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1.
Abstract Empirical estimates of the function and resilience of communities under different management regimes can provide valuable information for sustainable natural resource management, but such estimates are scarce to date. We quantified the functional richness and relative resilience of bird communities inhabiting five regions in southeastern Australia that represented different management regimes. First, we show that functional richness and relative resilience were reduced at species-poor sites in all regions. Second, we show that bird communities in agricultural regions had fewer body mass groups and fewer functional groups than expected by chance. This suggests that both the function and the resilience of bird communities in agricultural regions were reduced. The likely mechanisms for the observed loss of function and relative resilience are: (1) the simplification of landscape texture resulting in selective extinction of certain body mass groups; and (2) the selective extinction of certain functional groups that are particularly sensitive to intensive land use. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

2.
Biological invasions are an increasing global challenge, for which single-species studies and analyses focused on testing single hypotheses of causation in isolation are unlikely to provide much additional insight. Species interact with other species to create communities, which derive from species interactions and from the interactions of species with the scale specific elements of the landscape that provide suitable habitat and exploitable resources. I used logistic regression analysis to sort among potential intrinsic, community and landscape variables that theoretically influence introduction success. I utilized the avian fauna of the Everglades of South Florida, and the variables body mass, distance to nearest neighbor (in terms of body mass), year of introduction, presence of congeners, guild membership, continent of origin, distribution in a body mass aggregation or gap, and distance to body-mass aggregation edge (in terms of body mass). Two variables were significant predictors of introduction success. Introduced avian species whose body mass placed them nearer to a body-mass aggregation edge and further from their neighbor were more likely to become successfully established. This suggests that community interactions, and community level phenomena, may be better understood by explicitly incorporating scale.  相似文献   

3.
Ecological Resilience, Biodiversity, and Scale   总被引:37,自引:7,他引:30  
We describe existing models of the relationship between species diversity and ecological function, and propose a conceptual model that relates species richness, ecological resilience, and scale. We suggest that species interact with scale-dependent sets of ecological structures and processes that determine functional opportunities. We propose that ecological resilience is generated by diverse, but overlapping, function within a scale and by apparently redundant species that operate at different scales, thereby reinforcing function across scales. The distribution of functional diversity within and across scales enables regeneration and renewal to occur following ecological disruption over a wide range of scales. Received 11 April 1997; accepted 9 July 1997.  相似文献   

4.
Agronomists, environmentalists, land managers, policy makers and development agents who make decisions at different levels (plot, farm, ecosystem, landscape, ecoregion, country) increasingly demand scientific information to understand cross-level links and interactions in systems that behave hierarchically. The purpose of this work is to study cross-scale relations and interactions in agricultural ecosystems of the Argentine Pampas. Based on public censuses and surveys from 1960 to 1996, data on crops cultivation, fossil energy (FE) consumption and energy productivity were used for the analysis. The whole region was divided into eight increasing geographic scales, and the impact of one scale on the broader ones was assessed through a simple analysis of energy productivity. Regression analysis was used to identify cross-scale linear slopes and to determine cross-scale interactions. We assume that non-parallel slopes in different years are attributable to cross-scale interactions. Given that the results show highly significant differences among inter-year slopes, we must accept that cross-scale interactions have occurred. Beyond any random behavior, it seems quite possible that decisions made at smaller scales may have a demonstrable effect on broader scales. Specific research is needed to elucidate key cause–effect relationships among scales. In principle, the possible interaction between intensification factors (for example, FE consumption) and spatial scales is a plausible hypothesis to be tested in the study area.  相似文献   

5.
ABSTRACT

Oceanic people and places are increasingly labelled as either ‘resilient’ or ‘vulnerable’ to disasters and climate change. Resilience is often described in disaster discourse as a strategy designed to overcome vulnerability by helping communities to ‘bounce back’ in the wake of ‘natural’ disasters. Using ethnographic research conducted with Community Disaster and Climate Change Committees (CDCs) in Vanuatu in the wake of Tropical Cyclone Pam, this paper seeks to problematise disaster responses that see the ‘community’ as a space to be acted upon by outsiders, or where people will respond in a unified way to the challenges of rebuilding after disaster. Using political ecology framings this paper critiques the ideas of resilience that appear entrenched in community-based disaster and climate change adaptation discourse and practice in Oceania. Rather than presupposing resilience or vulnerability, this paper details the dispersal and distribution power and agency amongst individual actors and groups that either supported or manipulated, the distribution of goods by Community Disaster Committees. In this way, it moves beyond the limitations of conceptual framings of resilience in disaster management and climate change into a more considered appraisal of power, by exploring what James Ferguson has termed ‘the politics of distribution’ in the context of disaster.  相似文献   

6.
This study tested an hypothesis concerning patterns in species abundance in ecological communities. Why do the majority of species occur in low abundance, with just a few making up the bulk of the biomass? We propose that many of the minor species are analogues of the dominants in terms of the ecosystem functions they perform, but differ in terms of their capabilities to respond to environmental stresses and disturbance. They thereby confer resilience on the community with respect to ecosystem function. Under changing conditions, ecosystem function is maintained when dominants decline or are lost because functionally equivalent minor species are able to substitute for them. We have tested this hypothesis with respect to ecosystem functions relating to global change. In particular, we identified five plant functional attributes—height, biomass, specific leaf area, longevity, and leaf litter quality—that determine carbon and water fluxes. We assigned values for these functional attributes to each of the graminoid species in a lightly grazed site and in a heavily grazed site in an Australian rangeland. Our resilience proposition was cast in the form of three specific hypotheses in relation to expected similarities and dissimilarities between dominant and minor species, within and between sites. Functional similarity—or ecological distance—was determined as the euclidean distance between species in functional attribute space. The analyses provide evidence in support of the resilience hypothesis. Specifically, within the lightly grazed community, dominant species were functionally more dissimilar to one another, and functionally similar species more widely separated in abundance rank, than would be expected on the basis of average ecological distances in the community. Between communities, depending on the test used, two of three, or three of four minor species in the lightly grazed community that were predicted to increase in the heavily grazed community did in fact do so. Although there has been emphasis on the importance of functional diversity in supporting the flow of ecosystem goods and services, the evidence from this study indicates that functional similarity (between dominant and minor species, and among minor species) may be equally important in ensuring persistence (resilience) of ecosystem function under changing environmental conditions.  相似文献   

7.
目的:分析乳腺癌患者心理韧性的影响因素,并分析心理韧性与焦虑的关系。方法:于2017年2月~2018年4月期间,选择蚌埠医学院第二附属医院收治的乳腺癌患者287例为研究对象,分别采用心理韧性量表(RS)、焦虑自评量表(SAS)评估研究对象的心理韧性及焦虑状态,并采用多因素Logistic回归分析法分析乳腺癌患者心理韧性相关的影响因素,应用多元逐步线性回归分析法分析乳腺癌患者心理韧性与焦虑的关系。结果:乳腺癌患者RS得分为(76.72±9.82)分。单因素分析显示,不同年龄、居住地、家庭月收入及费用支出形式患者的RS得分比较差异有统计学意义(P0.05);不同文化程度、婚姻状况、手术类型及肿瘤分期患者的RS得分比较差异无统计学意义(P0.05)。多因素Logistic回归分析结果显示,年龄为20~40岁、居住地为农村、家庭月收入3000元、费用支出形式为自费是乳腺癌患者心理韧性的影响因素(P0.05)。乳腺癌患者SAS得分为(5.02±1.42)分,以心理韧性为自变量,焦虑为因变量进行多元逐步线性回归分析,结果显示,乳腺癌患者心理韧性为焦虑的预测因子,其心理韧性水平越高,焦虑程度越低(P0.05)。结论:乳腺癌患者心理韧性水平偏低,且其对患者焦虑状态具有预测作用,年龄为20~40岁、居住地为农村、家庭月收入3000元、费用支出形式为自费是乳腺癌患者心理韧性的影响因素,临床治疗中应该根据以上影响因素进行相关干预。  相似文献   

8.
Taiwan's endemic catfish Clarias fuscus is gradually disappearing from its native habitat, and has been proposed for genebank preservation. Environmental pressures, including exotic species interference and habitat destruction, as well as possible competitive advantages of the hybrids over this species. In order to quickly and effectively provide a reliable DNA fingerprint for the pure strain of C. fuscus we used RAPD markers to assess C. fuscus, C. mossambicus, and C.batrachus. Of the 200 primers screened to prime PCR amplification of DNA from wild-caught C. fuscus, 16 yielded reproducible DNA bands. Unique RAPD markers generated from 3 PCR primers (#211, #245 and #287) are shown to be alleles present in the genomes of C. mossambicus but absent in the genome of C. fuscus. Hybrids of C. fuscus and C. mossambicus, therefore, could possibly be distinguished by the use of these specific molecular markers. Catfish caught from the Mingder Dam were then cautiously removed from the preserved stock because of the appearance of hybrid markers in their genomes.  相似文献   

9.
Cross-scale resilience theory predicts that the combination of functional diversity within scales and functional redundancy across scales is an important attribute of ecosystems because it helps these systems resist minor ecological disruptions and regenerate after major disturbances such as hurricanes and fire. Using the vertebrate fauna of south Florida, we quantified how the loss of native species and invasion by nonnatives may alter functional group richness within and across scales. We found that despite large changes in species composition due to potential extinctions and successful invasions by nonnative species, functional group richness will not change significantly within scales, there will not be any significant loss of overall redundancy of ecology function across scales, and overall body mass pattern will not undergo substantial change. However, the types of functions performed will change, and this change may have profound effects on not only the Everglades ecosystem but on the entire landscape of south Florida. Received 14 November 2000; accepted 20 December 2001.  相似文献   

10.
The recent proliferation of studies on mindfulness produced varying theoretical models, each based in part on how mindfulness is assessed. These models agree, however, that mindfulness encompasses moment-to-moment or situational experiences. Incongruence between dispositional and situational assessment would be problematic for theory and empirical research. In particular, it remains to be established whether situational measurement is an accurate method for mindfulness assessment and whether dispositional measures are able to accurately detect mindfulness skills in various situations. The association between dispositional and situational mindfulness processes (i.e., situational attention awareness and emotion acceptance) was examined in two studies. In Study 1 (N = 148), independent groups who reported high and low levels of dispositional mindfulness skills were compared on a continuous measure of situational mindfulness skills. In Study 2 (N = 317), dispositional mindfulness questionnaires were used to predict situational use of mindfulness skills. Results suggest not only that situational measures accurately detect use of mindfulness skills, but also that dispositional measures can predict one’s use of situational mindfulness skills. Findings from both studies were consistent across both positive and negative situations. Moreover, neither neuroticism nor extraversion was shown to have a moderating effect on the relationship between dispositional and situational use of mindfulness skills. The implications of these findings for clinical practice and future investigations pertaining to measurement validity in this area are discussed.  相似文献   

11.
12.
Questions: (1) What is the recovery potential of soil seed banks of intact, average and degraded floodplain woodlands? (2) Will soil seed banks of different functional groups (native and exotic, dryland and wetland) display contrasting responses to site degradation? Location: Semi‐arid, seasonally flooded woodland of eastern Australia. Methods: Diversity, abundance and composition of soil seed banks were assessed using a glasshouse study. Surface soil samples were taken from a total of nine sites with three levels of degradation (intact, average, degraded) from three microsites (sub‐canopy, canopy edge, open). Results: A total of 26 662 individuals of 82 species germinated. Seed abundance increased tenfold from intact to degraded sites, but there was no effect on richness. Species composition of all functional groups varied significantly among degradation states. Seeds of native wetland and exotic dryland species were more abundant in degraded than in intact sites. However, the abundance of native dryland germinants did not differ among degradation classes and no seeds of exotic wetland species were observed. Richness of exotic dryland species was significantly higher in degraded sites. Conclusions: Increasing disturbance promoted seed banks of exotic but not native dryland species and native but not exotic wetland species. Unexpectedly, disturbance promoted the abundance of native seeds more than exotics, although this was driven by a single species. Our results suggest that the dryland phase of the floodplain community is more resilient to degradation than predicted.  相似文献   

13.
14.
A recent paper (Nehrt et al., PLoS Comput. Biol. 7:e1002073, 2011) has proposed a metric for the "functional similarity" between two genes that uses only the Gene Ontology (GO) annotations directly derived from published experimental results. Applying this metric, the authors concluded that paralogous genes within the mouse genome or the human genome are more functionally similar on average than orthologous genes between these genomes, an unexpected result with broad implications if true. We suggest, based on both theoretical and empirical considerations, that this proposed metric should not be interpreted as a functional similarity, and therefore cannot be used to support any conclusions about the "ortholog conjecture" (or, more properly, the "ortholog functional conservation hypothesis"). First, we reexamine the case studies presented by Nehrt et al. as examples of orthologs with divergent functions, and come to a very different conclusion: they actually exemplify how GO annotations for orthologous genes provide complementary information about conserved biological functions. We then show that there is a global ascertainment bias in the experiment-based GO annotations for human and mouse genes: particular types of experiments tend to be performed in different model organisms. We conclude that the reported statistical differences in annotations between pairs of orthologous genes do not reflect differences in biological function, but rather complementarity in experimental approaches. Our results underscore two general considerations for researchers proposing novel types of analysis based on the GO: 1) that GO annotations are often incomplete, potentially in a biased manner, and subject to an "open world assumption" (absence of an annotation does not imply absence of a function), and 2) that conclusions drawn from a novel, large-scale GO analysis should whenever possible be supported by careful, in-depth examination of examples, to help ensure the conclusions have a justifiable biological basis.  相似文献   

15.
During a proper immune response, quiescent T cells become activated upon antigen presentation to their antigen-specific T cell receptor. This leads to clonal proliferation of only those T cells that bear a receptor that recognizes the antigen. Chromatin decondensation is a hallmark of T cell activation and is required for T cells to acquire the ability to proliferate after antigen engagement. This change in chromatin condensation can be detected using antibodies raised against histone proteins. These antibodies cannot bind to their epitopes in naïve T cells as well as they can in activated T cells. We describe how to simultaneously stain T cell-specific surface markers, track viability with a fixable dead cell stain, and measure chromatin status via intracellular staining of Histone H3 proteins. Stained cells are analyzed by flow cytometry and chromatin condensation status is measured as the mean fluorescence intensity (MFI) of the Histone H3 stain. Chromatin decondensation during T cell activation is demonstrated as an increase in the MFI  相似文献   

16.
The formation of reactive oxygen species (ROS) in intact heart tissue has been assessed by direct ESR measurements, and indirectly by the formation of characteristic tissue products and the protective effects of various antioxidants. The development of lipid soluble esters of compounds which can be trapped intra-cellularly after hydrolysis, and which fluoresce after oxidation, has provided a new tool to investigate ROS in vitro. The utility of 2',7'-dichlorofluorescin diacetate (DCFDA) in isolated-perfused rat heart tissue was investigated in the present study. DCFDA and its deacetylated form were incubated with various levels of hydrogen peroxide or t-butylhydroperoxide (tBOOH). Conversion of the diacetate form to a fluorescent product required 4-5 h with hydrogen peroxide and up to 24 h with tBOOH. In contrast, the deacetylated form fluoresced at 80% of maximum levels 1 h after the addition of 100 mM tBOOH. DCFDA was loaded into heart tissue by infusing for lO min at a final concentration of 10,aM in Krebs-Henseleit bicarbonate buffer. After a lO min washout period, analysis of freeze-clamped heart tissue revealed that the trapped material was readily converted to a fluorescent product by tBOOH, indicating hydrolysis had occurred. Fluorescence of material trapped in heart tissue was approximately 24% of the maximum achieved after oxidation with lOOmM tBOOH. This value decreased to 18 and 13% when the loading and washout periods were from 0 to 20 or 10 to 30min of hypoxia, respectively. Similar results were obtained with the less readily oxidized dicarboxy derivative of DCFDA. Infusion of 500μM tBOOH increased the oxidation of DCFDA in heart tissue from 24 to 31%. These data demonstrate that DCFDA can be loaded into heart tissue and is capable of reflecting relative changes in the oxidative state of this organ.  相似文献   

17.
摘要 目的:探讨认知行为疗法对腹腔镜肾癌根治术患者给应激反应、心理弹性及免疫功能的影响,为改善腹腔镜肾癌根治术患者康复效果提供参考依据。方法:按抛掷硬币法将2019年1月-2022年12月南京鼓楼医院收治的80例腹腔镜肾癌根治术患者随机分为对照组和观察组,对照组40例患者行常规干预,观察组40例患者行认知行为疗法干预。比较两组患者临床基本指标、应激反应、心理弹性、免疫功能及生活质量等指标变化情况。结果:干预后,观察组排气时间、尿管留置时间、下床活动时间以住院时间均短于于对照组(P<0.05)。两组干预后皮质醇、肾上腺素水平与心理弹性评分均较干预前升高(P<0.05),且观察组皮质醇、肾上腺素水平低于对照组,心理弹性评分高于对照组(P<0.05)。两组干预后CD3+、CD4+及CD4+/CD8+水平较干预前升高,CD8+水平较干预前降低(P<0.05);且观察组CD3+、CD4+及CD4+/CD8+水平高于对照组,CD8+水平低于对照组(P<0.05)。两组干预后生活质量各项评分均高于干预前(P<0.05),且观察组高于对照组(P<0.05)。结论:认知行为疗法干预腹腔镜肾癌根治术患者不仅可有效改善患者负性情绪,提升其心里弹性,还可降低患者应激反应,提高机体免疫功能,加快其术后康复进程,值得临床借鉴应用。  相似文献   

18.
This paper examines the functional relationships among species in an Australian rangeland community with mixed life forms. It follows a previous study (Walker and others 1999) that explored the role of dominant and minor species in maintaining functional diversity and resilience in a rangeland ecosystem. Unlike our previous results, which were based on estimates of five plant functional attributes, the dominant species in this second community apparently are functionally no more dissimilar to each other than to all other species. We suggest that the lack of clear results in mixed life form communities represents a confounding of the relationships between the “hard” attributes that actually govern how a plant performs in an ecosystem and the “soft” attributes that we use as surrogates. There are very few data on the hard functional attributes of plant species and consequently little information on precisely how the (soft) measurable traits are related to their imputed functions. What evidence there is shows that although the relationships are strong within life forms, they differ between life forms. This poses a problem for the development of research relating plant biodiversity to ecosystem function. Until such a database is developed, it will be very difficult to advance our understanding and measurement of functional diversity in mixed life form communities. Received 30 April 2001; Accepted 23 January 2002.  相似文献   

19.
利用广义Lyapunov函数来研究微分系统关于两种量度的相对稳定性,讨论它们之间的关系。得出微分系统关于两种量度的相对稳定性等价于广义Lyapunov函数具有某种相应的性质。  相似文献   

20.
Youth experience adversity that increases their risk for immediate and long-term health consequences. Resilience has traditionally been conceptualized as an internal disposition or trait that supports youth to overcome that risk and avoid the negative impact on their health and wellbeing. However, this model of resilience overemphasizes the role of the individual and their capacity to control their environment, while minimizing the integral role of relational, social, structural, and cultural contexts in which they live. Instead, social ecological resilience (SER) emphasizes the influence of social and environmental factors on individual processes and outcomes and offers different pathways for preventive interventions to promote youth health and wellbeing. Within preventive medicine, it is important for researchers and practitioners to understand the processes that support or impede SER, particularly in youth when adversity can impact health throughout the lifespan. The purpose of this review was to examine the contributions and scope of the SER model in research on youth, with the goal of advancing SER-informed research and interventions within preventive medicine. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach as a guiding framework, we conducted a narrative review of the literature. The review characterizes 37 existing studies across the fields of education, psychology, and social work in terms of topic, focal population, methods, use of SER, and implications. We conclude with recommendations for future applications of SER to promote the health and wellbeing of youth.  相似文献   

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