The dimensionality of stability depends on disturbance type

Ecosystems respond in various ways to disturbances. Quantifying ecological stability therefore requires inspecting multiple stability properties, such as resistance, recovery, persistence and invariability. Correlations among these properties can reduce the dimensionality of stability, simplifying the study of environmental effects on ecosystems. A key question is how the kind of disturbance affects these correlations. We here investigated the effect of three disturbance types (random, species‐specific, local) applied at four intensity levels, on the dimensionality of stability at the population and community level. We used previously parameterized models that represent five natural communities, varying in species richness and the number of trophic levels. We found that disturbance type but not intensity affected the dimensionality of stability and only at the population level. The dimensionality of stability also varied greatly among species and communities. Therefore, studying stability cannot be simplified to using a single metric and multi‐dimensional assessments are still to be recommended.     

Ecological Discord and the Importance of Scale in Scientific Inquiry

Scale is widely recognized today as an important concept in ecology because the scale of investigation determines the patterns and processes that can be observed. Ecological investigations can produce different outcomes depending on the scale at which observations are made, and ecological disagreements have occurred simply because investigators addressed the same question using different scales. Here I draw on quail research to illustrate the importance of scale in ecological studies and how lack of scale consideration can lead to discord. I use northern bobwhite (Colinus virginianus) as the focal species and discuss 2 areas of investigation (woody-cover requirements and influence of rainfall) that are characterized by confusion and disagreement but where consideration of scale brings clarity. In the process, I discover 2 formerly unrecognized patterns: northern bobwhite use of woody cover is inversely related with spatial extent of observation, and the influence of rainfall on northern bobwhite abundance decreases with decreasing spatial extent. In both cases, consideration of scale clarifies muddled knowledge and creates a unified framework for management. Future ecological investigations should formulate research questions within a scale framework, provide an explicit statement of scale in methods, and interpret findings within a scale context to help advance wildlife science and management. © 2020 The Wildlife Society.     

Exploring resilience with agent-based models: State of the art,knowledge gaps and recommendations for coping with multidimensionality

Anthropogenic pressures increasingly alter natural systems. Therefore, understanding the resilience of agent-based complex systems such as ecosystems, i.e. their ability to absorb these pressures and sustain their functioning and services, is a major challenge. However, the mechanisms underlying resilience are still poorly understood. A main reason for this is the multidimensionality of both resilience, embracing the three fundamental stability properties recovery, resistance and persistence, and of the specific situations for which stability properties can be assessed. Agent-based models (ABM) complement empirical research which is, for logistic reasons, limited in coping with these multiple dimensions. Besides their ability to integrate multidimensionality through extensive manipulation in a fully controlled system, ABMs can capture the emergence of system resilience from individual interactions and feedbacks across different levels of organization. To assess the extent to which this potential of ABMs has already been exploited, we reviewed the state of the art in exploring resilience and its multidimensionality in ecological and socio-ecological systems with ABMs. We found that the potential of ABMs is not utilized in most models, as they typically focus on a single dimension of resilience by using variability as a proxy for persistence, and are limited to one reference state, disturbance type and scale. Moreover, only few studies explicitly test the ability of different mechanisms to support resilience. To overcome these limitations, we recommend to simultaneously assess multiple stability properties for different situations and under consideration of the mechanisms that are hypothesised to render a system resilient. This will help us to better exploit the potential of ABMs to understand and quantify resilience mechanisms, and hence support solving real-world problems related to the resilience of agent-based complex systems.     

Effect of habitat degradation on competition,carrying capacity,and species assemblage stability

Changes in species’ trophic niches due to habitat degradation can affect intra‐ and interspecific competition, with implications for biodiversity persistence. Difficulties of measuring species’ interactions in the field limit our comprehension of competition outcomes along disturbance gradients. Thus, information on how habitat degradation can destabilize food webs is scarce, hindering predictions regarding responses of multispecies systems to environmental changes. Seagrass ecosystems are undergoing degradation. We address effects of Posidonia oceanica coverage reduction on the trophic organization of a macroinvertebrate community in the Tyrrhenian Sea (Italy), hypothesizing increased trophic generalism, niche overlap among species and thus competition and decreased community stability due to degraded conditions. Census data, isotopic analysis, and Bayesian mixing models were used to quantify the trophic niches of three abundant invertebrate species, and intra‐ and interspecific isotopic and resource‐use similarity across locations differing in seagrass coverage. This allowed the computation of (1) competition strength, with respect to each other and remaining less abundant species and (2) habitat carrying capacity. To explore effects of the spatial scale on the interactions, we considered both individual locations and the entire study area (“‘meadow scale”). We observed that community stability and habitat carrying capacity decreased as P. oceanica coverage declined, whereas niche width, similarity of resource use and interspecific competition strength between species increased. Competition was stronger, and stability lower, at the meadow scale than at the location scale. Indirect effects of competition and the spatial compartmentalization of species interactions increased stability. Results emphasized the importance of trophic niche modifications for understanding effects of habitat loss on biodiversity persistence. Calculation of competition coefficients based on isotopic distances is a promising tool for describing competitive interactions in real communities, potentially extendible to any subset of ecological niche axes for which specimens’ positions and pairwise distances can be obtained.     

The implications of palaeontological evidence for theories of ecological communities and species richness

Abstract Palaeontological evidence raises several questions that relate to current explanations of ecological communities, to the classification of communities and to interpretations of species richness. The first question relates to the stability of species detected in the fossil record. Coupled with that is the issue of incidental association of species on the same trophic level through differential effects of climatic change on the different species. Such observations are seen to support the ‘individualistic’ concept of communities. Recent statements about this concept leave unresolved questions about the acquisition of adaptation, and about the place of adaptation theory in theories of ecological communities and interpretations of ‘regional species richness’. At issue is whether there is justification for continuing to classify communities as a basis for understanding them. There is good reason to reject this approach for one in which questions about communities and ‘local’ and ‘regional’ species richness are replaced by more specific and basic questions about the relationship between adaptation, distribution and abundance, and ecological interactions. Some recent efforts to incorporate species theory into community theory fail because their basis remains the flawed concept of ‘local community’.     

User perceptions of avatar-based patient monitoring: a mixed qualitative and quantitative study

Background

A new patient monitoring technology called Visual Patient, which transforms numerical and waveform data into a virtual model (an avatar) of the monitored patient, has been shown to improve the perception of vital signs compared to conventional patient monitoring. In order to gain a deeper understanding of the opinions of potential future users regarding the new technology, we have analyzed the answers of two large groups of anesthetists using two different study methods.

Methods

First, we carried out a qualitative analysis guided by the “consolidated criteria for reporting qualitative research” checklist. For this analysis, we interviewed 128 anesthesiologists, asking: “Where do you see advantages in Visual Patient monitoring?” and afterward identified major and minor themes in their answers. In a second study, an online survey with 38 anesthesiologists at two different institutions, we added a quantitative part in which anesthesiologists rated statements based on the themes identified in the prior analysis on an ordinal rating scale.

Results

We identified four high-level themes: “quick situation recognition,” “intuitiveness,” “unique design characteristics,” and “potential future uses,” and eight subthemes.The quantitative questions raised for each major theme were: 1. “The Visual Patient technology enabled me to get a quick overview of the situation.” (63% of the participants agreed or very much agreed to this statement). 2. “I found the Visual Patient technology to be intuitive and easy to learn.” (82% agreed or very much agreed to this statement). 3. “The visual design features of the Visual Patient technology (e.g., the avatar representation) are not helpful for patient monitoring.” (11% agreed to this statement). 4. “I think the Visual Patient technology might be helpful for non-monitor experts (e.g., surgeons) in the healthcare system.” (53% of the participants agreed or strongly agreed).

Conclusion

This mixed method study provides evidence that the included anesthesiologists considered the new avatar-based technology to be intuitive and easy to learn and that the technology enabled them to get an overview of the situation quickly. Only a few users considered the avatar presentation to be unhelpful for patient monitoring and about half think it might be useful for non-experts.

     

Race,ethnicity and disciplinary divides: what is the path forward?

We pose several questions that emerged for us from Valdez and Golash-Boza’s “U.S. Racial and Ethnic Relations in the twenty-first Century.” First, we raise questions about their framing of the problem with current scholarship – are immigration/ethnicity and race scholars talking past each other or are they having more fundamental disagreements? Second, we raise questions about their critique of the “the race literature” – do too many of us ignore questions of agency and inclusion? Finally, we raise questions about the stability and utility of the concepts they deploy (“race” and “ethnicity”) and draw on recent scholarship that has argued that we need new language or frameworks to adequately describe the reality on the ground.     

Plant response strategies to stress and disturbance: the case of aquatic plants

The environmental factors controlling the establishment and development of plants in different ecosystems are of two types, stress and disturbance. The effects of stress or disturbance on aquatic systems are discussed in relation to the following questions:Can we predict the state and rate of recolonization after a disturbance? What are the strategies of recolonization developed by plants? How high is the resilience of a disturbed system? Two theories, the intermediate disturbance hypothesis, and the patch dynamics concept proposed to predict the composition, structure and dynamics of plants due to physical-chemical factors, were tested on two scales, that of communities and that of species, within two alluvial floodplains (the Rhine and the Rhône systems in France).With regard to the change of community on a larger scale (i.e. the whole network of the cut-off channels in the floodplain), large gradients of connection and disturbance induce high diversities within communities. Moreover, the highest flood disturbance induces a higher species richness and the occurrence of a particular species. The change in species is analysed using biological traits (morphological, reproductive or physiological). In the floodplain of the river Rhône, the response of plants corresponds well to theory, i.e. that habitats with an intermediate disturbance are richer than more or less disturbed habitats. So we can predict, through the biological traits, the functioning of a habitat. The last remaining question is that of the resilience of the system, which can be discussed in terms of species competition and the risk of biological invasion after an opening of habitat.     

Boreal mixedwood forests may have no "representative" areas: some implications for reserve design

We tested the shifting mosaic steady state theory in a ?73 600 km² landscape within the boreal mixedwood region of Alberta. Canada. The theory predicts that, at some spatial scale, mean vegetation attributes are temporally stable. It follows that contiguous sub-regions (stable mosaics) exist whose attributes are similar to regional values. The scale at which this stability occurs may be interpreted as the minimal size for an ecological reserve designed to represent the region. We argue that the appropriate attributes to test the theory in this case are the age and size structures of various forest stand populations. Using forest inventory data, we searched for stable mosaics (“representative areas”) at multiple spatial scales, using two different spatial decompositions of the study area. Areas were compared using 2-dimensional similarity metrics based on goodness-of-fit statistics. We found that the age and size structures of the entire study area could not be replicated at any smaller scale, which disconfirms the theory for the boreal mixedwood. Each of five compositionally distinct populations of forest stands have characteristic age and size structures, and patterns of spatial variability, which we relate to aspects of the regional ecology. Stand age and size structures have independent spatial variability. We observed multi-scaled heterogeneity in forest composition, which appears to arise partly from infrequent fire episodes when many large fires occur. These episodes are probably not uniform in their effect on forest structure. We evaluate two methods for constructing reserve systems in non-equilibrium landscapes, using small collections of disconnected subunits. Small areas can readily be built that more closely match landscape properties than any contiguous area of reasonable size. The degree of representativeness and total size of the constructed areas is sensitive to the size of the constituent pieces; in the mixedwood, there is a natural scale of 1,500 km² which is near-optimal. Reserves constructed in this way are unlikely to be temporally stable. We therefore propose a dynamic strategy for maintaining reserve systems over time within a managed landscape. Under this “floating reserve” strategy, portions of the system would be periodically replaced in response to the aging of components, unexpected large scale disturbance, or refinements in conservation objectives.     

Moderate patchiness optimizes heterogeneity,stability, and beta diversity in mesic grassland

Heterogeneous disturbance patterns are fundamental to rangeland conservation and management because heterogeneity creates patchy vegetation, broadens niche availability, increases compositional dissimilarity, and enhances temporal stability of aboveground biomass production. Pyrodiversity is a popular concept for how variability in fire as an ecological disturbance can enhance heterogeneity, but mechanistic understanding of factors that drive heterogeneity is lacking. Mesic grasslands are examples of ecosystems in which pyrodiversity is linked strongly to broad ecological processes such as trophic interactions because grazers are attracted to recently burned areas, creating a unique ecological disturbance referred to as the fire–grazing interaction, or pyric herbivory. But several questions about the application of pyric herbivory remain: What proportion of a grazed landscape must burn, or how many patches are required, to create sufficient spatial heterogeneity and reduce temporal variability? How frequently should patches burn? Does season of fire matter? To bring theory into applied practice, we studied a gradient of grazed tallgrass prairie landscapes created by different sizes, seasons, and frequencies of fire, and used analyses sensitive to nonlinear trends. The greatest spatial heterogeneity and lowest temporal variability in aboveground plant biomass, and greatest plant functional group beta diversity, occurred in landscapes with three to four patches (25%–33% of area burned) and three‐ to four‐year fire return intervals. Beta diversity had a positive association with spatial heterogeneity and negative relationship with temporal variability. Rather than prescribing that these results constitute best management practices, we emphasize the flexibility offered by interactions between patch number and fire frequency for matching rangeland productivity and offtake to specific management goals. As we observed no differences across season of fire, we recommend future research focus on fire frequency within a moderate proportion of the landscape burned, and consider a wider seasonal burn window.     

Adaptive Long-Term Monitoring of Soil Health in Metal Phytostabilization: Ecological Attributes and Ecosystem Services Based on Soil Microbial Parametersxs

Phytostabilization is a promising option for the remediation of metal contaminated soils which requires the implementation of long-term monitoring programs. We here propose to incorporate the paradigm of “adaptive monitoring”, which enables monitoring programs to evolve iteratively as new information emerges and research questions change, to metal phytostabilization. Posing good questions that cover the chemical, toxicological and ecological concerns associated to metal contaminated soils is critical for an efficient long-term phytostabilization monitoring program. Regarding the ecological concerns, soil microbial parameters are most valuable indicators of the effectiveness of metal phytostabilization processes in terms of recovery of soil health. We suggest to group soil microbial parameters in higher-level categories such as “ecological attributes” (vigor, organization, stability) or “ecosystem services” in order to facilitate interpretation and, most importantly, to provide long-term phytostabilization monitoring programs with the required stability through time against changes in techniques, methods, interests, etc. that will inevitably occur during the monitoring program. Finally, a Phytostabilization Monitoring Card, based on both ecological attributes and ecosystem services, for soil microbial properties is provided.     

Risking Your Life without a Second Thought: Intuitive Decision-Making and Extreme Altruism

When faced with the chance to help someone in mortal danger, what is our first response? Do we leap into action, only later considering the risks to ourselves? Or must instinctive self-preservation be overcome by will-power in order to act? We investigate this question by examining the testimony of Carnegie Hero Medal Recipients (CHMRs), extreme altruists who risked their lives to save others. We collected published interviews with CHMRs where they described their decisions to help. We then had participants rate the intuitiveness versus deliberativeness of the decision-making process described in each CHMR statement. The statements were judged to be overwhelmingly dominated by intuition; to be significantly more intuitive than a set of control statements describing deliberative decision-making; and to not differ significantly from a set of intuitive control statements. This remained true when restricting to scenarios in which the CHMRs had sufficient time to reflect before acting if they had so chosen. Text-analysis software found similar results. These findings suggest that high-stakes extreme altruism may be largely motivated by automatic, intuitive processes.     

Structural sensitivity and resilience in a predator–prey model with density-dependent mortality

Numerous formulations with the same mathematical properties can be relevant to model a biological process. Different formulations can predict different model dynamics like equilibrium vs. oscillations even if they are quantitatively close (structural sensitivity). The question we address in this paper is: does the choice of a formulation affect predictions on the number of stable states? We focus on a predator–prey model with predator competition that exhibits multiple stable states. A bifurcation analysis is realized with respect to prey carrying capacity and species body mass ratio within range of values found in food web models. Bifurcation diagrams built for two type-II functional responses are different in two ways. First, the kind of stable state (equilibrium vs. oscillations) is different for 26.0–49.4% of the parameter values, depending on the parameter space investigated. Using generalized modelling, we highlight the role of functional response slope in this difference. Secondly, the number of stable states is higher with Ivlev's functional response for 0.1–14.3% of the parameter values. These two changes interact to create different model predictions if a parameter value or a state variable is altered. In these two examples of disturbance, Holling's disc equation predicts a higher system resilience. Indeed, Ivlev's functional response predicts that disturbance may trap the system into an alternative stable state that can be escaped from only by a larger alteration (hysteresis phenomena). Two questions arise from this work: (i) how much complex ecological models can be affected by this sensitivity to model formulation? and (ii) how to deal with these uncertainties in model predictions?     

Ecological Genetics and the Restoration of Plant Communities: Mix or Match?

We present a conceptual framework for choosing native plant material to be used in restoration projects on the basis of ecological genetics. We evaluate both the likelihood of rapid establishment of plants and the probability of long-term persistence of restored or later successional communities. In addition, we consider the possible harmful effects of restoration projects on nearby ecosystems and their native resident populations. Two attributes of the site to be restored play an important role in determining which genetic source will be most appropriate: (1) degree of disturbance and (2) size of the disturbance. Local plants or plants from environments that “match” the habitat to be restored are best suited to restore sites where degree of disturbance has been low. Hybrids or “mixtures” of genotypes from different sources may provide the best strategy for restoring highly disturbed sites to which local plants are not adapted. Cultivars that have been modified by intentional or inadvertent selection have serious drawbacks. Nevertheless, cultivars may be appropriate when the goal is rapid recovery of small sites that are highly disturbed.     

长江口潮间带大型底栖动物群落演替

2006年1月在崇明岛西端的潮间带湿地进行了一项生态工程,经过土方工程的区域被选为大型底栖动物群落演替区,因为其中的大型底栖动物群落受到了较大破坏,在其周边未受干扰区设立对照样点。试图通过群落重建群的研究分析3个问题：（1）在群落恢复过程中不同的生态学指标如何变化？（2）群落演替过程中什么先增长,生物量还是复杂性？（3）是否可以选择生态学指标以利于演替过程中3类不同增长模式（生物量、网络结构和信息量）的识别？多变量分析用于检验被干扰区群落是否已经得到恢复。Shannon-Wiener指数、Margalef指数、Pielou均匀度指数、能质（exergy）和结构能质（Specificexergy）用于分析演替过程中群落状态的变化。结果显示物种随时间的更替与群落结构变化密切相关。物种丰富度增长迅速,而且对照区和演替区的物种组成非常相似。演替进行1个月左右之后,演替区的生物多样性已经超过了对照区。能质和结构能质提供了群落结构发展的有用信息,但仍然缺乏鉴别系统所处信息状态的能力。多样性分析结果可以从中度干扰假说（Intermediate Disturbance Hypothesis）得到很好地解释。总体而言,干扰的空间尺度决定了群落的恢复特征,如果干扰区域明显小于周边未受干扰的区域,那么群落的复杂性（信息量和网络结构）将先于生物量得到恢复。     

蚂蚁扰动对土壤有机碳循环过程的影响研究进展

蚂蚁作为生态系统的消费者和分解者,其对土壤有机碳库的影响一直是学术界研究的热点。目前研究主要从蚂蚁对土壤宏量元素储量、理化性质、微生物群落活动等方面探究蚂蚁对土壤有机碳库的影响。本文综述了蚂蚁扰动对土壤有机碳循环过程特征的影响。蚂蚁筑巢改变了蚁穴土壤的微生境、微气候与土壤理化性质,并通过重构土壤微生物群落结构特征、调控地表植被演替过程与格局等方式,直接或间接的影响蚁巢中土壤有机碳来源、碳库分配过程、有机碳库稳定性、有机质微观分子特征等,在微域、局地乃至景观尺度上影响土壤有机碳的循环过程。未来研究应着重从量化蚂蚁扰动及其导致的环境因子波动对土壤碳通量变化的贡献、建立定量模型联系并统一蚂蚁影响下土壤碳循环过程、厘清蚂蚁影响土壤有机碳库稳定性的机制等方面开展深入研究,揭示蚂蚁作为“生态工程师”在调控土壤碳循环过程中的作用机制。     

Conflict between dynamical and evolutionary stability in simple ecosystems

Here, we address the essential question of whether, in the context of evolving populations, ecosystems attain properties that enable persistence of the ecosystem itself. We use a simple ecosystem model describing resource, producer, and consumer dynamics to analyze how evolution affects dynamical stability properties of the ecosystem. In particular, we compare resilience of the entire system after allowing the producer and consumer populations to evolve to their evolutionarily stable strategy (ESS) to the maximum attainable resilience. We find a substantial reduction in ecosystem resilience when producers and consumers are allowed to evolve compared to the maximal attainable resilience. This study illustrates the inherent difference and possible conflict between maximizing individual-level fitness and maximizing resilience of entire ecosystems.     

Patient shielding: The need for a European consensus statement

Contact shielding has been in widespread use for the last 60–70 years aiming to protect against genetic effects, cancer, and other detriment. Since 2012, studies have begun to appear in the literature that question the continued use of such shielding, especially when radiographic technology has changed so much over the intervening period This literature has culminated in several professional bodies such as the American Association of Physicists in Medicine (AAPM) and the British Institute of Radiology (BIR) issuing guidance and statements recommending against the continued routine use of patient contact shielding. Many professional societies have also endorsed these statements. National statements on the matter continue to be produced. It is notable however that the major European bodies involved in diagnostic radiology and radiation safety have not to date issued a statement on patient shielding. This commentary looks at reasons for that and argues that it is now time for a European consensus statement on patient shielding.It is the authors belief that there are advantages to building on the work done by the AAPM and BIR, using the opportunity to amplify the statements, propagate the intent of the original statements, refine the message to deal with questions that have arisen since their publication.Α working group, Gonad and Patient Shielding (GAPS) has been formed by members from a) the European Federation of Organisations for Medical Physics (EFOMP), b) the Eurosafe Imaging initiative of the European Society of Radiology (ESR), c) the European Federation of Radiographers Societies (EFRS), d) EURADOS and e) the BIR to produce a joint statement on the proper application of patient shielding in diagnostic and interventional radiology.     

Criticality and disturbance in spatial ecological systems

Classical criticality describes sudden changes in the state of a system when underlying processes change slightly. At this transition, patchiness develops which lacks a characteristic or dominant spatial scale. Thus, criticality lies at the interface of two important subjects in ecology, threshold behavior and patchiness. Most ecological examples of criticality involve processes of disturbance and recovery; the spatial and temporal scales of these processes enable three different types of critical system to be distinguished: classical phase transitions, self organized criticality (SOC) and 'robust' criticality. Here, we review the properties defining these three types and their implications for threshold behavior and large intermittent temporal fluctuations, with examples taken from spatial stochastic models for predator-prey, infected-susceptible, and disturbance-recovery interactions. In critical systems, spatial properties of patchiness alone are insufficient indicators of impending sudden changes, unless complemented by the spatial and temporal scales of disturbance and recovery themselves.     

The experimental paradigm and long-term population studies

Most ecologists recognize the value of long-term studies to population and community ecology, and many also subscribe to the experimental approach as the most effective way of obtaining ecological knowledge. But if we are experimentalists, do we need long-term studies? I argue that the answer to this question is yes, that we must combine these two approaches to solve the major ecological questions of the next century. Most of the challenging questions facing ecologists involve systems subject to long-term time trends or high environmental variability.
Because of the statistical power of many ecological methods, long-term studies are essential to measure time trends in ecosystems. Ignoring statistical power has been a major problem with short-term studies, which have predominated in the ecological literature.
Some examples of long-term studies on larch bud-moth Zeiraphera diniana , winter moth Operophthera brumata and snowshoe hares are discussed briefly to illustrate the four major desiderata of long-term projects: spatial scale, sampling design, hypothesis testing and timeframe.
Two reasons for not doing long-term studies are to assess density-dependence and to monitor ecosystem health. The density-dependent paradigm is bankrupt and has produced much argument and little understanding of population processes. Monitoring of populations is politically attractive but ecologically banal unless it is coupled with experimental work to understand the mechanisms behind system changes.