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1.
Awards by the National Science Foundation Anthropology Program are analyzed and patterns of overall NSF support, proposal submissions, and success rates discerned. An attempt is made to explain these.  相似文献   

2.
国家自然科学基金资助的生物入侵基础研究概况   总被引:1,自引:0,他引:1  
基于1999~2010年国家自然科学基金资助项目,分析了我国生物入侵基础研究概况。在这期间,生物入侵领域得到资助的项目数和经费均呈现快速上升的趋势,资助的项目从1999年的3个增加到2010年的69个,资助的经费从1999年的94万元增加到2010年的1838万元。得到资助的项目数在不同学科的分布不均匀,其中,植物保护学科得到资助的项目数为123个,生态学科得到资助的项目数为82个,这2个学科得到资助的项目数占总项目数的67.9%,得到资助的经费占总经费的66.3%。资助项目的主要研究内容涉及22种入侵植物病原微生物、26种入侵动物和24种入侵植物,从中可以透视本领域的研究重点。资助的项目主要集中在华北、华东和华南地区的国家级科研机构和高等院校,这种区域分布格局与我国入侵生物的地理分布格局相吻合。为了进一步推动国家自然科学基金对生物入侵领域各项工作的资助,本文提出了一些合理化的建议。  相似文献   

3.
本文统计分析了2007-2016年度国家自然科学基金"病毒、病毒感染与宿主免疫(申请代码:H1904)"学科领域内的项目申请及资助情况,希望能对一线科研人员有所帮助.  相似文献   

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Laudan's thesis that conceptual problem solving is at least as important as empirical problem solving in scientific research is given support by a study of the relation between the chromosome theory and the Mendelian research program. It will be shown that there existed a conceptual tension between the chromosome theory and the Mendelian program. This tension was to be resolved by changing the constraints of the Mendelian program. The relation between the chromosome theory and the Mendelian program is shown to be a good illustration of the influence of science itself on the rational standards governing scientific development.I thank A. A. Derksen, N. Roll-Hansen and the anonymous referees for their helpful comments.  相似文献   

6.
Detecting the early signs of stress is imperative for the conservation of natural ecosystems. They may, however, go unrecognized because ecosystems, when disturbed, may act as sinks that absorb the external impact without showing any evident changes. This seems to be the case for Lake Santo, a small water body located in a mountainous area of northern Italy. Tourism activity in this area began to develop in the early 1970s and grew continuously over the following 20 years. This activity caused a continually increasing nutrient load into the waters, but surprisingly the lake has remained oligo-mesotrophic, as it was before human pressure became a stressor to the lake. To anticipate possible severe damage to the ecosystem, we searched for early signs of stress by carrying out a retrospective analysis based on a whole-ecosystem approach using trophic flow networks. Ecosystem properties of the lake as calculated from network analysis for the disturbed (year 1991) and unimpacted (year 1973) configurations were compared, with the support of sensitivity analysis and statistical tests. We found evidence that in the period 1970–90 nutrient enrichment did change the course of normal development as the observed increase in system throughput was accompanied by a drop in the level of mutual organization of flows, which instead would be expected to increase during the natural progression of the ecosystem. The scenario that emerged from the comparison of system-level indices, cycling activity, trophic structure, and trophic efficiency indicates that the ecosystem has been subjected to stress. In particular, the type of disturbance corresponds to a quantitative definition of eutrophication.  相似文献   

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Nutrient dynamics of large grassland ecosystems possessing abundant migratory grazers are poorly understood. We examined N cycling on the northern winter range of Yellowstone National Park, home for large herds of free-roaming elk (Cervus elaphus) and bison (Bison bison). Plant and soil N, net N mineralization, and the deposition of ungulate fecal-N were measured at five sites, a ridgetop, mid-slope bench, steep slope, valley-bottom bench, and riparian area, within a watershed from May, 1991 to April, 1992.Results indicated similarities between biogeochemical properties of Yellowstone grassland and other grassland ecosystems: (1) landscape position and soil water affected nutrient dynamics, (2) annual mineralization was positively related to soil N content, and (3) the proportion of soil N mineralized during the year was negatively related to soil C/N.Grazers were a particularly important component of the N budget of this grassland. Estimated rates of N flow from ungulates to the soil ranged from 8.1 to 45.6 kg/ha/yr at the sites (average = 27.0 kg/ha/yr), approximately 4.5 times the amount of N in senescent plants. Rates of nitrogen mineralization for Yellowstone northern range grassland were higher than those measured in other temperate grassland ecosystems, possibly due to grazers promoting N cycling in Yellowstone.  相似文献   

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Ecological stoichiometry offers a framework for predicting how animal species vary in recycling nutrients, thus providing a mechanism for how animal species identity mediates ecosystem processes. Here we show that variation in the rates and ratios at which 28 vertebrate species (fish, amphibians) recycled nitrogen (N) and phosphorus (P) in a tropical stream supports stoichiometry theory. Mass-specific P excretion rate varied 10-fold among taxa and was negatively related to animal body P content. In addition, the N : P ratio excreted was negatively related to body N : P. Body mass (negatively related to excretion rates) explained additional variance in these excretion parameters. Body P content and P excretion varied much more among taxonomic families than among species within families, suggesting that familial composition may strongly influence ecosystem-wide nutrient cycling. Interspecific variation in nutrient recycling, mediated by phylogenetic constraints on stoichiometry and allometry, illustrates a strong linkage between species identity and ecosystem function.  相似文献   

11.
In this ‘perspectives’ article, we share experiences gained from the century-old Kruger National Park (KNP) in South Africa to illustrate the dynamic complexity of biophysical and socio-political systems, the interactions that occur between them, and the consequences for ecosystem-scale functions and resources and for their management. As in KNP, the social-ecological milieu surrounding many national parks and protected areas is changing rapidly. There will be significant managerial adjustments as human populations grow and the needs for resources accelerate. The changes, driven largely by global-scale environmental shifts as well as by new knowledge, are intimately intertwined with evolving societal perceptions, values, and expectations. Many KNP resource-related issues of the past century originated more internally and were largely environmental, whereas the emerging issues are more external and largely social. Here, we illustrate how interrelated scientific and managerial advances in integrating biophysical and social systems are acting to conserve and rehabilitate resources within KNP, and to aid in their conservation. Where appropriate, we relate these advances to similar examples in the region or other protected areas in the world. Strategies to address emerging issues are identified and discussed—and their combined effects on resource conservation and management are evaluated. In our experience the approach to conservation within KNP has been successful, despite well-intended but damaging management actions in the past. We believe that the perceived success stems from a willingness to continually incorporate new knowledge into management, to foster close working and personal associations among scientists, managers, and rangers, to acquire an intimate knowledge and understanding of the social-ecological system by the administrators as well as by the staff, and to be actively ‘forward’ thinking in an increasingly complex and uncertain world. We accept that many decisions taken today will be challenged by future managers and scientists, and we expect that some will be found wanting as emerging knowledge and continued learning shape future decisions. Further, evolving political, social, and environmental contexts may mean that protected areas will need to be managed in different ways. Therefore, we emphasize the importance of minimizing the permanency and impact of decisions so that today’s actions do not compromise future decisions when meaningful changes need to be made.
Robert J. NaimanEmail:
  相似文献   

12.

Background

Clonal plants spread laterally by spacers between their ramets (shoot–root units); these spacers can transport and store resources. While much is known about how clonality promotes plant fitness, we know little about how different clonal plants influence ecosystem functions related to carbon, nutrient and water cycling.

Approach

The response–effect trait framework is used to formulate hypotheses about the impact of clonality on ecosystems. Central to this framework is the degree of correspondence between interspecific variation in clonal ‘response traits’ that promote plant fitness and interspecific variation in ‘effect traits’, which define a plant''s potential effect on ecosystem functions. The main example presented to illustrate this concept concerns clonal traits of vascular plant species that determine their lateral extension patterns. In combination with the different degrees of decomposability of litter derived from their spacers, leaves, roots and stems, these clonal traits should determine associated spatial and temporal patterns in soil organic matter accumulation, nutrient availability and water retention.

Conclusions

This review gives some concrete pointers as to how to implement this new research agenda through a combination of (1) standardized screening of predominant species in ecosystems for clonal response traits and for effect traits related to carbon, nutrient and water cycling; (2) analysing the overlap between variation in these response traits and effect traits across species; (3) linking spatial and temporal patterns of clonal species in the field to those for soil properties related to carbon, nutrient and water stocks and dynamics; and (4) studying the effects of biotic interactions and feedbacks between resource heterogeneity and clonality. Linking these to environmental changes may help us to better understand and predict the role of clonal plants in modulating impacts of climate change and human activities on ecosystem functions.  相似文献   

13.
Alcino J. Silva   《Journal of Physiology》2007,101(4-6):203-213
Studies of cognitive function include a wide spectrum of disciplines, with very diverse theoretical and practical frameworks. For example, in Behavioral Neuroscience cognitive mechanisms are mostly inferred from loss of function (lesion) experiments while in Cognitive Neuroscience these mechanisms are commonly deduced from brain activation patterns. Although neuroscientists acknowledge the limitations of deriving conclusions using a limited scope of approaches, there are no systematically studied, objective and explicit criteria for what is required to test a given hypothesis of cognitive function. This problem plagues every discipline in science: scientific research lacks objective, systematic studies that validate the principles underlying even its most elemental practices. For example, scientists decide what experiments are best suited to test key ideas in their field, which hypotheses have sufficient supporting evidence and which require further investigation, which studies are important and which are not, based on intuitions derived from experience, implicit principles learned from mentors and colleagues, traditions in their fields, etc. Philosophers have made numerous attempts to articulate and frame the principles that guide research and innovation, but these speculative ideas have remained untested and have had a minimal impact on the work of scientists. Here, I propose the development of methods for systematically and objectively studying and improving the modus operandi of research and development. This effort (the science of scientific research or S2) will benefit all aspects of science, from education of young scientists to research, publishing and funding, since it will provide explicit and systematically tested frameworks for practices in science. To illustrate its goals, I will introduce a hypothesis (the Convergent Four) derived from experimental practices common in molecular and cellular biology. This S2 hypothesis proposes that there are at least four fundamentally distinct strategies that scientists can use to test the connection between two phenomena of interest (A and B), and that to establish a compelling connection between A and B it is crucial to develop independently confirmed lines of convergent evidence in each of these four categories. The four categories include negative alteration (decrease probability of A or p(A) and determine p(B)), positive alteration (increase p(A) and determine p(B)), non-intervention (examine whether A precedes B) and integration (develop ideas about how to get from A to B and integrate those ideas with other available information about A and B). I will discuss both strategies to test this hypothesis and its implications for studies of cognitive function.  相似文献   

14.
Summary Ecosystem management often proceeds within the context of sub‐optimal relationships between ecologists and ecosystem managers, and management outcomes could be improved with greater collaboration between members of these disciplines. This paper identifies an ecosystem management problem resulting from the interaction between timber harvesting and browsing wallabies, and this case study is used to exemplify how ecological data and expertise can contribute to the process of ecosystem management. It is argued that appropriate use of existing ecological data, establishment of strategic new research and the implementation of management actions as experimental hypothesis tests can facilitate achievement of management objectives, but greater collaboration between ecologists and managers is required before this can occur. Reasons for sub‐optimal relationships are outlined, and the potential for structural change within large State‐run ecosystem management agencies to improve interactions between managers and ecologists is discussed.  相似文献   

15.
Heneghan  Liam  Bolger  Thomas 《Plant and Soil》1998,205(2):113-124
Investigations of the role of microarthropods (Acari and Collembola) in organic matter decomposition and nutrient cycling have shown that they may contribute to primary productivity in nutrient poor conditions. The potential of microarthropods to affect other ecosystem properties, such as above ground plant diversity or succession, lags somewhat. In this contribution we demonstrate: (1) that the effect on the mobilization of nutrients promoted by microarthropods must be measured at the microhabitat scale appropriate to the scale of the faunal activity, and (2) that small changes in the structure of microarthropod assemblages can have significant effects on the local mobilization of nutrients. In the first of two experiments we measured the nutrients leaching from field mesocosms containing litter and mineral soil, with and without fauna. After eight months, the C:N ratios of the litter differed significantly indicating that the fauna were effective in altering the decomposition rate. However, the patterns of release over time and the concentration of the measured nutrients differed little between the two sets of mesocosms. In a second experiment microarthropod assemblages, which differed only slightly, were introduced into laboratory microcosms and the nutrient fluxes were measured over a ten week period. Significant differences were detected in the concentration of nitrogen, K and Mg leached and in CO2 evolved. We suggest that when the potential influence of microarthropods on ecosystem properties is being assessed, specific knowledge of the relevant details of interactions at the smallest scale must be considered. These details can be incorporated or dismissed when interactions on the next level of the ecological hierarchy are examined. Using such analysis we suggest that the creation of soil nutrient hot-spots by microarthropods may have implications for maintaining plant species of lowered competitive ability in a given system.  相似文献   

16.
Two mass-balance trophic models are constructed to describe the Gulf of Thailand ecosystem (10–50 m depth): one model pertains to the initial phase of fisheries development, and the other to when the resources were severely depleted. The two phases are compared, and changes brought about by fishing discussed. A dynamic simulation model, Ecosim, is then used successfully to reproduce the 1980 state of the fishery based on the 1963 model and the development in catches. In addition the 1980 model is used to predict how the ecosystem groups may bounce back following marked reduction in fishing pressure. Finally, the 1963 model is used to study alternative scenarios for how the fisheries development could take place, notably the effect of exploiting only the resources of larger species. The study validates that the Ecosim model can be used to predict ecosystem level changes following changes in fishing pressure, therefore fishing induced changes can to a large extent explain the changes in ecosystem pools and fluxes observed over time.  相似文献   

17.
Some expected changes in climate resulting from human greenhouse gas emissions are clear and well documented, but others may be harder to predict because they involve extreme weather events or heretofore unusual combinations of weather patterns. One recent example of unusual weather that may become more frequent with climate change occurred in early spring 2007 when a large Arctic air mass moved into the eastern United States following a very warm late winter. In this paper, we document effects of this freeze event on Walker Branch, a well‐studied stream ecosystem in eastern Tennessee. The 2007 spring freeze killed newly grown leaf tissues in the forest canopy, dramatically increasing the amount of light reaching the stream. Light levels at the stream surface were sustained at levels considerably above those normal for the late spring and summer months due to the incomplete recovery of canopy leaf area. Increased light levels caused a cascade of ecological effects in the stream beginning with considerably higher (two–three times) rates of gross primary production (GPP) during the late spring and summer months when normally low light levels severely limit stream GPP. Higher rates of stream GPP in turn resulted in higher rates of nitrate (NO3?) uptake by the autotrophic community and lower NO3? concentrations in stream water. Higher rates of stream GPP in summer also resulted in higher growth rates of a dominant herbivore, the snail Elimia clavaeformis. Typically, during summer months net NO3? uptake and snail growth rates are zero to negative; however, in 2007 uptake and growth were maintained at moderate levels. These results show how changes in forest vegetation phenology can have dramatic effects on stream productivity at multiple trophic levels and on nutrient cycling as a result of tight coupling of forest and stream ecosystems. Thus, climate change‐induced changes in canopy structure and phenology may lead to large effects on stream ecosystems in the future.  相似文献   

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The Pearl River Delta offers humans a variety of land-use alternatives. A complex ecosystem which has been in existence in the Delta for centuries has greatly contributed to the region's agricultural productivity. The principal components are mulberry trees, silkworms, pond fish, and humans, interrelated in a harmonious and mutually beneficial way. The system is not only highly efficient and soundly balanced ecologically, but provides much higher economic returns than do other agrarian practices in the Delta.This paper—one of the first to appear in the West by a Chinese ecologist—describes a form of land use which is both environmentally and economically beneficial. Whether the system, or part of it, can usefully be duplicated elsewhere in the developing world may deserve some further study. —Laurence J. C. Ma, Department of Geography, University of Akron, Akron, Ohio.  相似文献   

20.
Vegetational data from Senjogahara moor, Nikko National Park, Japan have been analysed using two contrasting but parallel multivariate approaches as a basis for future studies. The plant communities objectively defined using a divisive polythetic classificatory approach (TWINSPAN) have been successfully overlayed on an ordination of the same data using detrended correspondence analysis (DCA). The results reveal a vegetational mosaic reflecting differential levels of flood damage to the vegetation and its subsequent rates of recovery, in a space-time continuum. The results from the TWINSPAN classification show that 13 plant communities are present in the sample area and these correlate closely with complete absence, slight, or extremely heavy disturbance. The form of the disturbance as either channel erosion or alluvial depositional features is shown to also correspond quite closely with the vegetational types and is reflected in the ordination axes derived from DCA.  相似文献   

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