Thermal manikin measurements--exact or not?

According to the European prestandard ENV 342:1998, the thermal insulation of cold-protective clothing is measured with a thermal manikin. Systematic studies on the reproducibility of the values, measured with different types of clothing on the commonly used standing and walking manikins, have not been reported in the literature. Over 300 measurements were done in 8 different European laboratories. The reproducibility of the thermal insulation test results was good. The coefficient of variation was lower than 8%. The measured clothing should fit the manikin precisely, because poorly fitting clothing gave an error in the results. The correlation between parallel and serial insulation values was excellent and parallel values were about 20% lower than serial ones. The influence of ambient conditions was critical only in the case of air velocity. The reproducibility of thermal insulation test results in a single laboratory was good, and the variation was lower than 3%.     

Ranking of individual mountain birch trees in terms of leaf chemistry: seasonal and annual variation

Summary. The quality of tree leaves as food for herbivores changes rapidly especially during the spring and early summer. However, whether the quality of an individual tree in relation to other trees in the population changes during the growing season and between years is less clear. We studied the seasonal and annual stability of chemical and physical traits affecting leaf quality for herbivores. Rankings of trees in terms of the contents of two major groups of phenolics in their leaves, hydrolyzable tannins and proanthocyanidins (condensed tannins), were very stable from the early spring to the end of the growing season. There were also strong positive within-season correlations in the levels of some other groups of phenolics in the leaves (kaempferol glycosides, myricetin glycosides and p-coumaroylquinic acid derivatives). The contents of individual sugars and the sum content of protein-bound amino acids showed patterns of seasonal consistency in mature leaves, but not in young developing leaves. The seasonal correlations in leaf water content and toughness were also strongest in mature leaves. The correlations between two years at corresponding times of the growing season were strongly positive for the major groups of phenolics throughout the season, but were more variable for the contents of proteins and some sugars. Leaf toughness and water content showed strong positive correlations in mature leaves. Despite the consistency of tree ranking in terms of leaf phenolics, the relative resistance status of trees may, however, change during a growing season because there was a negative correlation between the content of hydrolyzable tannins (early-season resistance compounds) in leaves early in the season and the content of proanthocyanidins (late-season resistance compounds) late in the season, and vice versa. Thus, assuming that phenolics affect herbivore preference and performance, different plants may suffer damage at different times of the growing season, and the overall variation between trees in the fitness consequences may be low. In addition, the adaptation of herbivorous insects to mountain birch foliage in general, as well as to specific tree individuals, may be constrained by variation in the relative resistance status of the trees.     

Reduced nest defence intensity and improved breeding success in terns as responses to removal of non-native American mink

Lack of parental experience or differences in reproductive effort may lead to variation in nest defence behaviour among individuals in a prey population. In this experimental study, we analysed nest defence behaviour using a model of an American mink, Mustela vison, a non-native predator, at colonies of arctic terns, Sterna paradisaea, in two large areas where mink had been removed and two comparable control areas with mink in the south-western archipelago of Finland, Baltic Sea, in June 2000. Furthermore, we recorded breeding success of arctic terns in the same four areas during 1998–2001. Arctic terns took higher risks in nest defence in control areas and in a short-term (mink-free for 2 years) removal area than in the long-term (mink-free for 8 years) removal area. Thus, colonies with recent experience of mink were more active in defending their offspring. The breeding success of arctic terns was significantly higher in mink-removal areas than in control areas. We conclude that arctic terns modify their nest defence behaviour in the presence of mink. However, they cannot defend their nests sufficiently against this mainly nocturnal predator, since their breeding success is reduced in areas where mink are present.Communicated by J. Graves     

Amino acids during development of mountain birch leaves

Summary. The nutritive value of tree foliage for herbivores decreases rapidly with leaf maturation, due in particular to the decline in leaf nitrogen content. Since the amino acid content of plants differs from the need of herbivores for individual amino acids, we examined developmental changes in the contents of amino acids throughout the growth season of mountain birch. The contents of free and protein-bound amino acids, as well as essential and nonessential ones, displayed different patterns with leaf maturation, suggesting that total nitrogen or protein levels are poor predictors of the nutritive status of leaves. The contents of protein-bound amino acids were 100 times higher than those of free amino acids, indicating that the role of free amino acids in nutrition of herbivores is probably less important than that of protein-bound amino acids. Among protein-bound amino acids, both the absolute and the relative contents of two nitrogen-rich essential amino acids, lysine and arginine, decreased during early leaf growth, presumably reducing nitrogen availability in developing leaves. Essential amino acids were mainly positively related to each other, suggesting the co-ordinated regulation of their synthesis. Changes in correlations among individual free amino acids reflected developmental changes in allocation preferences between biosynthesis pathways with leaf growth. Received 31 January 2003; accepted 17 March 2003. R1D=" Correspondence to: Teija Ruuhola, e-mail: teiruu@utu.fi     

Biosynthetic origin of carbon-based secondary compounds: cause of variable responses of woody plants to fertilization?

Summary. We propose that variation in the responses of carbon-based secondary compounds to fertilization in woody plants has a biosynthetic cause. The synthesis of phenylpropanoids and derived compounds (e.g., condensed tannins) competes directly with the synthesis of proteins, and therefore with plant growth, because of a common precursor, phenylalanine. In contrast, the biosynthesis of terpenoids and of hydrolyzable tannins proceeds presumably without direct competition with protein synthesis. Therefore, accelerated plant growth induced by fertilization may cause a reduction in concentrations of phenylpropanoids but may affect less or not at all the levels of other classes of secondary compounds. A meta-analysis based on fertilization experiments with 35 woody plant species supported the predicted differences fertilizing significantly decreased concentrations of phenylpropanoids but not of terpenoids or hydrolyzable tannins. Received 14 May 1998; accepted 23 June 1998.     

Bioaccumulation, bioavailability and environmental fate of chlorophenol impurities, polychlorinated hydroxydiphenylethers and their methoxy analogues

The bioaccumulation potential and environmental fate of polychlorinated hydroxydiphenyl ethers (HO-PCDEs; polychlorinated phenoxyphenols, PCPP), the major impurities of chlorophenol formulations and their methoxy analogues (MeO-PCDEs; polychlorinated methoxyanisoles, PCPAs) were investigated. Oligochaete worms (Lumbriculus variegatus) exposed to sediment spiked with a model substance of one HO-hexaCDE (4'-HO-PCDE 161) or its methoxy analogue (4'-MeO-PCDE 161) clearly accumulated the test compounds revealing the potential for environmental risk of HO-PCDEs and MeO-PCDEs. The HO-PCDE tested has earlier been reported as an abundant component in a Finnish chlorophenol formulation (Ky-5) and its methoxy analogue is recognized as an abundant MeO-PCDE in sawmill soil contaminated by the formulation. The occurrence of 4'-HO-PCDE 161 and its methoxy analogue among other HO-PCDEs and MeO-PCDEs in lake mussels (Anodonta piscinalis) incubated in a river contaminated via the manufacture of Ky-5 showed that these compounds are bioavailable and transported in the aquatic environment. Mussel comparison with sediment data pointed to a higher accumulation potential for MeO-PCDEs than for HO-PCDEs. The finding of HO-PCDEs in groundwater samples collected from a groundwater reservoir, which had been contaminated by chlorophenols, points to potential of HO-PCDEs for transport with water in soil.     

Environmental assessment of gas management options at the Old Ämmässuo landfill (Finland) by means of LCA-modeling (EASEWASTE)

The current landfill gas (LFG) management (based on flaring and utilization for heat generation of the collected gas) and three potential future gas management options (LFG flaring, heat generation and combined heat and power generation) for the Old Ämmässuo landfill (Espoo, Finland) were evaluated by life-cycle assessment modeling. The evaluation accounts for all resource utilization and emissions to the environment related to the gas generation and management for a life-cycle time horizon of 100 yr. The assessment criteria comprise standard impact categories (global warming, photo-chemical ozone formation, stratospheric ozone depletion, acidification and nutrient enrichment) and toxicity-related impact categories (human toxicity via soil, via water and via air, eco-toxicity in soil and in water chronic).The results of the life-cycle impact assessment show that disperse emissions of LFG from the landfill surface determine the highest potential impacts in terms of global warming, stratospheric ozone depletion, and human toxicity via soil. Conversely, the impact potentials estimated for other categories are numerically-negative when the collected LFG is utilized for energy generation, demonstrating that net environmental savings can be obtained. Such savings are proportional to the amount of gas utilized for energy generation and the gas energy recovery efficiency achieved, which thus have to be regarded as key parameters. As a result, the overall best performance is found for the heat generation option – as it has the highest LFG utilization/energy recovery rates – whereas the worst performance is estimated for the LFG flaring option, as no LFG is here utilized for energy generation.Therefore, to reduce the environmental burdens caused by the current gas management strategy, more LFG should be used for energy generation. This inherently requires a superior LFG capture rate that, in addition, would reduce fugitive emissions of LFG from the landfill surface, bringing further environmental benefits.