Dynamics Of Ecological Systems Research Articles

Stoichiometric and Accumulation Characteristics of Nitrogen and Phosphorus in Artificial and Natural Herbaceous Plants along Lakeshore Buffer Zone

Lakeshore buffer zones serve as transitional areas between terrestrial and aquatic ecosystems, playing a crucial role in intercepting non-point source pollutants, purifying river and lake water, and maintaining ecological system dynamics. This study focuses on the vegetation of the lakeshore buffer zone in Songhua Lake, the largest artificial lake in Northeast China. The nitrogen (N) and phosphorus (P) pollutant contents and accumulation characteristics of herbaceous plants were investigated and analyzed in different regions and with different species. The study results indicate that there were no significant differences in N and P content, N: P ratio, and average accumulation among vegetation in the near-water, middle, and far lakeshores of the buffer area. The herbaceous plants with the highest N and P content and N: P ratios were Artemisia sieversiana, Sium suave, and Artemisia sieversiana, respectively. Purus frumentum planted in the middle lakeshore accumulated the highest amounts of N and P, reaching 87.97 g plant−1 and 3.86 g plant−1, respectively. The aboveground parts of plants showed significantly higher accumulation of N and P compared to the underground parts. The average enrichment coefficient for aboveground parts and underground parts for N were 4.83 and 4.35, respectively, all exceeding 1. However, their capability to enrich P was relatively weak, with only the aboveground parts of F − 3 showing some enrichment ability. Among herbaceous plants, Artemisia sieversiana and Sium suave exhibited the strongest capability for transporting N and P from underground to aboveground. Overall, harvesting aboveground biomass for the ecological removal of N and P in the study area appears feasible. Biomass is a critical factor influencing the nutrient interception capacity of vegetation, with Purus frumentum identified as an optimal restoration plant for sustainable management practices, and Artemisia sieversiana and Sium suave have the potential for rapid remediation.

Post-Colonial Ecocritical Dynamics in Ghosh's The Hungry Tide

The dynamics of ecological systems of the bioregion i.e., the Sundarbans of the Bay of Bengal dominates the novel 'The Hungry Tide' by Amitav Ghosh. Here, I analyze how the text destabilizes and subverts the Universalist claim of Western superiority based on false dichotomy between nature and culture by applying postcolonial eco-critical insights. The basic tenet of postcolonial ecocriticism is that social injustice is embedded in the injustice of nature and it sees equity in both by rejecting Universalist claims of Eurocentrism which sees nature and local communities as resources. To prove the claim, the researcher has gone through theoretical critical insight of Graham Huggan and Helen Tiffin who talk about postcolonial ecocriticism. Besides, the researcher also used the eco-critical insight as per the need of the paper. The qualitative interpretative research is based on the textual analysis of the primary text applying the postcolonial eco-critical insights. The paper concludes that social inequality and injustice in nature must be eradicated so as to liberate both.

Tracking states and transitions in semiarid rangelands: A spatiotemporal archetypal analysis of productivity dynamics using wavelets

Climate change poses challenges in classifying ecosystem dynamics, as they are influenced by shifting dynamics resulting from changes in climate forces and meteorological variables, including temperature and water availability. To address this, our study presents a novel approach using Continuous Wavelet Transform (CWT) and power spectrum analysis to classify vegetation dynamics, considering the time-dependent variability of ecosystem frequencies. We applied our method to centred and standardized MODIS NDVI time series for the period 2000–2021, using an experimental field station in northern Patagonia as a case study. By performing a continuous wavelet transform on the data for each pixel, we obtained instantaneous power spectra, capturing variability across different dates and pixels. These spectrums were then consolidated into a comprehensive database, and subsequently classified using archetypal analysis. We identified a convex combination of archetypal spectrums that best represented the entire power spectrum database. Mapping the resulting archetypes and their weights in both space and time allowed us to explore pixels' variations in archetype weights in relation to factors such as time, topography, and climate. In addition, to examine the potential relationship between the NDVI time series and climate drivers, we computed the Average Cross-Wavelet Power Spectrum (ACWPS) to different climatic indices. Three archetypes were sufficient to explain the majority of power spectrum variability in the study area. These archetypes exhibited distinctive characteristics: 1) medium-frequency variability (2–4 years), 2) low-frequency variability (>4 years), and 3) an annual (i.e. seasonal) cycle with low-frequency variability. Spatially, the first two archetypes were predominantly observed in highland steppes, while the third archetype prevailed in lowland areas associated with meadows. At the beginning of the studied period, Archetypes 1 and 3 dominated, but after the Puyehue-Cordón Caulle Volcanic Complex eruption in 2011 their prominence diminished, and Archetype 2 became more prevalent in the whole study area. Finally, all three NDVI series representative of archetypes showed a relative peak at approximately four years, which could be linked to the Indian Ocean Dipole variability. These results highlight an abrupt shift in the system's behaviour, primarily related to changes in variability distribution rather than mean values. This disturbance-induced transition aligns with the theory of state and transitions in ecological system dynamics. We propose that the states in this model are not fixed but represent alternative dynamic behaviours, akin to different types of limit cycles. Consequently, employing a wavelet analysis-based classification method provides a robust means of studying and understanding such variability and transitions, thereby offering clarity and comprehension of ecosystem states. Notably, this methodology proves particularly effective for large databases of detailed time series.

ORTEGA v1.0: an open-source Python package for context-aware interaction analysis using movement data

BackgroundInteraction analysis via movement in space and time contributes to understanding social relationships among individuals and their dynamics in ecological systems. While there is an exciting growth in research in computational methods for interaction analysis using movement data, there remain challenges regarding reproducibility and replicability of the existing approaches. The current movement interaction analysis tools are often less accessible or tested for broader use in ecological research.ResultsTo address these challenges, this paper presents ORTEGA, an Object-oRiented TimE-Geographic Analytical tool, as an open-source Python package for analyzing potential interactions between pairs of moving entities based on the observation of their movement. ORTEGA is developed based on one of the newly emerged time-geographic approaches for quantifying space-time interaction patterns among animals. A case study is presented to demonstrate and evaluate the functionalities of ORTEGA in tracing dynamic interaction patterns in animal movement data. Besides making the analytical code and data freely available to the community, the developed package also offers an extension of the existing theoretical development of ORTEGA for incorporating a context-aware ability to inform interaction analysis.ConclusionsORTEGA contributes two significant capabilities: (1) the functions to identify potential interactions (e.g., encounters, concurrent interactions, delayed interactions) from movement data of two or more entities using a time-geographic-based approach; and (2) the capacity to compute attributes of potential interaction events including start time, end time, interaction duration, and difference in movement parameters such as speed and moving direction, and also contextualize the identified potential interaction events.

Stability and bifurcation analysis of a discrete-time plant-herbivore model with harvesting effect

<abstract><p>The dynamics of plant-herbivore interactions are essential for understanding ecosystem stability and resilience. This article investigated the effects of incorporating a harvesting effect on the dynamics of a discrete-time plant-herbivore system. An analysis was performed to determine the existence and stability of fixed points. In addition, studies have shown that the system experienced transcritical, period-doubling, and Neimark-Sacker bifurcations. Moreover, we provided numerical simulations to substantiate our theoretical results. Our research indicated that harvesting in excessive amounts may have negative effects on the populations of both plants and herbivores. However, when harvesting was done at moderate levels, it promoted the coexistence and stability of both populations. The findings of our analysis provided a deep understanding of the intricate dynamics of ecological systems and underscored the need to use sustainable harvesting methods for the management and preservation of ecosystems.</p></abstract>

A Time for Every Purpose: Using Time-Dependent Sensitivity Analysis to Help Understand and Manage Dynamic Ecological Systems.

AbstractSensitivity analysis is often used to help understand and manage ecological systems by assessing how a constant change in vital rates or other model parameters might affect the management outcome. This allows the manager to identify the most favorable course of action. However, realistic changes are often localized in time-for example, a short period of culling leads to a temporary increase in the mortality rate over the period. Hence, knowing when to act may be just as important as knowing what to act on. In this article, we introduce the method of time-dependent sensitivity analysis (TDSA) that simultaneously addresses both questions. We illustrate TDSA using three case studies: transient dynamics in static disease transmission networks, disease dynamics in a reservoir species with seasonal life history events, and endogenously driven population cycles in herbivorous invertebrate forest pests. We demonstrate how TDSA often provides useful biological insights, which are understandable on hindsight but would not have been easily discovered without the help of TDSA. However, as a caution, we also show how TDSA can produce results that mainly reflect uncertain modeling choices and are therefore potentially misleading. We provide guidelines to help users maximize the utility of TDSA while avoiding pitfalls.

Spatial patterns through diffusion-driven instability in modified predator–prey models with chaotic behaviors

Understanding the connection between spatial patterns in population densities and ecological heterogeneity is significant to the understanding of population dynamics and the governance of species in a given domain. In this paper, the spatiotemporal complexity of prey–predator dynamics with fractional Laplacian derivative and migration is investigated. To provide good guidelines on the choice of parameters, the linear stability analysis of the models was investigated. The fractional Laplacian operator was defined in terms of the left- and right-handed Riemann–Liouville derivative which in turn were approximated by using the fourth-order compact difference scheme, and the resulting system of ODEs was advanced in time using the fourth-order exponential time-differencing Runge–Kutta method. In the simulation experiments, different Turing dynamics such as spots, stripes, and other chaotic patterns are observed. Overall, pattern formation in predator–prey models is useful for understanding the dynamics of ecological systems, predicting the long-term behavior of the system, and studying the impact of environmental factors on the dynamics of the system.

Signs of Life and Death: The Semiotic Self-Destruction of the Biosphere

This article applies some conceptual tools from semiotics to better understand the disastrous impacts of the world economy on global ecology. It traces the accelerating production of material disorder and waste to the logic of the money sign, as economic production processes simultaneously increase exchange-values and entropy. The exchange of indexical and iconic signs is essential to the dynamics of ecological systems and the proliferation of biological diversity. The human species has added a third kind of sign, the symbol, and more recently a fourth: all-purpose money. Money does not refer to any referent either through contiguity, similarity, or convention. It is an empty sign, capable of assuming any significance that its owner attributes to it. The article argues that the concept of symbolic reference should be restricted to cultural and linguistic phenomena. Money qualifies as a new species of sign based on its exceedingly open mode of reference. It does not refer to any object by social convention but owes its specific properties precisely to the absence of such conventions. The logic of money pivots on decontextualisation: it presupposes and encourages the detachment of exchange values, people, and concepts from the particular and the local. Selective advantage is no longer primarily about calibration within local contexts, but increasingly a matter of transcending or emancipating oneself from the specific. This drift toward decontextualisation reverses the evolution of complexity and diversity throughout the planetary biosphere.

Temporal resolution of birth rate analysis in zooplankton and its implications for identifying strong interactions in ecology.

Expanding on Haeckel's classical definition, ecology can be defined as the study of strong and weak interactions between the organism and the environment, hence the need for identifying strong interactions as major drivers of population and community dynamics. The solution to this problem is facilitated by the fact that the frequency distribution of interaction strengths is highly skewed, resulting in few or, according to Liebig's law of the minimum, just one strong interaction. However, a single strong interaction often remains elusive. One of the reasons may be that, due to the ever-present dynamics of ecological systems, a single strong interaction is likely to exist only on relatively short time intervals, so methods with sufficient temporal resolution are required. In this paper, we study the temporal resolution of contribution analysis of birth rate in zooplankton, a method to assess the relative strength of bottom-up (food) versus top-down (predation) effects. Birth rate is estimated by the Edmondson-Paloheimo model. Our test system is a population of the cladoceran Bosmina longirostris inhabiting a small northern lake with few planktivorous predators, and thus likely controlled by food. We find that the method's temporal resolution in detecting bottom-up effects corresponds well to the species' generation time, and the latter seems comparable to the lifetime of a single strong interaction. This enables one to capture a single strong interaction "on the fly," right during its time of existence. We suggest that this feature, the temporal resolution of about the lifetime of a single strong interaction, may be a generally desirable property for any method, not only the one studied here, intended to identify and assess strong interactions. Success in disentangling strong interactions in ecological communities, and thus solving one of the key issues in ecology, may critically depend on the temporal resolution of the methods used.

Centering the Margins: Dynamic Systems, Targeted Universalism, and Special Education

This commentary outlines the potential benefits of applying advances in the science of learning and development to special education service delivery and research. Building from a dynamic ecological systems perspective of development, it is argued that special education should focus on the whole child in context to leverage the correlated contributions of multiple factors in the learning and development of students with disabilities. The concept of targeted universalism is presented as a framework for creating universal service delivery structures that are centered on tailoring supports to the daily experiences and functioning of students who receive special education. Person-oriented analysis and longitudinal, idiographic designs are considered as an approach to guide the development and evaluation of such frameworks.

Rethinking Estuary Urbanism—Preparing Australian Estuary Cities for Changes to Come in the Climate and Biodiversity Emergency

This research investigates the challenges and opportunities of urban estuaries exposed to spatial, urban, and environmental shifts exacerbated by climate change, ecological disturbances, and population growth, taking the cities of Perth, Western Australia and Newcastle, New South Wales, as case studies. Approaching the design of estuary cities in the Climate Century demands a form of estuary urbanism and new paradigms in design, which embrace the constant presence of water. Water becomes the instrument of change to re-think the design of the city and its relationship with the non-built environment since the climate crisis is also a water crisis. Adaptation and mitigation strategies are still emerging fields in design and planning disciplines. Design disciplines can strongly contribute to generating site-specific climate-adaptative responses while re-establishing the connection between built and natural environments, improving ecological balance and spatial quality, and promoting well-being and cultural values. The methodology involves both analytical and projective-explorative methods promoting a site-specific approach, working across scales and disciplines to understand urban estuaries within larger catchments and as complex hydrological and ecological systems. A fundamental goal is the creation of site-specific design strategies to operate in low to medium-density precincts, leveraging water and nature as design tools to improve urban resilience and liveability. There is capacity here to establish design methods and principles that inform future practices through urbanism responding to dynamic ecological and water systems and the unpredictability effects of climate change.

Dispersal and plant arrangement condition the timing and magnitude of coffee rust infection

One central issue in coffee-leaf rust (Hemileia vastatrix) epidemiology is to understand what determines the intensity and the timing of yearly infections in coffee plantations. However, most experimental and theoretical studies report infection as an average at the plot level, obscuring the role of potentially key factors like rust dispersal or the planting pattern. Here, we first review the rust epidemic patterns of different sites, which reveal large variability in the duration and magnitude of the different epidemiologic phases. We then present a spatially explicit and parametrised model, where the host population is subdivided into discrete patches linked through spore dispersal, modeled as simple diffusion. With this model, we study the role of the planting arrangement, the dispersal intensity and plant-level variables on the maximum average tree infection (MATI) and its timing. Our results suggest that the epidemic timeline can be divided into two phases: a time lag and a growth phase per se. The model shows that the combination of the dispersal magnitude and plant aggregation modifies the MATI and the time to MATI, mainly by preventing some plants from reaching their maximum peak during the epidemic. It also affects the epidemic curves, which can have a stepped, or a rather smooth pattern in plots with otherwise similar conditions. The initial rust infection modulates the time lag before the epidemic and the infected leaf-fall rate drastically changes the MATI. These findings highlight the importance of explicitly considering the spatial aspects of coffee agroecosystems when measuring and managing rust infection, and help us to further understand the spatio-temporal dynamics of ecological systems in general.

Partial observability and management of ecological systems.

The actual state of ecological systems is rarely known with certainty, but management actions must often be taken regardless of imperfect measurement (partial observability). Because of the difficulties in accounting for partial observability, it is usually treated in an ad hoc fashion, or simply ignored altogether. Yet incorporating partial observability into decision processes lends a realism that has the potential to improve ecological outcomes significantly. We review frameworks for dealing with partial observability, focusing specifically on dynamic ecological systems with Markovian transitions, i.e., transitions among system states that are influenced by the current system state and management action over time. Fully observable states are represented in an observable Markov decision process (MDP), whereas obscure or hidden states are represented in a partially observable process (POMDP). POMDPs can be seen as a natural extension of observable MDPs. Management under partial observability generalizes the situation for complete observability, by recognizing uncertainty about the system's state and incorporating sequential observations associated with, but not the same as, the states themselves. Decisions that otherwise would depend on the actual state must be based instead on state probability distributions (“belief states”). Partial observability requires adaptation of the entire decision process, including the use of belief states and Bayesian updates, valuation that includes expectations over observations, and optimal strategy that identifies actions for belief states over a continuous belief space. We compare MDPs and POMDPs and highlight POMDP applications to some common ecological problems. We clarify the structure and operations, approaches for finding solutions, and analytic challenges of POMDPs for practicing ecologists. Both observable and partially observable MDPs can use an inductive approach to identify optimal strategies and values, with a considerable increase in mathematical complexity with POMDPs. Better understanding of POMDPs can help decision makers manage imperfectly measured ecological systems more effectively.

Properties in Stage-Structured Population Models with Deterministic and Stochastic Resource Growth

Modelling population dynamics in ecological systems reveals properties that are difficult to find by empirical means, such as the probability that a population will go extinct when it is exposed to harvesting. To study these properties, we use an aquatic ecological system containing one fish species and an underlying resource as our models. In particular, we study a class of stage-structured population systems with and without starvation. In these models, we study the resilience, the recovery potential, and the probability of extinction and show how these properties are affected by different harvesting rates, both in a deterministic and stochastic setting. In the stochastic setting, we develop methods for deriving estimates of these properties. We estimate the expected outcome of emergent population properties in our models, as well as measures of dispersion. In particular, two different approaches for estimating the probability of extinction are developed. We also construct a method to determine the recovery potential of a species that is introduced in a virgin environment.

New method to obtain the acute sill of an ecological model with complex polynomial perturbation

This research aims to highlight and examine an example of ecological complexity. By taking into account the interference between predator and prey, we introduce an ecological system with a general functional response. This model is perturbed by a novel class of fluctuations in the polynomial form. Analytically, we present an alternative method to obtain the acute threshold between stationarity and predator disappearance. Our analysis enriches and improves the work of Zhou et al. (2021) by unifying the criteria of said asymptotic characteristics. Numerically, we audit the accuracy of our threshold in three particular situations: linear, quadratic and cubic perturbations. We establish that the increasing order of disturbance has a passive influence on the extinction time of predators. This finding highlights that complex noise sources have a positive role in the transient dynamics of ecological systems.

Legions of Pigs in the Early Medieval West

Over a millennium ago, images began to appear in Christian church settings—as decorations of holy book covers, within the pages of books, and on church walls—of Jesus exorcizing a multitude of demons, named Legion, from a man into a herd of pigs who then rush into the sea and drown. In using this biblical story to frame the narrative of Legions of Pigs in the Early Medieval West, Jamie Kreiner makes clear the ambiguities of the pig as “both unholy and redemptive, both historically situated and universally relevant” (195). The pigs as Legion and a legion of pigs on farm and field are intertwined.Rather than approaching the history of the pig as only an issue of agricultural production, Kreiner examines it as “a history of the counterintuitive connections that developed between the micro-universes of pig husbandry and early medieval institutions and ideas on a wider scale” (4). She uses the pig as an entry point for thinking through how early medieval people thought about their environment. Her approach is to place the pig within wider social, cultural, and economic contexts of the Late Antique and Early Medieval periods, roughly AD 400 to 1000. While the evidence is focused on Western Europe, particularly the kingdoms of the Carolingians and Ottonians, which occupied large parts of what are today France, Germany, the Low Countries, and northern Italy, and kingdoms on the British Isles, Kreiner deftly weaves in sources from across Europe, stretching to the Islamic lands that were in continuous contact with their Christian counterparts.In her introduction, Kreiner stresses that the flexibility of pigs resulted in dynamic ecological systems in early medieval Europe. Human communities adapted their systems to accommodate pigs, who while potentially highly productive could also be highly unruly. This plays out in chapter 1, which underscores the distinctions medieval people drew between wild boar and domestic pig, the variability of landscapes that swine could be raised on, and attempts to control unwanted pig behaviors.The micro-universe of pig husbandry is then set within the much larger context of medieval philosophy in chapter 2. In this chapter, pigs scarcely appear—and yet the chapter puts the pig and its Christianization (which is discussed later) into the intellectual context of the age through a highly accessible explanation of medieval notions of environmental connectivity and complexity.Chapter 3 gets back to the pigs and their landscapes. Kreiner approaches swine husbandry as extracting value out of the landscape or, as she calls it, “salvaging.” Through their ability to turn found foods in the environment into food on human tables, pigs made the landscape productive for people. How they did this—by forest foraging, pasture grazing, or stall feeding—varied according to ecological and economic conditions. Kreiner brings together an impressive collection of sources to explain that variability.In chapter 4, the focus is on the assemblage of humans and pigs and the social groups that were created and modified by those relations. The section on swineherds in particular gives a fascinating behind-the-scenes look at the economic and social status of those closest to pigs. She also shows how pork consumption was a Roman tradition, which had both ideological and practical implications, for example in the provisioning of soldiers with pork through taxes. Chapter 5 starts with the pig as Roman animal and then discusses how the pig became associated with Christians, both in symbolic and dietary forms. Kreiner stresses the counterintuitive connections here, as the pig takes on both diabolical natures and Christian conviction. The legions of pigs and Legion in pigs are co-constituted.Kreiner's book is written with non-medievalists in mind—she elucidates time-specific social and legal terms so that they are understandable without a background in the period. She finds just the right balance of using source materials to support her arguments without getting bogged down in details. Her writing style is a delight to read. This book demonstrates how medieval environmental and agricultural history can be written as a history of ideas and culture with wide appeal.

The Kinabalu Recorder, a new passive acoustic and environmental monitoring recorder

Abstract New low‐cost options to long‐term acoustic monitoring in terrestrial ecology are becoming increasingly available. However, integration of acoustic stations with sensors for logging of additional data, such as temperature and barometric pressure is rare. Separate environmental loggers often come at a cost of >US$100 whereas the same sensors for use with microprocessors come at a cost between US$ 1–15. The cost savings integration entails as well as the crucial need for the recording of some of these variables in acoustic studies mean that this is an important development avenue. Overcoming these issues is important to enable insights into the long‐term dynamics of ecological systems and how they respond to changes in the environment at varying temporal scales and is especially important for studies involving species that are heavily influenced by microclimate. Here we present a hardware system for both acoustic and environmental data logging where the board design is released under a creative commons license. The system has been field tested in a tropical setting and is called the Kinabalu Recorder. The presented configuration came at a cost of <US$100 per station. This cost is for professional manufacture and assembly of the boards, temperature and barometric sensor, two batteries, waterproof housing and two 64 GB micro SD cards. The system has been extensively tested in a tropical setting along an altitude gradient and with over 1.3 TB of data (>2,000 hr of data with over 10 months in the field) presents a robust solution to long‐term acoustic monitoring integrated with environmental data sensors. Work on hardware and software systems is an important part of the technological development of field biology as it allows greater flexibility in terms of cost and configuration of systems whilst promoting cross‐field collaboration and information flow.

Cross-boundary weed management in protected area–centered ecosystems: how can it work and what makes it harder to achieve?

AbstractInvasive species management in natural landscapes is generally executed at the scale of independent jurisdictions, yet the ecological processes and biodiversity to be protected from invasion occur over large spatial scales and across multiple jurisdictions. Jurisdictional land boundaries can influence the flows and dynamics of ecological systems, as well as the social systems that exist in these complex landscapes. Land management entities in large, protected area–centered ecosystems may use different approaches to address cross-boundary management challenges. To understand these differing strategies and their effects on cooperative invasive plant management, we interviewed employees with federal, county, and state agencies, research organizations, nonprofits, and local stakeholder groups in two national parks and their surrounding lands in California, USA. Although all participants stressed the importance of working together, they did so along a continuum of strategies ranging from simple communication to coordination of independent efforts to active collaboration. Barriers to collaboration can be categorized as originating within or externally to the management unit, including limited resources, differing agency priorities, paperwork requirements, and lack of support by higher-level managers. Strategies to reduce barriers depend on where they originate.

Effects of stochasticity on the length and behaviour of ecological transients.

There is a growing recognition that ecological systems can spend extended periods of time far away from an asymptotic state, and that ecological understanding will therefore require a deeper appreciation for how long ecological transients arise. Recent work has defined classes of deterministic mechanisms that can lead to long transients. Given the ubiquity of stochasticity in ecological systems, a similar systematic treatment of transients that includes the influence of stochasticity is important. Stochasticity can of course promote the appearance of transient dynamics by preventing systems from settling permanently near their asymptotic state, but stochasticity also interacts with deterministic features to create qualitatively new dynamics. As such, stochasticity may shorten, extend or fundamentally change a system's transient dynamics. Here, we describe a general framework that is developing for understanding the range of possible outcomes when random processes impact the dynamics of ecological systems over realistic time scales. We emphasize that we can understand the ways in which stochasticity can either extend or reduce the lifetime of transients by studying the interactions between the stochastic and deterministic processes present, and we summarize both the current state of knowledge and avenues for future advances.

Variability effects by consumers exceed their average effects across an environmental gradient of mussel recruitment.

The implicit assumption that properties of natural systems deduced from the average statistics from random samples suffice for understanding them focuses the attention of ecologists on the average effects of processes and responses, and often, to view their variability as noise. Yet, both kinds of effects can drive dynamics of ecological systems and their covariation may confound interpretation. Predation by crabs and snails on competitively dominant mussels has long been recognized as an important process structuring communities on rocky shores of the Northwest Atlantic Ocean. We experimentally manipulated the average intensity of predation in plots across a gradient of mussel recruitment to separately estimate the average and variability of responses of mussel recruitment and community composition. Predation did not affect the average number of mussels recruited to plots, nor the average multivariate composition of the community. Plots from which predators were excluded showed a ~ 30% increase in spatial variability of mussel recruitment. After 1year, the spatial variability in community composition was greater than that observed among plots that predators could access. An important, but less recognized, aspect of predation is its dampening effect on variability of community structure. As accelerating rates of environmental change disrupt species interactions, variability effects of ecological processes and corresponding responses are likely to be increasingly important determinants of community dynamics.