The paper analyzes the hypothesis that the distribution of dominant plant species and characteristics of plant communities are related to groundwater depth. The results showed that variations of groundwater depth impa...The paper analyzes the hypothesis that the distribution of dominant plant species and characteristics of plant communities are related to groundwater depth. The results showed that variations of groundwater depth impacted distributions and characteristics of dominant plant communities. However, besides groundwater depth, the community composition and species diversity were also influenced by physiognomy of the habitat. Based on the similarity coefficient, the differences between dominant plant communities were significant at different groundwater depths. Compared with other results relating to desert vegetation and groundwater depth, variations of community distribution were similar at the large spatial scale. However, in this extremely arid region, there were significant differences in community type and community succession when compared with other arid regions, especially in relationship to deep groundwater depth. With groundwater depth from deep to shallow, communities transformed with the sequence of Alhagi communities, Tamarix spp. communities, Populus communities, Phragmites communities, and Sophora communities. At groundwater depth of less than 6.0 m, the community type and composition changed, and the species diversity increased. Among these dominant species, Tamarix exhibited the biggest efficiency in resource utilization according to niche breadth, which means it possessed the best adaptability to environmental conditions at the oasis margins.展开更多
The contents of nitrogen and organic carbon in an agricultural soil were analyzed using reflectance measurements （n = 52） performed with an ASD FieldSpee-Ⅱ spectroradiometer. For parameter prediction, empirical mod...The contents of nitrogen and organic carbon in an agricultural soil were analyzed using reflectance measurements （n = 52） performed with an ASD FieldSpee-Ⅱ spectroradiometer. For parameter prediction, empirical models based on partial least squares （PLS） regression were defined from the measured reflectance spectra （0.4 to 2.4 μm）. Here, reliable estimates were obtained for nitrogen content, but prediction accuracy was only moderate for organic carbon. For nitrogen, the real spatial pattern of within-field variability was reproduced with high accuracy. The results indicate the potential of this method as a quick screening tool for the spatial assessment of nitrogen and organic carbon, and therefore an appropriate alternative to time- and cost-intensive chemical analysis in the laboratory.展开更多
Many riparian（Tugai） forests growing along rivers in arid and hyper-arid regions of Central Asia are dominated by the Euphrates poplar（Populus euphratica）. Besides generative reproduction, which is only possible u...Many riparian（Tugai） forests growing along rivers in arid and hyper-arid regions of Central Asia are dominated by the Euphrates poplar（Populus euphratica）. Besides generative reproduction, which is only possible upon flooding events and at a distance to the groundwater of less than 2 m, this phreatophytic tree species also reproduces vegetatively by forming clones that can cover land surface areas of several hectares. Along a gradient of groundwater distances, we investigated whether the fraction of clones in P. euphratica stands（1） increases with increasing distance to the water table;（2） is higher if supplied with water via river cut-offs; and（3） approaches 100% at a short distance to the groundwater, but at high salt concentrations in the upper soil layers, which would prevent germination and establishment of seedlings. AFLP（Amplified Fragment Length Polymorphism） analyses were conducted on leaf samples taken from mature P. euphratica trees growing at the fringes of the Taklimakan Desert in stands with different distances（2–12 m） to the groundwater at two plots at the middle and the lower reaches of the Tarim River and in a stand close to Ebinur Lake, Xinjiang, China. Genetic diversity was large among plots, but considerably smaller within plots. We found the highest genetic diversity（caused by regeneration from seeds） at plots that have a short distance to the groundwater or are supplied with additional water. There was no significant relationship between groundwater distance and clonal fraction. All investigated trees at the saline Ebinur Lake site belonged to one single clone. Our results demonstrate that the genetic pattern of this widespread species is not easily predictable even over small distances as it is a result of a complex interplay of stand history and dispersal of propagules（pollen, seeds, and vegetative diaspores） by wind and water. In conservation and restoration schemes, P. euphratica stands with a high genetic diversity and stands that grow at short distances to the water table and are regularly subjected to flooding（which favors generative over clonal reproduction） should be prioritized.展开更多
This paper examines the meanings and functions of gestures in comedy-related vase-paintings produced in southern Italy and Sicily during the 4th century BC.It discusses to what extent the gestures depicted in these im...This paper examines the meanings and functions of gestures in comedy-related vase-paintings produced in southern Italy and Sicily during the 4th century BC.It discusses to what extent the gestures depicted in these images convey a specific meaning,and to what extent their“reading”depends on the composition as a whole,i.e.,the choice,positioning,and cognitive framework of the pictorial elements such as figures and objects.A first group of gestures indicates communication processes in“conversational”scenes usually with two figures.In these scenes,the meaning of gestures is of low importance,but their relative position within the composition displays which conversation partner dominates the other,often by inverting social hierarchies.The second group consists of more specific gestures that express strong and often negative emotions.They originate from tragedy-related vase-paintings,and this incongruence between tragic gesture and comic context causes a comic effect.In general,gestures are just one part of the cognitive framework of comedy-related vase-paintings which refer to comedy;however,they create a complex network of cognitive frames and thus evoke independent comic narratives.展开更多
The Enterprise regime was intensively negotiated first in the Third United Nations Conference on the Law of the Sea (UNCLOS III) from 1973 to 1982 and then in the UN Secretary General’s informal consultations from 19...The Enterprise regime was intensively negotiated first in the Third United Nations Conference on the Law of the Sea (UNCLOS III) from 1973 to 1982 and then in the UN Secretary General’s informal consultations from 1990 to 1994. The United Nations Convention on the Law of the Sea (hereinafter the “Convention”) is a major achievement of the UNCLOS III and the Agreement Relating to the Implementation of Part XI of the United Nations Convention on the Law of the Sea of 10 December 1982 (hereinafter the “1994 Agreement”) is an achievement of the informal consultations. The Enterprise regime has been dramatically changed in many ways with the adoption of 1994 Agreement. Envisaged as an operational organ of the International Seabed Authority, the outlook of the Enterprise is still unknown. In this connection, this paper highlights a few questions which need to be answered urgently, and proposes the way forward for the operationalization of the Enterprise in terms of legal principles and institutional design.展开更多
Recent studies of Roman economy and on the economic history of Greco-Roman Egypt focus on new approaches and new sources for some traditional topics like textile industry, taxes and custom duties, money and credit bus...Recent studies of Roman economy and on the economic history of Greco-Roman Egypt focus on new approaches and new sources for some traditional topics like textile industry, taxes and custom duties, money and credit business, agriculture or professions like craftsmen and traders. Of great importance for current research interests are some studies that use the approach of the transaction cost- theory to explain ancient economic behavior. Furthermore, the combination of nautical methods and classical analysis of ancient evidence improves the knowledge of sea trade in Roman times. More and more traditional research based on source criticism and the inclusion of new ancient evidence is combined with theoretical approaches and comparative methods.展开更多
The increasing production and use of engineered silver nanoparticles（AgNP） in industry and private households are leading to increased concentrations of AgNP in the environment. An ecological risk assessment of AgNP...The increasing production and use of engineered silver nanoparticles（AgNP） in industry and private households are leading to increased concentrations of AgNP in the environment. An ecological risk assessment of AgNP is needed, but it requires understanding the long term effects of environmentally relevant concentrations of AgNP on the soil microbiome. Hence, the aim of this study was to reveal the long-term effects of AgNP on soil microorganisms. The study was conducted as a laboratory incubation experiment over a period of one year using a loamy soil and AgNP concentrations ranging from 0.01 to 1 mg AgNP/kg soil. The short term effects of AgNP were, in general, limited.However, after one year of exposure to 0.01 mg AgNP/kg, there were significant negative effects on soil microbial biomass（quantified by extractable DNA; p = 0.000） and bacterial ammonia oxidizers（quantified by amo A gene copy numbers; p = 0.009）. Furthermore, the tested AgNP concentrations significantly decreased the soil microbial biomass, the leucine aminopeptidase activity（quantified by substrate turnover; p = 0.014）, and the abundance of nitrogen fixing microorganisms（quantified by nif H gene copy numbers; p = 0.001）. The results of the positive control with Ag NO3 revealed predominantly stronger effects due to Ag＋ion release. Thus, the increasing toxicity of AgNP during the test period may reflect the long-term release of Ag^＋ions. Nevertheless, even very low concentrations of AgNP caused disadvantages for the microbial soil community, especially for nitrogen cycling, and our results confirmed the risks of releasing AgNP into the environment.展开更多
Aims Along central-Asian rivers in arid regions,lowering of the ground-water level constitutes a major threat to the riparian forests,whose tree layers are dominated by Euphrates poplar(Populus euphratica).Some of the...Aims Along central-Asian rivers in arid regions,lowering of the ground-water level constitutes a major threat to the riparian forests,whose tree layers are dominated by Euphrates poplar(Populus euphratica).Some of these fragile ecosystems are supplied with additional(‘eco-logical’)water for protection and conservation.We investigated interrelationships among groundwater distance,stand structure and above-ground wood production(at the tree and the stand level)in P.euphratica stands along a groundwater gradient(distances of 2.0-12.0 m)that also included a plot supplied with‘ecological water’.Methods We measured the height,diameter at breast height and basal area of poplar trees and determined the annual above-ground wood production for the three most recent years on the basis of tree-ring analyses and allometric regressions at three sites at the upper,mid-dle and lower reaches of the tarim River,Xinjiang,NW china.Important Findingsthe distribution of age classes differed significantly among the plots:in accordance with their life histories,stands growing at a larger distance to the groundwater harboured a larger fraction of old trees(>80 years)and,in most cases,a smaller fraction of young trees(≤20 years).the annual above-ground wood production per ha was highest on a plot with a short groundwater distance(2.0 m;maxi-mum of the 3-year investigation period:3.0 t ha−1 a−1)and lowest,at a plot with a large distance to the water table(6.6 m;minimum:0.23 t ha^(−1)a^(−1)).However,the plot located close to the groundwater(and to the river)at the middle reaches exhibited a relatively large interannual variation in above-ground wood production,which can be attributed to interannual variations in the river discharge.At the middle and the lower reaches,these interannual variations on plots with the most favourable water supply were even more obvious at the tree level.For the fraction of mature trees(60-99 years old),no significant differences in above-ground wood production were found between the plots with the most and the least favourable water supply.Overall,the productivity at the stand level was most closely correlated with the stand density(number of trees per ha,tree cover percentage).Productivity was negatively related to tree age,whereas groundwater distance alone was not a good predictor of above-ground wood production.In conclusion,vigorous growth of P.euphratica is possible at sites with groundwater distances of up to 12 m.Supply with‘ecological water’may be beneficial to trees growing at groundwater distances not larger than~6 m.However,allocation of water should focus on stands with a short distance to the groundwater because only under these conditions,natural gen-erative reproduction of the poplars is possible.展开更多
Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fr...Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fringe of the hyperarid Taklamakan Desert(north-west China).Methods In the foreland of the river oasis of Qira(Cele),we determined meteorological variables,plant biomass production,plant water potentials(WL)and the water flux through the plants.We calculated the hydraulic conductance on the flow path from the soil to the leaves(kSL)and tested the effects of kSL,WL and the leaf-to-air difference in the partial pressure of water vapour(Dw)on stomatal regulation using regression analyses.Important Findings Despite high values of plant water potential at the point of turgor loss,all plants sustained WL at levels that were high enough to maintain transpiration throughout the growing season.In A.sparsifolia,stomatal resistance(rs;related to leaf area or leaf mass)was most closely correlated with kSL;whereas in P.euphratica,~70%of the variation in rs was explained by Dw.In T.ramosissima,leaf area-related rs was significantly correlated with WL and kSL.The regulation mechanisms are in accordance with the growth patterns and the occurrence of the species in relation to their distance to the ground water.展开更多
Integrated observation platforms have been set up to investigate consequences of global change within a terrestrial network of observatories （TERENO） in Germany. The aim of TERENO is to foster the understanding of w...Integrated observation platforms have been set up to investigate consequences of global change within a terrestrial network of observatories （TERENO） in Germany. The aim of TERENO is to foster the understanding of water, energy, and matter fluxes in terrestrial systems, as well as their biological and physical drivers. Part of the Lower Rhine Valley-Eifel observatory of TERENO is located within the Eifel National Park. Recently, the National Park forest management started to promote the nat- ural regeneration of near-natural beech forest by removing a significant proportion of the spruce forest that was established for timber production after World War II. Within this context, the effects of such a disturbance on forest ecosystem functioning are currently investigated in a deforestation experiment in the Wtistebach catchment, which is one of the key experimental re- search sites within the Lower Rhine Valley-Eifel observatory. Here, we present the integrated observation system of the Wiistebach test site to exemplarily demonstrate the terrestrial observatory concept of TERENO that allows for a detailed mon- itoring of changes in hydrological and biogeochemical states and fluxes triggered by environmental disturbances. We present the observation platforms and the soil sampling campaign, as well as preliminary results including an analysis of data con- sistency. We specifically highlight the capability of integrated datasets to enable improved process understanding of the post-deforestation changes in ecosystem functioning.展开更多
For decades,researchers in information visualisation and graph drawing have focused on developing techniques for the layout and display of very large and complex networks.Experiments involving human participants have ...For decades,researchers in information visualisation and graph drawing have focused on developing techniques for the layout and display of very large and complex networks.Experiments involving human participants have also explored the readability of different styles of layout and representations for such networks.In both bodies of literature,networks are frequently referred to as being‘large’or‘complex’,yet these terms are relative.From a human-centred,experiment point-of-view,what constitutes‘large’(for example)depends on several factors,such as data complexity,visual complexity,and the technology used.In this paper,we survey the literature on human-centred experiments to understand how,in practice,different features and characteristics of node–link diagrams affect visual complexity.展开更多
Aims In contrast to temperate regions,the reasons for growth reductions of individual tree species along elevational gradients in tropical mountain ranges are poorly known,especially for tropical conifers.We aimed at ...Aims In contrast to temperate regions,the reasons for growth reductions of individual tree species along elevational gradients in tropical mountain ranges are poorly known,especially for tropical conifers.We aimed at testing whether climatic or edaphic conditions are responsible for the reduced growth of Pinus kesiya,a widely distributed pine species of southern and south-eastern Asia,at higher elevations.Methods We analysed the stem diameter increment and the isotope discrimination against ^(13)C(△^(13)C)in tree rings of P.kesiya along an elevational gradient of~900 to~2000 m a.s.l.in the mountain ranges of South-Central Vietnam,and related growth to△^(13)C and to climatic and edaphic variables.Important findings We found no consistent correlation patterns between the basal area increment(BAI)of the trees and temperature or precipitation.In contrast,across the elevational gradient,we obtained significantly negative correlations of BAI with△^(13)C and with the C/N ratios and theδ^(15)N signature of the upper mineral soil.BAI was positively correlated with the concentrations of plant-available phosphorus(P_(a))and of“base”cations(calcium,magnesium,potassium)in the soil.We conclude that lower temperatures at higher elevations exert an indirect effect on tree growth by inducing higher C/N ratios and by reducing the rate of nitrogen(N)and P mineralization,which may be further hampered by lower concentrations of“base”cations(upon enhanced leaching by precipitation)and a negative feedback from low availability of mineralized N and P at higher elevations.Our results may be transferable to the uppermost growth limit of P.kesiya and to other montane regions of the species’occurrence.展开更多
Aims We tested whether—in addition to weather conditions—the concentrations of nitrogen and phosphorus in the substrate have an effect on the radial stem increment of Nothofagus dombeyi trees in old-growth forest st...Aims We tested whether—in addition to weather conditions—the concentrations of nitrogen and phosphorus in the substrate have an effect on the radial stem increment of Nothofagus dombeyi trees in old-growth forest stands on volcanic soil at the western slopes of the Andes in South-Central Chile.Methods We took soil samples and tree increment cores from five proximate sites(1000-1300 m a.s.l.)that are located in the volcanic region of the Conguillío National Park and differ in the age of the substrate(Miocene—3500 years B.P.)and in its concentrations of nitrogen(N)and phosphorus(P).The soil samples were also analysed on their concentrations of other plant mineral nutrients,carbon(C)and nitrogen isotope ratios(δ^(15)N).Tree-ring widths and the stem basal area increment(BAI)were related to climate parameters.In selected tree rings,the stable isotope ratios of carbon(δ^(13)C)and oxygen(δ^(18)O)were determined and related to growth and climate parameters.Important FindingsConsistent with theory,the soils on the oldest substrate showed the highest(least negative)δ^(15)N values,but mineral N was the only nutrient whose concentration exhibited a straightforward(increasing)relationship with increasing substrate age.The BAI was largest on the soil with the highest concentration of plant-available P.In contrast to BAI,tree-ring chronologies did not differ among the study sites.However,tree-ring chronologies and BAI exhibited significantly positive correlations with summer precipitation,and negative correlations,with summer(December)temperature.A negative correlation was found betweenδ^(13)C and precipitation anomalies in the growing season(November-March).We interpret the negative correlations between growth and temperature,and betweenδ^(13)C andδ^(18)O in the tree rings,as an impairment of net carbon assimilation by anomalously warm weather conditions during the growing season.We conclude that the growth of N.dombeyi is mainly affected by high temperature and low precipitation in spring and summer irrespective of the substrate’s age,and enhanced by higher concentrations of plant-available P in the soil.Our results may be representative of N.dombeyi stands on volcanic substrate within their principal distribution range along the Andes of South America.展开更多
Aims Nothofagus species are constitutive elements of the temperate forests along the Southern Andes Mountains.The deciduous Nothofagus alpina is a fast-growing,but long-lived opportunistic pioneer spe-cies(‘pioneer-c...Aims Nothofagus species are constitutive elements of the temperate forests along the Southern Andes Mountains.The deciduous Nothofagus alpina is a fast-growing,but long-lived opportunistic pioneer spe-cies(‘pioneer-climax species’)and co-occurs with the evergreen N.dombeyi.We tested whether N.alpina is competitively superior to N.dombeyi in mature stands and whether intra-specific competition in N.alpina is stronger than inter-specific competition with N.dombeyi.Methods In a pristine old-growth forest in South-Central Chile,we compared the growth of N.alpina trees in pure stands and in mixture with N.dombeyi to the growth of N.dombeyi and calculated compe-tition indices.We related growth variables to climate data and weather extremes.Important Findings In N.alpina,juvenile basal area increment was signifi-cantly higher in pure than in mixed stands.Contrary to our hypothesis,N.dombeyi exhibited larger radial stem increments than N.alpina in the most recent 40 years.In the most recent two decades,this was caused by high growth rates of large N.dombeyi trees.In both Nothofagus species,stem growth was negatively related to temperature,but N.dombeyi responded more sensitively to weather conditions than N.alpina.In N.alpina,stem increment was negatively related to the intensity of competition,but the size of the competition effects on this species was similar in pure and mixed stands.Thus,compared to N.alpina,the‘pioneer-climax species’concept is even more appropriate for N.dombeyi with its relatively high growth rates even in the early stages of its life.展开更多
Sexual dimorphism is a widespread phenomenon in Lepidoptera.It is reflected in differences in life history,behavior and morphology.Analyses of differences in behavior are mostly difficult and time-consuming,especially...Sexual dimorphism is a widespread phenomenon in Lepidoptera.It is reflected in differences in life history,behavior and morphology.Analyses of differences in behavior are mostly difficult and time-consuming,especially in high mountain ecosystems.To enhance our knowledge on sexual dimorphisms of alpine butterflies,we performed a mark-release-recapture study on 2 species common in the Alps:Boloriapales and Boloria napaea.We analysed movement and foraging behavior to investigate differences between sexes.Both sexes were mostly sedentary and the movement distances of males and females similar.However,obvious differences in dispersal behavior between the sexes were found in the movement patterns.Three different patterns were distinguished.Most males showed intensive flight activity,but mostly flew only in a limited part of the entire habitat (i.e.,their individual home range)searching for females,whereas females were less flight active and flew only to find places for oviposition or feeding.The third pattern,where individuals flew larger distances,was only observed in a small number of males,which always returned to their home range.Nearly all feeding was observed on Asteraceae.However,males preferred the genera Leontodon and Crepis,while females preferred Leontodon and Carduus.Apart from this sexual difference in foraging,individuals of both sexes were found to be more or less specialised on nectar sources.Flight activity was generally greater in males than females.Therefore,we think that sex-specific requirements in nectar ingredients exist,that is,sugar for the intensive flight activity of males and amino acids for egg production of females.展开更多
基金funded by the National Basic Research Program of China (2009CB421303)the Key Project in Science & Technology Program of Xinjiang Uygur Autonomous Region (200933125)the Science and Technology Ministry Program (2009BAC54B03)
文摘The paper analyzes the hypothesis that the distribution of dominant plant species and characteristics of plant communities are related to groundwater depth. The results showed that variations of groundwater depth impacted distributions and characteristics of dominant plant communities. However, besides groundwater depth, the community composition and species diversity were also influenced by physiognomy of the habitat. Based on the similarity coefficient, the differences between dominant plant communities were significant at different groundwater depths. Compared with other results relating to desert vegetation and groundwater depth, variations of community distribution were similar at the large spatial scale. However, in this extremely arid region, there were significant differences in community type and community succession when compared with other arid regions, especially in relationship to deep groundwater depth. With groundwater depth from deep to shallow, communities transformed with the sequence of Alhagi communities, Tamarix spp. communities, Populus communities, Phragmites communities, and Sophora communities. At groundwater depth of less than 6.0 m, the community type and composition changed, and the species diversity increased. Among these dominant species, Tamarix exhibited the biggest efficiency in resource utilization according to niche breadth, which means it possessed the best adaptability to environmental conditions at the oasis margins.
文摘The contents of nitrogen and organic carbon in an agricultural soil were analyzed using reflectance measurements （n = 52） performed with an ASD FieldSpee-Ⅱ spectroradiometer. For parameter prediction, empirical models based on partial least squares （PLS） regression were defined from the measured reflectance spectra （0.4 to 2.4 μm）. Here, reliable estimates were obtained for nitrogen content, but prediction accuracy was only moderate for organic carbon. For nitrogen, the real spatial pattern of within-field variability was reproduced with high accuracy. The results indicate the potential of this method as a quick screening tool for the spatial assessment of nitrogen and organic carbon, and therefore an appropriate alternative to time- and cost-intensive chemical analysis in the laboratory.
基金funded by the German Federal Ministry of Education and Research(01LL0918K)
文摘Many riparian（Tugai） forests growing along rivers in arid and hyper-arid regions of Central Asia are dominated by the Euphrates poplar（Populus euphratica）. Besides generative reproduction, which is only possible upon flooding events and at a distance to the groundwater of less than 2 m, this phreatophytic tree species also reproduces vegetatively by forming clones that can cover land surface areas of several hectares. Along a gradient of groundwater distances, we investigated whether the fraction of clones in P. euphratica stands（1） increases with increasing distance to the water table;（2） is higher if supplied with water via river cut-offs; and（3） approaches 100% at a short distance to the groundwater, but at high salt concentrations in the upper soil layers, which would prevent germination and establishment of seedlings. AFLP（Amplified Fragment Length Polymorphism） analyses were conducted on leaf samples taken from mature P. euphratica trees growing at the fringes of the Taklimakan Desert in stands with different distances（2–12 m） to the groundwater at two plots at the middle and the lower reaches of the Tarim River and in a stand close to Ebinur Lake, Xinjiang, China. Genetic diversity was large among plots, but considerably smaller within plots. We found the highest genetic diversity（caused by regeneration from seeds） at plots that have a short distance to the groundwater or are supplied with additional water. There was no significant relationship between groundwater distance and clonal fraction. All investigated trees at the saline Ebinur Lake site belonged to one single clone. Our results demonstrate that the genetic pattern of this widespread species is not easily predictable even over small distances as it is a result of a complex interplay of stand history and dispersal of propagules（pollen, seeds, and vegetative diaspores） by wind and water. In conservation and restoration schemes, P. euphratica stands with a high genetic diversity and stands that grow at short distances to the water table and are regularly subjected to flooding（which favors generative over clonal reproduction） should be prioritized.
文摘This paper examines the meanings and functions of gestures in comedy-related vase-paintings produced in southern Italy and Sicily during the 4th century BC.It discusses to what extent the gestures depicted in these images convey a specific meaning,and to what extent their“reading”depends on the composition as a whole,i.e.,the choice,positioning,and cognitive framework of the pictorial elements such as figures and objects.A first group of gestures indicates communication processes in“conversational”scenes usually with two figures.In these scenes,the meaning of gestures is of low importance,but their relative position within the composition displays which conversation partner dominates the other,often by inverting social hierarchies.The second group consists of more specific gestures that express strong and often negative emotions.They originate from tragedy-related vase-paintings,and this incongruence between tragic gesture and comic context causes a comic effect.In general,gestures are just one part of the cognitive framework of comedy-related vase-paintings which refer to comedy;however,they create a complex network of cognitive frames and thus evoke independent comic narratives.
文摘The Enterprise regime was intensively negotiated first in the Third United Nations Conference on the Law of the Sea (UNCLOS III) from 1973 to 1982 and then in the UN Secretary General’s informal consultations from 1990 to 1994. The United Nations Convention on the Law of the Sea (hereinafter the “Convention”) is a major achievement of the UNCLOS III and the Agreement Relating to the Implementation of Part XI of the United Nations Convention on the Law of the Sea of 10 December 1982 (hereinafter the “1994 Agreement”) is an achievement of the informal consultations. The Enterprise regime has been dramatically changed in many ways with the adoption of 1994 Agreement. Envisaged as an operational organ of the International Seabed Authority, the outlook of the Enterprise is still unknown. In this connection, this paper highlights a few questions which need to be answered urgently, and proposes the way forward for the operationalization of the Enterprise in terms of legal principles and institutional design.
文摘Recent studies of Roman economy and on the economic history of Greco-Roman Egypt focus on new approaches and new sources for some traditional topics like textile industry, taxes and custom duties, money and credit business, agriculture or professions like craftsmen and traders. Of great importance for current research interests are some studies that use the approach of the transaction cost- theory to explain ancient economic behavior. Furthermore, the combination of nautical methods and classical analysis of ancient evidence improves the knowledge of sea trade in Roman times. More and more traditional research based on source criticism and the inclusion of new ancient evidence is combined with theoretical approaches and comparative methods.
基金supported by the Federal Ministry of Education and Research of Germany(Research unit Nano Umwelt,funding code 03X0150C)
文摘The increasing production and use of engineered silver nanoparticles（AgNP） in industry and private households are leading to increased concentrations of AgNP in the environment. An ecological risk assessment of AgNP is needed, but it requires understanding the long term effects of environmentally relevant concentrations of AgNP on the soil microbiome. Hence, the aim of this study was to reveal the long-term effects of AgNP on soil microorganisms. The study was conducted as a laboratory incubation experiment over a period of one year using a loamy soil and AgNP concentrations ranging from 0.01 to 1 mg AgNP/kg soil. The short term effects of AgNP were, in general, limited.However, after one year of exposure to 0.01 mg AgNP/kg, there were significant negative effects on soil microbial biomass（quantified by extractable DNA; p = 0.000） and bacterial ammonia oxidizers（quantified by amo A gene copy numbers; p = 0.009）. Furthermore, the tested AgNP concentrations significantly decreased the soil microbial biomass, the leucine aminopeptidase activity（quantified by substrate turnover; p = 0.014）, and the abundance of nitrogen fixing microorganisms（quantified by nif H gene copy numbers; p = 0.001）. The results of the positive control with Ag NO3 revealed predominantly stronger effects due to Ag＋ion release. Thus, the increasing toxicity of AgNP during the test period may reflect the long-term release of Ag^＋ions. Nevertheless, even very low concentrations of AgNP caused disadvantages for the microbial soil community, especially for nitrogen cycling, and our results confirmed the risks of releasing AgNP into the environment.
基金German Federal Ministry of Education and Research(BMBF),Funding Measure‘Sustainable Land Management’(project number:01LL0918K).
文摘Aims Along central-Asian rivers in arid regions,lowering of the ground-water level constitutes a major threat to the riparian forests,whose tree layers are dominated by Euphrates poplar(Populus euphratica).Some of these fragile ecosystems are supplied with additional(‘eco-logical’)water for protection and conservation.We investigated interrelationships among groundwater distance,stand structure and above-ground wood production(at the tree and the stand level)in P.euphratica stands along a groundwater gradient(distances of 2.0-12.0 m)that also included a plot supplied with‘ecological water’.Methods We measured the height,diameter at breast height and basal area of poplar trees and determined the annual above-ground wood production for the three most recent years on the basis of tree-ring analyses and allometric regressions at three sites at the upper,mid-dle and lower reaches of the tarim River,Xinjiang,NW china.Important Findingsthe distribution of age classes differed significantly among the plots:in accordance with their life histories,stands growing at a larger distance to the groundwater harboured a larger fraction of old trees(>80 years)and,in most cases,a smaller fraction of young trees(≤20 years).the annual above-ground wood production per ha was highest on a plot with a short groundwater distance(2.0 m;maxi-mum of the 3-year investigation period:3.0 t ha−1 a−1)and lowest,at a plot with a large distance to the water table(6.6 m;minimum:0.23 t ha^(−1)a^(−1)).However,the plot located close to the groundwater(and to the river)at the middle reaches exhibited a relatively large interannual variation in above-ground wood production,which can be attributed to interannual variations in the river discharge.At the middle and the lower reaches,these interannual variations on plots with the most favourable water supply were even more obvious at the tree level.For the fraction of mature trees(60-99 years old),no significant differences in above-ground wood production were found between the plots with the most and the least favourable water supply.Overall,the productivity at the stand level was most closely correlated with the stand density(number of trees per ha,tree cover percentage).Productivity was negatively related to tree age,whereas groundwater distance alone was not a good predictor of above-ground wood production.In conclusion,vigorous growth of P.euphratica is possible at sites with groundwater distances of up to 12 m.Supply with‘ecological water’may be beneficial to trees growing at groundwater distances not larger than~6 m.However,allocation of water should focus on stands with a short distance to the groundwater because only under these conditions,natural gen-erative reproduction of the poplars is possible.
基金European Union INCO-DC(Project No.ERBIC18CT980275).
文摘Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fringe of the hyperarid Taklamakan Desert(north-west China).Methods In the foreland of the river oasis of Qira(Cele),we determined meteorological variables,plant biomass production,plant water potentials(WL)and the water flux through the plants.We calculated the hydraulic conductance on the flow path from the soil to the leaves(kSL)and tested the effects of kSL,WL and the leaf-to-air difference in the partial pressure of water vapour(Dw)on stomatal regulation using regression analyses.Important Findings Despite high values of plant water potential at the point of turgor loss,all plants sustained WL at levels that were high enough to maintain transpiration throughout the growing season.In A.sparsifolia,stomatal resistance(rs;related to leaf area or leaf mass)was most closely correlated with kSL;whereas in P.euphratica,~70%of the variation in rs was explained by Dw.In T.ramosissima,leaf area-related rs was significantly correlated with WL and kSL.The regulation mechanisms are in accordance with the growth patterns and the occurrence of the species in relation to their distance to the ground water.
基金the support by the SFB-TR32 "Patterns in SoilVegetation-Atmosphere Systems:Monitoring,Modelling and Data Assimilation" funded by the Deutsche Forschungsgemeinschaft (DFG)TERENO (Terrestrial Environmental Observatories) funded by the Helmholtz Association of German Research Centers
文摘Integrated observation platforms have been set up to investigate consequences of global change within a terrestrial network of observatories （TERENO） in Germany. The aim of TERENO is to foster the understanding of water, energy, and matter fluxes in terrestrial systems, as well as their biological and physical drivers. Part of the Lower Rhine Valley-Eifel observatory of TERENO is located within the Eifel National Park. Recently, the National Park forest management started to promote the nat- ural regeneration of near-natural beech forest by removing a significant proportion of the spruce forest that was established for timber production after World War II. Within this context, the effects of such a disturbance on forest ecosystem functioning are currently investigated in a deforestation experiment in the Wtistebach catchment, which is one of the key experimental re- search sites within the Lower Rhine Valley-Eifel observatory. Here, we present the integrated observation system of the Wiistebach test site to exemplarily demonstrate the terrestrial observatory concept of TERENO that allows for a detailed mon- itoring of changes in hydrological and biogeochemical states and fluxes triggered by environmental disturbances. We present the observation platforms and the soil sampling campaign, as well as preliminary results including an analysis of data con- sistency. We specifically highlight the capability of integrated datasets to enable improved process understanding of the post-deforestation changes in ecosystem functioning.
基金This survey began as part of a working group output of the NII Shonan Seminar No.2015-1 Big Graph Drawing:Metrics and Methods,and we would like to thank this seminar series for the role it played in this surveyWe would like to thank Tamara Munzner for her ideas and feedback at this seminar which helped focus the topic of this paper.The second author would like to thank EPSRC First Grant EP/N005724/1+1 种基金The last author would like to thank the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 747985This work was supported by the Australian Research Council Discovery Project grant DP140100077.
文摘For decades,researchers in information visualisation and graph drawing have focused on developing techniques for the layout and display of very large and complex networks.Experiments involving human participants have also explored the readability of different styles of layout and representations for such networks.In both bodies of literature,networks are frequently referred to as being‘large’or‘complex’,yet these terms are relative.From a human-centred,experiment point-of-view,what constitutes‘large’(for example)depends on several factors,such as data complexity,visual complexity,and the technology used.In this paper,we survey the literature on human-centred experiments to understand how,in practice,different features and characteristics of node–link diagrams affect visual complexity.
基金supported by the State of Vietnam through a PhD grant to L.T.H.(Grant No.4358/QĐ-BGDĐT)by the Deutscher Akadamischer Austauschdienst(DAADProject No.57163751)through covering travel costs of R.S.and F.M.T.
文摘Aims In contrast to temperate regions,the reasons for growth reductions of individual tree species along elevational gradients in tropical mountain ranges are poorly known,especially for tropical conifers.We aimed at testing whether climatic or edaphic conditions are responsible for the reduced growth of Pinus kesiya,a widely distributed pine species of southern and south-eastern Asia,at higher elevations.Methods We analysed the stem diameter increment and the isotope discrimination against ^(13)C(△^(13)C)in tree rings of P.kesiya along an elevational gradient of~900 to~2000 m a.s.l.in the mountain ranges of South-Central Vietnam,and related growth to△^(13)C and to climatic and edaphic variables.Important findings We found no consistent correlation patterns between the basal area increment(BAI)of the trees and temperature or precipitation.In contrast,across the elevational gradient,we obtained significantly negative correlations of BAI with△^(13)C and with the C/N ratios and theδ^(15)N signature of the upper mineral soil.BAI was positively correlated with the concentrations of plant-available phosphorus(P_(a))and of“base”cations(calcium,magnesium,potassium)in the soil.We conclude that lower temperatures at higher elevations exert an indirect effect on tree growth by inducing higher C/N ratios and by reducing the rate of nitrogen(N)and P mineralization,which may be further hampered by lower concentrations of“base”cations(upon enhanced leaching by precipitation)and a negative feedback from low availability of mineralized N and P at higher elevations.Our results may be transferable to the uppermost growth limit of P.kesiya and to other montane regions of the species’occurrence.
基金Fondo Nacional de Desarrollo Científico y Tecnológico(Fondecyt),Chile(Fondecyt Regular 1090135).
文摘Aims We tested whether—in addition to weather conditions—the concentrations of nitrogen and phosphorus in the substrate have an effect on the radial stem increment of Nothofagus dombeyi trees in old-growth forest stands on volcanic soil at the western slopes of the Andes in South-Central Chile.Methods We took soil samples and tree increment cores from five proximate sites(1000-1300 m a.s.l.)that are located in the volcanic region of the Conguillío National Park and differ in the age of the substrate(Miocene—3500 years B.P.)and in its concentrations of nitrogen(N)and phosphorus(P).The soil samples were also analysed on their concentrations of other plant mineral nutrients,carbon(C)and nitrogen isotope ratios(δ^(15)N).Tree-ring widths and the stem basal area increment(BAI)were related to climate parameters.In selected tree rings,the stable isotope ratios of carbon(δ^(13)C)and oxygen(δ^(18)O)were determined and related to growth and climate parameters.Important FindingsConsistent with theory,the soils on the oldest substrate showed the highest(least negative)δ^(15)N values,but mineral N was the only nutrient whose concentration exhibited a straightforward(increasing)relationship with increasing substrate age.The BAI was largest on the soil with the highest concentration of plant-available P.In contrast to BAI,tree-ring chronologies did not differ among the study sites.However,tree-ring chronologies and BAI exhibited significantly positive correlations with summer precipitation,and negative correlations,with summer(December)temperature.A negative correlation was found betweenδ^(13)C and precipitation anomalies in the growing season(November-March).We interpret the negative correlations between growth and temperature,and betweenδ^(13)C andδ^(18)O in the tree rings,as an impairment of net carbon assimilation by anomalously warm weather conditions during the growing season.We conclude that the growth of N.dombeyi is mainly affected by high temperature and low precipitation in spring and summer irrespective of the substrate’s age,and enhanced by higher concentrations of plant-available P in the soil.Our results may be representative of N.dombeyi stands on volcanic substrate within their principal distribution range along the Andes of South America.
基金This work was supported by Fondo Nacional de Desarrollo Científico y Tecnológico(Fondecyt http://www.conicyt.cl/fon-decyt/)Chile Fondecyt Regular 1130353 and the International Collaboration Program DFG-Conicyt PCCI12040 http://www.conicyt.cl/pci/program-of-international-relations/.
文摘Aims Nothofagus species are constitutive elements of the temperate forests along the Southern Andes Mountains.The deciduous Nothofagus alpina is a fast-growing,but long-lived opportunistic pioneer spe-cies(‘pioneer-climax species’)and co-occurs with the evergreen N.dombeyi.We tested whether N.alpina is competitively superior to N.dombeyi in mature stands and whether intra-specific competition in N.alpina is stronger than inter-specific competition with N.dombeyi.Methods In a pristine old-growth forest in South-Central Chile,we compared the growth of N.alpina trees in pure stands and in mixture with N.dombeyi to the growth of N.dombeyi and calculated compe-tition indices.We related growth variables to climate data and weather extremes.Important Findings In N.alpina,juvenile basal area increment was signifi-cantly higher in pure than in mixed stands.Contrary to our hypothesis,N.dombeyi exhibited larger radial stem increments than N.alpina in the most recent 40 years.In the most recent two decades,this was caused by high growth rates of large N.dombeyi trees.In both Nothofagus species,stem growth was negatively related to temperature,but N.dombeyi responded more sensitively to weather conditions than N.alpina.In N.alpina,stem increment was negatively related to the intensity of competition,but the size of the competition effects on this species was similar in pure and mixed stands.Thus,compared to N.alpina,the‘pioneer-climax species’concept is even more appropriate for N.dombeyi with its relatively high growth rates even in the early stages of its life.
文摘Sexual dimorphism is a widespread phenomenon in Lepidoptera.It is reflected in differences in life history,behavior and morphology.Analyses of differences in behavior are mostly difficult and time-consuming,especially in high mountain ecosystems.To enhance our knowledge on sexual dimorphisms of alpine butterflies,we performed a mark-release-recapture study on 2 species common in the Alps:Boloriapales and Boloria napaea.We analysed movement and foraging behavior to investigate differences between sexes.Both sexes were mostly sedentary and the movement distances of males and females similar.However,obvious differences in dispersal behavior between the sexes were found in the movement patterns.Three different patterns were distinguished.Most males showed intensive flight activity,but mostly flew only in a limited part of the entire habitat (i.e.,their individual home range)searching for females,whereas females were less flight active and flew only to find places for oviposition or feeding.The third pattern,where individuals flew larger distances,was only observed in a small number of males,which always returned to their home range.Nearly all feeding was observed on Asteraceae.However,males preferred the genera Leontodon and Crepis,while females preferred Leontodon and Carduus.Apart from this sexual difference in foraging,individuals of both sexes were found to be more or less specialised on nectar sources.Flight activity was generally greater in males than females.Therefore,we think that sex-specific requirements in nectar ingredients exist,that is,sugar for the intensive flight activity of males and amino acids for egg production of females.
