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1.
ABSTRACT

This introduction sets out some of the key themes addressed by the papers in the special issue on ‘Confronting the Naturalness of Disaster in the Pacific’. Disasters are now widely understood not as ‘natural’ phenomena but as events or processes that unfold at the intersection between natural or artificial hazards and human populations. We review some of the effects of the naturalisation of disaster before turning to the ways in which Pacific disasters are defined through government, media and public discourses. These discourses feature their own distinctive accounts of possible forms of agency in the context of disaster, and draw on markedly different frames of reference in attributing cause and blame. Similarly, contrasting temporalities and spatialities are invoked in addressing disasters as bounded phenomena. We conclude with reflections on the nature of responses to disaster in the Pacific in the context of increasingly unstable cultural, economic and environmental grounds for action induced by global climate change  相似文献   

2.
The Amazon River, its huge basin, and the changes in biological processes that are rapidly occurring in this region are unquestionably of global significance. Hence, Global Change Biology is delighted to host a special thematic issue devoted to the Large‐scale Biosphere–Atmosphere Experiment in Amazônia (LBA), which is a multinational, interdisciplinary research program led by Brazil. The goal of LBA is no less modest than its subject: to understand how Amazônia functions as a regional entity in the Earth system and how these functions are changing as a result of ongoing changes in land use. This compilation of 26 papers resulting from LBA‐related research covers a broad range of topics: forest stocks of carbon (C) and nitrogen (N); fluxes of greenhouse gases and volatile organic compounds from vegetation, soils and wetlands; mapping and modeling land‐use change, fire risk, and soil properties; measuring changes caused by logging, pasturing and cultivating; and new research approaches in meteorology to estimate nocturnal fluxes of C from forests and pastures. Some important new synthesis can be derived from these and other studies. The aboveground biomass of intact Amazonian forests appears to be a sink for atmospheric carbon dioxide (CO2), while the wetlands and soils are a net source of atmospheric methane (CH4) and nitrous oxide (N2O), respectively. Land‐use change has, so far, had only a minor effect on basin‐wide emissions of CH4 and N2O, but the net effect of deforestation and reforestation appears to be a significant net release of CO2 to the atmosphere. The sum of the 100‐year global warming potentials (GWP) of these annual sources and sinks of CH4, N2O, and CO2 indicate that the Amazonian forest–river system currently may be nearly balanced in terms of the net GWP of these biogenic atmospheric gases. Of course, large uncertainties remain for these estimates, but the papers published here demonstrate tremendous progress, and also large remaining hurdles, in narrowing these uncertainties in our understanding of how Amazônia functions as a regional entity in the Earth system.  相似文献   

3.
Resilience is a general concept that aims to help understand how ecosystems respond to disturbances such as extinctions and invasions. Here, we propose a measure of one aspect of resilience, R X , which is one minus the expected change in functional diversity (X) caused by a species extinction or addition. We show how two components of biodiversity, species richness and functional diversity, and the structure of regional species pools affect this measure. Variation in species richness and in functional diversity have opposite effects on R X . Speciose assemblages generally have higher R X than depauperate ones, whereas functionally diverse assemblages have low R X relative to functionally depauperate ones. The effect of an extinction on R X reflects this tradeoff. In our analyses, extinctions usually cause only a small decrease in both functional diversity and R X . However, extinctions sometimes cause a large reduction in functional diversity and then tend to increase R X . Regional assemblages containing all rather unique species tend to result in speciose assemblages with relatively low R X and in low richness assemblages with relatively high R X . The opposite is true of regional assemblages containing functionally similar species. Information about the processes that structure regional assemblages will therefore increase understanding of ecosystem resilience. Generally, these results suggest that management for biodiversity may not always result in management for resilience.  相似文献   

4.
The production of perennial cellulosic feedstocks for bioenergy presents the potential to diversify regional economies and the national energy supply, while also serving as climate ‘regulators’ due to a number of biogeochemical and biogeophysical differences relative to row crops. Numerous observational and model‐based approaches have investigated biogeochemical trade‐offs, such as increased carbon sequestration and increased water use, associated with growing cellulosic feedstocks. A less understood aspect is the biogeophysical changes associated with the difference in albedo (α), which could alter the local energy balance and cause local to regional cooling several times larger than that associated with offsetting carbon. Here, we established paired fields of Miscanthus × giganteus (miscanthus) and Panicum virgatum (switchgrass), two of the leading perennial cellulosic feedstock candidates, and traditional annual row crops in the highly productive ‘Corn‐belt’. Our results show that miscanthus did and switchgrass did not have an overall higher α than current row crops, but a strong seasonal pattern existed. Both perennials had consistently higher growing season α than row crops and winter α did not differ. The lack of observed differences in winter α, however, masked an interaction between snow cover and species differences, with the perennial species, compared with the row crops, having a higher α when snow was absent and a much lower α when snow was present. Overall, these changes resulted in an average net reduction in annual absorbed energy of about 5 W m?2 for switchgrass and about 8 W m?2 for miscanthus relative to annual crops. Therefore, the conversion from annual row to perennial crops alters the radiative balance of the surface via changes in α and could lead to regional cooling.  相似文献   

5.
The importance of temperature in regulating physiological processes is without question; however, the interpretation of the relationship between temperature and ecological data is much more complicated. Consequently, it is difficult to decide how the nature of the temperature response terms should be included in models used to predict responses of microbial processes to increasing regional temperature. This analysis compiles several years of data from a research programme conducted in Chesapeake Bay, in an effort to examine how individual microbial processes ? as well as the balance between autotrophy and heterotrophy ? have responded to temperature, and to predict changes in microbial trophic state based on realistic increases in global temperature. The upper boundary on all of the pelagic microbial rate processes that were measured could be described remarkably well as a linear function of temperature, although there was substantial scatter in the data. Pelagic microbial rate processes (e.g. phytoplankton production, respiration, bacterial productivity) showed a remarkably constrained range of Q10 values from 1.7 to 3.4. The one notable exception to this was nitrogen uptake in the North and Mid Bay, which exhibited Q10 values < 1.0. Proxies for phytoplankton biomass (e.g. chlorophyll) were largely independent of temperature while bacterial abundance was significantly related to temperature and was found to have a Q10 of 1.88. Using these individual temperature responses, the balance of autotrophy and heterotrophy was assessed by calculating the community photosynthesis to respiration (P:R), NH4+ uptake to regeneration (U:R) and phytoplankton to bacterial productivity (PP:BP) ratios for current conditions (all ratios) and for a 2 and 5 °C temperature increase (NH4+ U:R excluded). The NH4+ U:R ratio stayed remarkable constant at ~1 over the entire temperature range supporting the importance of regenerative processes to nitrogen availability even during periods of heavy allochthonous inputs. These elevated temperature calculations for P:R and PP:BP suggest that the magnitude of autotrophic production during the spring bloom may decrease with increased regional temperature and, as a consequence, the Chesapeake Bay might become net heterotrophic on an annual timescale. These calculations should be considered with caution, but nonetheless demonstrate that the impact of increasing temperature on the balance of autotrophic and heterotrophic processes needs to be researched further.  相似文献   

6.
Fibroblast growth factor 2 (FGF2) is a highly abundant growth factor found within the pericellular matrix of articular chondrocytes, but studies investigating its role have been conflicting. The paper reported by Yan and colleagues in the previous issue of Arthritis Research & Therapy proposes that differences in responses to FGF2 are most likely due to changes in the balance between the two major articular cartilage FGF receptors, FGFR1 and FGFR3. They show that the catabolic and anti-anabolic effects of FGF2 are mediated primarily through FGFR1 whereas the beneficial effects are through FGFR3. This balance is dynamic and is altered in disease and following growth factor stimulation in vitro.  相似文献   

7.
There has been a surge of interest in phenotypic plasticity in the last two decades. Most studies, however, are being carried out within relatively narrow disciplinary frameworks. Consequently, researchers differ not only in their scientific agenda; they often use different terminologies and conceptual frameworks even when studying the very same phenomena. The diversity of approaches has often generated parallel bodies of theory on subjects that can be best understood in broader interdisciplinary terms. This special issue points out the differences between the concepts and questions that are characteristic of various approaches. Bridging all gulfs may be impossible and not necessarily desirable, yet, awareness of the varied approaches should be instrumental in promoting interdisciplinary advances. It is the contribution to such awareness that is the major purpose of this special issue, and for this reason it deals with molecular, physiological, ecological and evolutionary approaches to the study of developmental plasticity. So as to focus the discussion, six topics have been selected, ranging from the fundamental essence of developmental plasticity to its implications to ecology and evolution. These topics were considered by scholars who were chosen for the diversity of their research, not only their expertise. Rather than a comprehensive body of theory, the current issue thus seeks the diversity of opinions on the discussed topics. It is hoped that the confrontation, in its original Latin sense, which includes bringing together and discussion, of scholars who are studying these phenomena at very different levels and from different points of view will generate new insights and promote future interdisciplinary research.  相似文献   

8.
Ecological indication is the most relevant way to approximate the implications of cause–effect networks which go beyond spatio-temporal extents of direct experimental accessibility. Risk analysis and risk management of genetically modified plants are an application field where indication of potential effects on the landscape and regional scale is required. Long-term implications of commercial use can be assessed only to a limited extent through direct experimental approaches. Landscapes and regions normally cannot be subjected to experimental manipulation. However, empirical results obtained on smaller scales can help to indicate long term, delayed and combinatory effects to some extent when an appropriate up-scaling procedure of small-scale and short-term results is developed. Using oilseed rape cultivation in Northern Germany as an example, it is shown, how a model-based integration of known effects can be used to understand large-scale implications. The indication approach combines remote sensing data, weather data, biogeographic data, and model simulation of local interactions. Validated knowledge starting on the level of individual plants and plant populations was used. On the basis of state-of-the-art knowledge, the geo-statistical approach is outlined, how to draw conclusions for processes up to the regional scale.In this paper, we present an overview, which steps are necessary to gain a coherent picture. Each of the involved steps, representing a contribution from a different disciplinary and methodological background and operating on different scales, is documented in further details in the papers collated in this special issue. This introductory contribution to the special issue outlines, what the involved steps are and how they combine to produce the overall results. It was demonstrated, that local interactions aggregate in a non-trivial way. The understanding of regional cultivation density implications could be improved with an approach that integrated local information through model scenario calculations.  相似文献   

9.
Action spectra for the promotion of flowering by long periods of irradiation in the red and far-red regions of the spectrum have been determined by the use of interference filters. The percentage floral initiation was greatest at 710–720 um for both wheat and rape (about 1 k erg · cm?2· s?1). Lowering the temperature from 35 to 15°C did not shift the most effective wavelength, suggesting that the effect of high levels of radiation at 710 nm was not related to a balance between photoactivation of phytochrome and its destruction. In both wheat and rape, an increase in temperature promoted the flower-initiating action of broad-band far-red and 710 nm radiation more than the action of broadband red or 660 nm radiation. The flower-promoting effect of broad-band red and 600 nm radiation was particularly depressed by temperatures above 25°C. It is concluded that the promotion of flowering by long periods of high energy at 710 nm is caused by the activity of a high-energy pigment, rather than through a special effect of phytochrome.  相似文献   

10.
The action of abscisic acid on the kinetics of auxin transport through Zea mays L. (cv. Goudster) coleoptiles has been investigated. Abscisic acid applied simultaneously with indoleacetic acid-2-14C in the donor block reduced the transport intensity without materially affecting the basipetal velocity or the uptake. No effect on acropetal transport was observed. The data have been used to discuss the similarities in effects of abscisic acid and visible radiation and a hypothesis is proposed to explain the phenomena of phototropism.  相似文献   

11.
Mechanisms and consequences of biological invasions are a global issue. Yet, one of the key aspects, the initial phase of invasion, is rarely observed in detail. Data from aerial photographs covering the spread of Heracleum mantegazzianum (Apiaceae, native to Caucasus) on a local scale of hectares in the Czech Republic from the beginning of invasion were used as an input for an individual-based model (IBM), based on small-scale and short-time data. To capture the population development inferred from the photographs, long-distance seed dispersal, changes in landscape structures and suitability of landscape elements to invasion by H. mantegazzianum were implemented in the model. The model was used to address (1) the role of long-distance dispersal in regional invasion dynamics, and (2) the effect of land-use changes on the progress of the invasion. Simulations showed that already small fractions of seed subjected to long-distance dispersal, as determined by systematic comparison of field data and modelling results, had an over-proportional effect on the spread of this species. The effect of land-use changes on the simulated course of invasion depends on the actual level of habitat saturation; it is larger for populations covering a high proportion of available habitat area than for those in the initial phase of invasion. Our results indicate how empirical field data and model outputs can be linked more closely with each other to improve the understanding of invasion dynamics. The multi-level, but nevertheless simple structure of our model suggests that it can be used for studying the spread of similar species invading in comparable landscapes.  相似文献   

12.

Background  

In order to provide insights into the complex biochemical processes inside a cell, modelling approaches must find a balance between achieving an adequate representation of the physical phenomena and keeping the associated computational cost within reasonable limits. This issue is particularly stressed when spatial inhomogeneities have a significant effect on system's behaviour. In such cases, a spatially-resolved stochastic method can better portray the biological reality, but the corresponding computer simulations can in turn be prohibitively expensive.  相似文献   

13.
The objectives of this study were to test potential effects of solar ultraviolet-B (UV-B) radiation on (i) foliage nutritional quality and foliage decomposition rates of six plant species of this fen ecosystem (Nothofagus antarctica, Carex curta, C. decidua and C. magellanica; Acaena magellanica and Gunnera magellanica) and (ii) feeding preferences for these plant species of the slug Deroceras reticulatum prevalent in this ecosystem. In a mixed-diet selection slugs were offered leaves of the six species that had been grown for three years in experimental field plots under either near-ambient or reduced solar ultraviolet-B (UV-B) radiation. The chosen characteristics of leaf quality (nitrogen concentration, carbon:nitrogen ratio, specific leaf area) and leaf decomposition rates of the six species varied significantly among species but were not affected by the UV-B treatments. However, there were UV-B treatment effects on slug feeding preference for two plant species. For the tree species, Nothofagus, slugs had consumed only one-third as much foliage grown under near-ambient UV-B radiation as of foliage grown under reduced UV-B by the end of the feeding experiment. In contrast, leaves of the sedge C. decidua that had been grown under near-ambient UV-B were consumed twice as much as leaves grown under reduced UV-B radiation. Consumption of foliage for the other four species was similar for the two UV-B treatments. Additionally, diet selection of the slugs was also significantly affected by prior UV-B conditions under which foliage had been grown. Nothofagus leaves were consumed proportionately less and C. decidua proportionately more if the foliage had been grown under near-ambient UV-B radiation. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

14.
Reliable models are required to assess the impacts of climate change on forest ecosystems. Precise and independent data are essential to assess this accuracy. The flux measurements collected by the EUROFLUX project over a wide range of forest types and climatic regions in Europe allow a critical testing of the process‐based models which were developed in the LTEEF project. The ECOCRAFT project complements this with a wealth of independent plant physiological measurements. Thus, it was aimed in this study to test six process‐based forest growth models against the flux measurements of six European forest types, taking advantage of a large database with plant physiological parameters. The reliability of both the flux data and parameter values itself was not under discussion in this study. The data provided by the researchers of the EUROFLUX sites, possibly with local corrections, were used with a minor gap‐filling procedure to avoid the loss of many days with observations. The model performance is discussed based on their accuracy, generality and realism. Accuracy was evaluated based on the goodness‐of‐fit with observed values of daily net ecosystem exchange, gross primary production and ecosystem respiration (gC m?2 d?1), and transpiration (kg H2O m?2 d?1). Moreover, accuracy was also evaluated based on systematic and unsystematic errors. Generality was characterized by the applicability of the models to different European forest ecosystems. Reality was evaluated by comparing the modelled and observed responses of gross primary production, ecosystem respiration to radiation and temperature. The results indicated that: Accuracy. All models showed similar high correlation with the measured carbon flux data, and also low systematic and unsystematic prediction errors at one or more sites of flux measurements. The results were similar in the case of several models when the water fluxes were considered. Most models fulfilled the criteria of sufficient accuracy for the ability to predict the carbon and water exchange between forests and the atmosphere. Generality. Three models of six could be applied for both deciduous and coniferous forests. Furthermore, four models were applied both for boreal and temperate conditions. However, no severe water‐limited conditions were encountered, and no year‐to‐year variability could be tested. Realism. Most models fulfil the criterion of realism that the relationships between the modelled phenomena (carbon and water exchange) and environment are described causally. Again several of the models were able to reproduce the responses of measurable variables such as gross primary production (GPP), ecosystem respiration and transpiration to environmental driving factors such as radiation and temperature. Stomatal conductance appears to be the most critical process causing differences in predicted fluxes of carbon and water between those models that accurately describe the annual totals of GPP, ecosystem respiration and transpiration. As a conclusion, several process‐based models are available that produce accurate estimates of carbon and water fluxes at several forest sites of Europe. This considerable accuracy fulfils one requirement of models to be able to predict the impacts of climate change on the carbon balance of European forests. However, the generality of the models should be further evaluated by expanding the range of testing over both time and space. In addition, differences in behaviour between models at the process level indicate requirement of further model testing, with special emphasis on modelling stomatal conductance realistically.  相似文献   

15.
The accurate quantification of the energy available for sensible and latent heat transfer from plant canopies is essential for the prediction of impacts of climate on vegetation water use and growth. Unlike agricultural fields and extensive forests of more humid zones, vegetation growing in semi‐arid climates is usually sparse creating a heterogeneous surface of shrubs, annuals and bare soil. Under these conditions many of the assumptions of the basic equations used in microclimatology, which assume a uniform vegetated surface, may be violated. It is proposed here that heterogeneous canopies may require a formulation of their energy balance that includes a measure of the canopy complexity in order to both interpret field measurements and be used in predictive models. This paper explores the need for a more complex formulation of the vegetation energy balance through a series of experiments on a sparse clumped shrubland of Retama sphaerocarpa in the Tabernas Desert, Almería, south‐east Spain. These experiments investigated the importance of the radiative properties of each surface on energy balance of soil, annuals and shrubs individually, and the surface as a whole. The study evaluated the use of the fractional vegetative cover (f) and the radiative characteristics of each surface (reflection coefficients and emissivities) for calculating net radiation partitioning between shrubs and bare soil. Results indicated that partitioning of net radiation between components could be accurately calculated from values of fractional vegetative cover, reflection coefficients and emissivities for both bare soil and plant surfaces. A sensitivity analysis showed the importance of specific radiation properties of each surface. Measurements of horizontal long‐wave fluxes between components showed that the location of a plant with respect to other plants made little difference to its long‐wave energy balance. The results also emphasized the importance of soil water content on the energy balance, through its influence on albedo and soil heat storage. This was particularly true when measurements of soil heat flux were used to measure the available energy for soil under shrubs and bare soil because of strong hysteresis cycles. These cycles were larger in the bare soil than in the substrate under shrubs.  相似文献   

16.
The survival outlook for biodiversity is being profoundly and adversely influenced by the twin phenomena of discontinuities and synergisms. So potent are their impacts that they may well cause the mass extinction to overtake us more swiftly and extensively than is often expected. Despite their importance, however, we know all too little about these phenomena. They remain almost entirely a black hole of research. This paper, being an introduction to the special issue, presents a short selection of both phenomena, with an evaluation of their impacts on biodiversity. It concludes with an overview of the human enterprise and its probable future repercussions for biodiversity.  相似文献   

17.
Madagascar hissing cockroach in class The use of animals represents a special challenge and teaching‐learning situations in the classroom. There are sometimes high organizational costs and furthermore animals can cause different emotions such as happiness, but also disgust and fear. Despite their dissuasive effect, Madagascar hissing cockroach (Gromphadorhina portentosa) are well suitable for accomplishing education goals, such as the teaching and learning of competences in the area of scientific inquiry. On the basis of bizarre phenomena, like their hissing and their nocturnal lifestyle, the learners can perform observations and experiments. In addition they've got no special requirements in the care and keeping, so they can also become a permanent guest in the classroom.  相似文献   

18.
Competition for fresh water between agriculture and domestic and industrial uses is increasing worldwide. This is forcing subsistence and commercial agriculture to produce more with less water. Consequently, it is crucial to properly and efficiently manage water resources. This requires accurate determination of crop water loss into the atmosphere, which is greatly influenced by the exchange of energy and mass between the surface and the atmosphere. Measurement of these exchange processes can best be accomplished by micrometeorological methods. However, most micrometeorological methods are very expensive, difficult to set up, require extensive post-data collection corrections and/or involve a high degree of empiricism. This review discusses estimation of evapotranspiration using relatively inexpensive micrometeorological methods in temperature-variance (TV), surface renewal (SR) and mathematical models. The TV and SR methods use high frequency air temperature measurements above a surface to estimate sensible heat flux (H). The latent heat flux (λE), and hence evapotranspiration, is calculated as a residual of the shortened surface energy balance using measured or estimated net radiation and soil heat flux, assuming surface energy balance closure is met. For crops with incomplete cover, the disadvantage of these methods is that they do not allow separation of evapotranspiration into soil evaporation and plant transpiration. The mathematical models (single- and dual-source) involve a combination of radiation and resistance equations to determine evapotranspiration from inputs of automatic weather station observations. Single-source models (Penman-Monteith type equations) are used to determine evapotranspiration over homogeneous surfaces. The dual-source models, basically an extension of single-source models, determine soil evaporation and plant transpiration separately over heterogeneous or sparse vegetation. These mathematical models have also been modified to accommodate inputs of remotely-sensed radiometric surface temperatures that enable estimation of evapotranspiration on a regional and global scale.  相似文献   

19.
The hydrologic cycle in Slovakia is determined mainly by three basic components: precipitation (P), evapotranspiration (E) and runoff (R). The mean annual P total was 747 mm, E sum 476 mm and the mean R was 271 mm in Slovakia in 1951–1980 (E ≈ 0.65P and R ≈ 0.35P). T increase in 1.6°C and annual P decrease in 24 mm (3.1%) were detected in the 1881–2007 period. Regimes of potential and actual evapotranspiration, soil moisture and R have been changed mainly in the southern Slovakia. A physical model for the estimation of the energy balance equation components (total radiation balance and its components, potential and actual evapotranspiration, sensible heat flux) has been developed. Input data are the air temperature and humidity, cloudiness, the number of days with snow cover and precipitation, all measured in the network of 31 meteorological stations in Slovakia since 1951. The 20-year period 1988–2007 was by 0.9°C warmer than the normal period mean. The observed increase is at the upper limit of all climate change scenarios projected for Slovakia in 1991–2001. Annual P totals have not changed significantly, but substantial changes have been found in the P regime. The scenarios show significant changes in the hydrological cycle not only at river basins balance but also in case of soil water balance, mainly in the southern Slovakia.  相似文献   

20.
The Northern Hemisphere's boreal forests, particularly the Siberian boreal forest, may have a strong effect on Earth's climate through changes in dominant vegetation and associated regional surface albedo. We show that warmer climate will likely convert Siberia's deciduous larch (Larix spp.) to evergreen conifer forests, and thus decrease regional surface albedo. The dynamic vegetation model, FAREAST, simulates Russian boreal forest composition and was used to explore the feedback between climate change and forest composition at continental, regional, and local scales. FAREAST was used to simulate the impact of changes in temperature and precipitation on total and genus‐level biomass at sites across Siberia and the Russian Far East (RFE), and for six high‐ and low‐diversity regions. Model runs with and without European Larch (Larix decidua) included in the available species pool were compared to assess the potential for this species, which is adapted to warmer climate conditions, to mitigate the effects of climate change, especially the shift to evergreen dominance. At the continental scale, when temperature is increased, larch‐dominated sites become vulnerable to early replacement by evergreen conifers. At the regional and local scales, the diverse Amur region of the RFE does not show a strong response to climate change, but the low‐diversity regions in central and southern Siberia have an abrupt vegetation shift from larch‐dominated forest to evergreen‐conifer forest in response to increased temperatures. The introduction of L. decidua prevents the collapse of larch in these low‐diversity areas and thus mitigates the response to warming. Using contemporary MODIS albedo measurements, we determined that a conversion from larch to evergreen stands in low‐diversity regions of southern Siberia would generate a local positive radiative forcing of 5.1±2.6 W m?2. This radiative heating would reinforce the warming projected to occur in the area under climate change.  相似文献   

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