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Thimonier A Kull P Keller W Moser B Wohlgemuth T 《Environmental monitoring and assessment》2011,174(1-4):47-63
At Swiss long-term forest ecosystem research sites, ground vegetation was assessed during the period 1994-2003/2008 following two approaches: (1) visual assessment of the cover of species occurring in sixteen 1 m(2) quadrats, distributed over a 43 × 43 m area, and (2) phytosociological relevés in concentric circular plots of 30, 200, and 500 m(2). We first compared the two approaches with respect to diversity assessment. The number of species recorded in the 16 quadrats was in general higher than in the 30 m(2) plot and it represented 42% to 108% of the number of species recorded in the 500 m(2) plot. In a second step, we tested whether any temporal trends were apparent. In a few cases, a decrease or increase in Landolt's mean indicator values for light, nitrogen availability, soil pH, soil moisture, or temperature was found to be significant. However, these changes were usually restricted to one approach or one area. The only clear trend was detected in an unmanaged former coppice beech stand, for which all survey approaches indicated canopy closure. At another site, vegetation reacted to the local opening of the canopy following windthrow. In a third step, we compared the leaf area index (LAI), measured with an LAI-2000 instrument (Licor, Inc.) over each quadrat, with the indicator value of the vegetation for light (L). Within a site, there was no clear relationship between LAI and L values per quadrat. In contrast, across all sites, the relationship between LAI and L, averaged per site for all available years, was highly significant. 相似文献
423.
Three promising phytoextracting perennial weed species [ L. (ox-eye daisy), L. (curly dock), and L. (Canada goldenrod)] were planted in monoculture plots at two polychlorinated biphenyl (PCB)-contaminated sites in southern Ontario and followed over 2 yr to investigate the effects of plant age, contaminant characteristics, and species-specific properties on PCB uptake and accumulation patterns in plant tissues. Results from this study indicate that, for each of these weed species, shoot contaminant concentrations and total biomass are dependent on plant age and life cycle (vegetative and reproductive stages), which affects the total amount of PCBs phytoextracted on a per-plant basis. Even at suboptimal planting densities of 3 to 5 plants m, all three weed species extracted a greater quantity of PCBs per unit area (4800-10,000 μg m) than the known PCB-accumulator L. ssp (cv Howden pumpkins) (1500-2100 μg m) at one of the two sites. Calculated PCB extractions based on theoretical optimal planting densities were significantly higher at both sites and illustrate the potential of these weeds for site remediation. This study also demonstrates that plants may accumulate PCBs along the stem length in a similar manner as plants. 相似文献
424.
Roadless and Low-Traffic Areas as Conservation Targets in Europe 总被引:1,自引:0,他引:1
Selva N Kreft S Kati V Schluck M Jonsson BG Mihok B Okarma H Ibisch PL 《Environmental management》2011,48(5):865-877
With increasing road encroachment, habitat fragmentation by transport infrastructures has been a serious threat for European
biodiversity. Areas with no roads or little traffic (“roadless and low-traffic areas”) represent relatively undisturbed natural
habitats and functioning ecosystems. They provide many benefits for biodiversity and human societies (e.g., landscape connectivity,
barrier against pests and invasions, ecosystem services). Roadless and low-traffic areas, with a lower level of anthropogenic
disturbances, are of special relevance in Europe because of their rarity and, in the context of climate change, because of
their contribution to higher resilience and buffering capacity within landscape ecosystems. An analysis of European legal
instruments illustrates that, although most laws aimed at protecting targets which are inherent to fragmentation, like connectivity,
ecosystem processes or integrity, roadless areas are widely neglected as a legal target. A case study in Germany underlines
this finding. Although the Natura 2000 network covers a significant proportion of the country (16%), Natura 2000 sites are
highly fragmented and most low-traffic areas (75%) lie unprotected outside this network. This proportion is even higher for
the old Federal States (western Germany), where only 20% of the low-traffic areas are protected. We propose that the few remaining
roadless and low-traffic areas in Europe should be an important focus of conservation efforts; they should be urgently inventoried,
included more explicitly in the law and accounted for in transport and urban planning. Considering them as complementary conservation
targets would represent a concrete step towards the strengthening and adaptation of the Natura 2000 network to climate change. 相似文献
425.
Chiara Chiapponi Enrico Pavoni Barbara Bertasi Laura Baioni Erika Scaltriti Edoardo Chiesa Luca Cianti Marina Nadia Losio Stefano Pongolini 《Food and environmental virology》2014,6(3):202-206
Hepatitis A virus (HAV) was detected in two samples of mixed frozen berries linked to Italian hepatitis A outbreak in April and September 2013. Both viruses were fully sequenced by next-generation sequencing and the genomes clustered with HAV complete genomes of sub-genotype IA with nucleotide identities of 95–97 %. 相似文献
426.
Pavoni Enrico Bertasi Barbara Galuppini Elisa Mangeri Lucia Meletti Francesca Tilola Michela Carta Valentina Todeschi Silvia Losio Marina-Nadia 《Food and environmental virology》2022,14(1):69-76
Food and Environmental Virology - To observe the prevalence of contamination by hepatitis A virus (HAV) and norovirus (NoV) in different food types, 9242 samples were analyzed over a 6-year period... 相似文献
427.
Shuang Chen Xinrong Ren Jingqiu Mao Zhong Chen William H. Brune Barry Lefer Bernhard Rappenglück James Flynn Jennifer Olson James H. Crawford 《Atmospheric environment (Oxford, England : 1994)》2010,44(33):4116-4125
A comparison of a model using five widely known mechanisms (RACM, CB05, LaRC, SAPRC-99, SAPRC-07, and MCMv3.1) has been conducted based on the TexAQS II Radical and Aerosol Measurement Project (TRAMP-2006) field data in 2006. The concentrations of hydroxyl (OH) and hydroperoxy (HO2) radicals were calculated by a zero-dimensional box model with each mechanism and then compared with the OH and HO2 measurements. The OH and HO2 calculated by the model with different mechanisms show similarities and differences with each other and with the measurements. First, measured OH and HO2 are generally greater than modeled for all mechanisms, with the median modeled-to-measured ratios ranging from about 0.8 (CB05) to about 0.6 (SAPRC-99). These differences indicate that either measurement errors, the effects of unmeasured species or chemistry errors in the model or the mechanisms, with some errors being independent of the mechanism used. Second, the modeled and measured ratios of HO2/OH agree when NO is about 1 ppbv, but the modeled ratio is too high when NO was less and too low when NO is more, as seen in previous studies. Third, mechanism–mechanism HOx differences are sensitive to the environmental conditions – in more polluted conditions, the mechanism–mechanism differences are less. This result suggests that, in polluted conditions, the mechanistic details are less important than in cleaner conditions, probably because of the dominance of reactive nitrogen chemistry under polluted conditions. 相似文献
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Stephanie Ann Farquhar Edith A. Parker Amy J. Schulz Barbara A. Israel 《Local Environment》2005,10(3):259-274
This article examines results from in-depth interviews conducted with parents of children with asthma living in an urban environment. We examine themes from the in-depth interviews related to participants' perceptions of the influence of their physical environment on their mental and physical health, and the actions that they take in an effort to protect their health within this context. The findings from this study suggest several implications for understanding the interface between the physical environment of urban communities and residents' health, as well as for the policy and practice of risk assessment strategies. 相似文献