ALBERT

Description: O2 litter and A1 horizon soil samples from various locations within the Santa Fe and Cibola National Forests of New Mexico were assayed for sulfate adsorption, organic S formation, and organic S solubilization and mineralization (mobilization). During a 48-h incubation, samples of O2 litter were found to adsorb between 1.6 and 4.1 nmol g−1 of added sulfate S and to form 2.0 to 9.8 nmol g−1 of organic S from this anion. Between 17 and 48% of this organic S was mobilized within 24 h. A1 horizon soils adsorbed 1.2 to 4.9 nmol g−1 of added sulfate S and formed between 1.6 and 4.8 nmol g−1 of organic S during 48 h. Between 20 and 50% of this organic S was mobilized within 24 h. Estimations of S-accumulation potentials for both horizons were made from these determinations. Intrinsic S pools were quantified to determine the S status of the samples prior to incubation. Carbon-bonded forms of S were found to predominate in samples from both horizons, while ester sulfate accounted for most of the remaining S. Sample pH, moisture content, and total carbon content were also determined. Attempts were made to correlate these characteristics and S pool sizes with laboratory determined potentials for sulfate adsorption, organic S formation, and mobilization. For some sites, relationships were established between sulfate adsorption, soil pH, and total C, whereas the total S and organic S content of most samples agreed well with organic S formation potentials.

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

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

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

Description: Data from 278 trees felled in a loblolly pine (Pinustaeda L.) plantation were used to include crown ratio as a measure of tree form in a taper equation. The data were divided into 10 crown ratio classes. A segmented taper equation was fitted to each of the 10 classes to detect trends in the coefficients. Coefficients were then expressed as functions of crown ratio. The resulting three-segment taper equation with crown ratio as an additional independent variable was more flexible and provided more accurate predictions of upper stem diameters. Similar techniques were used to include crown ratio in a two-segment taper equation. The three-segment equation fitted the data better than the two-segment equation and provided superior taper predictions for the test data set.

Description: A different approach to fitting taper equations has been developed, which eliminates the necessity of using several functions to predict diameter inside bark at different parts of the stem. The variable form taper function is easy to develop and saves computing time. For the data used in this study, it predicted tree profile as a function of height, diameter at breast height, and height from the ground with less bias than many of the taper-estimating systems found in the literature.

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

Description: The effect of aluminum (Al) on the growth of sugar maple (Acersaccharum Marsh.) was studied in two experiments in nutrient solution containing from 0 to 2000 μM Al at pH 4. Visible symptoms of injury to shoots or roots were not observed in either experiment. Reductions in seedling shoot size at the 1000, 1500, and 2000 μM concentrations were readily apparent; however, root biomass for these same concentrations did not differ significantly from the pH 4 controls. A plot of the relative total dry matter accumulation versus Al in solution showed that above 600 μM Al total seedling biomass declined exponentially. Of the mineral elements examined in these experiments, Ca was the most severely affected by increasing Al in solution. Even at 100 μM Al reductions in leaf, stem, and root Ca content were 17, 13, and 50% of the pH 4 controls, respectively. Some stimulation of growth and slightly higher P and K tissue concentrations were observed at low (100–500 μM) Al concentrations. At higher Al levels, P, K, and Mg were also reduced below the tissue content of the controls. The Al critical toxicity level for a 20% reduction in total seedling biomass was found to be 137 μg Al g dry weight−1 for newly expanded leaves.

Description: Biomass and nutrient contents of regenerating woody plants and litter fall were measured after a northern mixed conifer–hardwood forest was harvested by conventional and whole-tree methods. Before harvest, the central Ontario study site was occupied by a 95-year-old pine (Pinusresinosa, P. strobus) and aspen (Populustremuloides, P. grandidentata) stand growing on gently rolling, gravel-free outwash sands. Four years after harvest, aspen abundance increased 100-fold in both harvested areas, with higher densities after whole-tree harvest (WTH) (4.1 stems/m2) than after conventional harvest (CH) (2.7 stems/m2). No self-thinning of aspen occurred between 2 and 4 years after harvest. Total aboveground woody biomass accumulated at 2.0 t•ha−1•year−1 in the WTH area and 1.5 t•ha−1•year−1 in the CH area; the preharvest rate was 2.0 t•ha−1•year−1. Peak autumn litter production occurred earlier in the harvested areas than in an adjacent uncut area. Cycling of N and K in litter fall returned to preharvest rates after 4 years. Cycling of Ca in litter fall was lower after WTH than after CH. Vegetation uptake of N and K (litter fall plus woody biomass) in the harvested areas in year 4 exceeded the preharvest value. Increased N accumulation in woody biomass (3.0 kg•ha−1•year−1 before harvest, 10.6 kg•ha−1•year−1 after WTH) would place a relatively greater demand on forest floor N pools in the WTH than in the CH area owing to lack of N input in logging slash. Although WTH did not reduce initial rates of biomass production, Populus spp. had lower concentrations of N, Ca, and Mg in the WTH area than in the CH area. There may be a danger that WTH on less fertile sites in the region will produce dense, unproductive aspen stands with low rates of self-thinning.

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