ALBERT

Description: In an open-pollinated progeny trial of Pinusradiata D. Don, stem diameter assessments were cross-referenced for 410 families for ages 5, 10, and 17 years from planting. Also cross-referenced were Cyclaneusma needle cast (CYCLA) and wood density (PILO) measured by Pilodyn needle penetration. Estimated narrow-sense heritability for stem diameter declined mildly from 0.34 at age 5 to 0.25 at age 17. Estimated heritability of family means, however, only declined from 0.59 to 0.55. CYCLA and PILO gave, respectively, narrow-sense heritability estimates of 0.32 and 0.40, with repeatabilities of family means of 0.57 and 0.67. The genetic age-age correlations for stem diameter were all positive and somewhat higher than phenotypic (family-mean) age–age correlations. Such correlations indicated comparable or slightly slower rank changes among progeny families than had been reported previously for diameter, basal area, or stem volume in P. radiata and Pinustaeda L., but faster rank changes than the literature reports for tree height. A considerable contribution of CYCLA to rank changes in stem diameter was evident from path coefficients and partial correlations. PILO made no evident contribution to rank changes. Predicted gains for stem diameter at age 17 were almost maximal using year-10 data, while using CYCLA as an auxiliary selection criterion enhanced expected gain, particularly with selection at year 5. Predicted gains for stem diameter, with age–age correlations extrapolated according to the Lambeth relationship, indicated maximal gains per annum with selection at 7–8 years for rotations of 25–30 years.

Description: The internal transport of carbon dioxide by water flow has until now been omitted when interpreting measurements of photosynthesis and respiration. Theoretical and empirical analyses of the behaviour of carbon dioxide within a tree show that the consideration of dissolved carbon transportation may be important when estimating the respiration rate, but not so important when considering photosynthetic production.

Description: Radial growth following a shelterwood seed cut in a 174-year-old stand of white spruce (Piceaglauca (Moench) Voss) in interior Alaska was compared with growth in an adjacent undisturbed stand of the same age. After a 2-year lag, radial growth of residual trees accelerated an average of 27% in 5 of the next 6 years. Net mean increase in growth after 8 years was 164%. Basal area growth of individual shelterwood trees increased 26.8% over the 14-year posttreatment period, while control trees increased 16.5%.

Description: Biomass allocation to roots was studied in holm oak (Quercusilex L.), a dominant evergreen tree in broad-leaved sclerophyllous Mediterranean forests. The root systems of 32 single-stemmed holm oaks growing in shallow soils on largely unfissured bedrock were excavated in a mesic site and a xeric site in the Montseny Mountains (northeast Spain). Individual root:shoot biomass ratios (roots with diameter

Description: The responses of CO2 assimilation rate (A), transpiration rate (E), and leaf conductance (g) to increasing leaf to air water vapor concentration difference (ΔW) were investigated (i) using excised shoots from mature trees of Abiesalba, Abiescephalonica, Abiesmarocana, and Abiesnordmanniana and (ii) in situ on a mature tree of Abiesbornmulleriana. Gas-exchange responses to increasing soil drought were also studied in plants of A. bornmulleriana, A. cephalonica, and Cedrusatlantica. Stable carbon isotope composition measurements were carried out on annual growth rings of A. bornmulleriana to estimate the time-integrated values of the ratio of intercellular leaf (Ci) to ambient (Ca) CO2 concentration. Increasing ΔW around the shoots reduced A and g in such a way that either Ci remained constant or its decrease was not pronounced enough for the changes in A to be accounted for by changes in g only. This suggests a direct effect of ΔW on photosynthesis. The different Abies species showed clear differences in water-use efficiency. Abiescephalonica and A. marocana had lower water costs of CO2 assimilation (E/A) than A. nordmanniana and A. alba. It has also been shown that A. cephalonica and A. marocana are characterized by an optimal stomatal control of leaf gas exchange. Stomata closed very rapidly in A. bornmulleriana in response to water supply being withheld, even prior to there being any important decrease in leaf predawn water potential. The stomatal response in C. atlantica was more gradual. In A. bornmulleriana, drought adaptation appears to be linked to the ability to avoid internal water stress, whereas drought adaptation in C. atlantica involves the ability to tolerate internal water stress. The high stomatal sensitivity mA. bornmulleriana is also supported by the isotopic carbon composition data, as shown by the substantial interannual variations in the estimates of Ci/Ca, ranging from 0.48 for the dryest years to 0.61 for the rainy years.

Description: The renewal of boreal fir stands after harvesting is related to the abundance of fir advanced regeneration. The objective of this study was to compare the advanced regeneration in 45-years-old balsam fir stands of second growth to determine if ecological site conditions could explain some regeneration problems noted in the balsam fir – white birch ecoclimatic domain. Seven ecological phases were studied; these are among the most common in the Laurentians north of Québec. On the basis of fir seedling densities (2 years old and more), three groups could be distinguished using a cluster analysis method for grouping means. Dry balsam fir – herb-and-moss type on well drained tills formed a first group characterized with very high seedling densities (〉 60 000 seedlings/ha). A second group, characterized with high seedling densities (25 000 – 40 000 seedlings/ha), was constituted of three phases with an important moss cover:the mesic balsam fir – moss-and-herb type on moderately well drained tills, the humid balsam fir – moss-and-herb type on imperfectly drained tills with seepage, and the humid balsam fir – moss type on imperfectly drained tills. A third group, with low seedling densities (

Description: Stand tables from forest inventories representing more than 22 × 106 ha of forests in tropical Asia were used to estimate aboveground biomass (point and 99% confidence interval). The mean inventory-based biomass for moist forests (225 Mg/ha) was lower than that reported by direct measurements for mature forests in the same region (350 Mg/ha), whereas the mean inventory-based biomass for dry forests (82 Mg/ha) was higher than estimates based on direct measurements (55 Mg/ha). Our analyses demonstrated that human use of the forests in tropical Asia is intense, leading to degradation. Between two national forest inventories of Peninsular Malaysia in 1972 and 1981, the total area and biomass of forests declined by 18 and 28%, respectively. Modeling land-use changes and carbon dynamics of tropical Asian forests must take into consideration human impact on vegetation because such use of forests reduces their biomass and may stimulate forest growth and carbon uptake.

Description: Measuring the mass of snow on cut branch tips soon after snowfalls during two winters provided comparisons of catch by Engelmann spruce (Piceaengelmannii Parry), subalpine fir (Abieslasiocarpa (Hook.) Nutt.), and lodgepole pine (Pinuscontorta var. latifolia Engelm.). Analysis of these and other reported measurements confirmed (i) snow bridging by cohesion, (ii) bouncing of snow crystals by elastic rebound, and (iii) branch bending as mechanisms that determine the sigmoidal growth curves characterizing snow interception relative to snowfall. The fraction of snowfall intercepted by the branches was largest when storm accumulations were 3–4 mm water equivalent, with low specific gravity (0.04–0.07). Percent catch in snowfalls with 10 mm water and low specific gravity was near 50% for Engelmann spruce and about 45% for subalpine fir and lodgepole pine, but values decreased to near 30% in 20-mm storms. Catch was inversely proportional to the density of snow accumulations in the specific gravity range 0.04–0.13. Average branch catch was only about 10% of a storm with 10 mm water equivalent at 0.13 specific gravity. Meteorological conditions were more important than branch growth form in determining snow interception amounts on the conifers tested. The results suggest, as a hypothesis, a computational function for the fraction of snowfall caught on conifer crowns.

Description: Western hemlock (Tsugaheterophylla (Raf.) Sarg.) seedlings from four dormancy induction treatments (DIT) (i.e., long-day dry, long-day wet, short-day dry, short-day wet) were planted on a coastal reforestation site in British Columbia and monitored for physiological response and morphological development over the first growing season. Seedlings in all DIT showed a similar net photosynthetic, needle conductance, and shoot water potential response to seasonal low temperature, non droughty, and late summer drought conditions. Pressure–volume analysis at the beginning of the growing season (late February) showed short-day wet seedlings to have lower saturated and turgor loss point osmotic potentials than other DIT, while at the end of the growing season (October) there was no osmotic potential difference between DIT. At the end of the growing season, short-day wet seedlings had a much lower maximum modulus of elasticity than other DIT, indicating their shoots were still elongating. Morphological assessment 1 month after field planting showed short-day DIT seedlings had less needle damage and greater root development in response to continuous low temperature exposure. Four months after planting, long-day wet seedlings had the greatest shoot (i.e., height, root collar diameter) and root development in response to mild temperatures and high soil moisture conditions. Eight months after planting, survival was between 95 and 97% for all DIT. Long-day DIT seedlings had the greatest height and all DIT had similar root collar diameter and root development. Short-day DIT seedlings had the best shoot/soil roots ratio. Short-day wet seedlings had the least number of stem units per centimetre of new shoot development throughout the growing season. Results are discussed in reference to stock quality assessment presented in the first paper of this series.

Description: Seedlings of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), lodgepole pine (Pinuscontorta Dougl.), and white spruce (Piceaglauca (Moench) Voss) were grown in a container nursery from February to July 1988 and then exposed to three temperatures and three levels of drought stress applied factorially during mid-July to October 1988. Seedlings were retained in a shelter house until January 1989, when they were cold-stored until early May. Measurements of stomatal conductance (gs), transpiration (E), and specific leaf area (SLA) were made at the end of the treatment period in September 1988 and again after growth the following year at the end of June. Root growth capacity (RGC) was tested in early May 1989. Results were considered in conjunction with performance of other samples of the same plants that had been planted in sand beds in April 1989, where irrigation was regulated to provide three levels of moisture stress. Low temperature (13 °C) generally reduced gs and E, which were adjusted for xylem pressure potential, and SLA in all species by the time nursery treatment was completed at the end of September. No effect of nursery temperature treatment on gs and E could be detected when new needles were measured in June and July (after 9 to 12 weeks of growth), but SLA of lodgepole pine increased with nursery temperature treatment, and SLA of white spruce decreased with nursery temperature treatment. RGC was higher for the 13 °C treatment than for the 16 and 20 °C treatments. Survival of outplanted seedlings was mainly inversely related to nursery temperature. Low nursery temperature reduced gs, E, and SLA and increased RGC. SLA of planted lodgepole pine increased with level of nursery drought treatment, and severe nursery drought increased gs under stress, when measured in June. No other effects of drought were detected, although drought treatment was effective in increasing survival of planted seedlings.

Description: The net annual flux of carbon from south and southeast Asia as a result of changes in the area of forests was calculated for the period 1850 to 1985. The total net flux ranged from 14.4 to 24.0 Pg of carbon, depending on the estimates of biomass used in the calculations. High estimates of biomass, based on direct measurement of a few stands, and low estimates of biomass, based on volumes of merchantable wood surveyed over large areas, differ by a factor of almost 2. These and previous estimates of the release of carbon from terrestrial ecosystems to the atmosphere have been based on changes in the area of forests, or rates of deforestation. Recent studies have shown, however, that the loss of carbon from forests in tropical Asia is greater than would be expected on the basis of deforestation alone. This loss of carbon from within forests (degradation) also releases carbon to the atmosphere when the products removed from the forest burn or decay. Thus, degradation should be included in analyses of the net flux of carbon from terrestrial ecosystems. Degradation may also explain some of the difference between estimates of tropical forest biomass if the higher estimates are based on undisturbed forests and the lower estimates are more representative of the region. The implication of degradation for estimates of the release of carbon from terrestrial ecosystems is explored. When degradation was included in the analyses, the net flux of carbon between 1850 and 1985 was 30.2 Pg of carbon, about 25% above that calculated on the basis of deforestation alone (with high estimates of biomass), and about 110% above that calculated with low estimates of biomass. Thus, lower estimates of biomass for contemporary tropical forests do not necessarily result in lower estimates of flux.

Description: Measurements of the spatial mean values of global irradiance, photosynthetic photon flux density, and the downward longwave irradiance under a 26-year-old, second-growth Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) forest canopy on a 26° south-facing slope were made with a tramway system, which scanned a 20-m transect in 12 min. The diffuse solar irradiance under the canopy was measured with a stationary pyranometer equipped with a shadow band. The extinction coefficients for the direct, global, and photon components were derived as functions of the solar incident angle over the range of 15° to 85°. The extinction coefficient for the diffuse radiation was found to correlate well with the ratio of the direct to diffuse irradiance above the canopy. Complete diurnal cycles of the downward longwave irradiance were simulated with a simple model based on the air temperature inside the stand. Analyses of the measurements of all the shortwave and longwave components were made using an effective leaf area index, which was derived from the measurements of the direct irradiance above and below the stand. It was found that the distribution of the leaf inclination angle of a Douglas-fir canopy has strong planophile characteristics, and that in the case of a forest stand on a slope, it is critical to obtain the characteristics of the light transmission through the canopy over the entire incident angle range before effective leaf area index is calculated. Warren Wilson's 57.5° approximation did not hold for the Douglas-fir canopy, which had distinct foliage clumping features.

Description: The temporarily increased fire hazard that is believed to result from the process of thinning is included in a single-stand model for assessing the economic benefits of juvenile spacing. Formulas for the expected net present value and the land expectation value are given along with methods for determining the age of financial maturity and the optimal rotation age. A numerical example is given to illustrate the degree of loss due to the increased fire risk. The problem of commercial thinning when the risk of fire is present is addressed using continuous-time models. It is shown how, when the fire hazard is exogenous to the thinning activity, the problem reduces to one of deterministic optimal control with the discount rate adjusted upward by an amount equal to the fire hazard rate. In the case when the fire hazard increases whenever thinning is taking place, it is shown that in general the optimal thinning policy is qualitatively different from that which is optimal in the no-risk case and involves periods of thinning at the maximum rate interspersed with periods of no thinning activity.

Description: An aseptic technique was used to collect 227 sap samples from 84 tapholes, including several initial and successive collections, of 27 sugar maples (Acersaccharum Marsh.) over six sap flow seasons (mid-February to late April). In this technique, all material used is sterilized, and the bark as well is sterilized with alcohol. Of the 227 sap samples, 62.5% were sterile or essentially sterile (0–10 colony forming units of microorganisms per millilitre), and of the 74 sap samples from initial collections, 83.8% were sterile or essentially sterile, in contrast with successive collections from the same taphole (P = 0.001). The 35 composite sap samples collected from 1800 nonaseptically tapped tapholes on 900 trees, which were our control, were all contaminated with greater than 800 colony forming units of microorganisms per millilitre. Sap obtained with the aseptic tapping technique produced 92.8% light amber grade syrup and 7.2% medium amber grade syrup. Sap obtained with the traditional tapping technique produced 61.8% light amber syrup, 11.8% medium amber syrup, 14.7% dark amber syrup, and 11.8% syrup that was darker than the dark amber grade. The grade was determined both visually and by a spectrophotometric method. We have substantiated that maple sap is sterile in maple xylem. If sap microbial contamination is minimized and cold sap storage is used, lighter color grade syrup than what is achieved with traditional practices (P = 0.001) can be produced to the end of the season. To avoid the usage of a chemical taphole sanitizer, we recommend cleaner ways for tapping maple trees.

Description: EM (expectation–maximization) algorithm procedures were used to estimate mating-system parameters in four natural populations of Thujaorientalis L. from China using seven allozyme marker loci (Fest1, Idh1, Idh2, Mr, Pgi2, Skdh1, and 6Pg2). The mean single-locus outcrossing rate was 0.70 for the species, but estimates showed that there was significant heterogeneity among loci within populations. Multilocus estimates of the outcrossing rate showed that there was significant heterogeneity among populations and among trees within populations. The mean multilocus outcrossing rate (0.75) was higher than the outcrossing rate (0.63) observed in a closely related conifer, Thujaoccidentalis L., but lower than estimates that have been reported for most other conifers. Significant heterozygote deficiencies, relative to Hardy–Weinberg and mating-system equilibria, were observed in all filial populations. In contrast, the maternal populations conformed to Hardy–Weinberg and mating-system equilibria at most loci. Self-fertilization and other forms of inbreeding (e.g., sibling mating) within the sampled populations are important contributors to the low outcrossing estimates in this conifer.

Description: An experiment to examine the use of sewage sludge as a fertiliser for pole-stage Corsican pine (Pinusnigra var. maritima (Ait.) Melville) is described. Dominant and codominant trees responded markedly to additions of sludge at rates of 200 and 400 m3•ha−1, increasing sawlog volume by over 50% in treated plots. Foliar analyses suggest that the trees have responded to phosphorus in the sludge. The greatest impact of sludge on the soil occurred in the litter layer; concentrations of nitrogen, phosphorus, calcium, zinc, copper, cadmium, and lead were all greater compared with concentrations of untreated controls. Nevertheless, at rates of sludge application appropriate to fertilising (200 m3•ha−1), additions of heavy metals are considered small and are unlikely to cause adverse environmental effects.

Description: Roots of 5-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) on three Oregon sites were excavated with explosives and analyzed for the effects of competition on root biomass and for planting-induced root deformities. The plantations were in Nelder designs with graduated spacing from 300 to 15 250 cm2 per tree. Competition treatments consisted of weed-free intraspecific competition, grass cover seeded after 1 year of seedling growth, and red alder (Alnusrubra Bong.) interplanted 1:1 among the Douglas-fir. All plantations were kept at low water stress in year 1. The ratio of standing aboveground to belowground biomass was the same for each competitor type. Shoot:root ratios averaged about 4:1, except in severely suppressed trees, where ratios dropped toward 1:1 in those near death. Neither shoot:root ratio nor tree size was affected by planting-induced root deformities such as J- or L-rooting. It appears that after 5 years all root systems have fully compensated for planting deformities and future growth and stability have not been jeopardized.

Description: Western hemlock (Tsugaheterophylla (Raf.) Sarg.) seedlings were grown in a greenhouse and subjected to four dormancy induction treatments (DIT) (i.e., long-day dry, long-day wet, short-day dry, and short-day wet) during midsummer. In the late summer and fall, seedling development was monitored and it was found that (1) short-day DIT caused a rapid cessation of shoot growth; (2) short-day DIT caused rapid fall development of needle primordia, while long-day DIT took until midwinter to produce the same number of needle primordia; and (3) short-day DIT seedlings had lower saturated and turgor loss point osmotic potentials and greater maximum modulus of elasticity in October than long-day DIT. Seedlings were tested with a comprehensive stock quality assessment procedure just before late winter field planting. These tests showed the following: (1) morphological parameters: short-day DIT reduced shoot to root ratios; (2) pressure–volume analysis: short-day wet seedlings had the lowest osmotic potentials at saturation and turgor loss point; (3) soluble sugar analysis: greater levels of total soluble sugars were found in non water stressed DIT compared with water stressed DIT seedlings; (4) seedling water movement: short-day DIT seedlings had the lowest resistance to water movement at low root temperature (5 °C); (5) low root temperature response: short-day compared with long-day DIT seedlings had greater photosynthesis and stomatal conductance at low root temperatures; (6) root growth capacity: seedlings from all DIT were capable of growing roots at optimum root temperature (22 °C), but short-day compared with long-day DIT had greater root growth at low root temperatures; (7) drought stress response: short-day wet seedlings had the highest photosynthesis and stomatal conductance levels as predawn shoot water potentials decreased; and (8) frost hardiness: short-day wet seedlings had the least needle damage when tested at temperatures of −15 and −18 °C.

Description: Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), lodgepole pine (Pinuscontorta Dougl.), and white spruce (Piceaglauca (Moench) Voss) seedlings were grown in Styroblock containers in a container nursery from February to July 1988 and then exposed to three temperatures and three levels of drought stress applied factorially during 18 July to 29 September 1988. Mean temperatures of 13, 16, and 20 °C were imposed in growth chambers, in a cooled plastic house, and in an ambient plastic house, respectively. Control, medium, and severe levels of drought stress were imposed in a series of eight cycles, resulting in mean xylem pressure potentials of −0.32, −0.50, and −0.99 MPa, respectively. Seedlings were kept in the ambient plastic house until January, when they were lifted and cold-stored until planting. Between 11 and 18 April 1989, seedlings were planted in 0.5 m deep sand beds, which provided hygric, mesic, and xeric conditions for testing all species and treatments. At the end of nursery growth, increase in nursery temperature increased height and height:diameter ratio in all species and shoot:root dry weight ratio in Douglas-fir and lodgepole pine. Increase in temperature also increased the number of seedlings with large well-formed buds in white spruce, but reduced the number in Douglas-fir. Drought stress reduced height and dry weight in all species and bud length in lodgepole pine. After 9 weeks in sand beds, low nursery temperature increased survival (19% for lodgepole pine and white spruce grown in the xeric bed), except for Douglas-fir grown in the xeric bed. Nursery drought stress also increased survival (16% for Douglas-fir and lodgepole pine in the xeric bed), but had little effect on white spruce. Low temperature and drought stress treatments that increased survival also reduced height and dry weight of lodgepole pine and white spruce after one growing season in sand beds. Survival showed significant negative correlations with height, dry weight, and height:diameter and shoot:root weight ratios. Low nursery temperature continued to affect growth after planting, increasing relative growth rate and allometric ratio (K) of Douglas-fir and decreasing K of white spruce.

Description: Three experiments were conducted to determine effects of N and P fertilizers on growth and levels of plant-tissue nutrients of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and western hemlock (Tsugaheterophylla (Raf.) Sarg.). Both pole-size trees in closed-canopy stands and potted seedlings were used. Soil series were Bunker for Douglas-fir and Klone for western hemlock in experiments 1 and 3, and Vesta in experiment 2. For each species in experiments 1 and 2, P and N fertilizers were tested in six or eight treatments using factorial design. In experiment 3, N and P fertilizers were individually tested on seedlings, at one rate of application each. Nitrogen fertilizers used were urea in experiment 1 and ammonium nitrate in the other two experiments; P was applied as triple superphosphate in all three experiments. In general, fertilization changed levels of some plant-tissue nutrients of the pole-size trees and potted seedlings. Neither height nor basal-area growth of the trees was significantly affected by any of the fertilization treatments in the first two experiments. Seedling growth of both Douglas-fir and western hemlock was dramatically improved by the P fertilizer, but was negatively affected by the N fertilizer. Results clearly show differences between pole-size trees and seedlings in response to N and P fertilizers. They also suggest that N not be applied where soils are high in N and low in P and that P applications be confined to sites with low-P soils, when trees are young, before canopy closure.

Description: Starch is the main carbohydrate storage form in conifers and is derived from the translocation of photosynthate (soluble sugars) in the phloem. We examined seasonal patterns in concentrations of both carbohydrate forms in the needles, twigs and branches, stems, and coarse and fine roots of mature Pinuselliottii Engelm. var. elliottii trees in a north Florida plantation. Starch showed marked and similar seasonality in all the tissues, with maxima in the late winter near the time of the inception of new growth in the spring. Sugars showed little seasonality, except in the fine roots. Repeated fertilization had little effect on either sugar or starch concentrations in all tissues. Using published biomass data from these same stands, we estimated that coarse roots store more than half of the starch in these stands over the year, with foliage and fine roots storing less than 5%.

Description: Inherently rapid growth in black spruce (Piceamariana (Mill.) B.S.P.) and radiata pine (Pinusradiata D. Don) could be characterised at a relatively early age (e.g., 3–6 months from germination) by growing progeny of family crosses in near-optimal phytotron or glasshouse environmental conditions. This observation was retrospective in nature, in that the studies of very early performance utilized stored seed from families that had been already tested to age 10+ years in field progeny trials. The very early traits that show the most significant family correlation with the field performance (height or stem volume) are total height, height growth, stem volume, or stem dry weight. The possibility that inherently rapid growth in trees may be causally related to concentration of endogenous plant hormones of the gibberellin class is discussed in relation to the recent finding (S.B. Rood, R.I. Buzzell, L.N. Mander, D. Pearce, and R.P. Pharis. 1988. Science (Washington, D.C.), 241: 1216–1218.) that heterotic growth (hybrid vigour) in maize was strongly related to the concentration of gibberellin A1 (a shoot growth effector in maize) and gibberellin A19 (a precursor to gibberellin A1). Preliminary evidence, based on analysis of hybrid and parental poplar tissue, and on the positive and significant growth response of black spruce slow-growing families (but not fast-growing families) to applied gibberellin (A4/7 mixture), supports the possibility that rapid-growing conifer families may have near-optimal (high) concentrations of endogenous gibberellins, and conversely, that some slow-growing families, at least, may have lower endogenous gibberellin concentrations.

Description: Effects of K and P deficiency on polyamines (putrescine, spermine, spermidine, and agmatine) in leaves and roots were investigated in poplar (Populusmaximowiczii Henry) cuttings growing in half-strength Hoagland solution with varying levels of K (0, 0.3, and 3 mM) and P (0, 0.05, and 0.5 mM). Putrescine contents increased in the leaves of plants grown without K and in roots of plants grown in 0.3 mM K and without K. In the absence of K, the putrescine levels in the roots and leaves were 80 and 25 times, respectively, those of the control (3 mM K). The zero-P treatment increased the putrescine content in the leaves and decreased the putrescine content in the roots. The accumulation of putrescine did not appear to be regulated solely by the K status of the plants. The spermine content in the leaves of 0.3 mM K and zero-P treatments decreased compared with the control, as did spermine in the leaves of the zero-P treatment. The spermine content in the leaves of 0.05 mM P treatment was similar to that of the control (0.5 mM P). This work shows that in poplar polyamine levels in leaves and roots are strongly influenced by the nutrient status of the plants.

Description: The Diagnosis and Recommendation Integrated System (DRIS) was used to describe the variation of 12 elements in woody tree tissue of balsam fir (Abiesbalsamea (L.) Mill.), sugar maple (Acersaccharum Marsh.), jack pine (Pinusbanksiana Lamb.), red pine (Pinusresinosa Ait.), and aspen (Populustremuloides Michx.) across Minnesota, Wisconsin, and Michigan, United States. DRIS indices of elemental balance for the growth decades 1956–1965 and 1966–1975 were compared with standards developed from the growth decade 1976–1985. The DRIS analysis indicated that older wood of most species was relatively depleted of N, P, K, S, Fe, Cu, and Al. In at least one of the five species, however, K, S, Cu, or Al was relatively more abundant in older than in younger wood. The older wood of all species was relatively enriched in Ca, Mg, Mn, B, and Zn. Sulfur in older wood became relatively more enriched from west to east across a gradient of wet sulfate deposition; the trend was strongest for hardwood species. These results support the potential use of DRIS for monitoring stoichiometry of tissue from woody increment cores as an indicator of environmental stresses such as air pollution.

Description: In the present study we describe biomass, productivity, and nutrient cycling in an 8-year-old Eucalyptustereticornis Sm. (Eucalyptus hybrid) plantation and compare them with those of a Populusdeltoides Bartr. plantation of the same age and area, a natural sal (Shorearobusta Gaertn. F.) forest, and other natural forests of the central Himalaya. The total vegetation biomass of the Eucalyptus plantation (126.7 t•ha−1) was lower than that of the P. deltoides plantation (176 t•ha−1) and natural forests (163.4–786.7 t•ha−1). The net primary productivity of the Eucalyptus plantation (23.4 t•ha−1•year−1) was similar to that of the P. deltoides plantation (25 t•ha−1•year−1) and the natural sal forest (22 t•ha−1•year−1). The net nutrient uptake of Eucalyptus was lower than that of Populus plantation and natural forests.

Description: For many types of forest studies, it is essential to identify the exact years of formation of annual rings in increment cores taken from living trees. To accomplish this, dendrochronologists employ cross dating, which involves both ring counting and ring-width pattern matching, to ensure against counting error, or errors, caused by missing or false rings. To date, published accounts of the cross-dating process generally describe a graphical method for achieving cross dating, known as skeleton plotting. However, when working with cores from living trees, skeleton plotting is seldom necessary. Such cores can commonly be cross-dated more quickly and easily by listing the narrow rings that are present in each core in a laboratory notebook and then comparing core notes for shared narrow rings. The latter approach permits faster recognition of ring-width patterns because calendar-year, rather than relative-year, dates are assigned to rings in cores. It also allows cross-dating records to be stored in a more concise manner.

Description: This study investigates the impact of postulated greenhouse warming on the severity of the forest fire season in Canada. Using CO2 levels that are double those of the present (2 × CO2), simulation results from three general circulation models (Geophysical Fluid Dynamics Laboratory, Goddard Institute for Space Studies, and Oregon State University) were used to calculate the seasonal severity ratings for six stations across Canada. Monthly anomalies from the 2 × CO2 simulation results were superimposed over historical sequences of daily weather. Then, seasonal severity ratings of the present were compared with those for 2 × CO2 using five variations involving temperature, precipitation, and relative humidity. The relationship between seasonal severity rating and annual provincial area burned by wildfire was explored. The results suggest a 46% increase in seasonal severity rating, with a possible similar increase in area burned, in a 2 × CO2 climate.

Description: Pollen contamination causes major losses to genetic improvement from selection and breeding of "plus" trees in conifer seed orchards. Genetic losses arise by the influx of "wild" conspecific pollen into seed orchards and its deleterious fertilization of superior genetic lines. This review firstly addresses the basis of the problem: pollen, conifer reproduction, and the concept of seed orchard management, especially in regard to reduction of contamination. Secondly, the physical processes of pollen liberation, dispersal, and deposition are described, and examples of previous studies illuminating these phenomena given. Thirdly, past research on measuring pollen dispersal in natural stands and seed orchards in discussed in the light of modelling techniques used to predict these types of dispersal pattern. Work on the other facets of contamination measurement, gene-flow studies, are listed. It is concluded that a detailed study that combines both the physical and gene-flow aspects of pollen dispersal should be initiated to compare and contrast the two methods, and that attempts to model pollen contamination should be sought.

Description: A comparison of four types of litter traps was conducted during three growing seasons in an old-growth Acersaccharum Marsh, dominated forest on rugged topography in northern Ontario, Canada. The comparison involved traps of two rim heights (0.25 and 1.0 m) and two surface areas (0.25 and 1.0 m2). A supplementary study, also described, compared the two smaller sizes of traps over the same time period. Analysis of variance showed significant effects of both height and surface area on the mass of litter trapped. In a four-way comparison, however, only small traps positioned close to the ground produced estimates that differed significantly from the others. The higher catches associated with these traps are probably the result of a more favorable microsite for entrapment and accumulation of windblown leaves. The number of traps of each type required to constitute a representative sample ranged from ca. 6 to 14 when calculated over three growing seasons. Over the course of a single growing season, the number of traps required increased substantially. No trap type exhibited a distinct advantage in this regard. Generally, however, traps that present a favorable microsite for accumulation of windblown leaves should be avoided in A. saccharum forest.

Description: We report the results of a study of the near infrared reflectance spectra of decaying forest foliage. During the decay process, a broad absorbance feature develops in the 1100–2000 nm region of the near infrared spectrum. The magnitude of this feature is directly related to the age of the material (or to degree of decomposition) and may be useful in determining degree of decay in field samples. More specifically, multiple linear regression equations derived from second-derivative near infrared reflectance spectra are presented that predict the concentrations of nitrogen, lignin, and cellulose in decaying foliage. We conclude that near infrared reflectance spectroscopy is a very viable and attractive method for the simultaneous determination of these components in decaying foliage.

Description: Treatment effects over time are frequently investigated using repeated measures designs, but analyses of these experiments frequently fail to address a primary objective of collecting data over time, namely description of the response curve. The analysis advocated in this paper utilizes the intrinsic continuity of the repeated measures factor by focusing on response curves. Treatments are compared by analyzing estimated coefficients of response curves proposed by the investigator. This approach provides more information on treatment effects than analyses that compare treatments separately at each time period. Analysis of estimated coefficients is easier to interpret than multivariate analyses of variance and does not require often biologically implausible assumptions of split-plot analyses currently in vogue. An example describing effects of aluminum on sugar maple (Acersaccharum Marsh.) seedling growth illustrates the method.

Description: An artificial soil mix suitable for magnetic resonance imaging was developed. This soil mix, consisting of quartz sand, peat moss, and kaolinite clay (5:3:2, by volume), has a natural texture and consistence and produces high-contrast images in soil media with up to 15% water content. Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings were grown in this soil mix in 12.5 cm diameter containers and periodically imaged over a 12-month period. These images showed roots growing undisturbed in the soil mix and initiation of numerous lateral roots. From these images, root lengths and growth rates were calculated. Calculated root lengths were in close agreement with measured lengths of excavated roots. Undisturbed lateral roots had measured growth rates of about 1 mm/day. Roots that reached the container wall and then grew down along the wall had significantly higher growth rates, over 2 mm/day. This phenomenon may have important implications for growth rate data from root window and minirhizotron experiments.

Description: A phosphorus deficiency bioassay based on the rate of uptake of 32P by forest tree roots was developed for use as a field predictor of the phosphorus status of trees in mature forest stands. Results of a study on the influence of the time of sampling on the results of the bioassay in the field, and on the influence of temperature and moisture under controlled conditions, are reported. Seasonal variations in 32P uptake were recorded in the field study, but the effects of moisture and temperature in the greenhouse experiments were inconclusive. However, it was assumed that the field bioassay response integrated the effects of moisture and temperature simultaneously, and that if the variation could be explained as a consequence of climatic differences over several seasons, then it should be possible to determine optimal sampling times.

Description: A bioassay based on the rate of uptake of 32P by forest tree roots was developed as a predictor of phosphorus fertiliser requirements for mature forest stands. Seasonal variation is known to be significant, and this paper reports on a study that examines the implications of spatial variation on the interpretation of bioassay results. Sampling stands growing on spaced-furrow ploughing indicated that positional or microsite differences interact with season of sampling. The ridges created by this kind of site preparation appeared to be nutritionally impoverished with respect to the flats and furrows, and this effect was most marked in summer. A greenhouse split-root experiment with conifer seedlings indicated that within-plant variability is of less consequence than the spatial variability of the forest floor. Sampling positions are suggested for standardizing sampling procedure.

Description: Since the early 1980s, some sugar maple (Acersaccharum Marsh.) forests in northeastern North America have shown severe signs of dieback and decline. This study was designed to determine the relationships of crown dieback of sugar maple with carbohydrate content for different tissues during fall and spring and with radial growth patterns. A 100-year-old sugar maple stand located in Tingwick (Quebec, Canada) was sampled in 1987 and 1988. Growth, starch, and water-soluble carbohydrates (sucrose, glucose, and fructose) were measured in relation to crown dieback for 55 sugar maple trees. Root and stem samples were collected in April (1988), during the bud burst period, and in October (1987 and 1988), just after leaf drop. Starch was the predominant carbohydrate. In April, stem samples contained higher concentrations of glucose and fructose than in October. Conversely, roots had higher concentrations of reducing sugars in October, especially in trees, that were heavily affected by dieback. Roots of such trees also contained lower starch concentrations in October than in April. A crown deterioration index emphasized the increase in reducing-sugar concentrations found in autumn in roots of the deteriorating trees. Basal-area increment at 1.4 m was assessed from ring widths of cores collected from the trees under study. A significant growth decrease was observed for trees with 25% or more crown dieback, particularly for the last 5-year period. Thus carbohydrate concentrations and growth measurements prove to be valuable parameters in assessing tree health. Moreover, it seems that the physiological imbalances observed in declining trees may decrease the resistance of sugar maple against biotic and abiotic stresses.

Description: Greenhouse container-grown ponderosa pine (Pinusponderosa var. scopulorum Engelm.) were cold acclimated and deacclimated in growth chambers during a 19-week regime. Seedling cold hardiness, bud dormancy, and ethylene and ethane evolution from excised needles were measured weekly. Ethylene and ethane evolution and the ethane/ethylene ratio declined from bud set to bud break and did not parallel changes in cold hardiness. Large standard errors of the ethylene evolution means made detecting statistical differences over time difficult. Significant deviations in the ethane evolution means were observed, however, and indicated a sharp decrease and recovery at the start of cold acclimation and a peak at the start of deacclimation. The ethane/ethylene ratio accentuated the declining trend from bud set to bud break and the two sharp deviations in the trend at the start of acclimation and deacclimation.

Description: Effects of nitrogen fertilization on growth, foliar nitrogen concentration, and monoterpenes were determined on 7- to 11-year-old jack pine (Pinusbanksiana Lamb.) on two sites in northwestern Wisconsin. One site established after wildfire; the other after clear-cutting. Jack pine budworm (Choristoneurapinuspinus Free.) larvae were caged on fertilized and unfertilized trees on each site. Relations among foliar nitrogen, monoterpenes, larval survival, and adult budworm weight were examined. Foliar nitrogen concentration, needle weight, shoot and diameter growth, and monoterpene production were lower on wildfire site trees than on clear-cut site trees, and were significantly increased on both sites by fertilization. Fertilization increased production of staminate cones on the wildfire site. Height growth differed between sites but was unaffected by fertilization. Contrary to expectations based on the resource availability theory, foliar nitrogen and monoterpene levels were positively related. Survival of jack pine budworm larvae was greater on clear-cut than on wildfire site trees, but was not significantly affected by fertilization. Larvae on low-nitrogen trees on the wildfire site clipped more foliage than those on the clear-cut site, suggesting compensatory feeding. Adult female weight was higher for larvae on wildfire than clear-cut site trees. Two monoterpene compounds and site-related differences were the best predictors of adult female weight based on regression.

Description: Harvest levels and road construction and maintenance schedules are reported for combinations of cut-block size and exclusion-period length. Exclusion-period length had a greater effect than block size on harvest and road schedules. Harvests constrained by 20- and 30-year exclusion periods were, respectively, an average of 15 and 30% below the progressive clear-cutting solution. A combination of small openings and long exclusion periods led to significant reductions in harvests (43%) and caused a high percentage of the road network to be constructed in the early decades. These long-term, spatially constrained forest plans were formulated as integer programs and solved with a random search algorithm.

Description: Hurricane Hugo caused much damage to the old-growth forests of the Congaree Swamp National Monument, but most of the damage to trees 〉20 cm dbh consisted of crown breakage and defoliation. Serious damage (〉25% of crown lost, snapped trunk, or uprooted) was more common in mixed bottomland forest (49% of trees seriously damaged) than in adjacent sloughs dominated by Taxodiumdistichum (L.) L.C. Rich, and Nyssaaquatica L. (19% of trees seriously damaged). Of the trees 〉20 cm dbh, about 12% were uprooted in the bottomland forest, whereas only 2% were uprooted in sloughs. The storm reduced diversity in sloughs because most trees of species characteristic of better drained sites, and especially those rooted on nurse logs and other unstable elevated microsites, were uprooted. Dynamics of the entire forest were greatly influenced by the capacity of most tree species to recover vegetatively after suffering even severe crown and stem damage. Trees with resprouted crowns, however, were particularly likely to be broken, presumably owing to the presence of stem rots and architecturally unsound branching patterns.

Description: The relationship between budburst phenology and damage by the pear thrips (Taeniothripsinconsequens (Uzel) (Thysanoptera: Thripidae)) to sugar maple (Acersaccharum Marsh.) foliage was investigated in two studies. In the first study, seedlings in cages were exposed to adult thrips at different stages of budburst. Compared with uninfested control seedlings, introduction of five adult thrips per bud reduced total leaf area and average leaf size, and caused chlorosis, tattering, and cupping of leaves. Leaf area reduction and damage symptoms were greater for seedlings exposed to thrips when leaf margins were first visible at the tip of the bud compared with earlier and later stages of budburst. In the second study, budburst date and number of thrips oviposition sites on leaves (an index of thrips activity) were measured in a common-garden test of maple saplings from open-pollinated families. Thrips activity was greater on early-breaking than late-breaking buds. Date of opening for these early-breaking buds coincided closely with peak capture of flying thrips. Both budburst date and number of oviposition sites on leaves differed among families. Sugar maple genotypes with late budburst escaped heavy thrips damage. The results indicate that timing of vegetative budburst in sugar maple can influence the degree of thrips damage.

Description: It is recommended that the proportional bias in logarithmic regressions be estimated from the ratio of the arithmetic sample mean and the mean of the back-transformed predicted values from the regression. Under the assumption of a lognormal distribution of errors, the conditions for application of this ratio estimator are optimal. A simulated sampling study has shown that this method gives more reliable results than the methods recommended by Baskerville (G.L. Baskerville. 1972. Can. J. For. Res. 2: 49–53) or that derived by Finney (D.J. Finney. 1941. J. R. Stat. Soc. 7(Suppl): 55–61). The new method is also less sensitive to departures from the assumption of a lognormal distribution than the other two methods.

Description: This study investigates the relationship between lightning activity and the occurrence of lightning-ignited forest fires in the Northwestern Region of Ontario. We found that the Duff Moisture Code (a component of the Fire Weather Index System) and the multiplicity of the negative lightning discharges were the most important variables for estimating the number of lightning-ignited fires on a daily basis for Universal Transverse Mercator zone15 in Ontario. Also, the results indicate that negative lightning ignited more fires than positive lightning discharges, which is contrary to popular belief. Nearly 50% of the variance in the forest fire occurrence data was explained using linear stepwise regression. Future work will focus on finer temporal and spatial scales.

Description: The dynamics of 12 elements in decomposing leaf litter of jack pine (Pinusbanksiana Lamb.), paper birch (Betulapapyrifera Marsh.), trembling aspen (Populustremuloides Michx.), and northern pin oak (Quercusellipsoidalis E.J. Hill) were examined on a Typic Udipsamment (Orthic Regosol) in northwestern Wisconsin. Whereas the concentrations and absolute amounts of N, Ca, S, Zn, Mn, Fe, Cu, and Al generally increased after 1 year of decomposition, the levels of P, K, Mg, and B in decomposing leaf litter decreased. Two-way analysis of variance tests revealed significant differences in dry matter and concentrations and contents of most elements as a function of species and time elapsed. Macronutrients commonly were released from decomposing leaf litter in the following order (fastest to slowest): aspen 〉 oak = birch 〉 pine. The changes in N, P, Ca, and S in decomposing leaf litter generally followed the three-phase process described for N by other investigators. A cubic function described the initial-loss, accumulation, and final-release phases of these nutrients in decomposing leaf litter.

Description: Old-growth Pinusponderosa Dougl. stands were surveyed at Crater Lake National Park to investigate potential accelerated mortality of large pines due to prescribed burning. Mortality of P. ponderosa greater than 22 cm diameter at breast height was higher in burned areas (19.5%) than in unburned areas (6.6%), and early-season burns had over 30% mortality. Mortality was associated with fire severity, as measured by scorch height and ground char, season of burning, and tree vigor. Pines of high, moderate, and low vigor were subjected to a prescribed burn in June; half of the trees had debris raked from tree bases as an additional treatment. Lethal heat loads (〉60 °C) occurred in 〉75% of samples at the soil surface and at 5 cm soil depth, with duration exceeding 5 h. Burning reduced fine-root dry weight 50–75% 1 and 5 months after burning; raking and burning reduced fine-root dry weight more than burning alone after 1 month and had similar effects to burning after 5 months. A low-vigor tree that had been raked and burned died by the beginning of the fourth dry season after burning. Present fuel loads may be too high to burn during spring if old-growth P. ponderosa are to be protected.

Description: Volume and mass of coarse woody debris (〉 20 cm diameter) in an old-growth forest on the Cumberland Plateau in southeastern Kentucky averaged 66.3 m3/ha and 21.8 Mg/ha, respectively. Coarse woody debris was patchily distributed among 80 sample plots (0.04 ha each), with 10 plots containing 39% of the total mass. Coarse woody debris mass was inversely, although not strongly, related to plot basal area. While 23 species contributed to the accumulation of coarse woody debris, five accounted for 72% of the total mass. These included Quercusprinus L. (25% of the total), Fagusgrandifolia L. (16%), Quercusalba L. (12%), Castaneadentata (Marsh.) Borkh. (11%), and Quercusvelutina Lam. (9%). The few studies of coarse woody debris in old-growth deciduous forests of North America suggest a regional pattern of accumulation correlated with temperature. In warmer regions, old-growth deciduous forests accumulate a mass in the range of 22–32 Mg/ha, while in cooler ecosystems, coarse woody debris ranges from 34 to 49 Mg/ha.

Description: A clear relationship (P  0.05) from one ecoregion to another. The effect of moisture gradient on stand vigor and the biological performances of the spruce budworm may explain the results obtained.

Description: We examined four stands in a subalpine old-growth forest in the Coast Mountains of southwestern British Columbia for gap-phase structure. Though the stands varied in the proportions of each species, all had a similar distribution of area under closed canopy and in gaps (overall means: 29% closed canopy, 52% expanded gap, 18% canopy gap). Median areas of canopy gaps and expanded gaps were 41 and 203 m2, respectively. Most gaps (90%) had more than one gap maker, and gap makers within a gap were often from mortality events separated in time. Half of all gap makers died standing, and only 13% were windthrown. Pacific silver fir (Abiesamabilis (Dougl.) Forbes) was represented among gap makers in a much higher proportion than among canopy trees in general (64 vs. 45%). The estimated forest turnover time varied from 280–1000 years, depending on assumptions about the time taken for gaps to be filled. Distinctive features of gap-phase structure and dynamics in this forest are the high proportion of area in gap, small gap size, multiple gap makers of varying stages of decay, and long tenure of gaps before they are filled.

Description: Determining how land-use change effects atmospheric CO2 concentrations requires new approaches to research because of the large area and the long period of time involved. This special issue of the CanadianJournalofForestResearch presents a series of papers that demonstrate one approach to the problem. Estimates of the flux of carbon to the atmosphere are based on site-specific information concerning the effects of land-use change on the carbon content of terrestrial vegetation. This spatially explicit approach combines historical and current information on land-use change for a specific area. South and southeast Asia was chosen for the study because the region is undergoing major land-use changes and makes a significant contribution to atmospheric CO2. The results of the study have assisted in reducing the uncertainty about the magnitude of carbon release while providing new constraints to the analysis.

Description: Twenty-five soil media representing 13 subsoils and organic overlays, and their mixtures, that had been used in pot culture fallow, or for growing root, leafy vegetable and grass crops, were studied to determine if the benefits of organic amendments to crop yields in optimally watered and fertilized soils were due to improvements in soil physical conditions. The soils were subjected to particle and aggregate size fractionation; and the stability of the aggregates was determined. The results suggested that admixing of residual organic overlays improved the structure of all mineral subsoils, except perhaps an alluvial sand. Aggregation and stability of aggregates 〉 2 mm were improved, thus leading to improved aeration, root proliferation and to increases in crop yields. In addition, grass crops were shown to be more effective than root and leafy crops for improvement of the structure of the various soils. Key words: Organic soils, soil aggregation, soil structure stability

Description: We report the results of incorporating two changes in the data base that we used for our previously published summary estimates of the quantity of carbon released to the atmosphere from tropical land-use change (R.P. Detwiler and C.A.S. Hall. 1988. Science (Washington, D.C.), 239: 42–47). First, and most important, we used new statistical approaches to estimate biomass. Second, we incorporated recent minor modifications in the estimates of land-use change provided by the Food and Agriculture Organization of the United Nations. Our new, best estimate of carbon release for 1980 is 0.58 ± 0.06 Gt/year. The range of 0.06 Gt/year is due only to the statistieal uncertainty associated with the biomass data base and not to the uncertainty associated with other factors. (Our previous high estimate, based on the use of destructively sampled biomass, remains at 1.6 Gt/year). This new estimate for the tropics as a whole is 26% higher than the analogous number by Detwiler and Hall (R.P. Detwiler and C.A.S. Hall. 1988. Science (Washington, D.C.), 239: 42–47). About 7% of this increase in our estimates of carbon release from the tropics is a result of the new estimates of land-use change for open forests; the rest is due to changing estimates of biomass. In addition, we explored further uncertainties in our data base. When we reduced our estimate of the proportion of cut biomass that goes to long-term storage from 16 to 3%, carbon release increased by about 30%. We also examined the hypothesis that shifting cultivation could be ignored in our analyses. When shifting cultivation was not considered at all in our analyses, an underestimate of 20% resulted for the carbon release in 1980 for the entire tropics. The results of using different data sources for particular countries with large areas in shifting cultivation showed larger differences in carbon flux.

Description: The grass Calamagrostiscanadensis (Michx.) Nutt. often forms a dense growth after logging in the boreal forest region of western Canada. Mowing treatments were applied experimentally to examine the effects of C. canadensis shoot biomass and litter on soil thermal regimes. In unmowed sites with heavy accumulations of shoot biomass and litter (768 g•m−2), thawing of soil in the spring was delayed by up to 1 month compared with sites subjected to frequent mowing. Mean soil temperature from May to August at the 10-cm depth averaged 3.8 °C warmer in mowed plots than in unmowed plots. Mowing also caused a three- to four-fold increase in the diurnal variation in soil temperature. Based on the results from different mowing treatments, it appeared that the presence of standing dead C. canadensis shoots and litter was more important than living biomass in producing cold soils. Undisturbed sites dominated by Epilobiumangustifolium L. (fireweed), which does not form a persistent litter layer, had warmer soils than unmowed C. canadensis sites. Cold soils could partly explain the poor growth of conifer seedlings that often occurs after planting in grass-dominated boreal sites.

Description: Storage carbohydrates are extremely important for new shoot and root development following dormancy or during periods of high stress. The hypothesis that ozone decreases carbohydrate storage and decreases new root growth during the year following exposure was investigated. Ponderosa pine seedlings (Pinusponderosa Dougl. ex Laws.) exposed to ozone in 1989 were harvested prior to shoot elongation (nongrowing seedlings) and following a root growth test (growing seedlings) in the spring of 1990 to evaluate starch and soluble sugar concentrations. Seedlings exposed to the highest ozone level had 34% less lateral root biomass and 65% less new root biomass the following spring. Exposure to 122 and 169 ppm-h (sum of hourly means, 24 h/day, over the exposure period) during the 1989 growing season resulted in significant decreases of carbohydrate pools examined in both nongrowing and growing seedlings the following spring. Starch concentrations were most affected: at the highest ozone level, there were decreases of 43 and 44% in coarse and fine roots, respectively, of nongrowing seedlings, and 50, 65, and 62% in coarse, fine, and new roots, respectively, of growing seedlings. The results suggest that (i) ponderosa pine seedlings exposed to 122 and 169 ppm-h ozone for one season have significantly less root starch reserves available just prior to and during bud break the following year and (ii) spring root growth is decreased following ozone exposure. The carry-over effects of ozone stress may be important in long-lived perennial species that are annually subjected to ozone.

Description: Sulfur deficiency has become a widespread limitation to crop production in western Canada. A variety of S sources are commercially available to alleviate these deficiencies but not all are equally effective. Three elemental S products (a finely-divided suspension and two elemental S + bentonite) and ammonium sulfate were compared over a 3-yr period in central Alberta. These products were applied to barley and canola at various rates (0–120 kg S ha−1) in a factorial arrangement with various supplemental rates of sulfate-S (0–40 kg ha−1) in two experiments Fertilizers affording effective and reliable alleviation of S deficiency in the year of application included sulfate forms and finely-divided elemental S products that can be readily mixed into the soil. The residual benefits of the various fertilizer products examined appeared to be comparable despite large differences in short-term availability. The absence of appreciable residual advantage of slow-release elemental S products was attributed to the short duration of S assimilation by canola and barley and the susceptibility to leaching of S oxidized after that period. Key words: Barley, canola, residual, rotation, S fertilizer, uptake, yield

Description: A common pedological feature in Podzols and Podzolic-like soils in the forest region of Hinton, Alberta is the presence of nodules in the Bf horizons with diameters of 1—20 cm. The nature of these nodules was investigated through physical, chemical, mineralogical and micromorphological examinations. Results showed that the nodule microstructure is mainly bridged-grain type compared to dominantly pellicular type for the soil matrixes. The basic building blocks are (a) coarse components (〉 5 μm): quartz, feldspars mainly albite, pseudo sands, sand-sized chlorites and small quantities of anthophyllite, sillimanite, andalusite and lithogenic hematite; (b) fine components (

Description: The effects of crop rotations and various cultural practices on soil organic matter quantity and quality in a Rego, Black Chernozem with a thin A horizon were determined in a long-term study at Indian Head, Saskatchewan. Variables examined included: fertilization, cropping frequency, green manuring, and inclusion of grass-legume hay crop in predominantly spring wheat (Triticum aestivum L.) production systems. Generally, fertilizer increased soil organic C and microbial biomass in continuous wheat cropping but not in fallow-wheat or fallow-wheat-wheat rotations. Soil organic C, C mineralization (respiration) and microbial biomass C and N increased (especially in the 7.5- to 15-cm depth) with increasing frequency of cropping and with the inclusion of legumes as green manure or hay crop in the rotation. The influence of treatments on soil microbial biomass C (BC) was less pronounced than on microbial biomass N. Carbon mineralization was a good index for delineating treatment effects. Analysis of the microbial biomass C/N ratio indicated that the microbial suite may have been modified by the treatments that increased soil organic matter significantly. The treatments had no effect on specific respiratory activity (CO2-C/BC). However, it appeared that the microbial activity, in terms of respiration, was greater for systems with smaller microbial biomass. Changes in amount and quality of the soil organic matter were associated with estimated amount and C and N content of plant residues returned to the soil. Key words: Specific respiratory activity, crop residues, soil quality, crop rotations

Description: In pursuit of identifying sustainable agricultural production practices, there is an urgent need to develop or identify parameters that effectively describe and differentiate changes in the quality and quantity of soil organic matter resulting from crop management or cultural practices. The effectiveness of the potentially mineralizable nitrogen (No) concept for this purpose was examined using data from a 30-yr crop rotation study, carried out on a Rego thin Black Chernozem at Indian Head, Saskatchewan. Although Kjeldahl N and hydrolyzable soil amino-N are effective for demonstrating the beneficial influence of fertilizers, legumes and continuous cropping on total soil organic N content, they are less effective in identifying changes in organic matter quality. We have shown that a parameter which we called the "initial potential rate of N mineralization" [potentially mineralizable N (No) × rate constant (k) at time = 0] was effective in distinguishing both the absolute and qualitative changes in soil organic N due to various cultural and management practices. The results showed that fertilizers can be as effective as legumes, used either for green manure or for hay, in increasing the quantity and improving the quality of soil organic matter. A 6-yr rotation including 1 yr of fallow, 2 yr of spring wheat (Triticum aestivum L.) and 3 yr of bromegrass (Bromus inermis Leyss) and alfalfa (Medicago sativa L.) hay had a greater quantity and improved quality of soil organic N relative to that of unfertilized continuous wheat (Cont W), but they were equivalent to that of fertilized Cont W. Key words: Soil quality, potential mineralizable N, crop rotations, legumes, fertilizer effects

Description: Growth chamber and laboratory studies were conducted to investigate the distribution and plant availability of copper (Cu) fractions in Saskatchewan soils. These studies included an examination of the distribution of Cu fractions in 27 soils and an evaluation of plant availability of native and added Cu fractions in beans (Phaseolus vulgaris L.) grown in seven soils. The soils in these experiments were selected to give a wide variation in physical and chemical properties. Total Cu content of the 27 soils ranged from 6.5 to 39.0 μg g−1 with an average of 21.0 μg g−1. A seven-step sequential fractionation showed that most of the total Cu (49.0–78.0%) was present in the residual fraction (Res-). The percentages of soil Cu in the exchangeable (Ex-), Pb-displaceable (Pb-), acid soluble (Aci-), Mn oxide bound (MnO-), organically associated (OM-) and Fe, Al oxide bound (FeO-) fractions averaged 2.2, 1.5, 2.0, 4.8, 7.9 and 11.1%, respectively. Amounts of Cu in MnO-, FeO-, Res- fractions and total Cu were interdependent and varied directly with DTP A- extractable Cu and clay content. The growth chamber experiment showed that the most of the applied Cu was accumulated in MnO-, OM-, FeO-, and Res- fractions. Therefore, sesquioxides and organic matter are the major components responsible for the adsorption of added Cu. The concentration of Cu and its uptake into navy beans were positively correlated with DTPA-extractable Cu, MnO-Cu, FeO-Cu and total Cu, which in turn were correlated with clay content. Plant Cu concentration and uptake can be predicted by an equation which includes DTPA-extractable Cu and clay content. These results showed that DTPA-extractable Cu is a good predictor of Cu availability in prairie soils. Key words: Cu fractions, distribution, availability, DTPA-extractable Cu, clay content, navy beans

Description: A red clover intercrop was evaluated in terms of its ability to provide soil erosion protection and its effects on silage corn yields on a Conestoga loam soil at the Elora Research Station, Elora, Ontario. The soil and runoff losses from experimental plots of silage corn (corn system) and silage corn intercropped with red clover (corn/clover system) were compared using the Guelph Rainfall Simulator II. Measurements were made in November 1987 and October 1988, and in April, May, June of 1988 and 1989. Rainfall was applied for 10 min (15 min in June of 1988) on a 1-m2 quadrat at an intensity of 16 cm h−1. Soil loss was significantly (P 

Description: Four erosion plots were monitored from 1983 to 1989 (6 yr) to evaluate the effects of two crop rotations and their constituent crops on runoff and soil loss under natural precipitation near Fort St. John in the Peace River region of British Columbia. Rotation 1 consisted of two cycles of summerfallow — canola (Brassica rapa)-barley (Hordeum vulgare L.), and Rotation 2 included summerfallow — canola-barley-barley underseed to red fescue (Festuca rubra L.)-fescue-fescue. Rainfall and snowmelt runoff were collected and sampled throughout the year to determine seasonal runoff and soil losses. Over the 6 yr, the cumulative runoff and soil losses were consistently greater under Rotation 1 than under Rotation 2. There was a greater than fourfold difference in total soil loss, and 33–35% more total runoff. Rainfall-induced runoff and soil losses were significantly higher for Rotation 1 than for Rotation 2. Snowmelt runoff accounted for 90 and 96% of the total annual runoff and for 39 and 80% of the total annual soil loss from Rotations 1 and 2, respectively. Two large rainfall events during 1983 and 1987, each causing a soil loss in excess of 2000 kg ha−1, accounted for between 85 and 91% of the 6-yr total rainfall-induced erosion from Rotation 1. No differences in runoff or soil loss were detected among crops but the comparisons were insensitive because of high residual variation. Key words: Runoff, soil loss, erosion plots, crop rotations

Description: Variabilities in measured values of wet aggregate stability (WAS) of replicate samples of treatment exceeding that between treatments can create problems in interpreting treatment effects. The variabilities in WAS of replicate samples of treatment can be minimized by subjecting soil aggregates to a high vacuum fast prewetting technique. However, this technique is laborious and time consuming. In this paper the effect of four prewetting techniques: (1) and (2) high vacuum fast (HVFW) and slow (HVSW) wetting; (3) and (4) no vacuum (atmospheric) fast (NVFW) and slow wetting (NVSW) on the variations in WAS and coefficient of variation (CV) of WAS are reported. The measured values in WAS and CV of WAS for each soil varied with wetting rate and/or gas pressure used. The highest variation in WAS was found with NVFW, HVFW, NVSW and HVSW, respectively. For three out of four soils, the CV of WAS for NVSW technique was less than 2%, which was similar to that obtained under HVFW technique. Compared to HVFW technique, NVSW technique is simple, less laborious and less time consuming. Key words: Wet aggregate stability, prewetting techniques, vacuum wetting.

Description: Saskatchewan producers growing primarily spring-seeded cereals may be interested in diversifying their cropping alternatives. Winter wheat (Triticum aestivum L.) could provide one possible option, but its management could cause conflict with the busy fall and early spring activities for spring-seeded crops. A study was conducted at five sites (Swift Current, 4 yr; Melfort, 4 yr; and Scott, Lashburn, and Loon Lake, 1 yr each) in four soil zones (Brown, Dark Brown, and Black Chernozems and Gray Luvisol). The effect of time of application of N (seeding to early spring), source of N (ammonium nitrate vs. urea), and method of application (broadcast, midrow band, and seed-placed) on yield and grain protein concentration were investigated. The results varied with site and year (weather). Time of N application only influenced yields at Swift Current (Brown soil) where application on cool unfrozen soil in mid-October was as good as application in early spring and better than at other times, and application onto frozen, snow-covered soil in December was least effective. At Swift Current and Melfort, grain protein concentration did not respond to time of application; however, at Scott, Lashburn and Loon Lake, protein was highest for spring-applied N, followed by mid-October, and lowest when N was applied on frozen snow-covered soil. The effect of N source rarely affected grain yield or protein and was dependent on site and method of placement. The dangers of seed-placing N, especially urea, on overwinter survival and yields were evident in 2 yr at Swift Current. There was rarely any difference in yield or grain protein concentration when N was banded or broadcast at seeding time. Taking into account convenience of operation, the most opportune time for Saskatchewan producers involved in growing both spring and winter wheat to apply N would be mid-October in the Brown soil zone. In the other soil zones, early spring would be best. Broadcasting the N was the most appropriate method of application at all sites. Urea would be chosen over ammonium nitrate because there was little advantage of one source over the other and urea is generally cheaper. Key words: Urea, ammonium nitrate, protein, grain yields, plant population

Description: Lambert sweet cherry (Prunus avium L.) established on Osoyoos loamy sand in 1983 was subjected to treatments involving all combinations of two types of irrigation (wellwater or municipal wastewater) and three rates of N fertilization (0, 68 and 136 g of N as NH4NO3 tree−1 yr−1), 1984–1987. The zero-N treatment was increased to 34 g N tree−1 in 1986–1987. Wastewater irrigation increased leaf N, P, K, B and Mn concentration, decreased leaf Mg and Ca and had few consistent effects on leaf Fe and Cu. Tree growth was increased after 2 yr but not after 5 yr by wastewater irrigation. Inadequate N and Zn nutrition appeared to limit long-term tree growth. After 5 yr, wastewater-irrigated soils had higher extractable P, K, and B and lower Ca and Mg than well-water-irrigated soils which had higher Ca and Mg to 0.9-m depth. Wastewater irrigation also increased extractable Na throughout the soil but insufficiently to adversely affect tree growth. Soil pH and electrical conductivity also increased during the experiment for both well- and wastewater-irrigated soils, but these increases did not cause alkalinity or salinity problems. Key words: Prunus avium L., wastewater irrigation, leaf nutrition, soil quality

Description: Reduced soil water under grazing is generally attributed to reduced infiltration as livestock trampling compacts the soil surface. Grazing can also have the opposite effect on soil water through reduced evapotranspiration when vegetation is removed. On the Canadian Prairies, grazing impacts on soil water have been assessed in short-term studies but impacts of long-term grazing have not been documented. In this study, impacts of long-term grazing on soil water were assessed in mixed prairie, parkland fescue grassland, and foothills fescue grassland ecosystems of southern and central Alberta. Grazing regimes were of light to very heavy intensities, grazed early, late, and continuously during the growing season. Soil water was measured with a neutron probe to a depth of 1 m from April through October over three growing seasons. Normal patterns of soil water recharge in autumn and spring and soil water depletion in summer due to evapotranspiration were not altered by grazing. Fluctuations in soil water were most pronounced in the uppermost 30 cm but still evident in the 30- to 50-cm and 50- to 80-cm depth intervals. Heavy intensity and/or early season grazing had a greater impact on soil water than light intensity and/or late season grazing. Season of grazing affected soil water more under light than heavy grazing intensities. On most sampling dates, soil water in grazed treatments was lower than in the ungrazed control, particularly in the 30- to 50-cm and 50- to 80-cm depth intervals. Differences between the control and grazed treatments were least pronounced during the summer months with evapotranspiration depleting soil water reserves in all treatments. Key words: Soil water, grazing, rangelands, water uptake

Description: A comparative composting trial with wood shavings (WS), sawdust (SD) and peat moss (PM) was carried out under field conditions. In each, fresh material was mixed with cattle manure in a 2:1 ratio by volume. The initial pH of the WS, SD and PM composts (CST) were 6.2, 5.1 and 5.3, respectively. The chemical and biological changes in CST related to maturity were determined. Samples taken at 0, 12 and 24 mo of composting were also mixed with soil and increasing rates of N and tested as growing media for faba beans (Vicia faba L.) and corn (Zea mays L.) under greenhouse conditions. During composting, the C/N and E4/E6 values decreased in all cases but much more rapidly in WS pile. Thus, after 36 mo of composting, the C/N value decreased from 43 to 17 in WS pile and from 48 to only 35 in PM pile. As indicated by a low C/N ratio (17) and lower humic absorbance values (E4/E6 = 6.4), WS material was practically mature after 24 mo, more rapidly than SD and PM composts which presented initial lowest pH values. The microbial respiration rate (CO2), the pH and N–NO3 values increased during composting in all materials but much more in WS than in SD or PM pile. All composts were not harmful to plant growth even after a short time of composting (12 mo), but yields increased with the duration of composting. These data showed that it was possible to obtain, in field conditions, a compost from ligneous materials in 24 mo. Key words: Compost, composting, corn (Zea mays L.), faba beans (Vicia faba L.), microflora, peat moss, sawdust, wood shavings

Description: A 3-yr program was carried out in central Alberta to evaluate the immediate and residual contributions of various fertilizer sulfur sources to the pool of plant-available sulfate in soil. Three elemental sulfur products, a finely-divided suspension and two elemental sulfur + bentonite products, and ammonium sulfate were applied at various rates (0–120 kg S ha−1) in factorial arrangement with various supplemental rates of sulfate (0–40 kg S ha−1). Temporal patterns of plant-available sulfur release varied significantly among fertilizer S sources, suggesting different agronomic niches for the various forms. While ammonium sulfate and the finely divided S suspension provided almost immediate correction of S deficiency, the S-bentonite products appeared be better suited to long-term maintenance of soil S fertility. The relatively slow release of plant-available S in the latter products was attributed to ineffective dispersion of the products in the soil. These slow-release characteristics need to be considered in the formulation of fertilizer recommendations on soils previously amended with S-bentonite products. Key words: Oxidation, plant availability, residual effect, S fertilizers

Description: This study was undertaken to examine the relationship between periglacial processes and the development of soil structure in some Turbic Cryosols. Three active nonsorted pattern ground features (mud hummocks) were examined for field macrostructure and micromorphological characteristics. The surface of unvegetated mud hummocks exhibited granic fabric expressed as strong granular structure. Cryoturbic movement caused surface materials to be cycled downward toward the permafrost table and upward into the hummock core. Resultant compression caused coalescence of discrete structural units resulting in matrigranodic fabric and subangular blocky structure. Porphyroskelic fabric associated with massive and occasionally prismatic structure was observed in the core of the hummocks although some remnant granularity was evident in thin section. Cycled fragments of surface vegetation 10–1000 μm in length were observed dispersed through all soil horizons. All horizons within the active layer contained more than 2% organic carbon. Key words: Turbic Cryosol, micromorphology, soil structure, cryoturbation

Description: Winter wheat (Triticum aestivum L.) can be successfully overwintered in most regions of the Canadian prairies if it is sown without prior tillage into standing stubble immediately after harvest of the previous crop. Soil nitrogen (N) is usually deficient in this production system and N fertilization is necessary to optimize yield and maintain minimum quality standards. In the present study, the effect of seed-placed (SP), early-spring broadcast (BC), and SP/BC combinations of ammonium nitrate fertilizer (AN) on winter survival, grain yield and protein production of winter wheat was investigated in 15 field trials conducted over a wide range of soil types and environmental conditions in Saskatchewan. Ammonium nitrate fertilizer placed in a 20-mm-wide band with Norstar winter wheat seed produced average grain yield responses for 34, 67, and 101 kg N ha−1 treatments that were 98, 84, and 71% of comparable BC treatments, respectively. Average grain protein yield responses for the 34, 67, and 101 kg ha−1 SP N treatments were 94, 82, and 74% of comparable BC treatments, respectively. Grain protein concentration responses were similar for comparable BC and SP N treatments. Yield responses for 34 kg N ha−1 SP and BC treatments indicated that AN could be seed-placed at low rates without significantly reducing N-use efficiency. However, significant reductions in winter survival potential in all trials where differential winterkill occurred suggested that even rates as low as 34 kg N ha−1 SP AN should be avoided when cultivars with marginal winter hardiness are utilized. Key words: Winter wheat, no-till, seed-placed N, yield, protein, winter survival

Description: The efficiency of 15N-labelled fertilizer on early harvested potaotes (Solanum tuberosum L., 'Norland') was studied in field experiments on two soil series (Saint-Damase loamy sand and Soulanges sandy loam) during a 2-yr period. The 15NH415NO3 fertilizer was band applied at 0 and 140 kg N ha−1 in 1985 and 0, 70, 140 kg ha−1 in 1986 and four harvests were made during the growing season. The foliage was in full canopy development at 65 or 75 d and its dry matter yield increased significantly with the application of fertilizer-N. At this time about 70% of the total N uptake was in the foliage. From this peak, foliage N decreased gradually with time to about 28% at 95 or 100 d as N was transferred to the tubers. The N concentration in tubers was nearly constant during the growing season. As tuber dry matter increased at each successive harvest, N uptake increased proportionally. Between the first two harvest dates, from 65 to 75 d, the average rates of N accumulation in tubers were 2.1 and 4.5 kg N ha−1 d−1 for the control and N fertilized plot, respectively. The root dry matter and N concentration increased with fertilizer-N and were generally lowest on the final harvest day. Marketable tuber yield responded to N fertilization on the severely N-deficient fields in 1985. But in 1986, the 140 kg N ha−1 treatment delayed the growth of marketable tubers. The percentage of N derived from fertilizer (Ndff) was also very high in 1985 fields and was at a maximum at 65 d (64–69%) with the 140 kg N ha−1 treatment. These values were lower for the same treatments in 1986 fields (39%) because of the larger amounts of available N in soils. The maximum coefficient of utilization (ICU) of labelled fertilizer N was 72–76% in 1985 and 63–68% in 1986. At the final harvest, about 36–50% of the applied fertilizer-N was found in the tubers. Key words: Nitrogen fertilization, 15N-labelled fertilizer, N use efficiency, harvest periods, potato

Description: Since there is little information on compound particles in the size range 2–20 μm, the genesis of the initial stages of soil aggregation was examined by transmission electron microscopy on ultrathin sections of the rhizospheres of Lolium perenne L. grown in attapulgite. Since attapulgite contains neither microorganisms nor organic matter, microorganisms were added as a soil suspension and all the organic matter was supplied by the ryegrass roots. Clusters were formed de novo by accumulation of attapulgite particles on root gel, on root cell fragments, and on microbial extracellular polysaccharides. Microaggregates were formed by the fusion of attapulgite-coated bacteria, colonies and cell remnants. Aggregates persisted after the death of the microorganisms. Key words: Microaggregates, clusters, soil ultrastructure, rhizosphere, extracellular polysaccharides

Description: A soil bacterium has been isolated from field soils receiving annual applications of 2,4-D and tentatively identified as Pseudomonas testosteroni Marcus and Talalay. When added to a sprayer tank containing an aerated solution of simple mineral salts and 2,4-D amine formulations, this organism used the herbicide as a carbon source, with stoichiometric release of chloride. This system has been used to biologically degrade 2,4-D amine residues from farm operations and herbicide containers. Key words: Degradation, bacterium, residues, soil, 2,4-D

Description: Maize plants were grown in nutrient solution containing 0, 15, 30, 50 mg organic carbon L−1 of humic substances (HS) (M.W. 〈 12 KDa) extracted from a cambisol. After 14 d of growth the second and third leaves were collected and analyzed for chlorophyll and protein content and for the activities of ATP sulphurylase (ATP-s) and O-acetylserine sulphydrylase (OAS-s) to evaluate the effect of HS on maize sulphate assimilation pathway. Humic substances induced significant decreases in chlorophyll content, whereas the protein level slightly increased up to 30 mg L−1 of HS. ATP-s and OAS-s were positively affected by HS. The stimulations were different according to the enzyme and leaf investigated. Our results suggest that HS might play an important role in the efficiency of maize plants to assimilate sulphate. Key words: ATP-sulphurylase, chlorophyll, humic substances, maize, O-acetylserine sulphydrilase

Description: Field experiments were conducted for 3 yr on a Black Chernozemic soil at Melfort in northeastern Saskatchewan to determine the yield response and N uptake of seven crop/cultivars to autumn and spring applied N. The crop/cultivars were, rapeseed (Brassica napus L. 'Midas' and 'Target'; Brassica campestris L. 'Torch' and 'Echo'); wheat (Triticum aestivum L. 'Manitou'); barley (Hordeum vulgare L. 'Conquest') and flax (Linum usitatissimum L. 'Noralta') (main plots). Ammonium nitrate fertilizer treatments consisted of three rates of autumn broadcast N, 0, 34 and 67 kg N ha−1 (subplots), combined with N at 0, 11, 22, 45, 67 and 134 kg N ha−1 side-banded with seed in the spring (subsubplots). At the 67 kg N ha−1 rate, autumn application was inferior to spring application in increasing grain yield and N uptake for three of the seven crops (Torch and Echo rapeseed and Manitou wheat). Nitrogen fertilizer applied at 134 kg N ha−1 in spring produced grain yields that were not significantly higher than the split application of 67 kg N ha−1 applied in autumn and 67 kg N ha−1 applied in spring. All crops responded to spring applied N and continued to increase in yield up to the high rates of 67 or 134 kg N ha−1. Key words: Time of N application, N, crops, cultivars

Description: Field studies were conducted in Prince Edward Island (PEI) on the Fe nutrition of cereals and forages and to determine the relationship between plant Fe and soil pH. The Fe concentration in barley (Hordeum vulgare L.) and oats (Avena sativa L.) boot stage tissue (BST) and grain ranged from 35 to 65 and from 19 to 42 mg kg−1, respectively, in the control and from 38 to 57 and from 22 to 45 mg kg−1, respectively, in the soil applied Fe treatments. In the foliar applied Fe treatments, the cereal BST contained as much as 121 mg Fe kg−1 in the FeSO4.7H2O treatments and up to 86 mg kg−1 in the chelate-Fe treatment, but neither of these two sources increased Fe concentration in the grain. In the first cut of forages in the foliar treatments, the Fe was as high as 131 mg Fe kg−1, but no differences were generally found between the control and Fe treatments in the second cut. Over the soil pH ranges of 4.5–6.9, no consistency was found in the correlation coefficient (r) values between plant Fe and soil pH. In spite of the Fe concentrations as low as 19 mg kg−1 in cereal grain and 23 mg kg−1 in forages in the control treatments, no yield response to added Fe was found. However, the Fe concentrations as found in this study would be considered deficient for livestock and mineral supplements of Fe to the feeds may be desirable. Key words: Cereals, forages, soil pH, plant iron, acid soils

Description: Micromorphological observations, C/N values and 14C datings of organic matter were used to evaluate impacts of biological activities on the development of loose and cemented podzolic horizons of a toposequence in the St-Lawrence Lowland. In well-drained soils, the B horizons containing roots have two distinct microstructure types: (1) a microstructure with organic aggregates in root zones (

Description: Two soils from a large depressional area, one with (AL) and one without (NL) a volcanic-ash layer, were investigated to determine the effect of the ash layer on soil properties. The soil parent materials, including the ash layer, were deposited in a lacustrine environment. Both soils had well-developed A and B horizons with secondary salinity. The AL soil contained less Na in the B horizon than the NL soil, resulting in a soil classification of salinized Gleyed Solonetzic Dark Brown Chernozem at the AL site and salinized Gleyed Dark Brown Solonetz at the NL location. Saturated hydraulic conductivity and moisture retention values indicated that the volcanic-ash layer enhanced the depth of effective drainage. This was supported by greater rooting depth, weaker B horizon structure, lower salinity, and dominance of different ions in the upper solum of the AL than in the NL soil. The distribution of soluble ions in the profiles indicated that the ash layer had negligible impact on the height of capillary rise. Lower soluble ion contents in the lower profile of the AL than the NL soil were attributed to the presence of an indurated or cemented layer between the water table and the ash layer in the AL soil. Key words: Soil properties, volcanic-ash, water movement, soluble salt movement, indurated horizon

Description: not available

Description: A tubular metallic probe was built. Water and gases released into the sample chamber of the probe from the 45- to 60-cm depth could be collected in 1-min segments without exposure of the peat surface in the hole to the atmosphere. The evolved gases were identified and concentrations measured by gas chromatography. The water movement into the hole was found to vary by 3 orders of magnitude, apparently depending on whether the probe pierced a significant pocket of trapped (occluded) methane, or was close to, or away from any such pocket. It was concluded that the instrument developed would be suitable for characterizing the occurrence and movement of the gas-fluid mixture in peatland layers which would facilitate the development of new or modified mathematical models of gas and water transmission in peatlands. The study also indicated that methane, but not carbon dioxide, is occluded in the gaseous phase in amounts significant enough to influence water movement. Key words: Water movement, methane, bog

Description: Two growth chamber experiments were conducted to assess the plant availability of Zn fractions in nine Saskatchewan soils. In one experiment, two rates of Zn (0, and 5 mg kg−1) were applied to navy beans grown on seven soils ranging in pH from 6.2 to 7.8. Most of the applied Zn was recovered in Pb-displaceable and Mn oxide associated fractions after a 7-d incubation. Growth of navy bean plants was normal in all soils and treatments. Dry matter yield did not respond to Zn application. The positive correlations between amounts of Zn in exchangeable, Pb-displaceable and acetic acid soluble fractions and plant uptake indicated the importance of these Zn fractions in influencing availability of Zn. The DTPA soil test was not a successful method for prairie soils with diverse soil properties on the basis of correlations. In the second experiment, three rates of Zn (0, 5 and 10 mg kg−1) were applied to alfalfa grown on two soils with pH of 5.5 and 7.9. The total dry matter yield of alfalfa grown on the calcareous soil was increased significantly by Zn application. No yield response to added Zn was observed in the acidic soil. In both soils, applied Zn increased the Zn concentration and total Zn uptake of alfalfa significantly over the control treatment. Changes in the distribution of applied and native Zn in different fractions before seeding and at second harvest suggest that Zn taken up by plants in the calcareous soil was from exchangeable, acid soluble and possibly residual Zn. Zinc uptake by plants grown on the acid soil was from exchangeable, Pb-displaceable, acid soluble and possibly from Mn oxide associated fractions. Key words: Zn fractions, plant availability, navy beans, alfalfa, pH

Description: Pedogenesis and its effect on calcium (Ca), magnesium (Mg) and phosphorus (P) was studied on a sequence of seven Gray Luvisol soils in central Saskatchewan. The soils were formed on calcareous glacial till under trembling aspen (Populus tremuloides Michx), mixedwood (aspen and white spruce) (Picea glauca (Moench) Voss)) and coniferous (black spruce and jack pine) (Picea mariana (Mill) BSP and Pinus banksiana Lamb) forests. Soils under aspen had the highest concentration of total and exchangeable Ca and Mg in litter layers and Ae horizons, and had Ae and Bt horizons that were least acidic. The most acidic Ae and Bt horizons and lowest amounts of Ca and Mg occurred under coniferous forests, whereas the soils under mixedwood stands were intermediate. The thickness of eluvial (Ae and AB) horizons increased along the aspen to coniferous sequence. All soils had about 40% less P in their A and B horizons than was calculated to have been present at the start of soil formation. The greatest decrease in P was observed in the thickest and most acidic soil under coniferous forest. The present litter layers and vegetation make up only a small proportion of the P removed from the mineral soil. Unusually large amounts of P appear to have been translocated from A and B horizons during development of Gray Luvisols, in comparison to Chernozemic or even Podzolic soils. Our hypothesis proposes that P is ineffectively retained in the solum as P-clay-humus, or iron-P complexes and that organic P moves along with the soil water, laterally and downslope through permeable Ae horizon over less permeable Bt horizons, or vertically through macropores. Key words: Boreal forest, nutrient cycling, phosphorus losses, weathering, soil formation

Description: Sixteen soil sampling schemes were evaluated in a case study using geostatistical analyses to determine their impact on directional sample variograms and kriging. Soil bulk density measurements for each sampling scheme were obtained from an intensively sampled grid, and kriging was used to estimate the bulk densities not included in the sampling scheme. The kriged bulk density estimates for all sampling schemes were verified using a minimum of 6168 observed values. Grid sampling for this study required more samples than stratified random sampling and the stratified-grid sampling schemes, but the accuracy of the kriged estimates was comparable for all sampling schemes. Key words: Kriging, variogram, soil density

Description: GIS are ideal software tools for managing spatially referenced data. While such systems offer tremendous opportunities for efficient integration of land resource data, certain types of data combination and analysis are not appropriate. Data from the Soil Landscapes of Canada (SLC) Map for Alberta, detailed soil sites and long-term climate stations are used to demonstrate the importance of this consideration. Key words: Geographic information systems, GIS, soil sites, soil map

Description: not available

Description: The effect of magnesium application on the production and chemical composition of flue-cured tobacco was observed over a period of 3 yr to determine the most effective source and the best rate of Mg application. Magnesium increased gross return and magnesium content of the plant while decreasing potassium and zinc contents. Only the Mg applied as double sulfate of potassium and magnesium (Sulpomag) increased yield, gross return and Mg content of the plant. An application of 10 kg ha−1 of Sulpomag is satisfactory to reach a good production on soils low in Mg. Key words: Flue-cured tobacco, magnesium, rate, form, total alkaloids, total nitrogen, reducing sugars

Description: In order to estimate the reliability of soil information presented in a detailed soil survey (1:20 000 scale) conducted in a flat terrain (Vercheres county, Quebec), 35 randomly selected delineations were inspected with 10 sites per delineation. Reliability was evaluated according to parent material (marine, estuarine and fluvial) and kind of map units (simple and compound). As a whole, mineral soils have been mapped and defined reliably for most criteria commonly used in soil interpretation systems. Reliability of soil information differed significatively with parent material. Taxonomic purity of marine, fluvial and estuarine soils delineations were 70, 58 and 28%, respectively. Although less precise, compound map units were more reliable than simple map units. Among the 13 soil variables studied, A and B horizons texture, B horizon designation and depth to carbonates were the more frequently in error. Results finally indicated that reliability is also a function of the delineation area and inspection density. In order to improve reliability of soil information and accelerate soil survey in future projects, it is suggested to adjust inspection density according to parent material, to reduce the number of classes for a few variables and to avoid excessive use of soil series'variants and delineations of small size (

Description: not available

Description: Soil water properties were estimated in the field, using guidelines established in Canada, for five volcanic-derived soils in Tanzania. Many of the estimates for horizons near the surface were satisfactory but those for water retained at − 1500 kPa by horizons below a depth of 1 m were far too low. These low estimates combined with underestimates of air porosity at − 10 kPa for many of the samples resulted in very poor estimates of available water capacity. The guidelines were not directly applicable for estimating water properties of most of the soils studied. The samples had bulk densities of 0.9–1.3 Mg m−3, air porosities at − 10 kPa ranging from 3 to 27%, and available water capacities of 280–116 mm to depths of 140 cm or to a petrocalcic layer. X-ray analysis indicated weakly crystalline clays in all of the soils. Tiron extracted from 7 to 38% of the material from the

Description: Nine years after liming a sandy loam orchard soil to pH 6.0 with calcium hydroxide or dolomitic lime, pH and extractable Ca and Mg were still higher where limed than where unlimed. However, pH had decreased below 5.0 in the limed and N-fertilized plots. Delicious (Malus domestica Borkh.) apple tree nutrition benefited from the two soil amendments. Leaf Mg was increased by dolomite. Leaf Ca was increased by calcium hydroxide. Leaf Mn, although highest in unlimed soils, increased over time for both limed and unlimed soil. Key words: Apple, lime application, reacidification

Description: Phosphate solubility and sorption characteristics of 39 agricultural soils in the northwestern Canadian Prairie were studied to gain insights into the retention of fertilizer P added to soil. The soils were mostly acidic with base saturation of 59–95%. The solubility of P as determined by the equilibrium P concentration and phosphoric acid potential was low and appeared to be controlled by sorption of phosphate by soil components. The mean equilibrium solution P concentration was 0.03 mg L−1. Phosphorus concentration in saturation extracts was about one order of magnitude higher, but would have included organic and colloidal P since P analysis in these extracts was done by ICP. Sorption capacity of P as determined by Langmuir isotherm was greater for the Dark Gray and Black soils and gleysols, i.e., soils with higher amounts of organic matter, than the Gray Luvisolic and Solodic soils by about 30%. Partial correlation showed that clay content, Al-organic matter complexes (AlOM) and amorphous iron oxide (FeOX) were significantly correlated with P sorption capacity. When both topsoils and subsoils were considered, clay content was the most important soil property influencing P sorption capacity, followed by AlOM and FeOX (standard partial regression coefficients, b′, of 0.47, 0.39 and 0.38, respectively). When only topsoils were considered, AlOM and FeOX became more important than clay content in influencing P sorption (b′ = 0.47, 0.47, and 0.33, respectively). Native P, estimated by oxalate and anion-resin extractions, was associated with the hydrous iron oxides only, although soil pH also affected the resin-extractable P fraction. Key words: P retention, solubility, Luvisols, solodic soils

Description: To investigate pH-controlled chemical reactions associated with the neutral salt measurement of exchangeable cations in acid soils, and to estimate the potential error caused by such reactions, a series of experiments was performed which modify an established BaCl2 extraction method. Results showed that dissolution of amorphous silica, aluminum hydroxides and organic material occurs during neutral salt extraction, contributing cations to solution which are indistinguishable from exchangeable cations. As a result overestimates of exchangeable Al and Ca occur, but the error is not significant (〉 10%) except in certain Ae horizons which are low in total CEC and high in exchangeable acidity. The 2-h BaCl2 method is recommended over the 4-hour NaCl method to minimize interference from weathering reactions. Key words: Cation exchange, exchangeable acidity, Al, H, acid forest soils, weathering

Description: This paper examines those variations in soil properties of woody fallows that may be expected as a result of the use of the tree Gliricidia sepium (Jacq.) in fallow management in the forest areas of Nigeria. A comparative analysis of fallows of the tree and natural fallows was carried out. The results show that differences might be expected between the soil under the two fallow types with respect to pH, boron and available phosphorus. It is suggested that the tree is a suitable species for fallow enhancement in terms of soil restoration but that its use would involve some modification of soil management practices such as the amount and type of fertilizers applied. Key words: Gliricidia sepium, fallow management, soil restoration, woody fallows

Description: Available soil water (ASW) in the rooting zone of mature peach (Prunus persica (L.) Batsch 'Harken/Siberian C.') trees was determined with a neutron probe at incremental depths down to 240 cm between 1979 and 1982. The trees were either not irrigated (I0) or irrigated at a frequency necessary to prevent ASW from falling below 25% (I25) or 50% (I50) in the top 30 cm of soil. Water content in the top 120 cm from May to September for I0 plots was about 37 mm less than I25 plots and 73 mm less than I50 plots. Nonirrigated plots (I0) had the lowest ASW (〈 30%) in the soil profile to a depth of 240 cm from mid-growing season onwards. By contrast, irrigated plots (I50) had high ASW (100%) at and below the 100-cm depth during the whole growing season. Leaf stomatal conductance was significantly lower for non-irrigated trees indicating that they were the most severely stressed. The severity of plant water stress increased with decreasing frequency of irrigation as indicated by reduced stomatal conductance. Key words: Prunus persica, available soil water, stomatal conductance

Description: Numerous researchers estimate and report laboratory-determined lower limit of available water contents using −1.5 MPa water potentials. For medium-textured soils, laboratory-measured lower limits should be determined at potentials of at least −4 MPa, and possibly −10 MPa, when using pressure membrane procedures. However, because the lower limit of available water is dependent upon environmental, plant and soil factors, we agree with Ratliff et al. (1983) that field-measured lower limits are preferable to laboratory-measured lower limits. Field-measured lower limits of available water did not vary markedly between spring wheat, alfalfa and grass. Key words: Lower limit of available water, wheat, alfalfa, grass

Description: Black spruce (Piceamariana (Mill.) B.S.P.) containerized seedlings were raised at high fertilizer regimes, i.e., "nutrient loaded," during greenhouse culture to assess whether increased preplant nutrient reserves improved site-specific outplanting performance. Growing media electrical conductivity levels during the greenhouse phase ranged between 0.9–1.2 and 0.3–0.6 dS/m for loaded and nonloaded seedlings, respectively. Although similar in total biomass and P and K content at rotation end, the loaded seedlings contained 78% more N than the nonloaded seedlings, demonstrating induced luxury consumption of N from loading. After overwintering, the seedlings were planted on intact potted surface soils from three ecological site types (upland Feathermoss, lowland Alnus, and lowland Ledum) of contrasting fertility. In the first growing season, N loading significantly increased height growth and dry matter production on all substrates; relative response was higher on the more N-deficient lowland sites. Plant nutrients were markedly diluted after establishment, except for N of nonloaded seedlings. The loading response was closely associated with the buildup of preplant N, which served as a critical nutrient source for internal retranslocation to new growth. Loading stimulated not only N uptake after outplanting, but also uptake of other nutrients presumably because of the expanded root system with this treatment. Balanced nutrient loading offers a cost-efficient alternative to field fertilization by promoting outplanting performance of container stock, and by avoiding competition response and operational constraints often associated with on-site fertilization.

Description: Urea labelled with 15N was applied to the foliage of Pinusradiata D. Don seedlings growing outdoors in a nursery during winter. Thereafter seedlings were either left outdoors or kept under controlled-environment conditions simulating winter (6 weeks) followed by spring (6 weeks). The fate of urea N was followed by analysis of 15N. All 15N was taken up within 6 h and existed initially in the aqueous acetone soluble fraction. Nitrogen enrichment was highest in glutamine, arginine, proline, 4-aminobutyric acid, glutamic acid, and pipecolic acid. Within 1 week, amino acid and soluble-15N enrichment declined in the needles. This was more rapid in the faster growing seedlings kept outdoors. Concurrent increases of 15N in the insoluble fraction were observed in all seedlings. Subsequently, a decline in 15N enrichment predominantly from the amino acids (glutamine and arginine) was apparent. Nitrogen extracted from the insoluble-N fraction was used to sustain seedling growth. Foliar N concentration, which in this experiment was almost entirely dependent upon stored reserves, declined from 2.1 to 1.1% N over the 12-week period. Trends in foliar starch concentrations were not affected by growth conditions. Starch concentrations in needles declined during the 1st week after [15N]urea application but thereafter increased during winter and declined in spring. These results confirmed the importance of reserve N in juvenile needles for shoot expansion during spring.

Description: Organic forest floor materials were surveyed on spring and fall slash-burned sites in the Sproat Lake region of Vancouver Island 2 years after burning. Dominant organic matter types, distinguished according to morphological criteria, were sampled and incubated in the laboratory for 26 weeks with periodic leaching and measurement of mineral N. Mineralization data closely fit a first-order kinetic model. Field mineralization, estimated using mass of each organic matter type in the field and first-order model parameters corrected for local temperature, ranged from 2 to 6 g N•m−2•year−1, depending on burn severity, suggesting that slash burning did not reduce N availability below levels required to support early plantation growth, except in situations of severe burns on coarse-textured soils. Differential consumption of forest floor organic matter types increased spatial variability in N mineralization and resulted, at the most severely burned site, in 50% of mineralizable N being derived from materials covering only 5% of the site. Significant correlation between N mineralization and codes and indices of the Canadian Forest Fire Weather Index System indicated that predictions of slash-burn impacts on site fertility may be made from weather conditions prior to and during burning.

Description: During the past 2 decades red spruce (Picearubens Sarg.) has exhibited growth decline throughout its range. Examination of roots of affected trees in many locations has shown death of fine feeder roots. This study examined the mycorrhizae of red spruce in New Jersey, where it is rare. At two localities just below the Kittatinny Ridge in northwestern New Jersey (elevation 425 m), samples of eight long roots from 40 trees were examined, half from mesic and half from wetland areas. All trees sampled showed 〉60% ectomycorrhizal tips (average, 89%, sd = 0.17). All mycorrhizae were monopodial. Three morphotypes predominated at both sites. Cenococcumgeophilum Fr. colonized over 92% of the sampled trees and accounted for an average of 36% of ectomycorrhizal tips per tree. Ninety percent of trees had plump, pallid mycorrhizae with a smooth mantle, which ranged in color from beige to reddish brown. All wetland trees, but only 40% of the mesic trees, exhibited mycorrhizae with a diffuse network of extramatrical hyphae and a sheathed white tip. Other morphotypes were present in 15–20% of trees. These minor morphotypes were more abundant and more diverse on trees with low levels of colonization by C. geophilum and the white-tip morphotype. There was more variation in level and type of colonization between trees than within individual trees.

Description: Nutrient distributions, concentrations, and fluxes in two red spruce (Picearubens Sarg.) stands in the Great Smoky Mountains are described and used to evaluate various hypotheses for recent decline of this species. These forests, like others in the southern Appalachians, were relatively rich in N and low in base cation status. The combination of high atmospheric N and S deposition, little or no N or S retention, relatively high N mineralization, and extremely acid soils caused soil solutions to be dominated by NO3−, SO42−, Al, and H+. Soil solution Al in these sites (most of which was in monomeric form) occasionally reached levels noted to inhibit base cation uptake and root growth in solution culture studies. These pulses of Al were driven by pulses of NO3− and, to a lesser extent, SO42− in soil solution. However, fine roots were present at depths of up to 60 cm in the mineral soil, indicating that Al concentrations had not become consistently toxic to roots. Solution fluxes (both throughfall and soil leaching) exceeded litter-fall fluxes for all the macronutrients at both sites, a typical situation for K and S, but most unusual for N, P, Ca, and Mg. There are significant implications of these fluxes and of the apparent net uptake of N by foliage in terms of how vegetation uptake and translocation are calculated. Some new formulations are suggested, but measurement errors in systems with such a predominance of hydrologic fluxes make foliar leaching and, therefore, uptake and translocation calculations extremely uncertain. Although there are no outward signs of decline in these forests (other than balsam fir (Abiesbalsamea (L.) Mill.) mortality due to the balsam woolly adelgid (Adelgespiceae (Ratz.))), the high rates of NO3− leaching rates and the borderline soil solution Al values suggest that these systems are under stress. Whether these factors actually lead to a dieback or growth decline remains to be seen.

Description: Based on stem analyses, national site-index equations and height-growth equations for white spruce (Piceaglauca (Moench) Voss) were developed covering an area from the Yukon to Newfoundland. The objective was to construct a single set of curves for each relationship by combining all regions, instead of separate curves for individual provinces or regions. The results of these tests indicated that the objective could be reached without any significant loss of accuracy. In developing the equations a modified form of the Chapman–Richards function was employed, and results are presented in tabular and graphical forms.