Optimal management of a flammable multi-stand forest for timber production and maintenance of nesting sites for wildlife

Decline of cavity-using wildlife species is a major forest management issue. One of the causes of this problem is the loss in cavity tree abundance, resulting from short rotation silviculture, stand-replacing disturbance events and timber harvesting in disturbed stands. Cavity tree availability cannot be guaranteed due to the stochastic nature of disturbance events. We developed a Markov model to predict future cavity tree availability under alternative tree felling and fire protection strategies using information on cavity tree dynamics and fire history. Stochastic dynamic programming was used to find a strategy that maximizes timber revenues less forest management costs, including the cost of an artificial nest-box program that must be implemented whenever cavity trees become critically scarce. The requirement to implement a nest-box program in such circumstances strongly influenced the optimal tree felling strategy and resulted in a higher probability of having cavity trees in the future. This reflected an increase in the retention of old growth forest and stands with fire-killed cavity trees as well as stands of younger trees to provide a future source of cavities. These results demonstrate the need to consider the costs of artificial habitat enhancement and the risk of future cavity tree scarcity in multiple-use forest management planning.     

Isolation of symbiont and associated fungi from ectomycorrhizas of Sitka spruce

Isolation of symbiont and associated fungi from ectomycorrhizas of Sitka spruce from three Irish forest plantations is described. Frequent emergence of dark sterile mycelia and Oidiodendron spp., predominantly O. maius, restricted the recovery of potential symbionts. Inhibition of the former by benomyl resulted in a sixfold increase in basidiomycetes isolated. Pure culture syntheses confirmed the ectomycorrhizal ability of potential symbiont isolates and demonstrated the parasitic nature of dark sterile mycelial types. Antagonism of Mycelium radicis atrovirens, Phytophthora cinnamomi and Heterobasidion annosum by O. maius observed in paired cultures supports the possible involvement of this species in biological control of conifer root pathogens.     

The impact of shade on morphology,growth and biomass allocation in <Emphasis Type="Italic">Picea sitchensis</Emphasis>, <Emphasis Type="Italic">Larix</Emphasis> × <Emphasis Type="Italic">eurolepis</Emphasis> and <Emphasis Type="Italic">Thuja plicata</Emphasis>

To determine the effect of shade on morphology, growth and biomass allocation in Picea sitchensis, Larix × eurolepis and Thuja plicata, seedlings were grown in the open or under shadehouses providing 25%, 50% and 75% reductions of full-light for two growing seasons. For most of the characteristics assessed there was no significant interaction between species and shade indicating that the morphological responses to changing shade treatments were not species-dependent. After two growing seasons the mean height increment for the three species was significantly greater in 25% (76.1 cm) and 50% shade (74.9 cm) than in the open (69.5 cm). Root collar diameter increment, shoot, root and total biomass declined significantly with increasing shade while the opposite was true for the height:diameter ratio. In both western red cedar and hybrid larch the shoot:root ratio was significantly greater in the shade while in Sitka spruce this characteristic was not influenced by shade. While all species had significantly greater specific shoot areas in 75% shade than in 0% shade, this trend was particularly pronounced in hybrid larch. In hybrid larch and western red cedar, the normalised specific projected shoot area increased significantly with increasing shade. The opposite trend was observed for Sitka spruce. We conclude that in the main the species studied demonstrated similar shade acclimation responses despite their reported differences in shade tolerance.     

Analysis of proanthocyanidin cleavage products following acid-catalysis in the presence of excess phloroglucinol

The analysis of proanthocyanidin cleavage products after acid-catalysis in the presence of excess phloroglucinol was investigated. In the developed analytical method, a solution of 0.1 N HCl in methanol, containing 50 g/L phloroglucinol and 10 g/L ascorbic acid was prepared. The proanthocyanidin of interest was reacted in this solution (5 g/L) at 50 degrees C for 20 min, and afterward combined with 5 volumes of 40 mM aqueous sodium acetate before analysis by reversed-phase HPLC using an aqueous acetic acid and methanol gradient. This procedure was used to investigate the composition of proanthocyanidins isolated from the seed and skin tissue of Vitis vinifera L. berries. The results compared favorably to results obtained when benzyl mercaptan was used as the trapping nucleophile, indicating that phloroglucinol is an effective reagent for this analysis.     

Enzyme activities and microbial community structure in semiarid agricultural soils

This study investigated the effect of management on -glucosidase, -glucosaminidase, alkaline phosphatase, and arylsulfatase activities and the microbial community structure in semiarid soils from West Texas, USA. Surface samples (0–5 cm) were taken from a fine sandy loam, sandy clay loam, and loam that were under continuous cotton ( Gossypium hirsutum L.) or in cotton rotated with peanut ( Arachis hypogaea L.), sorghum ( Sorghum bicolor L.), rye ( Secale cereale) or wheat ( Triticum aestivum L.), and had different water management (irrigated or dryland), and tillage (conservation or conventional). The enzyme activities were higher in the loam and sandy clay loam than in the fine sandy loam. Soil pH was not affected by management, but the soil organic C and total N contents were generally affected by the different crop rotations and tillage practices studied. The trends of the enzyme activities as affected by management depended on the soil, but in general crop rotations and conservation tillage increased the enzyme activities in comparison to continuous cotton and conventional tillage. The soil enzyme activities were significantly correlated with the soil organic C ( r -values up to 0.90, P< 0.001), and were correlated among each other ( r -values up to 0.90, P <0.001). There were differences in the fatty acid methyl ester profiles between the fine sandy loam and the sandy clay loam and loam, and they reflected the differences in the enzyme activities found among the soils. For example, a 15:0 ranged from 1.61±0.25% in cotton-peanut/irrigated/no-till in the fine sandy loam to 3.86±0.48% in cotton-sorghum/dryland/conservation tillage in the sandy clay loam. There were no differences due to management within the same soil.Trade names and company names are included for the benefit of the reader and do not infer any endorsement or preferential treatment of the product by USDA-ARS     

The evolutionary relationship between bere barley and other types of cultivated barley

Genetic Resources and Crop Evolution - We used genotyping-by-sequencing to investigate the evolutionary history of bere, the oldest barley variety still cultivated in Britain and possibly in all of...     

Compositional investigation of phenolic polymers isolated from Vitis vinifera L. Cv. Pinot Noir during fermentation

Phenolic polymer material extracted during commercial red wine fermentations (Vitis vinifera L. cv. Pinot noir) was isolated and analyzed to characterize its chemical composition. Phenolic polymer isolates were prepared from samples taken throughout fermentation and isolated by adsorption chromatography. Isolates were subjected to phloroglucinolysis to analyze the proanthocyanidin amount as well as the subunit composition. Results of phloroglucinolysis revealed that the proanthocyanidin content of individual phenolic polymer isolates varied from 27 to 54%. Subsequent analyses were done in an attempt to quantify materials other than known proanthocyanidin subunits. Results of all experiments indicate that up to 82% of the phenolic polymer isolates could be accounted for by mass. While this figure accounts for a significant portion of the polymeric phenolic material, further investigation will be needed to qualify the remaining 18%.     

Contamination environnementale par les métaux et maladie de Parkinson

Parkinson's disease (PD) has been proposed to result from the interaction of aging and environment in susceptible individuals. The prevalence of PD in Quebec was 84 per 100 000 in 1985. The regional variation observed has been linked with several environmental factors. We intended to verify the existence of a relation between the development of PD with exposure to 3 metal pollutants: Fe, Mn, and Al. The choice of these metals rests on their potential presence in the environment caused by the industrial activity in the region studied, and on the fact that it theoretically favors the prevalence of the illness. Environmental exposure to these metals and the resulting risks were evaluated using red spruce as a bio-indicator. The metal concentrations in tree rings were determined by neutron activation analysis. These concentrations permitted a temporal estimation of contamination in each of the territories studied, from 1938 to 1987. The risk of environmental exposure was assumed to be proportional to the concentration of the metal. The calculated risks combined with the history of residence allowed a comparison between parkinsonians and controls. It appeared that environmental exposure to the metals was not significantly different between those two groups.