ALBERT

Notes: An algorithm (Weather Reader) was developed and used to analyze daily weather records from all existing Canadian and American weather stations of eastern North America (in excess of 2100 stations), from 1930 through 2000. Specifically, the Weather Reader was used to compile daily minimum, mean, and maximum air temperatures for weather stations with at least 30 years of data, and was used to calculate accumulated degree days for winter thaw–freeze events relevant to yellow birch (Betula alleghaniensis Britt.) from beginning to end. A thaw–freeze event relevant to yellow birch was considered to take place when (i) the station daily maximum temperature reached or exceeded +4°C after being below freezing for at least 2 months of the winter, (ii) sufficient growing degree days accumulated (〉50 growing degree days) to cause the affected yellow birch trees to prematurely deharden, and (iii) the daily minimum temperature dropped below −4°C causing roots and/or shoots of dehardened trees to experience freeze-induced injury and possibly dieback. The threshold temperature of +4°C represents the daily temperature above which biological activity occurs in yellow birch. The station growing degree day summaries were subsequently spatially interpolated with the Kriging function in GS+™ and mapped in ArcView™ GIS in order to display the geographic extent of the most severe thaw–freeze events. The ArcView™ maps were then compared with the extent of historically observed yellow birch decline. It was found that the years 1936, 1944, and 1945 were particularly uncharacteristic in terms of region-wide winter thaw–freeze extremes, and also in terms of observed birch decline events during 1930–1960. An overlay of suspected accumulated birch decline based on thaw–freeze mapping and observed decline maps prepared by Braathe (1995), Auclair (1987), and Auclair et al. (1997) for 1930–1960 demonstrated similar geographic patterns. The thaw–freeze projection for 1930–1960 was shown to coincide with 83% of the birch decline map appearing in Braathe (1995) and 55% of the geographic range of yellow birch in eastern North America. Thaw–freeze mapping was also applied to two significant events in 1981. Greatest impact was recorded to occur mostly in southern Quebec and Ontario, and several American Great Lake States, specifically in northern Michigan and New York, where the greatest growing degree day accumulation prior to refreeze in late February (February 28th) was projected to have occurred; and in southern Quebec, most of Atlantic Canada, and Maine, prior to a late spring frost in mid-April (April 17).

Notes: : We examined hydrogeochemical records for a dozen watersheds in and near Kejimkujik National Park in southwestern Nova Scotia by relating stream ion concentrations and fluxes to atmospheric deposition, stream type (lake inlet versus outlet; brown versus clear water), and watershed type (catchment area, topography, soils, and dominant forest cover type). We found that fog and dry deposition make important contributions to S, N, Cl, H, Ca, Mg, K, and Na inputs into these watersheds. Seasalt chloride deposition from rain, snow, fog, and dry deposition equal total stream outputs on a region-wide basis. Chloride outputs, however, differ among watersheds by a factor of about two, likely due to local differences in air flow and vegetational fog interception. We found that most of the incoming N is absorbed by the vegetation, as stream water NO3- and NH4+ are very low. Our results also show that the vegetation and the soils absorb about half of the incoming SO42. In comparison with other North American watersheds with similar forest vegetation, Ca outputs are low, while Mg and K outputs are similar to other regions. Soil exchangeable Ca and soil cation exchange capacity are also very low. We found that first-order forest streams with no upstream lakes have a distinct seasonal pattern that neither corresponds with the seasonal pattern of atmospheric deposition, nor with the seasonal pattern of downstream lake outlets.

Notes: Abstract The biomass growth and nutrient cycling model ‘ForSVA’ (forest-soil-vegetation-atmosphere model) is used to analyze potential changes in nutrient cycling (Ca, Mg, K, N, S) and forest biomass production in response to four climate-change scenarios. The analysis is done for an old-growth hardwood stand within the Turkey Lakes watershed north of Lake Superior, Ontario. With ForSVA, any effects due to species interactions, competition, and resulting species shifts are not addressed explicitly. Instead, the calculations are based on functional relationships that primarily respond to soil and climate conditions in general, and to structural changes within the forest itself. The simulations cover a period of about 200 years, and suggest that a principal change in annual pattern of soil moisture is to be expected for the UKMO climate scenario, and that this scenario will likely induce a major change of vegetation covertype resulting from major changes in seasonal soil moisture conditions and a general lack of snow during winter. In contrast, the OSU, GISS and GFDL scenarios should not cause a principal change in forest type, but the soil will be somewhat drier than what is currently the case. However, increased precipitation rates and/or air temperatures during summer and spring should, in combination, increase actual evapotranspiration rates, and such increases should increase net primary production. For example, calculations with GFDL suggest that cumulative wood biomass at the Turkey Lakes site can be expected to increase by 25%. Foliage biomass and fine root production can be expected to increase by 70% from current conditions. It is assumed that within-tree allocation of photosynthate is not affected by climate.

Notes: Abstract Two adjacent soils with contrasting sulfate sorption were examined in terms of (i) water-soluble and ion-exchangeable Al, Fe, Ca, Mg, K, Mn and Zn, (ii), water- and bicarbonate-extractable sulfate, (iii) Truog-extractable P, (iv) dithionite-extractable Al, Mn and Fe and (v) treatment response to irrigation with simulated acid precipitation. The biomass of 8 year old black spruce saplings growing on the soils, and the distributions of Al, Fe, Ca, Mg, K, Mn, P and Zn within these plants, were also examined. The soils were well to moderately-well drained, with the mineral soil exposed by site preparation prior to planting. The exposed soil underneath individual saplings was treated with acid sulfate solutions (75 mm containing 2 to 50 mg L−1 H2SO4) applied during each of three consecutive growing seasons. The results indicate that Al, much like Fe, Ca, Mn and Zn, accumulated with time in the foliage, but K, Mg and P were highest in young plant tissues. Much of Al and Fe taken up remained in the fine roots. Aluminum uptake increased with the amount of dithionite-extractable Al (free Al oxide) in the soil. Growth of the black spruce saplings was not visibly affected by readily accessed Al in each soil, or by acid irrigation.Instead, growth was restricted by factors other than soil Al and acid irrigation in spite of (i) low soil pH, (ii) high levels of exchangeable Al, and (iii) high levels of Al in fine roots. Sulfate retention across and within the two soils was positively correlated with free Al oxide. The two soils responded to acid irrigation by accelerated silicate weathering and enhanced ion leaching. Sulfate sorption reduced these effects.

Notes: Abstract Experiments with solution cultures revealed that 1-yr-old black spruce (Picea mariana [Mill.]) seedlings growing in nutrient solutions experienced reductions in water uptake and moist plant weight when treated with water-soluble inorganic Al at the time of rapid shoot elongation. These reductions occurred with solution concentrations for Al at ≥ 16 mg L−1. Wilting was noticed with Al ≥ 8 mg L−1. In contrast, oxalated Al treatments had no visible effects on either water uptake or moist plant weight during shoot elongation. Later, near the time of budset, neither inorganic nor oxalated Al had an effect on moist plant weight or water uptake. This suggests that black spruce seedlings may or may not be susceptible to water-soluble inorganic Al depending on the degree of Al complexation afforded by the rooting medium, and by the plant roots at different times of the growing season. Water uptake was affected by the type of rooting medium in which the seedlings grew. For example, water uptake from peat was greater than water uptake from solution. Water uptake from sand was intermediate. Water uptake from solution-only cultures was probably affected by restricted O2 supply.

Notes: Abstract A computer simulation was done to illustrate how the equilibrium solubility and speciation of Al in well-aerated soil solutions may be affected by pH (from 2.0 to 10.0), organic acids (citric, oxalic, phthalic, and salicylic acid), metal ions (K, Mg, Ca, Al, Fe), inorganic ligands (F, OH, SO4, PO4, CO3, and SiO3), and type of Al-containing solid [kaolinite, gibbsite, or amorphous Al(OH)3] thought to be present. The simulation indicated that the type of Al-oxide/hydroxide considered has a substantial influence on the inorganic and organic equilibrium composition of the soil solution, and on the occurrence (or non-occurrence) of other Al-minerals such as KA13(SO4)2(OH)6 (alunite) and Al(SO4)(OH)-5H2O (jurbanite).

Notes: Abstract Two-year old black spruce seedlings (Picea mariana [Mill.] B.S.P.) of greenhouse-grown paper-pot stock were subjected to chemically well-characterized nutrient solutions for 28 days to assess the elemental uptake (A1,P,Ca) of these plants in response to organic versus inorganic Al in the rooting medium (pH=3.0; 0 ≤ total Al ≤ 48 mg L−1). Oxalate additions to the nutrient solutions (0 ≤ Ox ≤ 2.4 mmol) served as organic Al-complexing agent. The results indicated that the plants took up Al in proportion to the Al concentration of the rooting medium, with Al uptake from the Al-Ox treatments somewhat more extensive than the Al uptake from the inorganic Al treatments. Furthermore, root Al ≫ shoot Al for both cases. The pattern of P uptake was similar to that of Al uptake but for the roots only, i.e. root P was proportional to root Al.Increased root P was not associated with increased shoot P. Calcium content of the roots was slightly reduced with increased inorganic and organic Al, but increased strongly with increasing oxalate in the rooting medium.

Notes: Abstract Experiments were conducted to monitor the pH and the persistence of simple organic acids (oxalic, citric, malic, glycolic acid) with and without Al complexation in rooting cultures (sand, peat, solution-only) under non-sterile conditions, and to characterize pertinent short-term responses of black spruce seedlings (Picea mariana [Mill.]) to subsequent changes in the rooting solutions. It was shown that the organic acids decayed within about five days unless the cultures were treated with a decay-controlling fungicide such as Captan, an antoxidant containing N-(trichloromethylthio)-4-cyclohexene-12-dicarboximide. Aluminum complexation did not increase the persistence of the organic acids except for oxalic acid. In all cases, the decay of the organic acids (or of the equivalent carboxylates) led to a simultaneous increase of solution pH which was most pronounced in the non-buffered solution cultures without Al. Captan did not affect the growth of black spruce seedlings, but was lethal to yellow birch (Betula alleghaniensis Britton) seedlings. The pH of tissuemized roots taken from the black spruce seedlings following treatments with oxalate and citrate (within and without Al) reflected the change of pH within the culture solutions.