ALBERT

Description: Analysis of dead boles of Piceasitchensis (Bong.) Carr. and Tsugaheterophylla (Raf.) Sarg. in open- and closed-canopy forests of the Olympic Peninsula Washington, U.S.A., revealed that hemlock mortality in both forest types was due mainly to windthrow, whereas spruce typically died upright. The open forest contained 120 t/ha of dead bole wood; the closed forest contained 161 t/ha. Hemlock boles decayed more rapidly than the larger spruce boles, although both showed considerable variability. On a per-hectare basis, 146–223 kg of N, 147–197 kg of Ca. 39–61 kg of K, 18–29 kg of Mg, 6–14 kg of Na, and 17–29 kg of P were contained in dead boles of the open- and closed-canopy forests, respectively. Except for N and Mg, the nutrient concentrations of the wood were not significantly different after 33–68 years of bole decay. The N:P ratios increased with increasing decay for both species.

Description: The decay rate of Abiesconcolor (Gord. & Glend.) Lindl. logs and cover, mass, and volume of logs and snags in six midelevational forest stands of Sequoia National Park, California, are reported. Based on a chronosequence, Abiesconcolor boles have a decay rate-constant of 0.05 year−1 and a half-life of 14 years. A decay classification system was developed for Abiesconcolor, Calocedrusdecurrens (Torr.) Florin, Pinusjeffreyi Grev. & Balf., and Pinuslambertiana Dougl. logs. Dimensions taken from maps of six permanent plots were combined with decay-class information to estimate volume, mass, and projected cover of logs and snags. Total mass ranged from 29 Mg ha−1 in a Pinusjeffreyi forest to 400 Mg ha−1 in a Sequoiadendrongiganteum (Lindl.) Buchh. dominated stand. Volume, projected cover, and nitrogen storage exhibited patterns similar to mass, ranging from 84 to 1160 m3 ha−1, 3.1 to 9.3%, and 41 to 449 kg ha−1, respectively.

Description: Logs, forest floor, and mineral soil were sampled and measured, and snags were measured, in a 450-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand on the H.J. Andrews Experimental Forest, Oregon. Logs, some still identifiable after 300 years on the forest floor, contained large amounts of organic matter (222 Mg/ha), C (100 Mg/ha), water (559–10 700 L/log), N (183 kg/ha), and Ca (141 kg/ha), and smaller amounts of P (5.5 kg/ha), K (22 kg/ha), Mg (14 kg/ha), and Na (3.7 kg/ha). Logs and snags covered about 17% of the forest floor and had an all-sided area index of 0.69 m2/m2. Through mineralization, C, N, and K were lost through time; Ca and Mg increased; and P and Na increased then decreased, showing no net change. Also through mineralization, cellulose and hot acid detergent soluble fraction decreased more rapidly than lignin. Lignin was apparently not lost until the later stages of decay, when N was also lost in significant amounts. This parallels the shift from initial dominance by white rots that degraded cellulose and lignin to later dominance by brown rots that preferentially degraded cellulose. Lignin and cellulose were eventually lost at more similar rates in later decay stages. This may have been due in part to a close association between the remaining cellulose and lignin in later decay stages. Lignin was a better predictor of the onset of N release than was the C:N ratio.

Description: Aboveground biomass and leaf area, net primary production, and nutrient cycling through vegetation were studied for 3 years after clear-cutting (stems only) of a 10.24-ha watershed in the Oregon Cascade Mountains. The riparian zone and four main habitats were analyzed separately. In 3 years, aboveground net primary production increased from 5 to 112 g•m−2•year−1 in the ridgetop habitat; midsummer aboveground biomass increased from 8 to 196 g/m2 in the riparian zone and from 198 to 327 g/m2 on the ridgetop. Other values were intermediate to these. Litter fall of species with perennial aboveground parts averaged 20–27% of standing biomass. Native annuals, especially Araliacalifornica Wats., dominated the riparian zone. Seneciosylvaticus L., an introduced species, dominated most of the rest of the watershed, except for the ridgetop habitat, which was dominated by residual woody shrubs. Uptake of N exceeded losses in streamflow the 1st year and was six times greater in the 2nd; uptake of P and K in that year was 2.5 and 3 times greater than losses. In the 3rd year, total uptake of K (2.5 g•m−2•year−1) equaled the preclear-cutting level, and uptake of N (1.3 g•m−2•year−1) and P (0.3 g•m−2•year−1) was about half that level. No correlation was found between plant uptake and nutrient loss in streamflow. Uptake of all elements exceeded return through leaching and litter fall by 16%, except that of Mg, which exceeded return by 44%. Because of early dominance by species with annuals, the proportion of elements redistributed internally by vegetation was generally low. The amount of nutrients in flux through vegetation, atmosphere, and stream was small in comparison to the amount lost in the removal of tree stems.

Description: Balsam fir (Abiesbalsamea (L.) Mill.) seedlings inoculated with Cenococcumgeophillum Fr. isolate 145A, Hebelomacrustuliniforme (Bull, ex Saint-Amans) Quel, isolate S166, and Laccarialaccata (Scop, ex Fr.) Bk. and Br. isolate 238B were grown in a split-plot factorial design with pH as main plots and Al concentration and ectomycorrhizal fungal species as subplots. No Al, 50 mg Al/g substrate, and 100 mg Al/g substrate were added to the potting soil mixture, which was adjusted to a final pH of 3, 4, or 5. The seedlings were watered with one-fifth strength Arnon's solution having a pH of 3, 4, or 5 and containing 100, 50, or 0 mg Al/L. The experiment was conducted to determine the effect of acidity and concentration of Al on ectomycorrhizal formation. As solution acidity and concentrations of Al increased, ectomycorrhizal formation, root weight, shoot weight, total weight, root:shoot ratio, and B concentration decreased; however, concentrations of Fe, Mn, P, and Zn in the seedlings increased. N, Ca, K, and Mg concentrations did not vary significantly in any of the treatments. Results of this study suggest that pH and Al have a complex effect on ectomycorrhizal formation and nutrient uptake in A. balsamea seedlings.

Description: An Armillaria (Ft.) isolate compatible with Armillaria biological species II according to haploid tester challenge, was taken from a dying high-elevation red spruce (Picearubens Sarg.) tree in New York and cultured in unbuffered Melin–Norkrans medium containing 0, 50, 100, or 200 mg/L of Al3+ as Al2(SO4)3 at pH 3, 4, or 5. Total fungal weight and hyphal extension increased significantly as pH rose yet increased only slightly when aluminum was added to the medium. The pH of the medium decreased as fungal weight increased. Weight was linearly correlated with hyphal extension (r2 = 0.87) at all aluminum concentrations and pH values tested. Fungal weight and hyphal extension significantly decreased when Armillaria II was cultured in a duplicate experiment with 0, 395, 790, or 1580 mg/L of [Formula: see text] as MgSO4, indicating that increasing [Formula: see text] concentrations were harmful to fungal growth. Field studies demonstrating predisturbance distribution of Armillaria functioning as a stress pathogen of P. rubens are needed to help determine whether soil conditions created by acid deposition are inhibiting Armillaria growth.

Description: Monthly samples of ectomycorrhizal mat soils from a maturing Douglas-fir forest and adjacent nonmat soils were collected and analyzed for respiration, acetylene reduction activity, denitrification rates, extractable ammonium, nitrogen mineralization, microbial biomass, temperature, pH, percent moisture, total phosphate, nitrogen, and carbon. Seasonal patterns suggested complex interactions among the host tree, ectomycorrhizal fungus, and the mat microbial community as influenced by seasonal changes in moisture, temperature, and light availability. The most dramatic changes in rates were found during moisture-temperature transition periods in the spring and fall. Respiration within the mat community was highest during the period when tree growth is normally the greatest (in the spring and fall). In addition, there was a major respiration peak observed in the winter that we hypothesize was caused by the utilization of labile carbon by microheterotrophs. Differences were also observed between mat and nonmat soils in respiration rates, microbial biomass carbon, acetylene reduction activity, and levels of mineralizable nitrogen, which were all generally higher in the mat soils, and pH and denitrification rates, which were generally lower in nonmat soils. There is also evidence that suggests that nitrogen is very tightly coupled within the mat communities.

Description: In southeast Alaska, where wildfires are rare, uprooting is the predominant disturbance influencing stand development in Tsugaheterophylla (Raf.) Sarg. – Piceasitchensis (Bong.) Carr. forests. We compared 1-year decomposition of confined cellulose filter paper placed in the organic horizon and at the organic–mineral interface on both tree-throw mounds and adjacent pits. Decomposition rates were not significantly different between pits and mounds, but filter papers within the organic layer lost 33.7% of their original dry mass, and packs within the mineral layer lost 14.5% of their mass. This effect was highly significant (p 

Description: Soil chemical and physical properties, forest floor weights, nutrient content and turnover rates, and litter fall weights and nutrient content under bigleaf maple (Acermacrophyllum Pursh) and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) were compared on five sites on the eastern margin of the Oregon Coast Range. Litter fall weight and nutrient content were significantly greater under maple on every site for every macronutrient and for most micronutrients. Forest floor biomass and nutrient content were extremely variable, much more so than litter fall, and there were no consistent differences between the two species. However, turnover rates for forest floor biomass and nutrients were significantly faster under maple for every nutrient at every site. Bulk density of mineral soil was also highly variable with significant differences at only two sites. Soil under maple was consistently higher in nitrogen, and less consistently, in potassium. There were no consistent trends in amounts of calcium, magnesium, or phosphorus. Soil organic carbon content under maple was significantly greater than under Douglas-fir on four of five sites. These differences may result from the more rapid turnover of forest floors under maple trees.

Description: Logs of Pseudotsugamenziesii (Mirb.) Franco that had been on the ground for up to 313 years were grouped into five decay classes that ranged from 1, essentially undecayed, to 5, soft and incorporated into the forest floor but still identifiable. The mean residence times on the forest floor were 7, 17, 33, 82, and 219 years for decay classes 1 through 5, respectively. The single-exponential model of litter decomposition was fitted to the density of these logs. The summation-exponential model was constructed by summing single-exponential models fitted to lignin, cellulose, and the acid detergent soluble fraction. Both models gave virtually identical, statistically significant fits to the data. Wood density of these Douglas-fir logs decreased more slowly than that of most species other researchers have studied. The single-exponential model gave mineralization rates (k) of 0.0063 and 0.0070 year−1 when residence time and decay class age (mean residence time of the decay class), respectively, were used as the independent variable. Lignin decayed more slowly than cellulose or the fraction soluble in hot acid detergent, both of which decayed at rates that were not significantly different; thus, the summation-exponential model is recommended when these constituents are of interest.