Ecological Complexity最新文献

Early-warning signals of a regime shift (EWS) indicate, for a wide range of systems, if a tipping-point is being approached. In ecology, EWS are well established from a theoretical perspective but are far from unequivocal when applied to field data. The gap between theory and application is caused by a set of limitations, like the lack of coherence between different EWS, data acquisition issues, and false results. Experiments assessing EWS may provide an empirical mechanistic understanding of why an EWS was observed (or failed to be observed), which often cannot be elucidated by simple computational modeling or pure environmental data. Here we focused on aquatic experiments to explore to what extent the existing EWS experiments can bridge the gap between the theory and real-world application. For that, we used the Thomson-ISI Web of Science© database to retrieve EWS experiments executed before early-2020, detailing their experimental designs and each EWS assessed. Success rates - correct anticipation of tipping points – were around 70% for the most used EWS (assessment of autocorrelation, variance, recovery, and shape of the distribution using abundance, Chlorophyll-a, Phycocyanin, and dissolved oxygen data). Yet, no EWS showed to be 100% reliable, and their use demands cautious interpretation. As a rule, we observed that experiments were not designed to tackle issues encountered in real-world situations. They lack a deep mechanistic understanding of why, when, and how an EWS was observed or not. When experiments did aim to assess issues encountered in the real world, the experimental designs were often of low ecological significance. We also investigated the relationship between sampling and the success rate of EWS, observing that the sampling regime might have to be tailor-made towards specific monitoring objectives. Moreover, experiments have taught us that the use of EWS can be more versatile than expected, going from monitoring the extinction of single populations to the anticipation of transient regime shifts. Most of the experiments presented here supported empirical proof of the existence of EWS in aquatic systems. Still, to bridge the gap between theory and application, experiments will have to move closer to real-world conditions and better support a mechanistic understanding of why EWS may succeed or fail to anticipate a regime shift. For that, we provide six elements to take into account when designing experiments that could enhance the capabilities of EWS to go beyond the stage of proof-of-concept.

To deal with real-life diversity of our ecosystem, this paper analyzes two prey-two predator model including both Type-I and Type-II functional responses. The interior equilibrium point of the proposed model is calculated; and behaviour of the model around that point is studied. Local stability at an interior equilibrium point is discussed; and possibility of Hopf-bifurcation with probable direction is studied. A generalized form of the Poincaré-Bendixon criterion is applied to establish the sufficient conditions for global stability of the proposed model surrounding at an interior equilibrium point. Numerical simulations are also conducted in support of our work. Conclusions of our findings and some probable future directions are also included at the end.

Climate change is expected to alter biological phenomena across the world, including the numbers and distributions of species and the timing of significant events in their life cycles such as reproduction and migration. Understanding how species will respond to future climate change is essential for effective wildlife management and conservation. Accordingly, in this research, we advanced the understanding of avian ecology by developing a framework for how climate change affects birds. In the first step, we evaluated the vulnerability of 537 species to climate change based on the distribution, physiology, phenology, biotic interactions, and protection status of the species in Iran. Then, we used MaxEnt models to predict the potential changes in the ranges of vulnerable species due to climate change in the next 70 years. In the third step, hotspots for birds under current and future conditions were identified using an ensemble forecasting framework and the potential changes in the hotspots in the next 70 years were predicted. Results of the climate vulnerability evaluation showed that around 40% of bird species in Iran are highly vulnerable. Our results showed that small parts of suitable habitats are currently located within protected areas. Moreover, the results showed that even smaller portions of suitable habitats will fall within protected areas in the future. The reduced coverage in the future will diminish the benefits of protected areas for the species and make the species more vulnerable to climate change. These results can be used by wildlife managers to identify areas with protection priority, and for prediction of corridors, core habitats, and new areas to establish protected areas in the future.

In the present study, a new neural network-based terminal sliding mode technique is proposed to stabilize and synchronize fractional-order chaotic ecological systems in finite-time. The Chebyshev neural network is implemented to estimate unknown functions of the system. Moreover, through the proposed Chebyshev neural network observer, the effects of external disturbances are fully taken into account. The weights of the Chebyshev neural network observer are adjusted based on adaptive laws. The finite-time convergence of the closed-loop system, which is a new concept for ecological systems, is proven. Then, the dependency of the system on the value of the fractional time derivatives is investigated. Lastly, the proposed control scheme is applied to the fractional-order ecological system. Through numerical simulations, the performance of the developed technique for synchronization and stabilization are assessed and compared with a conventional method. The numerical simulations strongly corroborate the effective performance of the proposed control technique in terms of accuracy, robustness, and convergence time for the unknown nonlinear system in the presence of external disturbances.

Although the quantification and evaluation of ecosystem services has been discussed on the Loess Plateau of China, few studies have specifically focused on quantifying the ecosystem services of trade-off and finding win-win areas. Based on previous studies about the evaluation of ecosystem services, we proposed a comprehensive spatial analysis method based on the InVEST and CASA models to analyse the spatial interaction between the four ecosystem services of water yield, sediment retention, NPP and habitat quality in the study area. The results showed that soil retention, NPP, and habitat quality gradually increased from 2000 to 2010 as water yield increased. Relationships among sediment retention, NPP and habitat quality were synergistic, but trade-off occurred between those three ecosystem services and water yield. Hotspots accounted for 3.27% of the basin, and these areas were mainly located in the downstream area of the basin and coincided with the forest and grassland areas. Coldspots accounted for 3.64% of the basin and were mainly in line with the upstream area and the urban road area in the basin. Win-win areas only accounted for 1.6% of the basin. The existence of win-win zones was positively correlated with soil silt content and was negatively correlated with distance to grassland, distance to forest, soil erodibility and slope. This research may be helpful for managing water resources and the sustainable development of the basin on the Loess Plateau of China.

Although often limited in terms of extent or accuracy, mental models—i.e., explanations of the surrounding world and how things work within it—provide confidence and frameworks to navigate life's uncertainties. Unfortunately, differing and yet similar mental models held collectively by groups can lead to problematic behavior, misunderstandings, and conflict on large scales. Such challenges are likely familiar to natural resource managers who, in the course of their work, must consider issues that are neither simple nor exclusively ecological or social in nature. Building mental models of various groups’ understanding of a complex natural resource may help managers address the impacts of resource-related behaviors but can be a difficult task when collecting modeling data from large and diverse user groups. Using a sequential, exploratory approach, our study addresses the utility of surrogate mental modeling to explore (a) mental models held by key players from six stakeholder groups associated with Utah's Bonneville Salt Flats (US), and (b) whether these key players were confident that their personal subjective models represented their own group's thinking about Bonneville. We sought to illuminate and compare stakeholder groups’ mental models of subjectively important social and ecological concepts related to Bonneville through the use of fuzzy cognitive maps (FCMs; i.e., semi-quantitative representations of mental models) constructed in Mental Modeler. Analysis revealed differences among groups’ FCMs and levels of perceived complexity, as well as areas of agreement regarding the strength, direction, and character of certain social-ecological relationships. Intersections and divergences in stakeholder mental models may provide logical starting points for communal knowledge-building that can perhaps lessen tension among groups attributable to conceptual misunderstandings of resource-specific complexity.

Ecological complex networks are common in the study of patched ecological systems where evolving populations interact within and among the patches. The loss of the dispersal connections between patches due to reasons such as erosion of migration corridors and road construction can cause an undesirable partitioning of such networks resulting in instability or negative impact on the metapopulations. A partitioning or spatial cut that is aware of the stability of the dynamics in the resulting daughter sub-networks can be an effective tool in dealing with the situation like proposing road alignment through a metapopulations network. This paper provides some mathematical conditions along with an heuristic graph partitioning algorithm that can help in finding ecologically suitable partitions of the metapopulations networks. Our study noted the crucial role of network connectivity (measured by Fiedler value) in stabilizing the metapopulations. That is, a sufficiently connected metapopulations network along with constrained internal patch dynamics has stable dynamics around its homogeneous co-existential equilibrium solution. With the considered mathematical model in this paper, network partitioning does not alter the internal patch dynamics around its homogeneous equilibrium point, but it can change the connectivity levels in the partitioned subnetworks. Thus, the proposed partitioning problem for an already stable metapopulations network is reduced to finding its subnetworks with desirable connectivity levels.

The paper is devoted to a compartmental epidemiological model of infection progression in a heterogeneous population which consists of two groups with high disease transmission (HT) and low disease transmission (LT) potentials. Final size and duration of epidemic, the total and current maximal number of infected individuals are estimated depending on the structure of the population. It is shown that with the same basic reproduction number $R_0$ in the beginning of epidemic, its further progression depends on the ratio between the two groups. Therefore, fitting the data in the beginning of epidemic and the determination of $R_0$ are not sufficient to predict its long time behaviour. Available data on the Covid-19 epidemic allows the estimation of the proportion of the HT and LT groups. Estimated structure of the population is used for the investigation of the influence of vaccination on further epidemic development. The result of vaccination strongly depends on the proportion of vaccinated individuals between the two groups. Vaccination of the HT group acts to stop the epidemic and essentially decreases the total number of infected individuals at the end of epidemic and the current maximal number of infected individuals while vaccination of the LT group only acts to protect vaccinated individuals from further infection.

Rapid qualitative field methods can be used to evaluate ecological integrity (EI) at a landscape level. This study evaluates the EI of 63 landscape types (LCTs) in Cyprus derived from Landscape Character Mapping. Following a stratified sampling, LCTs were evaluated using 209 Land Description Units (LDUs) i.e., homogeneous map entities, sharing a similar pattern of natural and cultural elements. In every LDU, six ecological integrity (EI) indicators were visually assessed consistently namely naturalness, habitat continuity, number of habitats, dominant habitat type, management intensity and scale. TwoStep Cluster Analysis was employed to identify EI categories, and Categorical Principal Components Analysis (CATPCA) to associate the individual indicators with overall EI in the LDUs. Linear regressions were used to predict EI based on the most important indicators. Forested and shrubland landscapes have consistently good EI with low variation, while urbanized and agricultural landscapes have lower EI. There is great variation in the number of agricultural landscape types and their EI. There are significant linear relationships between EI and naturalness, habitat continuity and intensity. The novelty of this work lies with the fact that it provides the first island-wide study in the Mediterranean assessing EI spatially through a small number of indicators. Results indicate that LCA can be an appropriate consistent and inexpensive spatial framework for assessing EI, which can be directly associated with management intervention to maintain or improve EI.

Association between species may strengthen the fitness of the species involved It is not rare that avian species associate on the breeding and feeding grounds. However, a species associated with a potential egg predator is less common. In this study, a synchronized breeding of Indian House Crow (Corvus splendens) and breeding Indian Pond Herons (Ardeola grayii) in urban conditions is reported. Both the crow abundance and the crow nest abundance increased with the number of heronry nests on sites. Crows were mostly observed when flying over or when resting nearby, but they also attempted egg predation from heronry nests. Crows also used the heronry sites for collecting nesting resources, such as twigs, scavenging dead chicks and for stealing the food brought to feed the heronry chicks. A dearth of suitable nesting places and provisions in an urban environment may be the reason why these birds share nesting trees. Vigilant breeding crows, despite their ability to depredate heron nests, may be more beneficial to herons as they are known to mob and distract heron predators, but a full cost-benefit analysis needs to be undertaken.