Ecological Complexity最新文献

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.

A model for the Colorado potato beetle (CPB), potato plant and mycorrhiza mutual interactions is presented, accounting for the symbiotic and predator-prey features of this system. The study is performed to determine if arbuscular mycorrhizal fungi (AMF) increase potato tolerance to CPB. To this end, data collected by biological experiments are used. The system exhibits several possible equilibria that are related to each other via bifurcations. The latter are investigated both analytically and through simulations. The results indicate that the use of mycorrhiza is effective in keeping the pest population at low levels.

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.

Vaccines do save lives; however, no vaccine provides complete immunity for all vaccinated individuals. Thus, some individuals remain susceptible to the contagious disease against which they were vaccinated. By relying on the supposed acquired immunity, these individuals can reduce the self-imposed prevention measures and, as a consequence, they can involuntarily promote the spread of the infection. Here, such individuals are taken into account in an epidemic model based on ordinary differential equations. Depending on the parameter values related to contagion and vaccine efficacy, a less responsible behavior post-vaccination can increase the basic reproduction number of the disease as compared to the case with no vaccine. This result is discussed by considering the current COVID-19 outbreak.

In the absence of valid medicine or vaccine for treating the pandemic Coronavirus (COVID-19) infection, other control strategies like; quarantine, social distancing, self- isolation, sanitation and use of personal protective equipment are effective tool used to prevent and curtail the spread of the disease. In this paper, we present a mathematical model to study the dynamics of COVID-19. We then formulate an optimal control problem with the aim to study the most effective control strategies to prevent the proliferation of the disease. The existence of an optimal control function is established and the Pontryagin maximum principle is applied for the characterization of the controller. The equilibrium solutions (DFE & endemic) are found to be locally asymptotically stable and subsequently the basic reproduction number is obtained. Numerical simulations are carried out to support the analytic results and to explicitly show the significance of the control. It is shown that Quarantine/isolating those infected with the disease is the best control measure at the moment.

Intermittent population trajectories are likely to emerge in almost any population that faces a predator yet has a refuge from that predator. Using the well-known model of Pomeau and Manneville for intermittent populations, a collection of a group of inherently unstable subpopulations can survive through the balance of extinction and migration rates, which is a metapopulation. This formulation also generates a meta-Allee point, which is to say a minimal number of subpopulations that must exist to sustain the population over the long term.