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Disturbance is common in natural ecosystems, but increasingly defines them. While there are many descriptions for the dynamics of an ecosystem's response to disturbance, there are few descriptions for the dynamics of the disturbance itself. I describe a novel application of a model based on the production of amplitude envelopes in acoustics and electronic music synthesis, with varying parameters Attack, Decay, Sustain, and Release (ADSR). I show that varying the parameters of the ADSR model is sufficient to produce and vary the qualitative disturbance regimes described by previous authors, and is capable of producing dynamics not previously considered. I tested the utility of the ADSR model by applying it to a logistic growth model. I found that manipulating the attack and release parameters of the ADSR model changes the population dynamics estimated by these models. This implies that responses to disturbance are determined not only by the resilience and resistance of the ecological system, but also the dynamics of the disturbance itself. My hope is that the ADSR model will prove useful to researchers in either describing disturbances in long‐term ecological data, or in producing disturbances for simulations or experiments. [ABSTRACT FROM AUTHOR]

Naturalistic plantings, such as meadow‐style plantings, can improve the quality of urban green spaces through aesthetic, biodiversity and low maintenance features. Species selection for, and maintenance of naturalistic plantings are key to their success. While herbaceous and grassy meadows can be mowed, naturalistic plantings with woody plants require more intense maintenance to remove biomass and promote resprouting. We aim to understand woody plant responses to diverse disturbance regimes to potentially inform the selection and management of woody species in urban plantings. We conducted a quantitative systematic literature review of 72 papers and investigated what main external (climate, disturbance regime) and internal (buds, life stage, storage reserves) factors influence the resprouting response of woody plants. We found resprouting literature is geographically widespread for woody plants, but studies are skewed towards Temperate climates in USA and Australia, with a focus on high severity and high frequency fire disturbance. Resprouting response was mostly defined as a continuous response to disturbance dependent on disturbance regime, climate and plant traits. Maintenance and management of naturalistic woody plantings, through hard pruning techniques such as coppicing, may be informed by analogous high severity and high frequency disturbance studies. However, the literature on woody plant resprouting has several knowledge gaps for lower severity and lower frequency disturbance regimes and in more arid climates. Future research should evaluate the response of naturalistic woody plantings to disturbance in specific urban contexts. [ABSTRACT FROM AUTHOR]

As coral reefs endure increasing levels of disturbance, understanding recovery patterns of reef‐building hard corals is paramount to assessing the sustainability of these ecosystems. At local scales, coral recovery slows down; however, it's unclear how this trend propagates across spatial scales due to the inherent complexity of coral dynamics. In this paper, we aimed to learn about fine scale heterogeneity of coral dynamics and explore implications for assessing coral recovery at larger spatial scales. We developed a spatio‐temporal statistical model to estimate long‐term trajectories of three types of corals and predict their recovery patterns at unobserved locations within a reef. Then, model predictions were used to derive metrics that capture the interplay between coral growth and decline from disturbance(s) across time, space and growth morphology. This model is developed in the context of a substantive case study at Heron Reef using a high spatio‐temporal resolution dataset. Our results revealed that successful coral community recoveries took place in different habitats of Heron Reef and associated with various reasons. Branching corals recovered in the southern slope, due to fast growth in locations that were previously abundant. Plate corals flourished in the northern slope due to fast growth, despite a large decline and low baseline cover. They also recovered in the southern slope but in this case there was both a low decline and baseline cover. At Heron Reef, the recovery of coral communities followed specific conditions that were acting at a fine scale in a complex and heterogeneous way within habitat. This implies that capturing the variability of fine‐scale coral dynamics is an important first step to detect accurate signals of coral recovery at larger spatial scales. The approach proposes here can be further extend to the scale of a reef and beyond enabling assessment of recovery patterns representative at management scales. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Applied Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The thermospheric density and its variations are crucial to aerospace activities as well as space weather research and operation. However, due to the difficulties in observing the thermosphere, there has been a lack of effective descriptions for the general characteristics of thermospheric density. In this paper, the Two‐Line‐Element data sets (TLEs) from multi‐target low Earth orbit satellites are used to derive a proxy of the daily average atmospheric density in the thermospheric shell located in the vicinity of LEOs' orbital altitude. It captures the overall characteristics of the thermosphere and exhibits good correlations (∼0.9) with modeled and observed thermospheric density. By applying the spectral whitening method to this proxy, a new index JsT ${J}_{s}^{T}$ is derived to describe non‐periodic perturbation of the density where the specific satellite passed by. The fact that the JsT ${J}_{s}^{T}$ obtained from different satellites within the same thermospheric shell presents significant consistency to each other means that the new index is a good indicator for the overall feature of the variations of thermospheric density, and it is possible to define a unified regional index JrT ${J}_{r}^{T}$ to describe density disturbances for the thermospheric shell where these satellites fly through. Moreover, the JrT ${J}_{r}^{T}$ at different altitudes also present good consistency suggesting the possibility of defining a global index JpT ${J}_{p}^{T}$, capable of describing the density variation of the entire thermosphere. Plain Language Summary: Due to limited in situ observation, the thermospheric density is not easy to obtain. Herein, we have extracted the density information of the thermosphere based on the Two‐Line‐Element data sets and developed a new index using the spectral whitening method, which describes aperiodic disturbances of the density. The construction of this index series can address the limitations of existing quantitative or graded descriptions of space weather disturbances and the problem of mismatched or inconsistent parameters/indices. Ultimately, this will contribute to the monitoring and warning of space weather causal chains. Key Points: A proxy of daily average thermospheric mass density was extracted from Two‐Line‐Element data setsBy applying the spectral whitening method to this proxy, a new index is derived to describe non‐periodic perturbations in the thermosphereA unified regional index was defined to describe density disturbances for the thermospheric shell where these satellites fly through [ABSTRACT FROM AUTHOR]

Summary: This paper investigates the tracking control problem of connected vehicle system suffer from disturbance and communication load. A new dynamic triggered‐based tracking approach was presented. First, an extended state observer is designed to estimate the equivalent disturbance, and the convergence of observed error is proved. Then, a tracking approach based on backstepping control is proposed. Furthermore, in order to reduce the consumption of network resources, a novel tracking method on dynamic event‐triggering strategy is developed, and all signals in connected vehicle system are ultimately uniformly bounded without Zeno behavior is verified. Finally, the effectiveness of the proposed control strategy is testified by simulation results. [ABSTRACT FROM AUTHOR]

This paper focuses on variable‐speed wind turbines where control is aimed at stabilizing the output power. A hybrid control algorithm is proposed which includes a new arrangement of two controllers along with an observer. Estimation of power coefficient via sliding mode observer reduces the amount of errors caused by changing the power coefficient parameter in different turbines. Moreover, the use of this special arrangement of sliding mode controller, proportional‐integral (PI) controller and sliding mode observer, removes one of the controller parameter denoting wind speed from the designed algorithm, which in turn eliminates disturbances related to wind speed changes. In order to show the efficiency of the proposed control method, the performances of the controllers are evaluated by simulation in MATLAB software. [ABSTRACT FROM AUTHOR]

Additionally, we observed that I Cassiopea i individuals spent less time in vegetated seagrass habitat (~1 day) and stayed longer on bare (artificial) bioturbation mounds (>10 days), suggesting that the individuals are mostly passing through habitats with high seagrass cover selecting open spaces to settle (corresponding to findings of Niggl & Wild, [8]). Keywords: bioturbation; Cassiopea; colonization; competition; disturbance; exotic seagrass; habitat preference; Halophila stipulacea; landscape modification; patch dynamics EN bioturbation Cassiopea colonization competition disturbance exotic seagrass habitat preference Halophila stipulacea landscape modification patch dynamics 1 5 5 04/05/23 20230401 NES 230401 In tropical ecosystems, autotroph organisms are continuously competing for space, with some plant species benefiting from disturbances such as fire, grazing, or bioturbation that clear habitats (Pulsford et al., [11]). In this paper, we report evidence of a novel ecological interaction in a tropical seagrass ecosystem between two autotroph species, the invasive seagrass I H. stipulacea i and the native upside-down jellyfish I Cassiopea i spp. We hypothesize that the arrival of the invasive I H. stipulacea i is likely to shift patch dynamics in the seagrass ecosystem and, thereby, niche competition between seagrasses and I Cassiopea i . [Extracted from the article]

This paper proposes an Adaptive Neuro Linear Quadratic Regulator (ANLQR) controller for Buck converter operating under harmful disturbances. Considering the real‐time condition of a converter with regular variations, Neural Network is adopted to improve and tune the gain of the LQR strategy with an adaptive mechanism. This strategy assumes the system as a Gray‐box process without the need for the exact mathematical model of the system which can result in lower computational burden, faster dynamics, and ease of implementation. ANLQR control strategy is a suitable alternative considering its significant robustness against different disturbances, particularly noise. It should be mentioned that the number of neurons is limited to 2 and 4 in each layer to decrease the computational burden with lower complexity. The advantages of this ANLQR method is justified for various operating situations through experimental and simulation outcomes. Moreover, LQR and PSO‐PID controllers are designed and compared with the presented strategy to carry on a comparison with the proposed method. Furthermore, this approach provides better outcomes with faster dynamics and better frequency adaption in the real‐time environments. [ABSTRACT FROM AUTHOR]

In this paper, we address the event‐triggered robust observer‐based control problem of a class of one‐sided Lipschitz systems subject to time delays and disturbances. We design an event‐triggered robust observer‐based controller to guarantee that the closed‐loop systems of the one‐sided Lipschitz systems are asymptotical stable with a disturbance attenuation level. Two examples are given to illustrate our obtained results. [ABSTRACT FROM AUTHOR]

Disturbances can alter the structure and function of ecosystems. In stream ecosystems, changes in discharge and physicochemistry at short, intermediate, and long recurrence intervals can affect food webs and ecosystem processes. In this paper, we compare pH regimes in streams at La Selva Biological Station, Costa Rica, where episodic acidification frequency across the stream network varies widely due to buffering from inputs of bicarbonate‐rich interbasin groundwater. To examine the effects of acidification on ecosystem structure and function, we experimentally increased the buffering capacity of a headwater stream reach and compared it to an unbuffered upstream reach. We compared these reaches to a naturally buffered and unbuffered reaches of a second headwater stream. We quantified ecosystem structural (macroinvertebrate assemblages on leaf litter and coarse woody debris) and functional responses (leaf litter and coarse woody debris decomposition rates, and growth rates of a focal insect taxon [Diptera: Chironomidae]). Non‐metric multidimensional scaling and analysis of similarity revealed that macroinvertebrate assemblages were relatively homogenous across the four study reaches, although the naturally buffered reach was the most dissimilar. Ecosystem function, as measured by chironomid growth rates, was greater in the naturally buffered reach, while decomposition rates did not differ across the four reaches. Our results indicate that biological assemblages are adapted to pH regimes of frequently acidified stream reaches. Our experiment informs the effects on structure and function at short time scales in streams that experience moderate acidification, but larger magnitude acidification events in response to hydroclimatic change, as projected under climate change scenarios, may induce stronger responses in streams. [ABSTRACT FROM AUTHOR]

In this paper, two robust model‐free adaptive control (RMFAC) methods are proposed for a nonlinear flapping wing micro air vehicle (FWMAV) subject to measurable and unmeasurable wind disturbances. Firstly, a novel disturbance‐related full‐form dynamic linearization technique (DFFDL) is developed to transform the FWMAV with measurable disturbances into a dynamic linearization data model. Then, a DFFDL based RMFAC method is designed based on the obtained data model for the FWMAV to suppress the wind disturbances. Next, the stability analysis shows that the system output tracking error converges into a bounded range. And the above result is extended to the case of unmeasurable disturbances. Finally, the simulation comparison results demonstrate the effectiveness of two proposed RMFAC methods. [ABSTRACT FROM AUTHOR]

Human activities have often altered sediment dynamics in rivers, leading to aquatic habitat degradation. The dominant paradigm in fish–sediment interactions focuses on excessive fine sediments as indicators of habitat and water quality degradation. In contrast, geomorphologists have provided frameworks linking altered sediment dynamics to much broader and more complex changes to channel morphology and stream habitats across spatial scales.In this paper we use an interdisciplinary approach with historical and contemporary channel morphology and fish community datasets to examine how altered sediment dynamics have affected stream fish community evolution in the Bayou Pierre, Mississippi, U.S.A.Erosional process regimes have advanced upstream consistent with models of knickpoint propagation and channel evolution, leaving most of the catchment in a state of increased sediment transport and local sediment deficits. Fish communities in modern samples have less α and β diversity and fewer habitat specialist taxa than in historical samples.Whole‐community analysis via non‐metric multidimensional scaling found a strong gradient of homogenisation towards a fauna comprised of small‐bodied taxa adapted to large rivers.Comparisons of community and geomorphic change on this gradient found that reaches that transitioned between process regimes had more community change, and that local habitat factors relating to advanced channel evolution were strongly positively related to total community change.These results demonstrate that a catchment‐scale geomorphic analysis provided a strong tool for understanding fish community change on a decadal scale. Our findings further demonstrate concordant ecological responses to a complex sequence of disturbances and suggest that a broader view of sediment dynamics offers a rich toolkit for ecological analyses. [ABSTRACT FROM AUTHOR]

Many secondary deciduous forests of eastern North America are approaching a transition in which mature early‐successional trees are declining, resulting in an uncertain future for this century‐long carbon (C) sink. We initiated the Forest Accelerated Succession Experiment (FASET) at the University of Michigan Biological Station to examine the patterns and mechanisms underlying forest C cycling following the stem girdling‐induced mortality of >6,700 early‐successional Populus spp. (aspen) and Betula papyrifera (paper birch). Meteorological flux tower‐based C cycling observations from the 33‐ha treatment forest have been paired with those from a nearby unmanipulated forest since 2008. Following over a decade of observations, we revisit our core hypothesis: that net ecosystem production (NEP) would increase following the transition to mid‐late‐successional species dominance due to increased canopy structural complexity. Supporting our hypothesis, NEP was stable, briefly declined, and then increased relative to the control in the decade following disturbance; however, increasing NEP was not associated with rising structural complexity but rather with a rapid 1‐yr recovery of total leaf area index as mid‐late‐successional Acer, Quercus, and Pinus assumed canopy dominance. The transition to mid‐late‐successional species dominance improved carbon‐use efficiency (CUE = NEP/gross primary production) as ecosystem respiration declined. Similar soil respiration rates in control and treatment forests, along with species differences in leaf physiology and the rising relative growth rates of mid‐late‐successional species in the treatment forest, suggest changes in aboveground plant respiration and growth were primarily responsible for increases in NEP. We conclude that deciduous forests transitioning from early to middle succession are capable of sustained or increased NEP, even when experiencing extensive tree mortality. This adds to mounting evidence that aging deciduous forests in the region will function as C sinks for decades to come. [ABSTRACT FROM AUTHOR]

In this paper, the development of passivity‐based control (PBC) algorithms to stabilize an unmanned powered parachute aerial vehicle is presented. The equations of motion of the system are presented in both Lagrangian and Hamiltonian formalisms. The proposed controllers are based on the Hamiltonian function of the system and guarantee the parachute aircraft system stabilization. In the first control law a classic PBC strategy is proposed, and in the second, an interconnection and damping assignment‐passivity‐based control (IDA‐PBC) is chosen because of its inherent robustness against parametric uncertainty and unmodeled dynamics. The control objective is to reach a desired final position despite the initial launch conditions. Numerical simulations with variation in the parachute mass weight and in the presence of wind are carried out to validate our proposed schemes. [ABSTRACT FROM AUTHOR]

A type‐2 fuzzy logic‐based adaptive backstepping control (T2FABSC) approach is designed for an H‐bridge inverter. This inverter has an LC filter to decrease the level of total harmonic distortion (THD) that can affect the efficiency of the system. Reduction of THD and stability insurance of the filter are challenging trade‐offs, tackled here by a controller design. The performance, however, is not suitable for actual applications under a wider range of disturbances, and the parameters need to be adjusted once more for more dependable operations. Backstepping control is given a Lyapunov definition‐based adaptive mechanism that can improve this scheme's stability and robustness in the face of numerous disturbances. Additionally, the system is viewed as a "Black box" without the need for a precise mathematical model, which might lead to a lighter computing burden and simpler implementation. Moreover, a fuzzy type‐2 structure is adopted that can optimize the gains of the adaptive Backstepping controller (ABSC) in challenging conditions. The antlion optimization algorithm is employed to optimize the parameters of the membership functions in the fuzzy system, hence improving the performance of the controller. In addition, compared with different optimization algorithms, it can more quickly and accurately locate the best solutions. Finally, the findings of both the simulations and the experimental outputs are examined, proving the T2FABSC's significant robustness and faster dynamics in a variety of challenging circumstances. [ABSTRACT FROM AUTHOR]

The presence of alien plant species in disturbed habitats is a well‐studied subject, however, the contribution of wind farm projects to alien plant invasion is often overlooked in environmental impact assessment. The present study tests a survey method for the assessment of plant diversity and the detection of alien plant invasion in two wind farm areas in Romania. Over 5 years, we recorded plant species incidence data in disturbed and undisturbed plots, making one visit per growing season each year. Using several plant community indicators and methods, such as species richness, beta diversity, non‐metric multidimensional scaling, and multinomial species classification, we reliably detected plant species assemblage, including 26 alien plant species among the 608 recorded. Disturbed plots harbor a higher number of alien plant species, supporting the hypothesis that disturbances caused by wind farms reduce habitats' resilience to alien plant invasions. Despite the presence of habitat specialist plant species in certain plots, the community of alien plants did not show a clear preference for disturbed or undisturbed plots. The results underscore the importance of surveying the wind farms beyond the disturbed sites through regular monitoring to accurately assess their impact on plant diversity and detect alien plant invasions. The regular monitoring of all plant species during growing seasons will provide useful data for informing conservation strategies for native plants, including the control and eradication of alien species in early invasion stages. [ABSTRACT FROM AUTHOR]

Field studies are necessary for understanding natural processes in spite of the human‐induced disturbances they cause. While researchers acknowledge these effects, no studies have empirically tested the direct (e.g., harvesting plants) and indirect (i.e., trampling) effects of researcher activities on biological structure and edaphic conditions. We leveraged field studies in Alabama and California to monitor the recovery of tidal marshes following research activities. Researcher effects on animals, plants, and sediment conditions remained prevalent almost one year after the disturbance ended. For instance, trampled plots had 14%–97% lower plant cover than undisturbed plots after >10 months of recovery. Researcher effects also impacted plant composition, leading to increased subordinate species abundance. We encourage field researchers to adopt strategies that reduce their scientific footprints, including reducing field visits, limiting field team size, and considering ways to limit potential environmental impacts during study design. [ABSTRACT FROM AUTHOR]

Fire‐dependent savanna provides key habitat for butterflies globally, but we know little about how fire regimes, including fire frequency and season, affect them. These impacts are likely to be primarily indirect, through changes in overall habitat structure, the abundance of larval host plants, and/or the provision of nectar resources for adults. We examined the relationships among fire regime, butterfly abundance and diversity, and vegetation structure and floral resources within a long‐term fire experiment near Darwin in the Australian monsoon tropics. We surveyed butterflies and floral resources throughout the 2019–2020 wet season in three replicate plots of each of six experimental treatments that had been operating for 15 years. All plots subject to fire had been burned in the previous dry season. We observed 24 butterfly species and 280 individuals representing all five butterfly families found in Northern Australia. Butterfly abundance was highest under early dry‐season (June) fire regimes (mean = 11.9 individuals per plot survey) compared with a late dry‐season (October) regime (mean = 6.7) and in the long‐term absence of fire (mean = 5.3), and this was correlated with the abundance of floral resources. The distribution of butterflies was also highly associated with floral resources within plots regardless of fire treatment. Butterfly species richness was significantly higher in early dry‐season (mean = 6.8) compared with unburned (mean = 3.3) plots but did not differ between early and late dry‐season (mean = 4.7) plots. Butterfly and floral diversity were similar across all early dry‐season fire treatments regardless of whether they had been burned every 1, 2, 3, or 5 years. Our finding that early dry‐season burning promotes butterfly diversity and abundance by increasing the supply of nectar resources has important implications for biodiversity management more broadly, given that nectar is a critical resource for many animal taxa. [ABSTRACT FROM AUTHOR]

Earth's biosphere is undergoing drastic reorganization due to the sixth mass extinction brought on by the Anthropocene. Impacts of local and regional extirpation of species have been demonstrated to propagate through the complex interaction networks they are part of, leading to secondary extinctions and exacerbating biodiversity loss. Contemporary ecological theory has developed several measures to analyse the structure and robustness of ecological networks under biodiversity loss. However, a toolbox for directly simulating and quantifying extinction cascades and creating novel interactions (i.e. rewiring) remains absent.Here, we present NetworkExtinction—a novel R package which we have developed to explore the propagation of species extinction sequences through ecological networks and quantify the effects of rewiring potential in response to primary species extinctions. With NetworkExtinction, we integrate ecological theory and computational simulations to develop functionality with which users may analyse and visualize the structure and robustness of ecological networks. The core functions introduced with NetworkExtinction focus on simulations of sequential primary extinctions and associated secondary extinctions, allowing user‐specified secondary extinction thresholds and realization of rewiring potential.With the package NetworkExtinction, users can estimate the robustness of ecological networks after performing species extinction routines based on several algorithms. Moreover, users can compare the number of simulated secondary extinctions against a null model of random extinctions. In‐built visualizations enable graphing topological indices calculated by the deletion sequence functions after each simulation step. Finally, the user can estimate the network's degree distribution by fitting different common distributions. Here, we illustrate the use of the package and its outputs by analysing a Chilean coastal marine food web.NetworkExtinction is a compact and easy‐to‐use R package with which users can quantify changes in ecological network structure in response to different patterns of species loss, thresholds and rewiring potential. Therefore, this package is particularly useful for evaluating ecosystem responses to anthropogenic and environmental perturbations that produce nonrandom and sometimes targeted, species extinctions. [ABSTRACT FROM AUTHOR]

Understanding the severity and extent of near surface critical zone (CZ) disturbances and their ecosystem response is a pressing concern in the face of increasing human and natural disturbances. Predicting disturbance severity and recovery in a changing climate requires comprehensive understanding of ecosystem feedbacks among vegetation and the surrounding environment, including climate, hydrology, geomorphology, and biogeochemistry. Field surveys and satellite remote sensing have limited ability to effectively capture the spatial and temporal variability of disturbance and CZ properties. Technological advances in remote sensing using new sensors and new platforms have improved observations of changes in vegetation canopy structure and productivity; however, integrating measures of forest disturbance from various sensing platforms is complex. By connecting the potential for remote sensing technologies to observe different CZ disturbance vectors, we show that lower severity disturbance and slower vegetation recovery are more difficult to quantify. Case studies in montane forests from the western United States highlight new opportunities, including evaluating post‐disturbance forest recovery at multiple scales, shedding light on understory vegetation regrowth, detecting specific physiological responses, and refining ecohydrological modeling. Learning from regional CZ disturbance case studies, we propose future directions to synthesize fragmented findings with (a) new data analysis using new or existing sensors, (b) data fusion across multiple sensors and platforms, (c) increasing the value of ground‐based observations, (d) disturbance modeling, and (e) synthesis to improve understanding of disturbance. Key Points: Increasing remote sensing capabilities improve observations of disturbance severity and recovery in varying critical zone settingsCase studies present how new approaches from multiple platforms and sensors better quantify post‐disturbance recovery of montane forestsWe suggest integrating the new approaches to refine remote sensing capabilities and resolve critical zone processes at multiple scales [ABSTRACT FROM AUTHOR]

Canada geese (Branta canadensis) migrating along coastal flyways are reliant on natural coastal ecosystems. Within these stopover sites, eelgrass (Zostera marina), the most common and widespread seagrass species in North America, is an important food resource for migrating waterfowl. Given the growing anthropogenic pressure on coastal ecosystems, geese migrating along coastal regions may find it increasingly difficult to access suitable stopover sites where food is abundant and human disturbance is low. We assessed the influence of hunting and eelgrass on the spatiotemporal distribution of Canada geese in the Tabusintac Bay, New Brunswick, Canada, a wetland of international importance. We surveyed Canada geese at 6 stations from mid‐September to late October, 2016 and 2017. We used 2‐part hurdle models consisting of generalized linear mixed models with binomial and negative binomial response distributions to model Canada geese presence and abundance, respectively, in relation to eelgrass abundance, distance to the mainland coastline, water depth, and tidal conditions in 3 different hunting intensity periods. Eelgrass abundance is a significant predictor of Canada geese presence early in the season, when hunting activity is low. At the onset of the hunting period, geese shifted diurnal distribution to areas farther offshore, indicating a response to avoid disturbance, and the abundance of Canada geese increased with increasing eelgrass availability, emphasizing the importance of eelgrass as a food source during fall migration in that region. Thus, our results highlight the effects of human disturbance and eelgrass abundance in influencing stopover behavior of Canada geese during fall migration in eastern Canada. [ABSTRACT FROM AUTHOR]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wildlife population dynamics are modulated by abiotic and biotic factors, typically climate, resource availability, density‐dependent effects, and predator–prey interactions. Understanding whether and how human‐caused disturbances shape these ecological processes is helpful for the conservation and management of wildlife and their habitats within increasingly human‐dominated landscapes. However, many jurisdictions lack either long‐term longitudinal data on wildlife populations or measures of the interplay between human‐mediated disturbance, climate, and predator density. Here, we use a 50‐year time series (1962–2012) on mule deer (Odocoileus hemionus) demographics, seasonal weather, predator density, and oil and gas development patterns from the North Dakota Badlands, USA, to investigate long‐term effects of landscape‐level disturbance on mule deer fawn fall recruitment, which has declined precipitously over the last number of decades. Mule deer fawn fall recruitment in this study represents the number of fawns per female (fawn:female ratio) that survive through the summer to October. We used this fawn recruitment index to evaluate the composite effects of interannual extreme weather conditions, energy development, and predator density. We found that density‐dependent effects and harsh seasonal weather were the main drivers of fawn fall recruitment in the North Dakota Badlands. These effects were further shaped by the interaction between harsh seasonal weather and predator density (i.e., lower fawn fall recruitment when harsh weather was combined with higher predator density). Additionally, we found that fawn fall recruitment was modulated by interactions between seasonal weather and energy development (i.e., lower fawn fall recruitment when harsh weather was combined with higher density of active oil and gas wells). Interestingly, we found that the combined effect of predator density and energy development was not interactive but rather additive. Our analysis demonstrates how energy development may modulate fluctuations in mule deer fawn fall recruitment concurrent with biotic (density‐dependency, habitat, predation, woody vegetation encroachment) and abiotic (harsh seasonal weather) drivers. Density‐dependent patterns emerge, presumably due to limited quality habitat, being the primary factor influencing fall fawn recruitment in mule deer. Secondarily, stochastic weather events periodically cause dramatic declines in recruitment. And finally, the additive effects of human disturbance and predation can induce fluctuations in fawn fall recruitment. Here we make the case for using long‐term datasets for setting long‐term wildlife management goals that decision makers and the public can understand and support. [ABSTRACT FROM AUTHOR]

Aim: Ecological disturbances are increasing as climate warms, and how multiple disturbances interact spatially to drive landscape change is poorly understood. We quantified burn severity across fire regimes in reburned forest landscapes to ask how spatial patterns of high‐severity fire differ between sequential overlapping fires and how landscape heterogeneity is shaped by cumulative disturbance patterns. We also characterized the amount and configuration of an emerging phenomenon: areas burned as high‐severity fire twice in successive fires. Location: Northwest USA. Time period: 1984–2020. Major taxa studied: Forests of western continental USA. Methods: We used a field‐calibrated atlas of satellite‐measured burn severity across diverse fire regimes (more than three decades, >200 short‐interval fires) to quantify landscape metrics of high‐severity (>75% tree mortality) fire in sequential overlapping short‐interval fires. We used generalized linear models to test differences in individual and cumulative landscape patterns of burn severity following the first and second fires. Results: The amount of severe wildfire and patch size/configuration were generally similar between successive overlapping fires and across fire regimes. However, overlapping individual fires produced cumulative landscape patterns of recent high‐severity fire that were consistently more homogeneous after two fires, with greater distances to remaining mature forest. Additionally, 19–25% of landscapes affected by short‐interval fires burned at high severity in both fires, highlighting the spatial extent of repeatedly and severely disturbed forests. Main conclusions When two individually heterogeneous fires overlap, burn mosaics can fit together like puzzle pieces, whereby twice‐burned landscapes are composed of large and simple‐shaped patches of cumulative recent high‐severity fire interspersed with small patches of mature/old forest. These cumulative spatial outcomes of interacting disturbances can be mechanisms of shifting ecosystem dynamics as global change unfolds and reburns continue. [ABSTRACT FROM AUTHOR]

The last century has seen a steep decline in biodiversity, and anthropization is considered one of the major drivers of this decline. Anthropogenic disturbances, due to human presence and/or activities, may be perceived as chronic stressors by wildlife and potentially lead to deleterious effects on traits related to fitness. The main objective of the present study was to highlight the effects of these anthropogenic elements on wild birds on sparsely urbanized farmland, far less studied than in urbanized areas. We investigated during four successive breeding seasons whether the anthropization level, assessed by infrastructure density around nests, and the harvesting conditions around nests may impact physiological, behavioural and life‐history traits of Montagu's harrier Circus pygargus chicks. Higher anthropization levels were associated with higher basal corticosterone levels in nestlings during only one breeding season and a lower body condition at fledging for females, probably because they suffered from higher starvation than males. Nestlings reared in more anthropized areas or in harvested crops before their fledging harboured more fault bars on rectrices than those reared in less anthropized areas or in unharvested crops regardless of year and sex, which is suggestive of higher stress during development. Nestling behaviours were also impacted by anthropization level and harvesting conditions: chicks in harvested crops were more aggressive and in areas with higher anthropization levels more prone to escape than others. Because Montagu's harrier is a protected species, the impacts highlighted in the present study are a matter of concern, especially regarding farmland landscape modifications, and we advise limiting perturbations in areas where Montagu's harriers usually nest. [ABSTRACT FROM AUTHOR]

Understanding patterns of species coexistence is a fundamental challenge in ecology. The physical environment is believed to play an important role, influencing patterns of dispersal and biotic interactions across space and time. Floodplain forest species are presumed to interact strongly with their environment, as evidenced by pronounced spatial variation in forest composition associated with flood‐driven abiotic constraints. Questions of how, and to what degree, fine‐scale heterogeneity interacts with broad‐scale hydrogeomorphology to influence patterns of functional composition remain unresolved. We examined how functional diversity (i.e. richness and range of functional traits) and ecological strategies (i.e. functional trait combinations) of floodplain forest communities varied across regional and local gradients of flooding in a northern temperate region of the United States of America. We found functional diversity of woody overstory species varied across hydrogeomorphic settings and that different settings altered associations between functional diversity and both the relative elevation above and proximity to rivers. Ecological strategies shifted over local gradients of relative elevation and distance to channel with different magnitudes and directions depending on the broader hydrogeomorphic context. We found evidence that interactions among flood regimes and landform position impose different levels of functional constraint. These results indicate patterns of community assembly are not easily discerned from landform type or position alone, but rather from filtering that operates and interacts with biota over multiple spatial scales. Our results imply that it is important to characterize flood dynamics in ways that can be clearly linked to ecological processes and that treatment of floodplain landforms as transferable units across river‐valley segments is problematic, even within a single basin. [ABSTRACT FROM AUTHOR]

The objective is to achieve the constrained containment of discrete‐time multiagent systems with external disturbances in directed networks. In contrast to the existing constrained containment results that ignore disturbances, this work incorporates the disturbances, the position, and velocity constraints of followers simultaneously. A projection‐based control protocol is developed to pull all followers into a target area formed by some leaders, and meanwhile, a certain level of disturbance attenuation performance is satisfied. By utilizing the multiple model transformations, convexity analysis, and the Lyapunov approach, a sufficient condition is derived to realize the constrained containment with H∞$$ {H}_{\infty } $$ performance. Some simulation results are provided to demonstrate the disturbance‐rejection performance of the proposed control method. [ABSTRACT FROM AUTHOR]

Environmental variability is an inherent feature of natural systems which complicates predictions of species interactions. Primarily, the complexity in predicting the response of organisms to environmental fluctuations is in part because species' responses to abiotic factors are non‐linear, even in stable conditions. Temperature exerts a major control over phytoplankton growth and physiology, yet the influence of thermal fluctuations on growth and competition dynamics is largely unknown. To investigate the limits of coexistence in variable environments, stable mixed cultures with constant species abundance ratios of the marine diatoms, Phaeodactylum tricornutum and Thalassiosira pseudonana, were exposed to different temperature fluctuation regimes (n = 17) under high and low nitrogen (N) conditions. Here we demonstrate that phytoplankton exhibit substantial resilience to temperature variability. The time required to observe a shift in the species abundance ratio decreased with increasing fluctuations, but coexistence of the two model species under high N conditions was disrupted only when amplitudes of temperature fluctuation were high (±8.2°C). N limitation caused the thermal amplitude for disruption of species coexistence to become lower (±5.9°C). Furthermore, once stable conditions were reinstated, the two species differed in their ability to recover from temperature fluctuations. Our findings suggest that despite the expectation of unequal effect of fluctuations on different competitors, cycles in environmental conditions may reduce the rate of species replacement when amplitudes remain below a certain threshold. Beyond these thresholds, competitive exclusion could, however, be accelerated, suggesting that aquatic heatwaves and N availability status are likely to lead to abrupt and unpredictable restructuring of phytoplankton community composition. [ABSTRACT FROM AUTHOR]

Disturbance is a key driver of community assembly and patterns of diversity. Whereas successional changes in vegetation have been well‐studied, postdisturbance successional patterns of wildlife communities remain poorly understood.Here, we investigated the roles of site age and habitat in shaping community assembly and the diversity of terrestrial mammals in Glacier Bay National Park, Alaska (GBNP), which has undergone the most rapid and extensive deglaciation in the world since the Little Ice Age. Deglaciation has extensively altered the landscape, opening up new habitat for recolonization by plants and animals.We used camera traps, small mammal trapping and vegetation surveys to investigate the patterns of mammalian succession and beta diversity following deglaciation, using a space‐for‐time substitution across 10 sites during summers 2017 and 2018. Site age and habitat characteristics were not strongly correlated (r < 0.46), allowing the influences of time since disturbance and habitat changes to be distinguished.PERMANOVA analyses indicated that mammal community assembly was more strongly influenced by site age than habitat, whereas habitat and age had similar effects on beta (between site) diversity. Beta diversity was higher for smaller, less mobile mammals than larger, more mobile mammals and was primarily driven by species turnover among sites, whereas relative turnover was much lower for larger mammals. A comprehensive review of historical distributions of mammals in GBNP supported our findings that species turnover is a driving influence of community assembly for smaller mammals.Our results indicate that body size of mammals may play an important role in shaping colonization patterns postdisturbance, likely via size‐related differences in mobility. Patterns of wildlife community assembly may therefore not track vegetation succession following disturbances if there are barriers to movement or if dispersal ability is limited, highlighting the importance of incorporating landscape connectivity and species traits into wildlife conservation efforts following disturbances. This knowledge may improve predictions of mammalian community assembly following major disturbance events. [ABSTRACT FROM AUTHOR]

Alteration in the river flow regime due to intermittent hydropower production (i.e., hydropeaking) leads to biodiversity loss and ecosystem degradation worldwide. Due to the increasing shear of volatile green energy (i.e., wind and solar), hydropeaking frequency is deemed to increase in the coming decades. However, our mechanistic understanding of how the frequency of repeated hydropeaking (i.e., series of multiple events) affects ecological processes is still limited. Here, we reflect on the impacts of altered flow frequency and relative duration on the persistency of aquatic habitats. We focus on the habitats at patch‐scale, being this the scale representing what organisms perceive when interacting with their environment. With a showcase we explore a temporally explicit approach to quantify altered habitat dynamics at patch‐scale due to hydropeaking. We then review how changes in habitat dynamics and persistency may affect ecological processes. Our findings suggest that (i) a time‐series approach allows to account for the inherent multi‐event nature of hydropeaking; (ii) hydropeaking can increase the dynamics of single habitat patches by at least one order of magnitude if compared to unregulated rivers; (iii) altered habitat dynamics at the patch scale can affect the survival of more sessile species and life cycle stages (e.g., invertebrates) or the energy budget of mobile species and life cycle stages (e.g., adult fish). However, the ecological significance and potential environmental thresholds of patch‐scale dynamics and persistency are still poorly investigated and need further attention. Moreover, methods for the aggregation of habitat dynamics and persistency from the patch to the reach‐scale are not available yet. [ABSTRACT FROM AUTHOR]

Mounting evidence suggests that climate change will cause shifts of tree species range and abundance (biomass). Abundance changes under climate change are likely to occur prior to a detectable range shift. Disturbances are expected to directly affect tree species abundance and composition, and could profoundly influence tree species spatial distribution within a geographical region. However, how multiple disturbance regimes will interact with changing climate to alter the spatial distribution of species abundance remains unclear. We simulated such forest demographic processes using a forest landscape succession and disturbance model (LANDIS-II) parameterized with forest inventory data in the northeastern United States. Our study incorporated climate change under a high-emission future and disturbance regimes varying with gradients of intensities and spatial extents. The results suggest that disturbances catalyze changes in tree species abundance and composition under a changing climate, but the effects of disturbances differ by intensity and extent. Moderate disturbances and large extent disturbances have limited effects, while high-intensity disturbances accelerate changes by removing cohorts of mid-and late-successional species, creating opportunities for early-successional species. High-intensity disturbances result in the northern movement of early-successional species and the southern movement of late-successional species abundances. Our study is among the first to systematically investigate how disturbance extent and intensity interact to determine the spatial distribution of changes in species abundance and forest composition. [ABSTRACT FROM AUTHOR]

Whitebark pine (Pinus albicaulis Engelm.) is a keystone high‐elevation tree species occurring across much of western North America, yet it has been listed as threatened under the US Endangered Species Act due to rapid population declines and extensive ongoing pressures from white pine blister rust (Cronartium ribicola), mountain pine beetle (Dendroctonus ponderosae), and increasing temperature and aridity associated with climate change. Past research has shown that whitebark pine mortality is more likely in hotter and drier sites, but no broad‐extent analyses spanning multiple ecoregions have directly quantified the relationship between mortality probability and its environmental drivers at a fine spatial scale. To address this gap, we used spatially continuous high‐resolution (30 m) maps of mortality in California produced by a remote sensing‐based change detection algorithm, and we developed generalized additive models to explain this mortality variability using relevant biophysical variables. We found that maximum daily temperature was strongly positively associated with mortality intensity and that mortality was also generally more intense in sites with greater solar exposure (e.g., south‐facing slopes). Our results support the interpretation that as climate warms and aridity increases, populations in "trailing edge" (i.e., hot, dry) sites are most vulnerable. The environmental relationships we quantify will aid in identifying the locations and environments with the greatest risk of future mortality as well as those likely to serve as refugia. [ABSTRACT FROM AUTHOR]

Mobile species are particularly affected by artificial barriers requiring large investments to restore connectivity. However, few large‐scale, long‐term studies have investigated the ecological outcomes of restoring connectivity for these species. Our study, spanning 15–20 years, quantified response trajectories, which represent temporal trends following disturbance, of three native salmonids colonizing 20 km of protected habitat following restoration of fish passage at Landsburg Dam, Cedar River, WA, in 2003. Built in 1901, the dam blocked the upriver movement of native anadromous coho and Chinook salmon and nonanadromous mountain whitefish for 102 years. Restoration effectiveness was also assessed by comparing temporal trends in freshwater productivity of juvenile coho and Chinook salmon in the Cedar River after restoration to a nearby undammed subbasin. We also compared summer densities of juvenile coho and Chinook salmon, and mountain whitefish above the dam measured a decade after restoration to undammed reference systems. Anadromous salmon and nonanadromous mountain whitefish populations increased linearly or nonlinearly following restoration. The positive, asymptotic response represented by adult Chinook salmon counts indicates a slowing in population recovery rate, plateauing a decade after restoration. In contrast, annual abundance of adult coho salmon increased at a constant rate, indicating additional capacity 15 years post‐restoration. Salmonid compositional diversity, driven largely by juvenile coho salmon, also increased nonlinearly, plateauing in a decade. We observed substantial spatial variation in the temporal response, as juvenile coho salmon and mountain whitefish population expansion slowed linearly with upstream distance from the restoration site. There was evidence that some of the annual variation in salmonid biomass in summer was a result of discharge variability in winter and spring, with biomass declining as flow variability increased. Species reintroduction and establishment had no discernible effect on stream‐rearing salmonids living above the dam before restoration, while increasing coho freshwater productivity at the subbasin scale. Results from our study showed recolonization by three mobile species, each with a unique life history, takes at least a decade or more and was dependent on species and life stage, size of the spawning population, distance from restoration site, and annual variability in streamflow. [ABSTRACT FROM AUTHOR]

Question: Natural areas are commonly managed for multiple purposes, including both conservation and recreational use. Hiking trails are an extremely common feature in natural areas that enable recreational use, but trail construction and use can also facilitate the spread of non‐native species by altering trailside conditions, creating disturbances, and acting as a conduit for non‐native propagules to be carried into the backcountry. Location: Powdermill Nature Reserve, Southwestern Pennsylvania, USA. Methods: We tested how distance from trailhead and trailside affected the understory plant cover and abundance and light and soil environment by establishing study plots at varying distances from the trailhead along perpendicular transects from the trailside. Results: We found that non‐native plant cover decreased with distance from the trailhead, with the majority occurring within 1 km of the trailhead, while non‐native cover increased by as much as 12% moving away from the trailside and toward the forest interior. Total species richness and diversity decreased with increasing distance from the trailhead and per‐species mean cover increased. Total cover decreased in plots with higher light levels. Conclusions: Our results suggest that hiking trails could be acting as a conduit for the spread of non‐native plants, with the greatest effect occurring near the trailhead where early detection and future management efforts could be concentrated. The measurable increase in non‐native cover moving away from the trailside is potentially a result of trails being constructed in an already‐invaded forest, with the effects of trail construction or active management reducing non‐native cover at the immediate trailside.Our study of non‐native species spread along recreational trails in a nature reserve in southwestern Pennsylvania found that non‐native cover was highest near the trailhead, but also higher in the forest interior than at the immediate trailside. We hypothesize that this unexpected result is due to active management of non‐native species by trail users. [ABSTRACT FROM AUTHOR]

Premise: Root‐sprouting (RS) is an evolutionarily independent alternative to axillary stem branching for a plant to attain its architecture. Root‐sprouting plants are better adapted to disturbance than non‐RS plants, and their vigor is frequently boosted by biomass removal. Nevertheless, RS plants are rarer than plants that are not root‐sprouters, possibly because they must overcome developmental barriers such as intrinsic phytohormonal balance or because RS ability is conditioned by injury to the plant body. The objective of this study was to identify whether phytohormones or injury enable RS. Methods: In a greenhouse experiment, growth variables, root respiration, and phytohormones were analyzed in two closely related clonal herbs that differ in RS ability (spontaneously RS Inula britannica and rhizomatous non‐RS I. salicina) with and without severe biomass removal. Results: As previously reported, I. britannica is a root‐sprouter, but injury did not boost its RS ability. Root respiration did not differ between the two species and decreased continuously with time irrespectively of injury, but their phytohormone profiles differed significantly. In RS species, the auxins‐to‐cytokinins ratio was low, and injury further decreased it. Conclusions: This first attempt to test drivers behind different plant growth forms suggests that intrinsic phytohormone regulation, especially the auxins‐to‐cytokinins ratio, might be behind RS ability. Injury, causing a phytohormonal imbalance, seems to be less important in spontaneously RS species than expected for RS species in general. [ABSTRACT FROM AUTHOR]

Restoration is the human activity of manipulating vegetation with the aim of accelerating attainment of stable vegetation. But current procedures seem to arrest succession instead. A comparison of primary and secondary successions with restoration activities suggests there is little overlap in these concepts. Thinking of the process of restoration as a tertiary succession helps highlight managerial options which may improve success, especially by addressing environmental and biological legacies. [ABSTRACT FROM AUTHOR]

Disturbed (de‐vegetated) coastal dunes can follow divergent evolutionary pathways, evolving to one of a range of possible morphologies in response to spatial and temporal variations in windiness (i.e. the speed and direction of competent winds) or vegetation cover (i.e. the magnitude and rate of vegetation loss). Here we examine the influence of these factors on the evolution of two adjacent barriers during a sustained dune restoration programme, at Doughboy Bay, Aotearoa/New Zealand. We document a shift from a stable prograded foredune barrier to a mobile dune state over a 15‐year period. The spatial and temporal patterns of sedimentation across the barriers reflect alongshore variations in incident wind direction. Changes in vegetation resulted from an alongshore gradient in wind speed, with little decline in vegetation cover recorded towards the more sheltered sections of the dunes and almost total loss of vegetation towards the centre of the bay. Subsequent changes in vegetation cover continued to reflect these gradients in wind speed and direction, with an increase in vegetation cover associated with relatively sheltered sections of coast and a continued decline or no change in vegetation cover across the more exposed parts of the barriers. Finally, localized sediment accumulation across both barriers is strongly associated with the presence of dune‐building species. This case demonstrates the influence of wind speed, wind direction and vegetation on post‐disturbance foredune morphologies and barrier development. We propose a three‐stage conceptual model of barrier evolution consistent with existing biogeomorphic disturbance models: (1) an initial 'reaction' phase, characterized by high vegetation cover and relatively little topographic change; (2) an 'activation' phase, characterized by low vegetation cover and rapid rates of topographic change; and (3) a 'stabilization' phase, characterized by increasing vegetation cover and topographic stability. Dune restoration interventions of this type would clearly benefit from an analysis of incident wind conditions prior to commencement and careful consideration of where and how to reintroduce native sand‐binding species. [ABSTRACT FROM AUTHOR]

Increasing demand for river water now conflicts with an increasing desire to maintain riparian ecosystems. Efficiently managing river flows for riparian vegetation requires an understanding of the time scale of flow effects, but this information is limited by the absence of long‐term studies of vegetation change in response to flow variation. To investigate the influence of short‐ and long‐term flow variability and dam operation on riparian vegetation, we determined the occurrence of 107 plant species in 133 permanent plots of known inundating discharge along the Gunnison River in Colorado on five different occasions between 1990 and 2013. Individual species moved up and down the gradient of inundating discharge coincident with increases and decreases in mean annual flow, and the correlations between flow and species occurrence were strongest when flows were weighted by time before vegetation sampling with a median half‐life of 1.5 years. Some tall, rhizomatous, perennial species, however, responded to flows on a longer time scale. Logistic regression of species occurrence showed a significant relation with inundation duration for 70 out of 107 species. Plot species richness and total vegetative cover decreased in association with desiccation at low inundation durations and with fluvial disturbance at high inundation durations. Within‐plot similarity in species occurrence between years decreased strongly with increasing inundation duration. Moderate inundation durations were dominated by tall, rhizomatous, perennial herbs, including invasive Phalaris arundinacea (reed canary grass). Over the 23‐year study period, species richness declined, and the proportion of rhizomatous perennials increased, consistent with the hypothesis that decreases in flow peaks and increases in low flows caused by flow regulation have decreased establishment opportunities for disturbance‐dependent species. In summary, annual‐scale changes in vegetation were strongly influenced by flow variation, and decadal‐scale changes were influenced by decreases in fluvial disturbance from upstream flow regulation beginning decades prior to the onset of this study. [ABSTRACT FROM AUTHOR]

In the United States, national chemical water quality criteria for the protection of aquatic life assume that aquatic ecosystems have sufficient resiliency to recover from criteria exceedences occurring up to once every 3 years. This resiliency assumption was critically reviewed through two approaches: (1) synthesis of case studies, and (2) population modeling. The population modeling examined differences in recovery of species with widely different life histories. One invertebrate (Hyalella azteca) and four fish species were modeled (fathead minnow, brook trout, lake trout, and shortnose sturgeon) with various disturbance magnitudes and intervals. The synthesis of ecosystem case studies showed generally faster recoveries for insect communities rather than fish, and recoveries from pulse (acute) disturbances were often faster than recoveries from press (chronic) disturbances. When the recovery dataset excluded severe disturbances that seemed unrepresentative of common facility discharge upsets that might cause criteria exceedences, the median recovery time was 1 year, 81% of the cases were considered recovered within 3 years, and 95% were considered recovered within 10 years. The modeling projected that short‐lived fish species with high recovery times could thrive despite enduring 50% mortality disturbances every other year. However, long‐lived fish species had longer recovery times and declined under the one disturbance every 3 years scenario. Overall, the analyses did not refute the long‐standing judgements that 3 years is generally sufficient for recovery from nonrepetitive, moderate intensity disturbances of a magnitude up to 2× the chronic criteria in waters without other pollution sources or stresses. However, these constraints may not always be met and if long‐lived fish species are a concern, longer return intervals such as 5–10 years could be indicated. Environ Toxicol Chem 2022;41:2887–2910. Published 2022. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Some three‐species motifs (unique patterns of interactions between three species) are both more stable when modelled in isolation and over‐represented in empirical food webs. This suggests that these motifs may reduce extinction risk for species participating in them, ultimately stabilising the food web as a whole. We test whether a species' time to extinction following a perturbation is related to its participation in stable and unstable motifs and assess how motif roles co‐vary with a species' degree or trophic level. We found that species' motif roles are related to their times to extinction following a disturbance. Specifically, having a larger proportion of the motif role made up by the omnivory motif was associated with longer times to extinction, even though the omnivory motif is less stable than the others when modelled in isolation. While motif roles were associated with extinction risk, they also varied strongly with degree and trophic level. This means that these simpler measures of a species' role may be sufficient to roughly predict which species are most vulnerable to disturbance (though motif roles can be used to refine these predictions), but that studies of species' motif participation can also reasonably comment on vulnerability to extinction. [ABSTRACT FROM AUTHOR]

The migration phase of birds is divided into two main states: stopovers and actual migratory flights. For soaring birds, such as storks, nighttime is especially important to conserve energy and to start the next day in favourable weather conditions. Although there is a large number of recent studies on white stork Ciconia ciconia, for example using advanced technologies such as GPS technology, the nocturnal behaviour of the species is still an enigma. Thus, we GSM–GPS‐tagged 90 immature storks and checked their nocturnal behaviour, especially roost disturbance, during their first autumn migration from breeding grounds in southern Poland to wintering places in Africa. Storks roosted on three types of site: on buildings, on the ground or in trees. Birds that roosted on the ground had a higher probability of nighttime disturbance than those that used trees or buildings. The probability of disturbance at night was also related to longitude and latitude; the most easterly birds and those at the start of the migration route were disturbed more often during the night. Furthermore, and interestingly, environmental conditions at roosts were also significantly related to the probability of disturbance; birds roosting at tree sites with higher NDVI (greener) and with higher levels of artificial light both had a lower probability of disturbance. A possible explanation of this could be related to lower potential predatory pressure at night. We found that after long flights birds were disturbed more often at night, and that disturbed birds migrated further the next day. For a better understanding of the nocturnal behaviour of storks, as well as of other migratory birds, the use of modern technological tools with greater precision is recommended. [ABSTRACT FROM AUTHOR]

Weed seed predation (WSP) is an important agro‐ecosystem service that naturally suppresses weed populations. Disturbances directly interfere with the activity of the seed predators, for example, harvest and soil tillage during a peak in weed seed availability (around cereal harvest). Plant soil cover and reduced soil tillage are factors that might positively affect WSP. We investigated cover crops and living mulch along with soil disturbance (no‐till and conventional seeding) in comparison to a fallow and repeated stubble tillage with a chisel plough in terms of WSP, activity‐density of carabid beetles and soil cover. A field experiment with a randomised complete block design and four replications was conducted at two sites from 2017 until 2019. WSP rates were assessed with seed cards and exclosure cages from July until November during a period of eight consecutive days each month. Living mulch exhibited the highest WSP rates of 72% with a maximum of 95% immediately following cereal harvest in August and September of 2017 and 2019, while the remainder of the treatments ranged from 2% to 5% WSP. In October and November mustard showed on average twice as high WSP rates compared to the other treatments (50% vs. 10%–25%). Seeding and soil tillage did not significantly influence carabid beetle activity‐density and WSP, except for living mulch. Predator groups (invertebrates and vertebrates) were not influenced by the various treatments, rather year and month determined the predator groups dominance. Besides their weed suppressive effects, living mulches and cover crops also facilitate WSP. [ABSTRACT FROM AUTHOR]

The COVID‐19 pandemic transformed social and economic systems globally, including fisheries systems. Decreases in seafood demand, supply chain disruptions, and public safety regulations required numerous adaptations to maintain the livelihoods and social resilience of fishing communities. Surveys, interviews, and focus groups were undertaken to assess impacts from and adaptive responses to the pandemic in commercial fisheries in five U.S. regions: the Northeast, California, Alaska, the U.S. Caribbean, and the Pacific Islands. Fishery adaptation strategies were categorized using the Resist–Accept–Direct (RAD) framework, a novel application to understand social transformation in a social‐ecological system in response to a disturbance. A number of innovations emerged, or were facilitated, that could improve the fisheries' resilience to future disruptions. Fishers with diversified options and strategic flexibility generally fared better, i.e., had fewer disruptions to their livelihoods. Using the RAD framework to identify adaptation strategies from fishery system actors highlights opportunities for improving resilience of fisheries social‐ecological systems to future stressors. [ABSTRACT FROM AUTHOR]

Ecologists have long debated the relative importance of biotic interactions versus species‐specific habitat preferences in shaping patterns of ecological dominance. In western North America, cycles of fire disturbance are marked by transitions between North American deermice (Peromyscus maniculatus), which predominate after wildfires, and southern red‐backed voles (Myodes gapperi), which gradually replace deermice 3–4 years postfire and maintain dominance as forests mature. While this shift has been frequently documented, the processes that mediate this turnover are debated. One possibility is competitive release, which predicts a reduction in vole competition may contribute to niche expansion and population growth in deermice. Alternatively, turnover in both species may be shaped by differences in their preferred habitat and resource base, as predicted by optimum foraging theory. We evaluate these hypotheses using stable isotopes and spatial mark–recapture of deermouse and vole populations sampled prior to and following a fire as part of a longitudinal study in the Greater Yellowstone Ecosystem. Fire disturbance was associated with a 94% decrease in vole abundance but a 102% increase in deermice. Even after accounting for microhabitat, vole and deermouse populations were negatively correlated spatially and temporally (R = −0.45), and competitor abundance was more important prefire than postfire. When vole abundance was high (prefire), vole dietary niche space was seven times broader than that of deermice. Postfire, deermouse dietary niche nearly tripled and was enriched in 13C (i.e., more C4 plants), while voles occupied a slightly reduced dietary niche (79% of prefire breadth). Our results suggest deermice are experiencing ecological release due to a reduction in vole competition but vole shifts are largely driven by habitat preferences. [ABSTRACT FROM AUTHOR]

Mountain birch forest covers large areas in Eurasia, and their ecological resilience provides important ecosystem services to human societies. This study describes long‐term stand dynamics based on permanent plots in the upper mountain birch belt in SE Norway. We also present forest line changes over a period of 70 years. Inventories were conducted in 1931, 1953, and 2007. Overall, there were small changes from 1931 up to 1953 followed by a marked increase in biomass and dominant height of mountain birch throughout the period from 1953 to 2007. In addition, the biomass of spruce (Picea abies) and the number of plots with spruce present doubled. The high mortality rate of larger birch stems and large recruitment by sprouting since the 1960s reveal recurrent rejuvenation events after the earlier outbreak of the autumnal moth (Epirrita autumnata). Our results demonstrate both a high stem turnover in mountain birch and a great ability to recover after disturbances. This trend is interpreted as regrowth after a moth attack, but also long‐term and time‐lagged responses due to slightly improved growth conditions. An advance of the mountain birch forest line by 0.71 m year−1 from 1937 to 2007 was documented, resulting in a total reduction of the alpine area by 12%. Most of the changes in the forest line seem to have taken place after 1960. Regarding silviculture methods in mountain birch, a dimension cutting of larger birch trees with a cutting interval of c. 60 years seems to be a sustainable alternative for mimicking natural processes. [ABSTRACT FROM AUTHOR]

Maintaining ecosystem processes within patches of remnant vegetation is critical to minimising biodiversity loss in agricultural landscapes. Foundation species—habitat‐forming organisms that interact with many other species—are therefore a priority for conservation and restoration in farming areas. Triodia spp. grasses are foundation species of arid and semi‐arid Australia that largely depend on fire for recruitment, but fire is suppressed or excluded in many agricultural areas.We tested the effectiveness of controlled burns and competitor removal (exotic and native grasses), both in isolation and combined, on recruitment rates of Triodia scariosa in remnant vegetation using a before‐after, control‐impact study across 126 plots. A subset of plots were located in an herbivore exclusion area inside a reserve.There was no recruitment of T. scariosa 1 year after burning, regardless of treatment or control, and the burns killed all existing plants. However, T. scariosa germinated by 2 years post‐burn, with the greatest recruitment in sites where both burning and grass removal were applied. Two years after burning, T. scariosa abundance (adults and recruits) remained low outside reserves, but returned to original levels in reserves and in areas where large herbivores were excluded.Synthesis and applications. Despite failing to increase overall abundance, we show that restoration of a foundation plant species in degraded, agricultural landscapes can be achieved through a combination of fire reintroduction and competitor suppression. Germination trials from soil samples suggest a depleted seed bank limited recruitment rates, and therefore emphasise the importance of carefully timing restoration actions to overcome recruitment bottlenecks. [ABSTRACT FROM AUTHOR]

Aims: Plant species' distribution ranges are expected to shift towards previously uncolonized locations in response to climate warming. Mountain trails, which often access to areas of special ecological value as well as remote and climatically extreme locations, could influence such shifts through changes in dispersal and disturbance. Trails may facilitate the dispersal of propagules to new locations, influence the seed bank by changing propagule input and persistence and change establishment success through the creation of gaps and disruption of biotic interactions. However, knowledge regarding the influence of mountain trails on seed rain, seed bank abundance and seedling emergence in alpine ecosystems is lacking. In this study, we examine the influence of hiking trails on dispersal patterns in mountain ecosystems. Location: Dovrefjell, Scandes mountains, Norway. Methods: We surveyed seed rain, seed bank abundance and seedling emergence along four hiking trails spanning climate gradients with a mean 2.5°C difference between warmest and coldest location at four elevations per trail and at 0.5, 7 and 17 m from the trail (48 plots, in 16 transects). Results: Seed rain was 3.4 times higher in trailside plots than in those 17 m away and declined with colder climate at all distances from trails. Seed bank abundance on trailsides at the warmest location was eight times higher than in plots at 17 m distance, while there was no significant difference at colder locations. Seedling establishment was disturbance‐driven along the whole climate gradient, with 3.5 times more seedlings on trailsides than at 17 m distance. Conclusion: Mountain trails have the potential to facilitate vegetation shifts by capturing more seed rain and creating opportunities for seedling establishment. Our findings highlight the importance of including trail effects in studies of vegetation shifts. [ABSTRACT FROM AUTHOR]

Situated in the coral triangle, the Philippines hosts some of the world's most diverse coral reefs. Yet there are few national marine protected areas (MPAs) in place that coincide with these reefs. Municipal MPAs partially alleviate this issue but a controlled comparison of the effects of different small‐scale management strategies on coral reefs is lacking.Danjugan Island Marine Reserve and Sanctuaries (DIMRS) is one of these community‐based MPAs that encompasses a collection of small (0.3–0.34 km2) marine reserves situated in a larger MPA where fishing is regulated through permits. The unique juxtaposition of different management strategies within DIMRS was used as a model system to test whether reserves are better for corals than limited fishing permits by comparing ecosystem indicators (coral cover, bleaching, disease, and morphological diversity).Total and live hard corals were 169% and 204% more abundant inside than outside no‐take zones in 2016. This distinction increased between 2002 and 2016 as a result of a more marked decrease in coral cover over time in the partially protected zones. A 70% higher coral community evenness outside the reserves further suggests that scleractinian coral communities on fished reefs are more disturbed.Live coral cover within the MPAs of DIMRS in 2016 (39 ± 4%) is above the current mean for Philippine reefs (23%) and is comparable with the long‐term average for reefs situated within Philippine MPAs (36%). This study suggests that exceptionally small reserves may benefit hard corals more than regulation via fishing permits. [ABSTRACT FROM AUTHOR]

Aim: The presence and use of trails may change plant species' realized climatic niches via modified abiotic and biotic conditions including propagule transport, allowing competition‐pressed alpine species to expand their rear edges towards warmer locations and lowland species to extend their leading edges towards cooler locations. We investigated whether mountain trails indeed act as corridors for colonization and shift species' realized climatic niches, resulting in higher species richness in trailsides. Location: Dovrefjell and Abisko area in the Scandes mountains of Norway and Sweden. Methods: We surveyed plant community composition and disturbances along 16 hiking trails in summer 2018 (Dovrefjell) and 2019 (Abisko). We linked changes in species' realized climatic niches to their climatic optimum and variation in species richness to climate, trail effects and resident plant community characteristics. Results: Plant species richness was on average 24% greater in trailside than in interior vegetation plots. Proximity to trails accounted for 9% and climatic harshness for 55% of variation in species richness explained in our model. Trailsides increased in richness, especially in relatively species‐poor sites and close to introduction points (each accounting for 24% of variation in our model of species gains). Shifts in rear edges and optima of realized climatic niches along trails related to species' undisturbed climatic optimum, with alpine species being more likely to move into warmer locations. While some disturbance‐associated species shifted their leading edges towards colder locations, contrary to expectations this was not the case for lowland species. Overall, shifts in climatic niches resulted in more species' niches overlapping in trailsides than in the interior vegetation. Main conclusion: Trails can locally increase species richness by creating opportunities for colonizing species and weaker competitors. Because of prevailing disturbance, they may even provide opportunities for persistence and downward expansion of alpine species, aiding conservation efforts. [ABSTRACT FROM AUTHOR]