were infected by mycorrhizal fungi throughout the growing season.

Description: Growth response of young, spaced balsam fir (Abiesbalsamea (L.) Mill.) to 3 successive years (1979–1981) of treatment with Bacillusthuringiensis Berliner for spruce budworm (Choristoneurafumiferana (Clem.)) control was examined in 20 plots on the Cape Breton Highlands, Nova Scotia. Defoliation commenced in 1976, 3 years before control operations began. Five plots were established both inside and outside the spray block, in areas that had been severely defoliated by budworm and in areas moderately defoliated. All plots in the severely defoliated area suffered heavy tree mortality, but mortality was significantly lower in the protected plots. In contrast, the moderately defoliated plots suffered virtually no tree mortality. The average volume increment of stem-analyzed trees from 1979 to 1981 was 0.63 dm3/tree for protected and 0.43 dm3/tree for unprotected trees in the severely defoliated area versus 4.15 dm3/tree for protected and 3.08 dm3/tree for unprotected trees in the moderately defoliated area. These volume increment values are equivalent to 8.8 m3/ha of growth between 1979 and 1981 for protected plots in the moderately defoliated area, compared with 6.1 m3/ha for unprotected plots. Therefore, a total gain of 2.7 m3/ha can be attributed to the 3 years of B. thuringiensis spraying. Long-term growth responses toB. thuringiensis spraying were not evaluated. Better results would be expected had protection started at the beginning of the budworm outbreak, instead of after 3 years of severe defoliation.

Description: Black alder, Alnusglutinosa (L.) Gaertn., seedlings were grown and kept well watered for 10 weeks, and then subjected to moisture stress conditioning for 5 subsequent weeks, where one-half of the seedlings were watered only when visibly wilted. The remaining seedlings (controls) were kept well watered. Moisture stress conditioning greatly reduced shoot, root, nodule, and total plant dry weight. The root–shoot ratio (grams/grams) of seedlings was significantly increased from 0.28 in the control seedlings to 0.33 in the water-stressed treatment. Acetylene reduction rates decreased only slightly in the range of water potentials between −0.50 and −1.29 MPa, then dropped rapidly below water potentials of −1.30 MPa. Moisture stress conditioning had no significant influence on this response. Although not significantly different, leaf and nodule osmotic potentials were consistently lower in the water-stressed plants.

Description: The relationships between foliage area and sapwood area between trees and within the crowns of 20 Piceasitchensis (Bong.) Carr., provenance Queen Charlotte Island, British Columbia (10 in a control plot and 10 in a plot fertilized with potassium and phosphorus 8 years before harvest) and 10 Pinuscontorta Dougl., provenance Ladysmith trees were examined using a physiological analysis based on Darcy's law. Foliage area index on the fertilized P. sitchensis plot was higher than on the control. The variation of foliage area density with depth in the canopies followed a normal distribution. Relationships between foliage area and sapwood basal area were linear but the slopes were different for the two species. There was no significant difference between the control and fertilized P. sitchensis trees. The relationship between foliage area and the product of sapwood area and permeability was linear and data from the three plots fell on the same line. Sapwood area, permeability, and their product decreased with depth through the crowns of the trees. Within the crowns, relationships between cumulative foliage area and sapwood area, and between cumulative foliage area and the product of sapwood area × permeability were different with species and treatment. A single linear relationship resulted when the product of cumulative foliage area above an internode × the internode length was plotted against sapwood area × permeability for the internode. This suggests that it is the drop in potential across a node and internode rather than the gradient of potential across the internode that is related to the flux of water through tree crowns. The data support the hypothesis that the relationship between foliage area and sapwood area depends on permeability of the sapwood and the local climate through its influence on transpiration rate, particularly via average water vapour pressure deficit of the air and stomatal conductance.

Description: Mathematical growth analysis techniques were used to assess the effects of atmospheric carbon dioxide enrichment on growth and biomass partitioning of Liquidambarstyraciflua L. (sweetgum) and Pinustaeda L. (loblolly pine) seedlings. Plants were grown from seed under high (1000 μmol•m−2•s−1) and low (250 μmol•m−2•s−1) photosynthetic photon flux density at CO2 concentrations of 350, 675, and 1000 μL•L−1 for 84 or 112–113 days. Elevated atmospheric CO2 concentration significantly increased height, leaf area, basal stem diameter, and total dry weight of sweetgum seedlings grown under high irradiance and to a lesser extent under low irradiance. Increases in dry matter accumulation were associated with early CO2 enhancement of net assimilation rate, but increases in amount of leaf surface area contributed more towards maintenance of larger size as seedlings aged. For sweetgum seedlings in particular, reduction of growth by low irradiance under normal atmospheric CO2 was compensated for by growing plants with elevated CO2. In contrast, elevated CO2 concentration produced no significant increase in growth of loblolly pine seedlings.

Description: Stomatal conductance was measured with porometers in two plots of Pinussylvestris L. with markedly different tree spacings (plot 1, 608 stems ha−1; plot 2, 3281 stems ha−1), and hourly rates of transpiration were calculated using the Penman–Monteith equation at intervals throughout one growing season. Stomatal conductance varied little in relation to height or age of foliage. There was a linear decrease in canopy conductance with increasing water vapour pressure deficit of the air. Transpiration rates on both plots increased during the summer (maximum 0.3 mm h−1); rates on plot 1 were always lower (ca. 0.7 times) than on plot 2. Needle water potentials were similar throughout the season and only slightly lower on plot 1 than on plot 2. The mean hydraulic resistance of the trees on plot 1 was 2.4 times that on plot 2. The results support a hypothesis that considers the changes in transpiration rate, conducting cross-sectional area, canopy leaf area, water potential, and hydraulic resistance following thinning as a set of homeostatic relationships.

Description: There is a need to provide quantitative relationships that will allow agronomists to estimate accurately the nitrogen-supplying power of soils while taking into account both temperature and soil moisture variations. The procedure for estimating net nitrogen mineralization proposed by Stanford and co-workers was used to determine Arrhenius relationships between the rate constants (k) and absolute temperature (°K) for 33 virgin and cultivated Western Canadian prairie surface (0–15 cm) soils. There was no significant difference in Arrhenius relationship between soils within each soil zone; thus, a single average Arrhenius equation was calculated per soil zone. Average Q10 for the Brown chernozemic soils was 2.75, for the Dark Brown, thin Black and thick Black chernozems, 2.18, and for the Gray luvisols, 2.0. These Q10 values are as high or higher than those reported in other parts of the world and may be related to the degree of degradation of the soil organic matter in these various soils. Culture had no marked effect on Q10 but sandy soils had higher Q10 than loams and clays. An equation for estimating net nitrogen mineralization for the Wood Mountain loam (a Brown chernozem) was tested using data from a previous study. The results were quite satisfactory, especially when the test data were derived under laboratory conditions where moisture was well controlled. The temperature functions presented herein can be used together with moisture functions and potentially mineralizable nitrogen results published earlier to make first estimates of net nitrogen mineralized during the growing season in the soils tested. Key words: Q10, Arrhenius relationship, potentially mineralizable nitrogen

Description: Potassium deficiency in grapes, as well as in other fruit crops grown on soils in the Niagara peninsula, is a common and often serious problem. Ap horizon samples from 12 of these soils and grape petiole samples from nine of the soil locations were analyzed to elucidate the behavior of the soil K and its availability to grapes. The soils ranged in texture from sandy loam to silty clay and their clay mineralogy was relatively uniform with mica as the main layer silicate. Vermiculite was quantified by potential K fixation methods and was concentrated in the clay. Up to 5.8% vermiculite was present in the soils which seemed to be sufficient to reduce K availability by K fixation. Amounts of exchangeable K extracted with NaCl or NH4Cl were relatively high (0.46–2.09 meq/100 g) but were not correlated with K uptake by grapes. Energies of K exchange obtained from immiscibly displaced soil solutions were closely related to vermiculite contents and amounts of K fixed after air drying. Energies of K exchange and ratios of exchangeable K over exchangeable Ca + Mg were highly correlated with K uptake by grapes. Soils with energies of K exchange less than or equal to −2800 cal/equiv. or K exch./(Ca + Mg) exch. equal to or more than 7% appeared to have adequate amounts of available K for grapes. These two analyses therefore show promise for predicting K availability to grapes. Key words: Exchangeability of K, energy of K exchange, fixation of K, soil mineralogy, availability of K to grapes

Description: In 1982, six crop rotation treatments that were initiated in 1967 on a Orthic Brown Chernozemic loam were sampled for soil NO3-N and moisture to a depth of 240 cm. Soil samples were taken on 18 May and 10 June from all treatments, on 2 Sept. on fallow treatments only, and on 14 Oct. from cropped treatments. Precipitation during the sampling period was about 23% above the long-term average. It was estimated that at least 123 kg NO3-N∙ha−1 were leached from the top 240 cm of fallow soils. Leaching appeared to result from a portion of the precipitation moving through macro soil pores. There was evidence that water and NO3-N might also move upwards from below the 240-cm depth. Of the six rotations examined, the 2-yr and 3-yr spring wheat (Triticum aestivum L.) rotations lost the most NO3-N. The presence of fall rye (Secale cereale L.) in a fallow-rye-wheat rotation was very effective in reducing NO3-N losses. Spring wheat, when grown continuously, was also very effective in reducing NO3-N losses but even here there was some evidence of leaching beyond the root zone. Application of fertilizer N and P at amounts based on soil test recommendations reduced NO3-N leached. It was estimated from long-term precipitation data, that over the past 100 yr about 20% of the soil organic N that was present at the time of breaking the land has been lost from the soil via leaching. It was concluded that leaching losses of N from the soils on the Canadian prairies had been greatly underestimated and were partly responsible for losses attributed to the more visible wind erosion. Key words: Nitrate movement, crop rotations, fertilizer and leaching, summerfallow and leaching, bimodal leaching

Description: A preliminary field study was conducted to investigate the influence of fall applications of nitrogen and phosphorus on winter survival of winter wheat on zero-tilled and conventionally tilled land. Nitrogen fertilization tended to decrease winter survival while phosphorus fertilization tended to increase survival. A N-P interaction was observed, with the decrease in survival in response to added N being more evident in the absense of applied P. Balanced N-P fertilization may therefore result in highest winter survival in both conventionally tilled and zero-tilled winter wheat. Key words: Zero-tillage, winter survival, nitrogen, phosphorus, winter wheat

Description: Increased use of sulphur (S) fertilizers in southern Alberta led to a series of field and phytotron experiments to investigate the importance of S fertilizers and the role of subsoil reserves of sulphate sulphur (SO4-S) for barley (Hordeum vulgare) and rapeseed (Brassica napus). Two types of experiments were conducted. In the field-plot studies, barley was grown on dryland soils low in surface SO4-S but underlain by subsoil high in SO4-S. Neither elemental nor SO4 forms of S significantly increased barley yields in a series of 10 experiments on those soils. The comparisons were made at three levels of N fertilizers. In a series of lysimeter studies, three successive crops were grown in soil low in inorganic S (2.0 μg SO4-S∙g−1), or soil supplemented with 25 μg 35SO4-S∙g−1 soil at specified depths in the lysimeters. Barley was adequately supplied with S from SO4-S at a depth of 54–72 cm. It obtained 55% of its S from a high SO4-S (25 μg∙g−1) layer of soil at that depth, although 40 days growth were required before the S was effectively utilized. Five times as much S was taken up by the barley when the entire soil received an additional 25 μg SO4-S∙g−1 as when only the 54- to 72-cm depth was supplemented; however, the yields were unaffected. Most of the excess S was retained in the straw. Rapeseed took up an increasing amount of SO4-S as the proportion of the lysimeters that initially contained SO4-S was increased. Rapeseed was also able to utilize SO4-S from a depth of 54–72 cm. Rapeseed showed deficiency symptoms when most of the added and soil reserves of S had been depleted by previous crops; its growth habit became indeterminate and seeds did not develop. Although total dry matter yield was not greatly affected, seed yield was markedly reduced in S-deficient rapeseed. Rapeseed took up 10 times as much S as did barley when the S supply was just adequate for seed production. Although rapeseed had a much higher S requirement than barley, both crops were adequately supplied by subsoil reserves of SO4-S under the field and controlled environment conditions studied. The studies suggest that fertilizer recommendations should be based on soil analysis to a depth of at least 60 cm. Key words: Sulphur fertilizer, sulphates, 35S, barley, rapeseed, nutrient uptake

Description: The effect of 10, 15, 20 and 25 °C soil temperatures on the extractability of soil and fertilizer phosphorus (P) was examined in two soils, one containing free carbonate (pH 7.8) and the other non-carbonated (pH 6.9). The time course of fixation and desorption reactions were monitored. The extractability of P was also assessed using sodium bicarbonate (NaHCO3) extractions, desorption curves, and short-term uptake by wheat seedlings. Phosphorus-32 was used throughout. Opposing effects of temperature were found. An increase in incubation temperature from 10 to 25 °C decreased the amount of applied P extracted probably due to accelerated fixation reactions. This effect was established 1 day after the P was applied and persisted for 57 days. An increase in extraction temperature over the corresponding incubation temperature increased the extractability of P, indicating endothermic desorption reactions. This effect was established 1 h after the extraction began and persisted for 48 h. Hence, the net effect of temperature on the extractability of P will depend upon the balance of these opposing processes. The time course of these processes had two phases. The effects of temperature were established during the initial phase (

Description: Growth chamber and field studies were conducted to assess the relative utilization of placed and broadcast 15N-urea by spring wheat. The field studies were conducted on zero and conventional (shallow) tillage systems, of 4-yr duration, located on Chernozemic soils at two locations in Saskatchewan. Placement below the seeding depth in comparison to broadcast application, generally reduced fertilizer N immobilization and increased fertilizer N uptake, recovery, and efficiency. Under moisture stress, placed applications were effective in enhancing dry matter yield and total N uptake. It is concluded that fertilizer N placement for these two contrasting tillage systems should be identical, thus some soil disturbance under zero tillage may be necessary to achieve optimum crop use of applied fertilizer N. The dominant N transformation processes and possible tillage induced differences, in regard to methods of N application, are discussed. Key words: Placed and broadcast N application, N efficiency, N utilization, 15N-urea, zero tillage, soil moisture

Description: The forest floor of a mature, naturally regenerated conifer stand on a well-drained podzolic soil in the Central Uplands of New Brunswick was sampled systematically. The forest-floor properties measured were: oven-dried mass per unit area, depth, moisture content, pH, potassium-chloride-extractable NH4-N and NO3-N, water-soluble phosphate, and ammonium-acetate-extractable K, Mg, and Ca. Total elemental C, N, P, K, Mg, Ca, Al, Fe concentrations were also determined. Coefficients of variation varied from 0.066 (total C) to 1.78 (2 N KCl-extractable NO3-N). Concentrations (measured in ppm or percent) were in each case less variable than absolute amounts (measured in kilograms per hectare). Frequency distributions were positively skewed (except for total C and N) and appeared to follow a gamma or Weibull distribution pattern. Key words: Ferro-Humic-Podzol, forest floor, lateral variability, spruce-fir forest, systematic sampling

Description: A descriptive system is outlined for characterizing, in thin sections, the micromorphology of organic soils and organic layers. In each thin section, distinct regions of morphology, fabric zones, can be recognized. Each fabric zone may be composed of various combinations of organic constituents. These constituents are designated as basic morphologic units and four main types are defined: particulate material, granular units, discrete compound particles, and massive-appearing fabric. The fabric zone and basic morphologic units can be coded in a fabric description symbol of the following simple general form [Fabric Unit]1 …[Fabric Unit]n, where [Fabric Unit] represents a particular fabric zone and its basic morphologic units. For example, [PpGa] [Ma] is a fabric description symbol indicating that two fabric zones are identified in the thin section. The first [PpBa] is the dominant fabric zone in the thin section (areal proportion) and is composed of two basic morphologic units, mainly recognizable plant fragments, Pp, and a lesser occurrence of amorphous granular material, Ga. The second fabric unit [Ma] indicates a fabric zone composed of one basic morphologic unit: amorphous massive-appearing fabric, Ma. The system is applied to the micromorphological characterization of a Typic Mesisol from Keswick, Ontario. Key words: Microcorphology, organic soils, descriptive method, characterization

Description: We, as well as others, have observed that nitrous oxide (N2O) fluxes increased markedly during soil thaw in early spring. This phenomenon was examined further by determining nitrous oxide concentrations in the soil profile and N2O fluxes from the soil surface during the winter-spring period and evaluating physical release and microbial production of N2O on thawing of frozen soil cores in the laboratory. In mid-winter, soil profile N2O concentrations were close to ambient and surface N2O fluxes were low. At thawing, high N2O concentrations (ranging from 1082 to 2066 mg∙m−3) were found at 10–30 cm in the soil profiles of a coniferous forest, and in manure- and straw-treated plots. Concurrently, N2O flux increased markedly and reached some of the highest values observed during the entire season. When thawing was complete, soil profile N2O concentrations and N2O flux declined. Soil cores were taken from frozen soil, warmed in the laboratory, and N2O release measured. Nitrous oxide was released on warming, and cores treated with CHCl3 had a slower release rate. The results indicate that some of the N2O flux occurring at thawing is due in part to physical release of N2O, and that additional N2O is likely produced by denitrification. Key words: Nitrous oxide, denitrification, frozen soils, nitrogen loss

Description: The effect of phosphorus fertilization on potato yields (Solanum tuberosum L.) was studied on 24 experimental sites varying from 44 to 1000 kg/ha of soil test P. The respective relative yields (yield with P fertilizer/maximum yield with P fertilizer x 100) varied from 20.3 to 100%. The Mitscherlich equation was used to relate relative yields to soil test P. According to their soil test value, the soils were partitioned in three classes by the Cate-Nelson method to establish poor (300 kg/ha of available P or less), medium (301–400 kg/ha P) and rich 401 kg/ha P or more) soil fertility classes. It was found that 94 kg/ha fertilizer P was necessary for maximum yields with an increase of 10% or greater on poor soils. On medium and rich soils, the requirement was 50 kg P/ha for a yield increase of 1–10%. Below a 1% increase, the P application should be lowered. At high rates diammonium phosphate (DAP) has been found to give tuber yield equal to those of superphosphates. On the other hand, at low rates, DAP application was more effective. DAP induced a higher mid-season P concentration in the petiole tissue Acidification by superphosphates increased aluminum, iron and manganese availability in the soil and reduced P solubility in the band area, in contrast to DAP. Key words: Potato, soil test phosphorus, source of phosphorus fertilizer, phosphorus fertilization, superphosphate, ammonium phosphate

Description: The change in the extractability of soil phosphorus (P) in response to temperature was examined in 12 Manitoba soils. These soils varied in carbonate and P contents. The soil P was labelled with 32P to facilitate measurements. Sodium bicarbonate extractions, anion exchange resin extractions, P desorption curves and short-term plant uptake using wheat were used to measure P extractability. An increase in soil temperature increased the extractability of P. This was apparent for P extracted by NaHCO3 only in soils low in P. The P extracted by resin appeared to respond similarly but was quite variable. Effects of temperature on the desorption curve parameters were significant only in soils high in P. The latter may reflect the detection limits for P using the desorption curve extraction system. Plant uptake was closely correlated to root growth. Both increased markedly as temperature increased. However, in certain soils the increase in P uptake due to temperature was far greater than the corresponding increase in root growth. The estimates of the labile pool accessed by plants increased as temperature increased. The principle hypothesis, that the effect of temperature on P extractability changed from soil to soil, was confirmed. The only controlling soil factor that could be identified was the basic soil P content. Key words: Temperature, soil phosphorus, carbonated, non-carbonated, plant uptake, wheat

Description: Differences between analyses of washed and unwashed filbert leaves were found for N, P, Mg, S, B, Mn, Zn and Cu but not for K and Ca. The contamination was attributed primarily to particulates since washing reduced average leaf weight measurements. The magnitude of the contamination varied among orchards and between years. It was concluded that washing leaves is essential for both micro- and macronutrient considerations. Key words: Filberts, leaf washing, macronutrients, micronutrients, contamination

Description: not available

Description: The effects of soil and solution pH and Na:Ca ratio in solution on the exchangeable Na, Ca, and (Na + Ca) of a Na-saturated Dark Brown Chernozemic soil were studied. At soil pH 9.0, the exchangeable Na, Ca, and (Na + Ca) were 14.5, 25.4, and 21.8% greater than at soil pH 6.0. Solution pH (6.0–9.0) had small but statistically significant effects on the amount of Na and Ca adsorbed by the soil. The logarithm of exchangeable sodium percentage (ESP) was related to the Na fraction in the solution by a polynomial equation, log ESP = 0.93 [Na/(Na + Ca)]2 + 0.16 [Na/(Na + Ca)] + 0.82. Not only is replacement of exchangeable Na with Ca important in the reclamation of this soil, should it become sodic and have a high pH, but also lowering of its surface charge, through lowering of its pH, would be an important factor in its reclamation. It appears impractical to reduce soil pH by applying acidified irrigation water. Acidic amendments such as gypsum and sulfur may be more suitable. Key words: Cation exchange, solution pH, soil pH

Description: Surface samples of five Quebec soils (St. Bernard, Ormstown, Howick, Dalhousie and Bearbrook) were selected to represent typical agricultural soils with a range of parent material. Soil minerals were fractionated by size into five separates and examined using X-ray diffraction (XRD) techniques and chemical analyses. In nearly all cases the non-clay separates (250–2.0 μm) contained feldspars, amphiboles and quartz as dominant minerals with only small amounts of layer silicates. Feldspars, amphiboles and quartz were also relatively abundant in the clay separates. The layer silicates in the clay separates consisted mainly of mica, chlorite and vermiculite. The soils had similar mineral suites, considered indicative of a low degree of weathering. Considering the mineral composition and the low degree of weathering, it is proposed that primary K-bearing minerals, including K-feldspars, are important sources of K in these soils. Key words: K release, particle size, soil mineralogy

Description: Leaf tissue nutrient concentrations measured over 3 years in 17 filbert orchards showed consistent correlations between N/S, Cu/S, Zn/Cu, Ca/K, Mg/K and Mg/Ca. Optimum concentrations of 1.44% Ca, 0.27% Mg, 0.14% S, 8.8 ppm Cu, and 19.5 ppm Zn were calculated using regression equations of the various correlations and optimum values of N and K (2.2% N and 0.8% K) reported in the literature. Correlations between leaf and soil nutrient concentrations were observed but they were not consistent over the 2 years and all depths (0–15, 15–30, 30–60 cm) of soil samples taken. Average leaf weight measurements were sufficiently consistent within orchards to allow detection of orchard to orchard differences. Several nutrients appeared to affect or be affected by average leaf weight. Average leaf weights appear to have potential as a biologically important measurement but the significance has yet to be derived. Key words: Filberts, macronutrients, micronutrients, optimum leaf concentrations, leaf weights

Description: Soils affected by tree-throw (arbroturbation) at three sites in Nova Scotia varied in development and microrelief characteristics. Soil horizonation was strongly developed and continuous through the mound-and-pit sequence at one site but was intermittent and irregular at the other two sites. Analytical data, particularly those for oxalate- and pyrophosphate-extractable Fe and Al reflected the morphological variations observed in the pedons. Classification of the arbroturbated soils according to the Canadian system is not a problem though it is necessary to indicate turbation by appending a phase to the soil class name at levels above the series. Mapping areas of such soils involves no change from regular procedures except in the description of the soil units. Hummocky microrelief due to arbroturbation presents some limitations in the use of land. Key words: Physical disturbance, classification, mapping, land use

Description: The 1981 Census of Agriculture statistics was used to estimate manure production from livestock activities in Quebec. Only 10 of the subdivisions (1%) were found to have an improved farmland base that was inadequate to meet the total manure stocking rate (TMSR) regulation (i.e. 0.3 ha per animal unit (AU) of production). There were two areas, one near Granby in the Yamaska River basin and another near the outlet of the Chaudiere River, where there was a substantial number of adjoining subdivisions with TMSRs above 2.0 AU∙ha−1. Analysis of soil survey data indicated a greater potential for groundwater contamination in the Chaudiere than in the Yamaska high-density subdivisions. However, about 15% of animal manure production in Quebec was on farms which did not meet the land base requirement. Hog waste constituted about 83% and poultry waste 13% of the manure produced on farms with inadequate improved land. Key words: Water pollution, animal waste, non-point sources, manure applications

Description: The potential of several field tests for differentiating podzolic B horizons from others was studied. The spodic horizon test involved determinations of 4 N KOH-extractable Al and the color of humic extracts. The 0.5% HCl-HF test and the acid oxalate test both involved a rating of the intensity of color of the extracts. For the samples tested, the HCl-HF test was the most promising on the basis of less dependence on correct sample weight, simplicity, and the best differentiation of the podzolic B horizons tested. For samples having borderline properties, however, such field tests might yield ambiguous results because sample weights and estimates of extract colors are not accurate. In most circumstances, sampling for laboratory analyses is recommended to resolve classification problems. Key words: Field test, podzolic B horizon, spodic horizon

Description: The K release characteristics of surface samples from five Quebec soils were investigated. Each soil was fractionated by size into six separates. Each separate was extracted with 1 M ammonium acetate (NH4OAc), with 1 M nitric acid (HNO3) and with sodium tetraphenylboron (NaTPB) and the K extracted was determined. The clay separates contained most of the HNO3 and NaTPB-extractable K. The average amounts of K removed by 1 M HNO3 and NaTPB from the clay was up to 16 times more than that released from silt or sand fractions. The strong relationship between extractable K and clay content was probably due to the similarity in mineralogical composition and degree of weathering of these soils. Clay-sized chlorite and vermiculite were destroyed by the HNO3 extraction but not by the NaTPB extraction. Crop response to K fertilizer was generally reduced as clay content and extractable K increased. Key words: Extractable K, NaTPB-K, HNO3-K

Description: Ontario Soil Survey data for 278 soil series were interpreted to describe relationships between soil characteristics and the movement of water in saturated zones of the soil profile. Based on family particle size classes, groups of soil families, similar in profile and parent material, were formed. Groups were ordered in terms of increasing ability of soil to transmit water, as interpreted by Soil Conservation Service guidelines. The ordered groups were separated into two parts using the European concepts for surface water gley and groundwater gley soils. Six groups of surface water gley soils were differentiated in which surface water was interpreted as the principle source of saturation. Groundwater was interpreted to be the principle source of saturation for three groups of groundwater gley soils. Principles applied to grouping and ordering were augmented by data for soil texture and structure to develop a generalized profile description for each group. The generalized profile description was translated into a five symbol code by which the interpretation is applied to individual soil series within a group. The code is intended to enhance application of soil survey data to design of buried agricultural drainage systems. Key words: Soil physical characteristics, drainage characteristics, hydrologic soil groups, surface water Gleysols, groundwater Gleysols, pseudogleysols

Description: Research on soil mesofauna distribution and diversity was conducted on a cultivated Gray Luvisol near Breton, Alberta. Particular reference was made to the soil Collembola (springtails) and the Acarina (mites). Seven different vegetative regimes (grass litter, balsam leaves, aspen leaves, straw litter, fescue grass, alfalfa, check) were established on 14 (2 m × 2 m) microplots. Microarthropod distribution and diversity were found to be dependent on a number of soil parameters such as temperature, moisture, depth, nutrient status, microhabitat availability and vegetative cover. Seasonal changes were also monitored. Examination of soil thin-sections revealed that a wide variety of fauna contribute to the reorganization of fabrics, especially in the upper 7 cm of soil. These fauna varied in their significance throughout the microplots. Fecal pellets of 280–350 μm size were encountered, commonly comprising mull-like material. Insect larvae are thought to be responsible but their type is unknown. The authors stress the need for further research in this area to establish the role and importance of the soil mesofauna in the soil ecosystem. Key words: Soil mesofauna, Acarina, Collembola, soil microstructure

Description: The equilibration of acid soils, a Sombric Ferro-Humic Podzol (CSSC-2) from British Columbia, an Orthic Ferro-Humic Podzol (CSSC-19) from Quebec and two horizons of a Dystric Brunisol (SSD-330, SSD-331) from British Columbia, with CaSO4 solution demonstrated that SO4 ions reacted with components of these soils. These reactions increased soil pH, ion activity product (Al)(OH)3 and neutral salt extractable exchangeable cations. The increase in pH and ionic activity product (Al)(OH)3 were noticeable on a single equilibration; however, increase in neutral salt extractable cations was only observed after subsequent equilibrations. After three equilibrations, the sums of NaCl extractable cations were 6.56, 11.99, 5.62 and 4.31 meq/100 g for soil samples CSSC-2, CSSC-19, SSD-330 and SSD-331, respectively. The corresponding values for the unequilibrated soils were 5.20, 7.49, 4.30 and 2.50 meq/100 g. On further equilibration there was no increase in total extractable cations for sample CSSC-2; however, for the other three samples there were increases which became progressively smaller. The reaction of SO4 ions with aluminum hydroxy clay complexes seems to be the mechanism for the increase of negative sites. Key words: Cation exchange capacity, CaSO4, acid soils

Description: Soil samples, mainly from eastern and northern Canada, were extracted with sodium hydroxide-pyrophosphate and the centrifuged extracts were fractionated into humic acid, fulvic acid and the polyphenolic component of the fulvic acid fraction. Details of the extraction and fractionation procedure were altered systematically and the effects of these changes on amounts of carbon in the various fractions were studied. A tenfold increase in the ratio of soil to extracting solution resulted in a marked increase (nearly double in some cases) in the ratio of humic acid carbon to fulvic acid carbon (Ch/Cf). Increasing the centrifugal force from 1150 × g to 8200 × g had little effect on Ch, but decreased Cf values. Dissolving and reprecipitating humic acid resulted usually in a decrease in Ch/Cf. Different shaking speeds and times, and extraction under nitrogen rather than air had minor, if any, effects on the Ch/Cf ratios. Most of the podzolic B horizons tested could be distinguished from the other 60 horizons by the combination of C ext (extractable carbon), Ch/Cf and Ca/Cf (carbon content of the polyphenols component of the fulvic acid fraction/fulvic acid carbon).Extractable organic fractions have some promise as bases of soil classification criteria but their potential is limited at present. The procedures are time-consuming and exacting, and results are not comparable between laboratories. Rigorous standardization of methods and interlaboratory comparisons of data might lead to more useful criteria based on organic matter composition. Key words: Humic acid carbon, fulvic acid carbon, polyphenols carbon, extractable carbon, classification criteria

Description: The objective of this study was to determine changes in N dynamics in an Orthic Black Chernozem as a result of two tillage practices (conventional and zero tillage) using the variations in the natural 15N abundance of different soil-N fractions. After 14 yr, no significant differences in isotope composition of total soil-N between the two tillage practices could be found. However, changes were detected in the natural 15N abundance of the acid-hydrolyzable N and various organo-mineral size fractions which led to useful comparisons of the nature of N under the two systems. The N-content of the hydrolyzable-N fraction was similar at the 0- to 4- and 8- to 16-cm depth under both tillage practices, while it was significantly different at the 4- to 8-cm depth. The δa15N of this fraction was consistently higher than that of total soil N at all depths only under zero tillage. This was associated with the presence of more labile N compounds under zero tillage. No differences in the isotopic composition of the organomineral size fractions were found at the 0- to 4-cm depth. At the 4- to 8- and 8- to 16-cm depths, the δa15N values of the finer particle size fractions were higher under zero tillage than under conventional tillage. This indicates a more labile nature of the N associated with these size fractions under zero tillage. Key words: δa15N, conventional tillage, zero tillage, total N, acid-hydrolyzable fraction, particle size fractions

Description: The persistence of the herbicide diclofop-methyl, methyl 2-(4-(2,4-dichlorophenoxy)) phenoxy)propionate, was measured in two soils under field conditions in southwestern Ontario. The hydrolysis of the herbicide ester to its corresponding acid, diclofop, 2-(4-(2,4-dichlorophenoxy)phenoxy)propionic acid, was slower at pH 5.5 than at higher pH but soil pH had no effect on subsequent degradation of diclofop or metabolites formed. After hydrolysis of the ester the acid degraded to 12–39% of the original concentration in 34 days and less than 14% of the applied herbicide, identified as diclofop, was recovered at the end of the growing season. During the course of the degradation small amounts of the metabolites 4-(2,4-dichlorophenoxy)phenol and 4-(2,4-dichlorophenoxy)phenetole were identified from their relative retention time (Rf) on silica gel plates along with traces of other nonidentified compounds. None of the identifiable products except diclofop was present at the last sampling date. Combustion of soils treated with 14C-diclofop-methyl revealed 26–32% of the radioactivity was not extracted at the end of the growing season. Key words: Hoegrass, diclofop degradation, soil residue, soil reaction, 14C-diclofop-methyl

Description: Cool soil temperature regimes with initial soil temperatures of 5 °C rising to 20 °C at the heading stage reduced the rate of growth of barley by approximately one-third compared to 15–25 °C but did not change the barley yield or the fate of the applied fertilizer N in the soil biomass, roots, or tops of the plant or that lost by denitrification. The primary isotope data, % Ndff or ’A’ values remained relatively constant irrespective of whether the straw was placed on the surface or mixed throughout the soil. In contrast, the nitrogen balance data verified that fertilizer N loss, presumably due to denitrification, was as high as 35% in certain treatments, and further that up to 40% of the added fertilizer N was immobilized where the straw was uniformly mixed in the soil. The nitrogen balance data were used to correct the original rate of fertilizer N application. When this was done, A values calculated on the basis of the revised rates of application showed that the amount of soil N which was denitrified or immobilized was approximately double that of the applied fertilizer N. Thus, it is possible where a N balance is included in an investigation to quantitatively assess the effect of management practices on available soil N. It is further concluded that differential immobilization or denitrification of the 15N fertilizer standard may invalidate yield-dependent isotope-derived data, such as dinitrogen fixation unless nitrogen balance data are available to permit the appropriate corrections to be made. Key words: Zero till, N-cycle, temperature, crop residues, barley

Description: A comparison of the drop-cone penetrometer and Casagrande methods for determining the liquid limit of soils showed that the former method is simpler, faster and provides more precise results. Key words: Casagrande, drop-cone penetrometer, liquid limit, soil survey

Description: A case study is presented to illustrate how factor analysis can be used to quantify probable causes of physical and chemical forest-floor variability. Twenty forest-floor variables were examined for a 30 × 30-m sampling plot located within a mature, naturally regenerated conifer stand. "Slough" (the degree of accumulation of decayed stumps, logs, branches, etc.), litter (hardwood- vs. softwood-type in terms of base-status) and insolation (degree of canopy closure) factors appeared to underlie the observed variability pattern. Factor identification was facilitated by the following variable association pattern: (i) total C with total Fe, Al, N, P, K; (ii) total C with LFH-mass and thickness; (iii) water-extractable P with 2 N potassium-chloride-extractable NH4-H; (iv) total and 1 N ammonium-acetate-extractable Ca with pH; and (v) ground cover vegetation density with forest floor moisture content and thickness. Key words: Forest floor, lateral variability, factor analysis

Description: Coarse and finely ground samples from Chernozemic and Luvisolic soils were heated for 2 h at temperatures ranging from 150 to 1150 °C prior to analysis for total As. Thermal pretreatment at temperatures of 150 to 750 °C increased the measured levels of As in all A and B and in some C horizon samples. Heating at 550 °C caused as much as a twofold increase in levels detected in some A horizons. Initial net loss of As through volatilization occurred for all samples starting at pretreatment temperatures of 750 °C and ending at 850 to 1000 °C. Following this initial loss, measured levels of As generally increased with further heating. Heating soils at 1100 °C and higher then caused nearly complete volatilization of As from all Ah horizon samples. Samples of B and C horizons heated at 1150 °C contained from 30% more to 80% less than the content in air-dried samples. Grinding had no significant effect on As measurements. The thermal dependence of As measurements is discussed in terms of forms of the element, mineral transformations, and efficacy of the HCl digestion procedure. Key words: Arsenic analysis, soil arsenic, form of arsenic, trace elements, arsenic geochemistry, methods of analysis

Description: This study examines the development costs of underground service installation in relation to various land factor constraints. Records from municipal development projects were found to be inadequate for apportioning development costs. Professional judgment from full-time cost estimators was found to be more useful. Although development costs on marginal agricultural lands are somewhat higher than on good quality lands, these additional costs are minimal when compared to the total investment in a development project. Key words: Soil interpretations, capability, land preservation, development costs

Description: Two non-replicated, unfertilized, dryland grain rotations—continuous wheat and wheat-fallow — were established in 1912 on a Dark Brown Chernozemic soil in southern Alberta. The effect of long-term cropping on the monosaccharide distribution in the hydrolysates of the water-stable aggregates was assessed. Although all the hydrolysates of the aggregates had the same suite of monosaccharides, the relative proportions changed with cultivation. The eight monosaccharides identified represented between 92 and 96% of the total GC detector response. The monosaccharide C of aggregate organic C for the native prairie varied from 6.9 to 7.6%, while for the continuous wheat and the wheat and fallow of the wheat-fallow rotation it varied from 3.6 to 5.5%, from 1.8 to 5.1%, and from 1.6 to 6.7%, respectively; the higher percentages were associated with the larger aggregate fractions. Except for galactose, the average relative proportions of the monosaccharides identified in the hydrolysates of the water-stable aggregates were not much different from those reported in the literature for the hydrolysates of whole soils. Key words: Monosaccharides, aggregate fractions, water-stable aggregates, capillary gas chromatography, long-term rotation

Description: The effects on soil properties of long-term potato cultivation and of erosion were studied by sampling soils along three transects in virgin forest sites and seven transects in potato fields with landforms and parent materials similar to those of the forest sites. The average thickness of solum was reduced from 35 cm in virgin forest to 27 cm in cultivated fields. More than 90% (28 of 30) of forested pedons were classified as Podzolic soils but only 27% (19 of 70) of the cultivated pedons met all of the criteria of Podzolic soils. The others were mainly Regosols and Brunisols. The main criterion that excluded the soils from the Podzolic order was one of the morphological criteria which states "… hue of 10 YR near the upper boundary (of B horizon) and becomes yellower with depth." Most of the Ap horizons (70%) still meet all the chemical criteria for the Podzolic order. By waiving the morphological criterion stated above for the cultivated sites, nearly 70% (48 of 70) of the soils observed remained as Podzols with only a minor amount of Regosols and Brunisols. It is proposed that the current morphological criterion should be retained for uncultivated soils, but waived for cultivated soils. This will decrease the contrast between the classification of cultivated and adjacent forest soils. We also suggested that the morphological changes resulting from cultivation and erosion can be dealt with at a lower categorocal level or as a phase of categorical levels. Key words: Chemical criteria, morphological criteria, soil erosion, soil transect

Description: Soil profiles on the lake bottom and on four successive postglacial lacustrine terraces situated on the edge of Ear Lake in west-central Saskatchewan were studied to contribute to the knowledge of processes associated with environments of soil formation since deglaciation. Detailed morphological studies and radiocarbon dates of selected horizons indicated incipient and well-developed paleosols have formed in response to progressive formation of the terraces. The ages of the paleosols revealed a possible relationship between postglacial climatic fluctuation and the formation of these terraces. Buried soils on the lower terraces meet the criteria for Solonetzic soils while surface soils of the upper terraces have Solonetzic characteristics. The study showed the presence of soils which have characteristics reflecting more than one interval of horizon differentiation and led to the suggestion that it may be erroneous to relate their properties solely to prevailing environmental conditions. Key words: 14C dates, terrace formation, soil age, Holocene soils, paleosol, Solonetzic soil

Description: The effects of the urease inhibitors, catechol and p-benzoquinone, and temperature on the hydrolysis of urea in five soils were investigated in a laboratory study. Urea hydrolysis decreased significantly with the amount of inhibitors applied and increased significantly with each 5 °C increase in temperature from 5 to 25 °C. The effectiveness of inhibitors generally decreased with increases in temperature from 5 to 25 °C. The correlation of hydrolysis of urea with organic matter contents of the soils was highly significant (r = 0.67** to 0.86**). Both catechol and p-benzoquinone tended to increase the energies and entropies of activation of soil urease and the effect was enhanced with a decrease in soil organic matter. It is suggested that an increase in the activation energy of the soil urease as a result of inhibitor use was related to an increase in the effectiveness of the inhibitor. Key words: Urease inhibitors, urea hydrolysis, energy of activation

Description: A saprolite deposit and the overlying soil profile developed in a glacial diamicton were sampled near Mount Orford, Southern Quebec. The two materials differed mainly by the magnetic mineral and extractable Al contents, by the Fedithionite/Feoxalate ratio and by the mineralogical composition. Illite and chlorite were the dominant clay minerals in the till whereas muscovite and kaolinite were the major minerals in the saprolite. A comparison was also made with another previously described saprolite deposit 4 km away from this one, in which chlorite was slightly transformed to smectite. It is suggested, from the mineral assemblages, that the two saprolites have probably formed at different times, the first one during Tertiary and the second one during an interglacial stage. Key words: Saprolite, glacial diamicton, kaolinite, muscovite, Tertiary alteration

Description: A number of clayey soils of the Red River-Osborne Association that developed under imperfectly to poorly drained conditions on the Red River Plain in Manitoba were studied. These soils, traditionally classified as Gleyed Chernozemic soils and Gleysolic, were characterized by morphological description, chemical and physical analyses. Most of the areas of the Red River Plain are cultivated and have had considerable improvement of surface drainage. Redox potentials, groundwater level and redox potential in the groundwater were determined at selected sites for various periods to a maximum of 2 years. Soils traditionally classified as Gleysols had shallow sola, minimal grumic features, and low chromas and mottles that would meet with present criteria; exchangeable Ca/Mg ratios were commonly near unity in the lower part of the solum. These soils were in an oxidized condition with Ept above 550 mV in the profiles; groundwater levels were below 1.4 m. Oxalate to dithionite extractable iron ratios were greater than 0.45 in the lower part of the solum on the Gleysols and those Gleyed Chernozemic soils with chromas of 2 or less with mottles. Gleyed Chernozemic soils with chromas of 2 or less with mottles would key as Gleysols using the present Canadian criteria; this would result in a change of traditional concepts. Classification of these soils according to the Canadian (taxon) and the U.S. systems are discussed. Key words: Chemical criteria, morphological criteria, water table, soil temperature, redox potential

Description: A number of imperfectly and poorly drained sandy soils from the Almasippi Association of the Lower Assiniboine Delta in Manitoba, traditionally classified as Gleyed Chernozems and Gleysols, were characterized by morhological descriptions, chemical and physical analyses. Soil temperature, groundwater levels, and redox potential of both soil and water were determined at selected sites for various periods to a maximum of 2 years. The upper 30 cm of the soils, traditionally considered as Gleysols, had undergone strong reducing conditions (100 to −200 mV) for at least 2 mo in the spring and early summer; these areas were covered with hydrophytic vegetation and remained saturated at or near surface to July. The subsoil below 45 cm remained in an oxidized state throughout the year. Exchangeable Ca/Mg ratio was near unity in the Gleysols and substantially greater in the Gleyed subgroups. Oxalate to dithionite-extractable iron ratios were greater than 0.45 in the lower part and below the solum of Gleysolic and Gleyed soils. In soils classified as Gleyed subgroups, water tables were below 1.3 m throughout the season and soil profiles were in an oxidized condition. Classification of these soils according to the present Canadian and U.S. system would require a change in concept and approach from the traditional view of Gleysolic soils in Canada. Key words: Redox potential, chemical criteria, morphological criteria, water table, soil temperature

Description: Concentrations of labile and total Al in soil extracts were measured as a function of equilibrium solution pH in six forest soil organic horizons acidified with HNO3 (0–20 cmol H+∙kg−1) under controlled conditions of ionic strength (0.05 M NaNO3), temperature (23 °C), and solution:soil ratio (25:1). Decreases of 0.1–0.2 in solution pH in the range of pH 2.4–4.5 resulted in increases and decreases in concentrations of labile and total Al. Organic acids and soluble C were the dominant Al-complexing ligands in solution, and acidification of each horizon decreased their concentration. Silicon and F concentrations in the equilibrium solutions were lower than that of C, but levels were similar to those of nonlabile Al. Nonlabile complexes were the dominant forms of soluble Al in horizons above pH 4, and labile Al comprised an increasing percentage of total Al as pH decreased, especially below pH 3. The results showed pH alone to be a poor predictor of log nonlabile (r2 = 0.06) or total Al (r2 = 0.33) concentration in these soils, but a good predictor of log labile forms (r2 = 0.77). Solution pH, however, was positively correlated with the log of the ratios of C-to-total Al (r2 = 0.78), C-to-nonlabile Al (r2 = 0.68), and C-to-labile Al (r2 = 0.88). The results should aid in predicting the changes in speciation and solubility of Al due to inputs of acid precipitation to forest soil organic horizons with variable pH and content of dissolved organic C. The observed variability in response of Al to acidification of organic horizons of forest soils indicated that it is not possible to generalize whether nonlabile and labile forms of Al will increase, decrease, or not change upon addition of mineral acid. Besides pH, concentrations of different Al-complexing ligands should be measured in equilibirum soil extracts. Key words: Acid precipitation, fluoride, silica, fulvic acid

Description: Four techniques for the measurement of denitrification rates in the field were compared. All involved the use of acetylene (C2H2) to block nitrous oxide (N2O reduction and subsequent measurement of accumulated N2O. Two extracted core techniques were compared with two in situ cylinder techniques. The single-wall cylinder technique involved partial insertion of a PVC tube into the soil, sealing the head-space, injection of C2H2 into the headspace and, after suitable time periods, assaying N2O concentration in the headspace. A double-wall cylinder technique was devised to allow more rapid C2H2 introduction into the soil core from an interwall space in situ. A comparison of the four techniques on a 1-m2 area in the field showed large spatial variability. Estimates of denitrification rates decreased in the order double-wall cylinder, single-wall cylinder, extracted encased core and extracted loose core. Variation among replicates varied between sampling occasions but, on aveage, decreased in the order single-wall cylinder, extracted encased core, extracted loose core and double-wall cylinder. Key words: Denitrification, field measurement techniques, acetylene blockage, spatial variability

Description: The effect of wastewater irrigation on soil salinity and crop yield was determined in a study at Swift Current, Saskatchewan. A toposequence consisting of the Orthic Regosol series, Calcareous Brown series, Orthic Brown series and Cumulic Orthic Brown series of the Birsay Association was seeded to alfalfa and irrigated with effluent from a secondary sewage lagoon. Since the applied effluent had a mean EC of 2.6 dS/m, soil salinization was a major concern. For 8 yr the four soils were sampled for salinity to a depth of 150 cm each fall. During the 8-yr period, alfalfa was sampled for dry matter yield twice each year from each soil. The results indicate that irrigation by 10–15% more than the normal recommended application rate (i.e., when low saline surface water is used for irrigation) will ensure sufficient leaching to maintain salt content in the root zone at a level not deleterious to plant growth. After 8 yr of effluent irrigation, new steady state salinity profiles were developed in the Orthic Regosol, Calcareous Brown and Orthic Brown series. At this steady state condition the salt contents in the upper 60 cm of the root zone in these three soil series were generally similar. They increased from the initial low ECe value of 0.6 dS/m to 2.5 dS/m. Salinity increased with depth toward the bottom of the root zone where the Orthic Brown series had an ECe value of 4.0 dS/m, while the Orthic Regosol and Calcareous Brown series had values of 6.0 dS/m. Effluent irrigation resulted in a small net reduction of salts in the 150-cm profile of the Orthic Regosol and the Calcareous Brown series, but caused an increase of salts in the Orthic Brown profile. In the Cumulic Orthic Brown series the salt content throughout the profile increased continually from a very low initial level, and had not reached a steady state condition after 8 yr of irrigation. The development of a high water table in this area resulted in salt movement into the root zone of the Cumulic Orthic Brown series that was distinctly higher than those of the other three series and caused alfalfa yields to decline from being highest at the start of this study to only about 80% of yields on the Orthic Brown series at the end. The observed yield reductions emphasize the importance of having adequate drainage to effect salt removal by leaching when crops are irrigated with saline sewage effluent. Key words: Wastewater irrigation, soil salinity, alfalfa yield

Description: Six soil profiles on a transect orthogonal to the Hudson Bay coast of Ontario are shown to be of increasing age from approximately 100 yr near the coast to 〉 5000 yr 70 km inland. The stages of Podzolic soil development from calcareous parent materials are documented. The Ah horizons required at least 750 yr to develop. The Ae-Bh horizon sequence required at least 1893 yr to form. The Ae-Bf horizon sequence required at least 2300 yr to develop. The depth of carbonate leaching and vermiculite formation in the A horizons are very closely correlated to soil age. Key words: Vermiculite, Podzolic B horizon, carbon dating, carbonate leaching

Description: The nature and components of acidity in a group of 20 Saskatchewan soils (pH 5.0–5.8) were investigated. KCl-exchangeable acidity was very low (0.3–2.2 mmol(+)∙kg−1) in all soils. Titratable acidity, determined as the difference between effective CEC and buffered (at pH 8.1) CEC, ranged from 9 to 191 mmol(+)∙kg−1 and constituted about 99% of the total acidity in the soils examined. Titratable acidity was highly correlated with organic carbon (r = 0.83) and with Al extracted using citrate-dithionite-bicarbonate (r = 0.95), potassium pyrophosphate (r = 0.92) and pH 4.8 ammonium acetate (r = 0.79). The combination of organic carbon and citrate-dithionite-bicarbonate-extractable Al accounted for 96% of the variation in titratable acidity. Although lime requirement determined by the Shoemaker-Mc-Lean-Pratt procedure was very highly correlated with titratable acidity (r = 0.98), the data show that the estimated amount of lime to raise soil pH to 6.8 actually exceeded the total (titratable plus exchangeable) acidity in 19 of the 20 soils. Key words: Extractable Al, organic matter, SMP buffer, cation exchange capacity

Description: Dissimilatory reduction of labeled nitrate in the presence of nonlabeled N2O, or NO, was studied in forest mor humus during anaerobic incubation. Data on the isotopic composition of the N2O and N2 pools suggested that all of the N2 formed had passed the N2O pool. This finding supported the earlier suggestion that N2O is an obligatory intermediate in the dissimilatory reduction of nitrate to N2. Due to a likely occurrence of nonenzymatic isotopic exchange between NO and nitrate, the technique used was considered unreliable to study the nature of NO as a possible intermediate in the sequence of nitrate reduction. However, qualitative observations indicated that NO was not a free, obligatory intermediate. Reduction of nitrate was strongly inhibited by the presence of NO. Reduction of N2O to N2 was significantly retarded by the presence of nitrate. The length of the lag period increased as the initial nitrate concentration was increased. Key words: Dissimilatory nitrate reduction, denitrification, nitrous oxide, nitric oxide

Description: An approach to integral land evaluation is described and its application to land use policy issues is demonstrated. The approach provides a link between bio-physical land-related information bases and the information requirements of land use planning. It is based upon the premise that the importance of a land unit for a particular use can be determined by assessing the available land units and their productivities relative to the societal requirements for products and services from the land. A mathematical model specifies land use constraints, representing limitations on resource availability and goals for production, and identifies land use options that are feasible under the specified conditions. This modelling approach provides quantitative information on land use flexibility and on the critical importance of certain land areas for specified uses, given both the bio-physical and socio-economic conditions. For demonstration, a prototype model for the agri-food sector is applied to Ontario under three scenarios, showing the sensitivity of different regions and land types for agricultural production. Key words: Integral land evaluation, physical land evaluation, land use policy, resource constraints, production targets, land use flexibility

Description: A 5-yr field study was conducted at Charlottetown, Prince Edward Island to determine the effect of losses of topsoil and organic matter likely to accrue from intensive potato production on the crop production potential of a loam to fine sandy loam Podzolic Grey Luvisol representative of major soil types used for potato production on P.E.I. The top 7.5 or 15 cm of the original 20-cm-thick Ap horizon was removed from strips on either side of a control (intact soil) strip. These strips were cropped under a 5-yr potato-barley rotation. Soil-loss treatments reduced the organic carbon content of the new 20-cm-thick Ap horizons formed by tillage by 9.4 and 37%, respectively, from 51.3 tonnes (ha∙20 cm)−1 in the original Ap horizon. Similarly, mineralizable nitrogen levels were reduced initially by 21 and 64%, respectively, compared with the intact soil. During the subsequent 2 yr, mineralizable nitrogen levels in the Ap horizons of the intact and minus 7.5-cm strips fell by 35%. Soil-loss treatments had no effect on Ap horizon texture, porosity, or bulk density. However, losses of topsoil reduced the soil’s capacity to store plant-available water (33 kPa – 1500 kPa) within the rooting zone above a Bt, horizon (bulk density 1.67 tonnes∙m−3) by 1.3 and 3.4 cm of water, respectively, from 9.8 cm for the intact soil. Rainfall patterns on P.E.I. suggest that such reductions in water storage capacity may reduce the soil’s crop production potential in 2 out of 5 yr. Key words: Topsoil loss, intensive cropping, Luvisol, organic carbon, mineralizable nitrogen, water storage capacity

Description: The "soil conditioner" Agrispon has been sold privately to Canadian farmers but it is not licensed for sale. The manufacturers claim that Agrispon will promote crop yields by hastening germination, increasing drought resistance, fixing atmospheric N2, and generally stimulating plant growth. No scientifically valid literature exists to substantiate these claims so experiments were undertaken to determine the elemental and microbiological constituents of Agrispon in order to interpret its effect on plant growth in a greenhouse study. Agrispon contained insufficient nutrients to substitute for recommended fertilizer additions. It contained only 10 times more bacteria than Lethbridge tap water and none of the bacteria isolated were capable of fixing atmospheric N2. Nor were any of the bacterial isolates plant or human pathogens. Agrispon had surprisingly low numbers of fungi, approximately 10/mL, and no algae were isolated. The fungal isolates were tentatively identified as members of the ubiquitous Penicillium spp., Fusarium spp., and species of the mycelia sterilia. The addition of Agrispon as seed-applied, pre-plant-incorporated, a combination of these two, or post-emergence product had no consistent effect on germination and no effect on any parameter of plant yield of wheat, barley, field beans, and corn relative to the unfertilized control. This was not surprising since elemental and microbiological analysis confirmed that Agrispon contained insufficient nutrients and no appropriate microorganisms that could conceivably benefit plant growth. Agrispon cannot be recommended for licensing in Canada or for private import by producers. Key words: Triticum aestivum, Hordeum vulgare, Phaseolus vulgaris, Zea mays, N2-fixing bacteria

Description: Measurements of soil pH were made in the 0- to 2.5-cm, 2.5- to 7.5-cm, and 7.5-to 15-cm depths of a loam soil in two long-term (17 yr) continuous wheat rotations. One rotation received only ammonium phosphate fertilizer, while the other rotation received ammonium phosphate fertilizer plus ammonium nitrate fertilizer at an average rate of N of 35 kg∙ha−1∙yr−1. Soil pH was not measured at the start of the experiment. Measurements made at eight times between April and October 1983 showed that average pH in the surface 15 cm was lower in the rotation receiving N and P, compared to the one receiving only P, by about 0.5 pH units (pH 5.9 vs. 5.4 in dilute CaCl2). The soil pH varied considerably during the growing season and seemed to be inversely related to soil NO3-N. These pH changes occurred in a well buffered soil with CEC of 23.5 meq∙100 g−1. Scientists recommending that producers on the Prairies move to a more extended crop rotation so as to reduce land degradation, should bear in mind that eventually there may be a need to lime the soils to maintain production since such a system will necessitate the increased use of N fertilizers. Key words: pH changes during growing season, pH versus depth, soil acidity

Description: The Tempe cell, modified by others to determine saturated hydraulic conductivity (K), was further modified to restrain swelling of the soil and to facilitate air and water movement across the top and bottom of the sample. An apparatus was developed whereby K and water content (θ) could be determined for several soil samples concurrently and suction levels could be varied without disturbing the sample. K and θ were determined for several prepared soil samples by the constant head permeameter method and by the Tempe cell with and without swelling restrained, and for soil cores by the Tempe cell with swelling restrained. With swelling restrained, the K results from the prepared samples did not differ significantly from those of the core samples. For the sandy to silty loam soils at suction levels 0, 10, and 20 kPa, θ of the core sample was less than that from the other samples, whereas for the clay loam soils, θ of the core sample was less than that from the others at suction levels of 0 and 10 kPa. For all methods, θ was correlated to clay content of the soil. These results indicate that the Tempe cell, as finally modified with swelling restraints, can be used to determine K and θ for characterizing the drainability of a nonstructured to weakly structured soil, using either prepared samples or cores. Key words: Hydraulic conductivity, pore volume, soil water content, Tempe cell

Description: A simple laboratory method for measuring CO2 evolution from soil was developed using 580-mL plastic containers. Rate of CO2 evolution was measured by exposing 0.1 N NaOH in the closed containers for 4 h and determining the altered conductivity of the absorbent. With 400 g of soil per unit plus 0.172% straw, a coefficient of variation

Description: Permafrost-free and permafrost-dominated black spruce (Piceamariana (Mill.) B.S.P.) ecosystems in interior Alaska were treated with low addition levels of high enrichment isotope (

Description: The isothermal adsorption and desorption of water vapor by forest fuels is represented with a two-parameter model based on an exponential relationship between Gibbs free energy change and equilibrium moisture content. The model is applied to five sets of sorption data in the literature to illustrate goodness of fit. Two of the data sets are well reproduced by the model; description of the remaining data is less satisfactory. Whether the deviations are due to experimental factors or a deficiency in the model is not determined. At constant temperature, hysteresis ratios tend to increase as percent relative humidity increases.

Description: An ecological method of forest site classification was used to classify and map local ecosystems of the Cyrus H. McCormick Experimental Forest near Marquette in the upper peninsula of Michigan, U.S.A. The field method of site classification was effective in distinguishing 11 ecosystem units that differed markedly in their vegetation as well as in their topographic and soil properties. Each ecosystem repeatedly occurred in a characteristic topographic position within the landscape. Ecosystems were identified in the field using combinations of biophysical properties such as slope, aspect, soil texture, soil drainage, and forest composition. Ecological species groups, groups of indicator plants, were especially helpful in distinguishing ecosystems in the field. Soils of ecosystems identified using the ecological method of classification differed significantly in their physical and chemical properties, and principal component analysis and numerical clustering confirmed that soils of the 11 upland ecosystems were different. Discriminant analyses combined with calculations of the probability of misclassification were used to compare the relative merit of physical factors (topographic and soil factors) and vegetation in classifying ecosystems. The simultaneous use of topographic, soil, and vegetal factors proved most efficient in classifying the upland ecosystems of the McCormick Experimental Forest.

Description: To compare long-term performance of rooted cuttings with seedlings in white pine (Pinusstrobus L.), two 37-year-old (40 years from propagation) experimental plantations of rooted cuttings and seedlings were measured for height, diameter at breast height (DBH), and wood specific gravity. In general, rooted cutting origin trees performed as well as or better than seedling origin trees for survival, height, and diameter at breast height. The number of roots per cutting at planting was significantly and positively correlated with DBH at years 9 and 40. Seedling origin trees had significantly higher (P = 0.05) wood specific gravity at one of the two test plantations.

Description: Longleaf pine (Pinuspalustris Mill.), although it has many excellent qualities, is not extensively planted because of its extended seedling "grass stage" accompanied by poor field survival. Treatments with cytokininlike substances in spring and early summer stimulated seedling height growth, and this effect was enhanced by gibberellic acid (GA3) and DPX 3778, an experimental triazinone derivative that is synergistic with gibberellins. The synthetic cytokinin benzyladenine and other active purine derivatives, although potent, tended to cause bud proliferation and death. A seaweed extract with cytokinin activity, Cytex, proved effective without the deleterious side effects. A promising technique is thus to apply combination sprays of Cytex, GA3, and DPX 3778 in the nursery to stimulate height growth during the 1st year in the field.

Description: The stimulation of lightwood formation (oleoresin soaking) in Pinusresinosa Ait. treated with the bipyridylium salt, paraquat (1,1′-dimethyl-4,4′-bipyridylium dichloride), affected various physiological parameters. Respiration, transpiration, and ethylene synthesis were markedly increased and were correlated with the increased production of rosin and turpentine. Photosynthesis, however, was severely inhibited, and phloem transport was not necessary for oleoresin deposition. These marked changes in function reflect a typical wounding response. Ethylene (supplied as Ethrel (2-chloroethylphosphonic acid)) was capable of replacing the stimulatory effect of paraquat, with a 14-fold increase in rosin over controls and a 25-fold increase in turpentine. This increase in turpentine content was accomplished by a significant enhancement in β-pinene content. Ethrel-treated trees also showed an increased abietic acid content, with a concomitant decrease in levopimaric acid.

Description: Results obtained by Kozak (A. Kozak. 1970. For. Chron. 46(5): 402–404.) concerning conditions for additivity of component biomass regression equations are formalized and extended. More specifically Kozak demonstrated, using multiple linear regression equations to model three biomass components (bole, bark, and crown) for individual trees, that corresponding total biomass can be determined as the sum of the component regression equations, provided that the same independent variables are used in each component equation. Clearly, Kozak's result can be extended to the case of k (≥2) component equations and we use this case to give more general conditions for the additivity problem. Results are also given for the estimation and inference problems associated with fitting the total biomass model using the additivity result. Additionally, by using the principle of fitting subject to constraints or what has been termed "conditional fitting," it is demonstrated in this paper that additivity of the component equations can be assured even when different independent variables are used in different component equations subject to certain assumptions being met. This principle is then used to generalize the additivity of component regression equations problem and, finally, an example is given to illustrate the application of this generalized additivity theory.

Description: The effects of stratification, clipping, sulfuric acid soaking, and pericarp removal on the germination of hop-hornbeam (Ostryavirginiana [Mill.] K. Koch) seeds were investigated. Untreated seeds failed to germinate. Removing the pericarp produced 34–37% germination. Gibberellic acid (GA3) improved germination of intact seeds, but was most effective for seeds with pericarps removed, resulting in 76–80% germination. Although stratification of intact seeds for 3 months produced 15% germination, a combination of pericarp removal, GA3 treatment, and stratification was best, resulting in 81% germination. For seed testing, the pericarps should be removed and seeds treated with 500 mg/L GA3 for 24 h at 20 °C. Germination at 20 °C with continuous light appears to be a good test condition.

Description: In a study aimed at investigating the effects of sampling for predictor variable values on yield estimates, independent simple random and stratified random samples of stand density and tree height were drawn from simulated pine plantations containing nine strata. Sample outcomes were substituted into a selected yield function to produce estimates of mean yield. Stratifying by both site index and numbers of trees per unit area improved the precision of the yield estimates by 2/3 over simple random samples. Total sample size had no effect on the magnitude of the improvements in the yield estimate. Site index was the more important of the two stratifying variables, but synergistic effects between the two characteristics for stratification were found. Estimating the mean yield with the average of the sample plot yields is recommended over using the alternative of using the mean values of the independent variables. Averaging the sample plot yields produced superior mean yield estimates with less bias and with smaller average error sizes especially when simple random samples were drawn.

Description: not available

Description: This paper derives cost–benefit rules to be used when examining whether unemployment and other market imbalances provide justification for national forest managers to depart from the classical Faustmann rotation rule. It turns out that a high level of unemployment in a particular year is not normally a sufficient condition to justify increased cutting in that year (even if full employment is expected to prevail in the future). Moreover, it may very well be socially unprofitable to increase cutting when there is excess demand for timber. These results are in stark contrast with those found in textbooks on applied welfare economics, saying that unemployment and (or) excess demand for goods always justify a higher level of production than the profit maximizing one. This is so because the latter rules are derived for ordinary produced goods in single-period models, while forest management must be considered in an explicit intertemporal framework.

Description: Three nitrogen (N) levels and six seedling spacings were applied factorially in a randomized block design, of four replications, to coastal and interior varieties of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), Sitka spruce (Piceasitchensis (Bong.) Carr), and lodgepole pine (Pinuscontorta Dougl.) in the nursery. After growing for 2 years in the nursery, seedling dimensions, dry weights, and needle N, phosphorus (P), and potassium (K) concentrations were determined. At the same time, samples of 400 trees per treatment were planted into the forest using the nursery design. Three years after outplanting, survival and height measurements were obtained for all species and, in addition, dry weights and nutrient concentrations for the coastal Douglas-fir. Both an increase in N fertilizer and wider spacing increased 2-year-old (2–0) seedling needle percent N, except in lodgepole pine. Wider spacing also increased percent P in interior Douglas-fir and percent K in lodgepole pine. Within the highest N fertilizer level the amount of variation in needle percent N accounted for by spacing was 75% in coastal Douglas-fir, 78% in interior Douglas-fir, and 92% in Sitka spruce. Needle percent N in 2–0 coastal Douglas-fir and Sitka spruce was positively correlated with survival (r2 = 0.24 and 0.35, respectively), total height (r2 = 0.48 and 0.61, respectively), and current height growth (r2 = 0.31 and 0.51, respectively) after 3 years in the forest. The relationships of spacing to 2–0 seedling percent N, and of 2–0 seedling percent N to outplanting performance indicated that, at least for Douglas-fir and Sitka spruce, spacing influenced outplanting performance through its effect on N nutrition. During 3 years in the forest, coastal Douglas-fir trees had maintained closely similar relative growth rates (RGR) in all treatments. Consequently, relative differences in 2–0 seedling dry weight between treatments of about threefold between 0.6- and 12-cm spacing and twofold between 60 and 235 kg N/ha fertilizer levels, had been maintained. After 3 years in the forest there were no differences in nutrient concentrations between nursery N treatments, indicating that reserves available at lifting had been dissipated, but nutrient concentrations tended to decrease with wider spacing. This suggested some unidentified wide spacing effect was promoting growth and causing nutrient dilution in the tissue.

Description: Regeneration surveys on nine logged areas in the vicinity of Fairbanks, Alaska indicated low levels of white spruce (Piceaglauca (Moench.) Voss.) regeneration. In view of the limited field data, Monte Carlo simulation methods were used to estimate the probabilities of obtaining various levels of white spruce stocking by the 1st and 10th years after logging. The simple model developed, combined the irregular seed production of white spruce with a declining seedbed availability to estimate quadrat stocking (4-m2 plots). Results of simulation experiments indicated that the probability of achieving greater than 40% stocking with white spruce by the 10th postharvest year was 0.63. This result was sensitive to initial postharvest seedbed conditions and the frequency of good to excellent seed years and nonspruce revegetation rates. Both the field data and simulation results indicate the prospects of obtaining adequate white spruce restocking after timber harvest by unassisted natural regeneration were poor. However, simulation results also indicate that seedbed management may increase the probabilities of regeneration success significantly.

Description: A competitive index for lodgepole pine (Pinuscontorta Dougl.) trees in central Oregon is developed from seasonal basal area growth and an indirect estimator of foliar leaf area. Differences in seasonal basal area growth and the ratio of basal area growth to sapwood basal area between trees with and without neighbors are used to document growth reductions owing to the proximity of competing individuals. A regression between basal area growth and sapwood basal area (an estimator of leaf area) is used as a predictor of maximum potential basal area growth for trees growing free of competition. The competitive index is determined as the ratio of actual to potential basal area growth for individual trees. This index standardizes growth against differences in tree size and site conditions. Plant and soil water relations are considered as possible mechanisms of competitive interaction. Moderate minimum seasonal values of predawn leaf pressure potentials (−0.76 to −0.92 MPa) and minor differences between trees in different competitive classes led to the conclusion that soil water may not be the primary mechanism of competition on this site.

Description: Secondarily treated sewage effluent was sprayed into a 50-year-old beech–maple forest near Harbor Springs, Emmet County, Michigan. Effluent was applied at rates of 0, 3.8, and 7.6 cm per week onto thinned and unthinned plots during the growing seasons of 1978 and 1979. Each spray rate and density combination was replicated four times. Acer sp. roots were examined each growing season to evaluate development of endomycorrhizae. Numbers of mycorrhizae were significantly greater in the sprayed than in the unsprayed plots but did not vary significantly with month or thinning.

Description: Extreme weather conditions associated with mountain pine beetle outbreaks were evaluated by graphical techniques for six locations throughout British Columbia. Three major associations of extreme weather patterns with lodgepole pine growth and mountain pine beetle outbreaks were identified. (i) Weather effects prior to, or early in, the growing season can reduce growth without releasing the beetle population. (ii) Weather conducive to beetle establishment and early brood development can occur too late in the season to have a noticeable effect on tree growth and therefore will not be recorded in the annual growth rings. (iii) Warm, dry periods during the summer are associated with tree growth reduction and the beginnings of outbreaks. In each of these three cases, extreme low precipitation levels were involved. Average precipitation in some months did not compensate for the effects of unfavourable extremes in other months on tree growth.

Description: Electrical resistance in young balsam fir (Abiesbalsamea (L.) Mill.) trees was inversely (nonlinear) correlated with specific volume increment, total foliar biomass, and the combined weight of the current and 1-year-old foliage. These relationships were stronger before budbreak than after. No relationship existed between concentrations of N, P, K, Ca, and Mg in the bark and wood collected around time of budbreak, and electrical resistance.

Description: Wood specific gravity and tracheid lengths were measured from increment cores and discs of 10 white spruce (Piceaglauca (Moench) Voss) trees from each of four stands in the Slave Lake forest of north central Alberta. Such measurements were used to indicate the variation of wood properties among trees and within individual stems. The specific gravity of white spruce grown in the Slave Lake area was somewhat greater than that found in the Edson and Footner Lake areas reported earlier. Tracheid length was comparable to that found in trees from Footner Lake and longer than that from the Edson trees on the same age basis. Within a tree, growth rate affected wood specific gravity negatively. However, no correlation was evident between these parameters among trees. Seven trees were examined intensively to determine the variation of properties within the stem. The complex variation patterns from pith-to-bark and stump-to-crown are reported. Contrary to the Edson and Footner Lake trees, a very high corewood specific gravity was not observed. Tracheid length increased from pith to the periphery and from stump to crown.

Description: Seeds produced by 50 Piceaabies L. and 50 Pinussylvestris L. trees near the timberline in eastern Finnish Forest Lapland were collected in late winter 1973–1981, counted, and analysed chemically (specially developed procedure with direct-current plasma emission spectrometry (DCP-AES)). Seed yields, their 1000-grain weights, and their quality varied considerably from year to year in both species, P. abies having good seed yields less often than P. sylvestris (only one good yield during the study period). The mean number of seeds produced by P. abies correlated positively with their 1000-grain weights; in P. sylvestris it did not. The nitrogen, crude fat, sugar, phosphorus, and magnesium contents correlated positively with the corresponding 1000-grain weights, suggesting that these constituents occur mainly in the endosperm and (or) embryo(s) of a seed. The crude fibre and calcium contents, however, correlated negatively with the 1000-grain weights, implying that they occur mainly in the testa. The sodium content did not increase or decrease with increasing 1000-grain weight. The composition of seeds with the same 1000-grain weight but representing yields of different years might also vary. The crude protein proportion in the P. abies seeds produced in different years varied from 9.4 to 19.3%, crude fat varied from 11.0 to 40.2%, and phosphorus varied from 0.30 to 0.83%; the corresponding ranges for P. sylvestris seeds were 10.9–30.9, 7.2–33.5, and 0.42–0.98%, respectively. Some aspects of defensive strategies of sympatric pine and spruce stands under hostile conditions at the timberline are discussed.

Description: The effects of two sources of nitrogen fertilizer applied at rates of 224 and 448 kg N/ha on growth of a thinned and unthinned 24-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand were studied. Ammonium nitrate yielded higher growth of diameter and volume than did urea over a 9-year period, particularly with thinning. Height growth was not affected by nitrogen source. The efficiency of nitrogen fertilization in terms of stem volume response per kilogram of nitrogen applied was greatest with ammonium nitrate in thinned plots. Tree mortality increased substantially with level of fertilization for both sources, and decreased markedly with thinning.

Description: Cambial electrical resistance (CER) was related to the number of cells per radial file of vascular cambium in dominant and codominant balsam fir (Abiesbalsamea (L.) Mill.) trees sampled during the growing season. Scanning electron microscopy (SEM) was used to examine the vascular cambial zone (VCZ) of balsam fir during the growing and dormant seasons. Trees selected for SEM were categorized as having growing season CER  12 kΩ. The two growing trees with CER  12 kΩ. Trees of either growing season category had dormant season CER 〉 12 kΩ and four cells per radial file of VCZ. The relationship between CER and the number of cells per radial file of VCZ supports the hypothesis relating CER to periodic growth rate in balsam fir.

Description: Natural inbreeding and relatedness among neighboring trees were studied in several central New Brunswick populations of white spruce (Piceaglauca (Moench) Voss). Coefficients of relationship (r) were estimated by comparing the self-, neighbor-, open-, and unrelated-pollination effects on percent full seed. The estimates were 0.29 and 0.28 for neighbor and open pollinations, respectively. The effects of natural inbreeding on juvenile traits, e.g., germination and early growth, were slight while the effect on height growth increased with age at least to age 7 years. Neighboring white spruce trees growing in natural stands appear to be related at about the half-sib level (r = 0.25). Based on percent full seed, open-pollination approximates a level of inbreeding expected from trees related at a level well above that of half-sibs. Differential selection at the pre-embryo to early seedling stages results in progenies again related at the half-sib level. It is suggested that an inbreeding equilibrium exists in natural stands of white spruce and that this equilibrium approximates that expected from half-sib matings (F = 0.125). The inbreeding equilibrium is controlled, at least in part, by the frequency of lethal genes in the populations.

Description: Light-saturated net photosynthetic rates per unit leaf area were 1.6–2.1 times greater for the photosynthetically mature leaves of plants of two hybrid Populus clones (NC-5260, 'Tristis No.1' (Populustristis Fisch. × P. balsamifera L.); NC-5326, 'eugenei' (P. deltoides Bartr. ex Marsh. × P. nigra L.)) grown in pots in the field than in comparable plants from a controlled environment growth room and a winter greenhouse. Stomatal resistances to CO2 in the field trees were only 0.4–0.6 of those in growth room and greenhouse trees. Mesophyll (residual) resistances to CO2 in field trees were 0.4–0.8 of those in growth room and greenhouse trees. Field plants had specific leaf weights 1.5–1.8 times higher than growth room and greenhouse plants, likely primarily owing to the greater average photosynthetic photon flux density in the field (835, 225, and 142 μE m−2 s−1 for field, growth room, and greenhouse conditions, respectively). When net photosynthetic rates (Ps) were corrected for the differences in specific leaf weights to derive net photosynthetic rate per unit leaf dry weight, the values were similar for plants from the three environments (Ps in field trees was 0.9–1.2 times Ps in growth room and greenhouse trees); gross photosynthetic rates per unit leaf weight were even more similar. Internal leaf CO2 concentrations, and photorespiration and dark respiration rates per unit leaf area were not related to growth environment. However, photorespiration rate as a percentage of net photosynthetic rate was lower in the field trees (12–16% in field trees, 19–24% in growth room trees, and 23–39% in greenhouse trees). Net photosynthetic rate was shown to be under strong genetic control in these clones. The effects of growth environment on variables of carbon exchange are sensitive to the basis of expression of those variables.

Description: Effects of mycorrhizae and solution pH on ammonium uptake and fluxes of hydrogen, calcium, and potassium in solution culture were determined using three Northwest coniferous species: Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), Sitka spruce (Piceasitchensis (Bong.) Carr.), and western hemlock (Tsugaheterophylla (Raf.) Sarg.). The ectomycorrhizal fungus was Hebelomacrustuliniforme (Bull, ex St. Amans) Quel. Ammonium uptake rates decreased with decreasing pH and were accompanied by decreasing H+ release to the external solution. The mycorrhizal fungus H. crustuliniforme enhanced ammonium uptake and generally released fewer hydrogen ions per ammonium ion taken up than did nonmycorrhizal roots. This altered stoichiometry in mycorrhizal seedlings could mediate pH changes in the rhizosphere of soil-grown plants. During ammonium uptake, calcium ions were released at low pH and taken up at higher pH. Potassium efflux occurred at all hydrogen levels, with less efflux at higher pH. The mycorrhizal association generally increased calcium uptake or decreased calcium and potassium efflux rates compared with nonmycorrhizal seedlings. This research demonstrates that the ectomycorrhizal fungus Hebelomacrustuliniforme can significantly improve ammonium acquisition, a major growth-limiting nutrient in most Pacific Northwest forests, and that pH strongly affects ammonium uptake.

Description: Fraser fir (Abiesfraseri (Pursh) Poir.) seed germinated under moist conditions at 5 °C. Daily illumination in combination with an initial benomyl treatment resulted in earlier commencement of germination (16 weeks) compared with nontreated seeds maintained in darkness (23 weeks). Germination was greatly enhanced by exposing seeds four times daily to 15 min. illumination from cool-white fluorescent lights.

Description: Using 3-year heights, the tallest 49 provenances were selected in a nursery test of 110 black spruce (Piceamariana (Mill.) B.S.P.) provenances. A field test of the selected provenances was planted in Wisconsin; two tests of 108 provenances, both in Minnesota. Characteristics evaluated in the nursery included heights after two, three, and five growing seasons, and growth initiation and cessation in the second and third growing season. Heights were measured in the field tests. Separate statistical analyses, ANOVA and simple correlation, were used for the full complement of provenances and for those that were selected. All nursery characteristics varied significantly; the correlations between latitude and height decreased with age, and were not significant after five season's growth. Differences among provenances in free growth may explain this. Selection at age 3 years was not effective; too many selection errors were evident in the test of the full complement of provenances. Early selection on the basis of heights and phenological characteristics is not an effective way of reducing large range-wide provenance tests to breeding populations.

Description: The effect of plot edge on tree growth on four uniformly spaced plots was assessed prior to using the data for development of growth simulation models. The plots were established with hybrid poplar (PopulusbalsamiferaL. × P. tristisFrisch.) cuttings at square spacings of 1, 2, 4, and 8 ft (0.30, 0.61, 1.22, and 2.44 m) with a larger open space to separate the plots. The survival, diameter, and height of individual trees were determined annually for 5 years. Data from the narrowest spacing (1 × 1 ft) (1 ft = 0.3048 m) and at the oldest age (5 years old) were used to describe attempts to determine the extent of any edge effect. The methodology involved the examination of diameter and survival trends across the plots. Regression analysis was also used to determine a uniform interior region with diameter at breast height as the dependent variable and location, number of live neighbors, and a measure of competition as possible independent variables. Each of the methods has limitations, but all of them provide some evidence as to the number of trees affected by the border.

Description: When inflexible rotation ages for regenerated timber are coupled with a strictly interpreted policy of nondeclining or even flow of timber volume, a mathematically feasible harvest schedule often does not exist. This problem of infeasibility can be avoided by relaxing the definition of even or nondeclining flow used in the postconversion period of the Timber Resources Allocation Method (RAM). Relaxed flow policies can lead to scheduled harvest volumes which fluctuate greatly from decade to decade in the postconversion period. Explicitly planning for these fluctuations seems to violate the principle of sustained yield and some believe it may lead to a poorly regulated forest. However, when frequent review and reassessment of harvest schedules for two Alberta forest management units were simulated, undesirable fluctuations in future harvest volumes did not occur and the resulting forest structures were reasonably regular.

Description: Heritability estimates for wood specific gravity of loblolly pine (Pinustaeda L.) in east Texas were high and relatively constant for all ages of wood sampled, but tracheid length was found to have low heritability at all ages. Heritability estimates for tracheid length declined with age after age 4 years. Coefficients of genetic prediction indicated that specific gravity of age 2 wood is a reliable predictor of wood specific gravity at age 25. Genetic covariances between juvenile and mature tracheid length were approximately zero. Coefficients of genetic prediction and genetic correlations between specific gravity and height and diameter at age 20 years indicated a strong negative relationship.

Description: Immature embryos were excised from capsules of Populusdeltoides Bartr. ex Marsh, resulting from the artificial pollination of female branches maintained in moist soil. Embryos excised 10–21 days postpollination produced multiple shoots (2–30) when cultured on a modified Murashige and Skoog medium. Embryos 28–35 days postpollination produced single or multiple shoots when cultured on the same medium. Embryos grown in reduced light produced more vigorous shoots than embryos grown at higher light intensities. The addition of glutamine to the medium in reduced light stimulated the embryos to thicken and increased the quality of the shoots produced. The methods described may be useful in rescuing embryos resulting from artificial hybridization in cases where they might otherwise be lost.

Description: This paper deals with finding the optimal size of a forest fire fighting organization. Fire occurrence and fire growth rate are assumed to be random variables with given probability densities. An objective function representing the expected cost is developed by using probabilistic arguments. The resulting nonlinear programming problem with nonnegativity constraints is solved and an extensive sensitivity analysis is presented for cost related and noncost parameters of the problem.

Description: The extent of beech bark disease was examined on 41 permanent inventory plots in western Massachusetts and on 25 plots in Bartlett Experimental Forest in New Hampshire. The amounts of disease-caused mortality and defect were correlated to differences in species composition and 12 other site variables. Stands dominated by hemlock had significantly more beech mortality than other stands. Importance of both beech and yellow birch decreased on plots with beech bark disease mortality. Hemlock benefited most from the loss of beech. Beech bark disease has not noticeably changed understory composition on these plots. In the long term, beech bark disease appears to have caused minor compositional changes on most of the areas studied.

Description: Oxyfluorfen (2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene) was applied at a rate equivalent to a field application rate of 3 kg active ingredient/ha to seed and to 1- to 6-week-old seedlings of loblolly pine (Pinustaeda L.) and sweetgum (Liquidambarstyraciflua L.) under greenhouse conditions. Loblolly pine was more tolerant of oxyfluorfen than sweetgum at all ages. Emergence of sweetgum was completely inhibited by oxyfluorfen, while loblolly pine seedling emergence was reduced by 33%. Tolerance to oxyfluorfen by both species increased with increasing seedling age. Except for the 6-week-old loblolly pine seedlings, dry weights of shoots and roots of treated seedlings were lower than controls. Oxyfluorfen injured the apical meristem of sweetgum at all ages but meristems of loblolly pine seedlings older than 2 weeks did not show any injury.

Description: Treatment with the gibberellin mixture A4 and A7 (GA4/7) enhanced female flowering on mature white spruce (Piceaglauca (Moench) Voss). Time of treatment, crown position, and GA4/7 concentration influenced treatment success. GA4/7 treatment initiated before meristematic differentiation began (late June) enhanced female strobilus production, whereas those initiated after late June were ineffective. Shoots treated with 250 mg•L−1 GA4/7 bore significantly more female strobili than shoots that received 500 mg•L−1. Treatment did not affect female production on uppermost crown positions, male strobilus production, or seed yield per cone. Female strobili predominated from axillary buds centrally located on untreated shoots. GA4/7 treatments that enhanced female production shifted the distribution of strobili to more distal shoot positions.