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31.
Wood (timber) is an important raw material for various purposes, and having biological composition it is susceptible to deterioration by various agents. The history of wood protection by impregnation with synthetic chemicals is almost two hundred years old. However, the ever-increasing public concern and the new environmental regulations on the use of chemicals have created the need for the development and the use of alternative methods for wood protection. Biological wood protection by antagonistic microbes alone or in combination with (bio)chemicals, is one of the most promising ways for the environmentally sound wood protection. The most effective biocontrol antagonists belong to genera Trichoderma, Gliocladium, Bacillus, Pseudomonas and Streptomyces. They compete for an ecological niche by consuming available nutrients as well as by secreting a spectrum of biochemicals effective against various fungal pathogens. The biochemicals include cell wall-degrading enzymes, siderophores, chelating iron and a wide variety of volatile and non-volatile antibiotics. In this review, the nature and the function of the antagonistic microbes in wood protection are discussed. 相似文献
32.
In plants, prolonged dormancy is often considered a response to resource depletion or environmental stress that comes at a fitness cost. However, apparent costs of dormancy could reflect the state in which plants entered dormancy, rather than effects of dormancy per se. We tested this hypothesis for a terrestrial orchid, Epipactis atrorubens, by analyzing differences in vital rates of dormant and emergent plants using generalized linear mixed models, applied to eight years of demographic data. Dormant E. atrorubens plants did not form one homogeneous stage class. Instead, the vital rates of dormant plants mirrored performance of plants in their life stage before dormancy. Plants emerging from dormancy were slightly (albeit only marginally statistically significantly) larger than plants transitioning from the matching aboveground stage class, especially for smaller and younger stage classes. Because small plants were most likely to go dormant, plants emerging from dormancy were also smaller than average, if one were to compare all previously dormant plants to all previously emergent plants. Therefore, misclassifying all dormant plants into a single stage class changes whether we view dormancy as intrinsically costly, in terms of future performance upon emergence. We suggest that prolonged dormancy may be a form of phenotypic plasticity in which plants distribute their performance and reproductive effort through time, rather than a simple stress response. 相似文献
33.
Ann-Sofie Lindberg Christer Malm Juha Oksa Désirée Gavhed 《International journal of occupational safety and ergonomics》2013,19(2):309-321
Objectives. The present study sought to identify firefighters’ rated physical demands for the most frequently occurring work tasks and to determine if the ratings differed between full-time and part-time firefighters to help create a basis for the development of physical employment tests for firefighters. Methods. An extensive questionnaire was completed by 125 and 68 firefighters in 2000 and 2010, respectively. The data were analysed with the Mann-Whitney U test and binominal test and ranked on the basis of the responses in each category. Results. Significant differences were seen between the full- and part-time firefighters. The work tasks rated as the most physically strenuous in terms of aerobic fitness, muscle strength, work posture and body control by most respondents were smoke diving upstairs (carrying a hose), victim rescue in different ways, carrying a stretcher over terrain and pulling a hose. Conclusions. Physically strenuous work tasks should be included in the end-point performance variables used to select physical performance tests for firefighters. The part-time firefighters with no experience in several of the work tasks suggests that work-related exercises are important if both groups of firefighters are expected to do similar work. 相似文献
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35.
There is increasing interestin broad-scale analysis, modeling, and prediction of the distribution and composition of plant species assemblages under climatic, environmental, and biotic change, particularly for conservation purposes. We devised a method to reliably predict the impact of climate change on large assemblages of plant communities, while also considering competing biotic and environmental factors. To this purpose, we first used multilabel algorithms in order to convert the task of explaining a large assemblage of plant communities into a classification framework able to capture with high cross-validated accuracy the pattern of species distributions under a composite set of biotic and abiotic factors. We applied our model to a large set of plant communities in the Swiss Alps. Our model explained presences and absences of 175 plant species in 608 plots with >87% cross-validated accuracy, predicted decreases in α, β, and γ diversity by 2040 under both moderate and extreme climate scenarios, and identified likely advantaged and disadvantaged plant species under climate change. Multilabel variable selection revealed the overriding importance of topography, soils, and temperature extremes (rather than averages) in determining the distribution of plant species in the study area and their response to climate change. Our method addressed a number of challenging research problems, such as scaling to large numbers of species, considering species relationships and rarity, and addressing an overwhelming proportion of absences in presence–absence matrices. By handling hundreds to thousands of plants and plots simultaneously over large areas, our method can inform broad-scale conservation of plant species under climate change because it allows species that require urgent conservation action (assisted migration, seed conservation, and ex situ conservation) to be detected and prioritized. Our method also increases the practicality of assisted colonization of plant species by helping to prevent ill-advised introduction of plant species with limited future survival probability. 相似文献
36.
Jacquelin DeFaveri Takahito Shikano Nurul Izza Ab Ghani Juha Meril? 《Marine Biology》2012,159(8):1659-1672
Detailed multispecies studies on the patterns of genetic variability and differentiation in marine environments are still rare. Using mitochondrial and nuclear genetic markers, we compared genetic variability and population structuring of threespine (Gasterosteus aculeatus) and ninespine (Pungitius pungitius) sticklebacks from the same eleven marine and six freshwater locations within the Baltic Sea basin. Analyses of both marker types revealed a significantly lower degree of genetic structuring in both marine and freshwater populations of threespine than those ninespine sticklebacks. Isolation-by-distance (IBD) was detected across the marine populations in both species, suggesting spatially limited gene flow. However, the levels of genetic diversity and differentiation across the localities were uncorrelated between the two species in both marine and freshwater environments. Accordingly, estimates of effective population sizes were larger and migration rates were higher for three- than for ninespine sticklebacks. Hence, ninespine stickleback populations from the Baltic Sea basin appear to be subject to stronger genetic drift than sympatric threespine sticklebacks, and the proximate reason for this difference is likely to be found from autecological differences between the two species. In accordance with the earlier studies, genetic variability was higher and the degree of genetic differentiation was lower in marine than in freshwater populations in both species. 相似文献
37.
Modeling species co-occurrence by multivariate logistic regression generates new hypotheses on fungal interactions 总被引:2,自引:0,他引:2
Signals of species interactions can be inferred from survey data by asking if some species occur more or less often together than what would be expected by random, or more generally, if any structural aspect of the community deviates from that expected from a set of independent species. However, a positive (or negative) association between two species does not necessarily signify a direct or indirect interaction, as it can result simply from the species having similar (or dissimilar) habitat requirements. We show how these two factors can be separated by multivariate logistic regression, with the regression part accounting for species-specific habitat requirements, and a correlation matrix for the positive or negative residual associations. We parameterize the model using Bayesian inference with data on 22 species of wood-decaying fungi acquired in 14 dissimilar forest sites. Our analyses reveal that some of the species commonly found to occur together in the same logs are likely to do so merely by similar habitat requirements, whereas other species combinations are systematically either over- or underrepresented also or only after accounting for the habitat requirements. We use our results to derive hypotheses on species interactions that can be tested in future experimental work. 相似文献
38.
Jaakko Paasivirta Hannu Hakala Juha Knuutinen Terttu Otollinen Jukka Srkk Leena Welling Raija Paukku Reino Lammi 《Chemosphere》1990,21(12):1355-1370
Chlorohydrocarbons and free and chemically bound chlorophenols, catechols and guaiacols were measured from lake sediments in Central Finland. Chlorohydrocarbons occurred at low backround levels except chlorocymenes from pulp mills and PCBs near the city of Äänekoski, where a local leakage occurrs. Free chlorophenols (hexane extractables) were found in all 18 areas studied, but the bound ones (extracted with strong alkali) only in the pulp mill reciepient lakes where they dominated. Preliminary analyses of chemically bound chlorophenols in high molecular fractions of spent bleach liquors and pulp mill effluents indicated that majority of chlorocatechols and guaiacols are bound already in the factory. 相似文献
39.
与芬兰农业变化有关的草地中植物种类丰富度和生境连通度的降低 总被引:9,自引:0,他引:9
Miska Luoto Seppo Rekolainen Jyrki Aakkula Juha Pykl 《Ambio-人类环境杂志》2003,32(7):447-452
20世纪中,欧洲半天然草地严重减少,物种多样性降低,这与社会-经济因素密切相关.农业生产的发展驱动着土地利用的变化,从而控制着景观维持生物多样性的能力.本研究中,我们把农业生产变化和景观破碎化、物种多样性联系在一起.结果表明,半天然草地的停止放牧引起了景观结构的显著变化,并使维管束植物种的数目降低.放牧草场数量的下降主要是受与农业政策措施有关的农场水平的经济效果和收益率的影响.自1995年芬兰加入欧盟以来,由于对半天然草地经营有了扶持政策,我们研究地区中放牧斑块的面积又一次增加了. 相似文献
40.
Phosphorus loss from different farming systems estimated from soil surface phosphorus balance 总被引:1,自引:0,他引:1
Petri Ekholm Eila Turtola Juha Grnroos Pentti Seuri Kari Ylivainio 《Agriculture, ecosystems & environment》2005,110(3-4):266-278
The phosphorus load originating from crop production and animal husbandry is a major contributor to the eutrophication of lakes, rivers and coastal waters. The P losses to surface waters may, however, differ drastically due to the diversity of agricultural production systems practised under contrasting environmental conditions. To assess the most problematic types of agriculture, we need information on the P load from different alternative farming practices. Such information cannot, however, be obtained solely from field runoff experiments, as the number of treatment combinations required to account for all relevant farming systems and environmental conditions far exceeds our research capabilities. To facilitate the comparison of P loads, we therefore need reasonably simple models. A key factor controlling the P load from agriculture is the past and present use of nutrients in fertilizers and manure in relation to a crop's uptake, i.e. the soil-surface balance of P. Here, we present a simple empirical model that relates the P surplus (or deficit) in a farm to the edge-of-field losses of algal-available P. Based on long-term fertilizer trials, the model first estimates the change in soil-test P of top soil with the aid of the soil-surface balance of P. Soil-test P is then used to approximate the concentration of dissolved reactive P in surface runoff and drainage flow, as adjusted for different P application types. The loss of particulate P is obtained from typical erosion rates. The model can be applied in life-cycle analyses and in assessing future developments. We illustrate use of the model by calculating the loss of algal-available P from conventional and organic crop and dairy farms located on clay and fine sand soils. 相似文献