Can alkaline residuals from the pulp and paper industry neutralize acidity in forest soils without increasing greenhouse gas emissions?

Alkaline residuals, such as wood ash and lime mud generated from pulp and paper mills, could be recycled as liming agents in sugar maple (Acer saccharum Marsh.) forests affected by soil acidification. The objectives of this study were (1) to evaluate soil chemistry, in particular soil acidity, after the application of three alkaline residuals from the pulp and paper industry, and (2) to determine if these alkaline residuals altered soil greenhouse gas (GHG) emissions as a result of the change in soil pH or due to their chemical composition. Soil properties and GHG fluxes were monitored for two years after alkaline residuals were applied to six forest sites dominated by sugar maple in southeastern Quebec, Canada. Each site received six treatments: wood ash applied at 5, 10 and 20 t ha-1, lime mud (7.5 t ha-1), a mixture of slaker grits and green liquor sludge (7 t ha-1) and an unamended control. These treatments had acid-neutralizing power from 0 to 9 t ha-1. All alkaline residuals buffered soil acidity as a function of their neutralizing power, and more neutralization occurred in the forest floor layer than in the underlying mineral soil. In the forest floor, the alkaline residual treatments significantly increased pH by more than one unit, nearly doubled the base saturation, and reduced exchangeable acidity, Al and Fe concentrations compared to control plots. The CO2 and N2O fluxes were lower after application of alkaline residuals, and this was related to the soil pH increase and the type of alkaline residual applied. Lime mud was more effective at reducing GHG fluxes than other alkaline residuals. We conclude that these alkaline residuals can effectively counteract soil acidity in sugar maple forests without increasing soil GHG emissions, at least in the short term.

The effect of a doubled glutathione level on parameters affecting the germinability of recalcitrant Acer saccharinum seeds during drying.

Approximately 20% of plant species, including silver maple (Acer saccharinum L.), produce seeds that are sensitive to desiccation, which is reflected in their poor storage potential and viability. In the search for a compound that can improve seed recalcitrance, freshly harvested seeds were soaked in either 2.5 mM reduced glutathione (GSH) or water and desiccated to comparable water levels of 55-20%. We examined the impact of a doubled endogenous level of glutathione on the seed germination capacity, the activity of enzymes involved in glutathione metabolism, the cell membrane components and integrity, reactive oxygen species, and ascorbate levels. GSH treatment resulted in slower dehydration and a higher germination capacity. The increased glutathione was mainly consumed by glutathione S-transferase, leading to more efficient detoxification, and by dehydroascorbate reductase (DHAR), accelerating the ascorbate regeneration. As a result, the cellular environment became more reduced, and protection of the membrane structures was enhanced. The ameliorated membrane integrity was manifested via a lower electrolyte leakage and a lower lipid peroxide level despite the higher level of hydrogen peroxide (H2O2) detected in the GSH-treated seeds. The degradation of phospholipids (PLs) was less intense and related to the phosphatidylinositol (PI) level, which is the precursor of the phospholipase D cofactor, whereas in water-soaked seeds, PL degradation was promoted by H2O2. The germination capacity of the dehydrated seeds depended primarily on the level of H2O2, lipid hydroxyperoxides, electrolyte leakage, GSH, the half-cell reduction potential of glutathione, PI, and the activity of DHAR and γ-glutamylcysteine synthetase. Interestingly, H2O2 affected all of the parameters. The germination of GSH-boosted seeds was strongly impacted by the pool of ascorbate, the half-cell reduction potential of ascorbate, and the glutathione peroxidase activity. In general, germination was DHAR activity-dependent. A strong negative correlation was detected in the water-soaked seeds, whereas a strong positive correlation was detected in the GSH-treated seeds. The enhanced level of glutathione likely improved the efficiency of the ascorbate-glutathione cycle, confirming its effect on seed germinability after dehydration.

Calcium and aluminum impacts on sugar maple physiology in a northern hardwood forest.

Forests of northeastern North America have been exposed to anthropogenic acidic inputs for decades, resulting in altered cation relations and disruptions to associated physiological processes in multiple tree species, including sugar maple (Acer saccharum Marsh.). In the current study, the impacts of calcium (Ca) and aluminum (Al) additions on mature sugar maple physiology were evaluated at the Hubbard Brook Experimental Forest (Thornton, NH, USA) to assess remediation (Ca addition) or exacerbation (Al addition) of current acidified conditions. Fine root cation concentrations and membrane integrity, carbon (C) allocation, foliar cation concentrations and antioxidant activity, foliar response to a spring freezing event and reproductive ability (flowering, seed quantity, filled seed and seed germination) were evaluated for dominant sugar maple trees in a replicated plot study. Root damage and foliar antioxidant activity were highest in Al-treated trees, while growth-associated C, foliar re-flush following a spring frost and reproductive ability were highest in Ca-treated trees. In general, we found that trees on Ca-treated plots preferentially used C resources for growth and reproductive processes, whereas Al-treated trees devoted C to defense-based processes. Similarities between Al-treated and control trees were observed for foliar cation concentrations, C partitioning and seed production, suggesting that sugar maples growing in native forests may be more stressed than previously perceived. Our experiment suggests that disruption of the balance of Ca and Al in sugar maples by acid deposition continues to be an important driver of tree health.

[Study on the seasonal variations of the active components in Acer truncatum leaves and the inhibitory ability on fatty acid synthase].

OBJECTIVE: To study the dynamic variations of the contents of total polyphenols, flvonoids and chlorogenic acid from Acer truncatum leaves in different months, and their inhibitory activities on fatty acid synthase. METHODS: Spectrophotometry was used to determine the contents of total polyphenols, flavonoids and chlorogenic acid in extracts and the extracts' inhibitory effects were also investigated. RESULTS: All Leaves picked from May to November have inhibitory effect. But the contents of polyphenols in leaves of July appeared to be higher than other months', and consequently exhibited stronger inhibition against FAS. CONCLUSION: A positive correlation between the content of polyphenols in leaves extract and the inhibitory efficacy on FAS could be established.

Superior wood for violins--wood decay fungi as a substitute for cold climate.

Violins produced by Antonio Stradivari during the late 17th and early 18th centuries are reputed to have superior tonal qualities. Dendrochronological studies show that Stradivari used Norway spruce that had grown mostly during the Maunder Minimum, a period of reduced solar activity when relatively low temperatures caused trees to lay down wood with narrow annual rings, resulting in a high modulus of elasticity and low density. The main objective was to determine whether wood can be processed using selected decay fungi so that it becomes acoustically similar to the wood of trees that have grown in a cold climate (i.e. reduced density and unchanged modulus of elasticity). This was investigated by incubating resonance wood specimens of Norway spruce (Picea abies) and sycamore (Acer pseudoplatanus) with fungal species that can reduce wood density, but lack the ability to degrade the compound middle lamellae, at least in the earlier stages of decay. Microscopic assessment of the incubated specimens and measurement of five physical properties (density, modulus of elasticity, speed of sound, radiation ratio, and the damping factor) using resonance frequency revealed that in the wood of both species there was a reduction in density, accompanied by relatively little change in the speed of sound. Thus, radiation ratio was increased from 'poor' to 'good', on a par with 'superior' resonance wood grown in a cold climate.

[Impact of soil cadmium contamination on chlorophyll fluorescence characters and biomass accumulation of four broad-leaved tree species seedlings].

In a greenhouse pot experiment,a gradient of soil Cd concentration was established by adding 0,50,100 and 200 mg CdCl2 x kg(-1) air-dried soil, and the seedlings of one-year-old Rosa davurica, Philadelphus schrenkii, Acer mandshurica and Lonicera maackii were transplanted. The measurement of the seedlings' chlorophyll fluorescence parameters and biomass accumulation after 70 days of transplanting showed that with increasing soil Cd content, all the test tree species had a decrease of Fv/Fm, phi(PSII), qP and biomass, but an increase of qN. A. mandshurica had the greatest responses, followed by P. schrenkii and L. maackii, and R. davurica. The tolerance of these tree species to soil Cd contamination followed the order of R. davurica > P. schrenkii and L. maackii > A. mandshurica.

Species diversity of polyporoid and corticioid fungi in northern hardwood forests with differing management histories.

Effects of forest management on fungal diversity were investigated by sampling fruit bodies of polyporoid and corticioid fungi in forest stands that have different management histories. Fruit bodies were sampled in 15 northern hardwood stands in northern Wisconsin and the upper peninsula of Michigan. Sampling was conducted in five old-growth stands, five uneven-age stands, three even-age unthinned stands and two even-age thinned stands. Plots 100 m x 60 m were established and 3000 m2 within each plot was sampled during the summers of 1996 and 1997. A total of 255 polyporoid and corticioid morphological species were identified, 46 (18%) of which could not be assigned to a described species. Species accumulation curves for sites and management classes differed from straight lines, although variability from year to year suggests that more than 2 y of sampling are needed to characterize annual variation. Mean species richness and diversity index values did not vary significantly by management class, although mean richness on large diameter wood (> or = 15 cm diam) varied with moderate significance. Richness values on small diameter debris varied significantly by year, indicating that a large part of year-to-year variability in total species richness is due to small diameter debris. Ten species had abundance levels that varied by management class. Two of these species. Changes in the diversity and species composition of the wood-inhabiting fungal community could have significant implications for the diversity, health and productivity of forest ecosystems.

Estimation of leaf transmittance in the near infrared region through reflectance measurements.

A method, which allows one to compensate for the incomplete collection of transmitted light (T) by an integrating sphere, has recently been developed, and shown to be reliable provided that the absorptance (A) of the leaf in the NIR region (750-800 nm) can be neglected, allowing one to set R+T=1, where R denotes the reflectance; this implies that proper compensation can only be applied to healthy leaves, which do not absorb in the NIR region. To overcome this limitation, the feasibility of an alternative, requiring neither measurements of T nor an elaborate analysis of radiative transport through a leaf, is explored. Not surprisingly, this simplistic alternative provides results which (in general) do not agree with those found by using the compensation method, but the two approaches converge in the spectral regions where absorptance is low (that is, where R+T> or =0.9). The "T-through-R" method, as described here, thus provides an additional check on the correction factor used in conjunction with the integrating sphere, and extends the applicability of the compensation method to situations where NIR absorptance is not negligible, e.g., in the presence of 'browning' pigments produced upon the oxidation of polyphenols during leaf senescence.

Ecophysiology of Acer rubrum seedlings from contrasting hydrologic habitats: growth, gas exchange, tissue water relations, abscisic acid and carbon isotope discrimination.

Eight red maple (Acer rubrum L.) provenances, four each from wet and dry sites, were grown under the same conditions and their physiological responses to soil water availability investigated. Under well-watered conditions, seedlings of wet-site provenances grew faster and had consistently higher net photosynthesis, leaf conductance, maximum carboxylation rate, maximum rate of coupled photosynthetic electron transport, apparent quantum use efficiency, light-saturated photosynthesis and dark respiration than seedlings of dry-site provenances. Under conditions of low soil water availability, only dry-site provenances responded with decreased osmotic potential at full hydration and at the turgor loss point; however, provenances from wet sites showed a smaller reduction in absolute growth rate, a greater reduction in gas exchange and a greater increase in abscisic acid concentrations than dry-site provenances.