Dynamic Ecological Model Research Articles

Study on ecological dynamic model for phytoremediation of farmland drainage water

Eutrophication of surface water bodies resulted from pollution of the farmland drainage water is a serious water pollution problem recently, which has been paid more and more attention. Phytoremediation is to use specific aquatic or terrestrial plants for water pollutants such as nitrogen in situ absorption, degradation and fixing, with low cost and good effect of removing nitrogen pollutants, which is gradually used in sewage disposal. However, impact factor of phytoremediation is not known comprehensively enough since people have done research on it recently, and study on related dynamics is not much either. So many numerical models are not accurate enough, and the selection of reaction parameters is not unified. In this paper, two kinds of phytoremediation constructed wetlands such as surface wetland named Cell A and vertical flow constructed wetland named Cell B are used. Through experiments design, operation of the field and sampling analysis, combined with the principle of nitrogen transformation model, phytoremediation of farmland in the water cycle nitrogen ecology dynamic conceptual numerical model is developed. A kinetic model of nitrogen physical-chemical biodegradation reaction is established in this study. And genetic algorithm with the least-squares method of nonlinear optimization is used via MATLAB, which is an independent program to determine the unknown parameters in the developed model. Simulated results showed that the concentration of ammonia nitrogen, nitrate nitrogen and organic nitrogen in the effluent of Cell A is better than other pools. The ecological dynamic model of nitrogen cycle and the first-order kinetic model of removing total nitrogen (TN) were compared and analyzed in the simulation of the Cell A. It is indicated that the developed ecological dynamic model in this study could accurately predict the change of the effluent concentration in the constructed wetland. And the model in this study can provide theoretical support for the design and operation of the constructed wetland and the prediction of the effluent concentration to facilitate the mastery for the actual purification effect of the constructed wetland.

LAS TRANSICIONES EDUCATIVAS Y SU INFLUENCIA EN EL ALUMNADO


 Las transiciones educativas de una etapa escolar a otra afectan a la población estudiantil en diferentes momentos de su vida académica, provocando cambios en su trayectoria educativa y social, e influyendo notablemente en su futuro. En ocasiones, el impacto de este proceso genera un descenso en el rendimiento del alumnado seguido de episodios de fracaso y abandono escolar. El objetivo de este trabajo es llevar a cabo una revisión de la literatura especializada en las transiciones educativas que permita ahondar en la temática y en sus posibles ámbitos de intervención. Paralelamente, el texto profundiza en la perspectiva holística, el enfoque comunitario y el modelo ecológico-dinámico sobre el que se asienta este proceso. Asimismo, se comentan aspectos susceptibles de interés acerca de las transiciones que suceden desde la Educación Infantil hasta la Educación Secundaria. En el apartado de conclusiones, se identifican barreras y dificultades, algunas propuestas de mejora a este respecto y futuras vías para avanzar en torno a esta línea de conocimiento.

Technical review on derivation methods for behavior dependent functional responses

Functional responses measure the trophic interactions between species, taking into account the density and behavior of the interacting species. In predator-prey interactions, the prey preference of the predator and the antipredator behavior of the prey together determine the feeding rate of the predator and the survival rate of the prey. Consequently, the behavior dependent functional responses make it possible to establish dynamic ecological models providing insight, among others, into the coexistence of predator and prey species and the efficiency of agents in biological pest control. In this paper the derivation methods of functional responses are reviewed. Basically, there are three classes of such methods: heuristic, stochastic and deterministic ones. All of them can take account of the behavior of the predator and prey. There are three main stochastic methods for the derivation of functional responses: renewal theory, Markov chain and the Wald equality-based method. All these methods assume that during the foraging process the prey densities do not change, which provides a mathematical basis for heuristic derivation. There are two deterministic methods using differential equations. The first one also assumes that during the foraging process the prey densities do not change, while the second one does not use that assumption. These derivation methods are appropriate to handle the behavior dependent functional responses, which is essential in the derivation of ecological games, when the payoff of prey and predator depends on the strategies of the prey and predator at the same time.

Research on the Assessment System Construction of EAP Writing Skill from an Eco-linguistic Perspective

This paper comes up with an assessment system of EAP writing development from an Eco-linguistic perspective based on a literature review of English writing construction and assessment of writing skills development under an ecological dynamic model. The paper clarifies that the writing construction in academic contexts consists of genre and rhetorical knowledge, process, strategy knowledge，and academic discourse community knowledge. The paper elucidates that the ecological dynamic assessment of EAP writing skills, as just being conducted at Tianjin Polytechnic University, has been proved to be workable in establishing bio-ecological links between the classroom learning contexts and the broader educational contexts at university. In the research, the individualized and comprehensive employment of assessment tools such as textual analysis，one-on-one interviews，case study and writing portfolios helps achieve dynamic assessment and facilitate ecological transfer of EAP writing competence.

START: A data preparation tool for crop simulation models using web-based soil databases

Soil profile data that characterize the physical and chemical properties of a soil are among the required set of inputs for ecological, crop and other dynamic simulation models. A web-based soil information system often provides the site-specific soil data of which formats are not readily compatible to crop models. The Soil daTA Retrieval Tool (START) was developed to automate a series of procedures for preparation of soil input data that includes the retrieval of soil profile data from the information system, reorganization of data, estimation of soil parameters, and creation of input files for simulation models. In a case study, the START was implemented to support the SoilGrids database operated by the International Soil Reference and Information Center. It took about 0.33% of time for the START to create soil input files compared with manual preparation. These results suggest that the START could provide an efficient approach for preparation of soil input files especially for sites where little soil information is available.

Quantification of the Indirect Use Value of Functional Group Diversity Based on the Ecological Role of Species in the Ecosystem

An important issue in biodiversity valuation is gaining a better understanding of how biodiversity conservation affects economic activities and human welfare. Quantifying the economic benefits of biodiversity for human well-being is not straightforward. Here, we expand the ecosystem service cascade by (i) attributing a methodology to the different steps of the cascade to assess the effects of changes in functional group diversity on economic activities; (ii) including multiple attributes for defining functional diversity and (iii) integrating a dynamic ecological model simulating complex interactions and feedbacks between species with an economic model assessing the effects of changes in functional group diversity for gross revenues. The stepwise methodological framework integrates a production function approach with a market price-based approach in order to investigate the indirect use value of functional group diversity based on the ecological role of species in the ecosystem. The methodology is applied to estimate the relationship between the gross economic value of Chinook salmon (Pacific Northwest, United States) and the diversity of freshwater macroinvertebrates. The results of our analysis emphasize the importance of biological diversity for sustaining ecosystem goods and services. The analysis provides a tractable framework for quantitatively exploring the economic consequences of changes in functional group diversity.

Simulation of Remote-Sensed Chlorophyll Concentration with a Coupling Model Based on Numerical Method and CA-SVM in Bohai Bay, China

Xiang, X.; Lu, W.; Cui, X.; Li, Z., and Tao, J., 2018. Simulation of remote-sensed chlorophyll concentration with a coupling model based on numerical method and CA-SVM in Bohai Bay, China. In: Wang, D. and Guido-Aldana, P.A. (eds.), Select Proceedings from the 3rd International Conference on Water Resource and Environment (WRE2017). Journal of Coastal Research, Special Issue No. 84, pp. 1–9. Coconut Creek (Florida), ISSN 0749-0208.Due to the high-complexity and non-linearity of the marine ecosystem, the internal functional mechanisms of the system have not been fully recognized. This lack of recognition of ecosystems restricts the use of traditional deterministic, aquatic, and ecological dynamic models based on mechanisms or assumptions. By introducing advanced intelligent algorithm support vector machine (SVM) and space display mode cellular automata (CA) from soft computing, a marine ecological module is constructed by combining SVM with CA. Simulation results such as water level, water depth, and flow velocity of the mechanism-based hydrodynamic modules are imported to the corresponding cell. The cell together with the existing cells and neighboring state, spatial location variables as well as extrinsic factors, exerts a combined effect on the cellular state of the cell soon afterwards, and then the coupling model based on the numerical method and soft computing is constructed. With the remote-sensed chlorophyll concentration data at Bohai Bay as the study object, the root-mean-square error (RMSE) of model simulation results were within the range of 0.042 μg/L to 0.373 μg/L, and the difference of spatial auto-correlation indicators Moran's I was within the range of 0.003 μg/L to 0.176 μg/L. Results indicate that an established coupling model encompasses a proper simulation of the temporal and spatial changing features of the chlorophyll concentration. This study thus integrates the traditional, hydrodynamic numerical module and ecological module based on soft computing methods, providing new means and ideas for simulated marine environment.

Quantifying effects of hydrological and water quality disturbances on fish with food-web modeling

Accurately delineating the effects of hydrological and water quality habitat factors on the aquatic biota will significantly assist the management of water resources and restoration of river ecosystems. However, current models fail to comprehensively consider the effects of multiple habitat factors on the development of fish species. In this study, a dynamic framework for river ecosystems was set up to explore the effects of multiple habitat factors in terms of hydrology and water quality on the fish community in rivers. To achieve this the biomechanical forms of the relationships between hydrology, water quality, and aquatic organisms were determined. The developing processes of the food web without external disturbance were simulated by 208 models, constructed using Ecopath With Ecosim (EWE). These models were then used to analyze changes in biomass (ΔB) of two representative fish species, Opsariichthys bidens and Carassius auratus, which are widely distributed in Asia, and thus have attracted the attention of scholars and stakeholders, due to the consequence of habitat alteration. Results showed that the relationship between the changes in fish biomass and key habitat factors can be expressed in a unified form. T-tests for the unified form revealed that the means of the two data sets of simulated and observed ΔB for these two fish species (O. bidens and C. auratus) were equal at the significance level of 5%. Compared with other ecological dynamic models, our framework includes theories that are easy to understand and has modest requirements for assembly and scientific expertise. Moreover, this framework can objectively assess the influence of hydrological and water quality variance on aquatic biota with simpler theory and little expertise. Therefore, it is easy to be put into practice and can provide a scientific support for decisions in ecological restoration made by river administrators and stakeholders across the world.

Spatially Explicit Metrics of Species Diversity, Functional Diversity, and Phylogenetic Diversity: Insights into Plant Community Assembly Processes

Spatial processes underlie major species coexistence mechanisms. A range of spatial analysis techniques are increasingly applied to data of fully mapped communities to quantify spatial structures in species and phylogenetic and functional diversity at some given spatial scale with the goal of gaining insights into processes of community assembly and dynamics. We review these techniques, including spatial point pattern analysis, quadrat-based analyses, and individual-based neighborhood models, and provide a practical roadmap for ecologists in the analysis of local spatial structures in species and phylogenetic and functional diversity. We show how scale-dependent metrics of spatial diversity can be used in concert with ecological null models, statistical models, and dynamic community simulation models to detect spatial patterns, reveal the influence of the biotic neighborhood on plant performance, and quantify the relative contribution of species interactions, habitat heterogeneity, and stochastic processes to community assembly across scale. Future works should integrate these approaches into a dynamic spatiotemporal framework.

Extinction phase transitions in a model of ecological and evolutionary dynamics

We study the non-equilibrium phase transition between survival and extinction of spatially extended biological populations using an agent-based model. We especially focus on the effects of global temporal fluctuations of the environmental conditions, i.e., temporal disorder. Using large-scale Monte-Carlo simulations of up to $3\times 10^7$ organisms and $10^5$ generations, we find the extinction transition in time-independent environments to be in the well-known directed percolation universality class. In contrast, temporal disorder leads to a highly unusual extinction transition characterized by logarithmically slow population decay and enormous fluctuations even for large populations. The simulations provide strong evidence for this transition to be of exotic infinite-noise type, as recently predicted by a renormalization group theory. The transition is accompanied by temporal Griffiths phases featuring a power-law dependence of the life time on the population size.

Ecological modeling and eutrophication—A review

AbstractDuring the several last decades, environmental scientists use numerical modeling as a tool in their studies and investigations of aquatic systems. Ecological and hydrodynamic models are developed in parallel regarding their complexity, uncertainty, and computational power. Ecological models have been used to assess ecosystem processes and interactions, simulate future scenarios, evaluate remedial practices in response to eutrophication etc. This review paper deals with the progress in ecological modeling related to eutrophication processes, specifically in models that describe the trophic state dynamics of hypoxic/anoxic aquatic ecosystems. Nine dynamic ecological models coupled or noncoupled with hydrodynamic models have been discussed based upon their history, complexity, limitations, recent detailed modeling applications, and their important results. The advantages and disadvantages of these models are presented along with their application areas.

Monetary Valuation of Natural Predators for Biological Pest Control in Pear Production

In spite of global actions, biodiversity is declining at an alarming rate. Despite the need for objectively comparable monetary standards to include biodiversity arguments in policymaking, research on the relationship between species diversity and its valuation from a societal perspective is still scarce.In this paper, a methodological framework for the valuation of natural predators based on their ecological role in the agroecosystem is introduced. The framework integrates a dynamic ecological model simulating interactions between species with an economic model, thereby quantifying the effect of reduced numbers of natural predators on the net farm income. The model attributes an objective monetary value to increased species diversity through the changes in the provisioning of a marketable good.Results indicate that the loss of three predators could decrease net farm income with 88.86€ha−1 to 2186.5€ha−1. For the pear production sector in Flanders in 2011, this constitutes to an indirect use value of 0,68 million € for one predator and 16.63 million € for the presence of three predators. The aim is to provide a justification for the argument for biodiversity conservation, based on the ecological function of species, through the delivery of comparable monetary standards.

Multiple time-scale analysis of nitrogen retention characteristics and influencing factors in Shanmei Reservoir, Fujian, China.

The retention effect of reservoir on nitrogen is an important influence factor on the eutrophication prevention and control. In order to reveal the differences of nitrogen retention characteristics and the influence factors at multiple timescales, an ecological dynamic model was developed in Shanmei Reservoir watershed. Based on the retention flux and retention rate calculation, the nitrogen retention effect was analyzed at three time scales of yearly, monthly and daily, respectively. Furthermore, multiple linear correlation analysis was conducted to analyze the influence of inflow runoff, ratio of inflow to outflow, residence time, velocity and temperature on the retention of nitrogen in the reservoir. The results showed that the process of nitrogen retention always displayed fluctuant characteristic at different time scales. On a yearly scale, the reservoir mainly played a role of nitrogen sink; on a monthly scale, seasonal variation of nitrogen retention and release effect made the reservoir as nitrogen sink in wet period and as nitrogen source in dry period; on a daily scale, the nitrogen retention process fluctuated intensely, with the retention rate ranging from -300% to 100% in dry year. At different time scales, ratio of inflow to outflow and velocity were always the important factors to affect nitrogen retention in the reservoir, with significant correlation coefficients consistently. With the time scale changing from yearly to monthly, daily, the influence degree of inflow runoff and temperature on nitrogen retention was gradually strengthened. The correlations between the residence time and retention rate could be positive or negative at different time scales.

Research on hybrid mechanism modeling of algal bloom formation in urban lakes and reservoirs

Algal bloom in urban lakes and reservoirs breaks out more frequently in recent years, making it a serious environmental problem in the world. Ecological dynamic model and data-driven model are two most representative methods to describe algal bloom formation mechanism; however, they both have certain drawbacks. In this paper, on the basis of deep analysis on formation mechanism of algal bloom, a hybrid mechanism modeling method was proposed, which synthesized the advantages of both models mentioned above. In order to obtain an appropriate model, a function model library (FML) of key impact factors (IFs) in algal bloom formation was first established, and then Tabu Search (TS) and Genetic Algorithm (GA) were applied for model structure optimization and parameters calibration, respectively. Simulation results show that the proposed method can effectively characterize the formation mechanism of algal bloom in different urban lakes and reservoirs, and it is also with higher modeling speed and wider extendibility.

Development of an Ecological Dynamic Model for a Duckweed-Donated Urban Eutrophic Wetland

Development of an Ecological Dynamic Model for a Duckweed-Donated Urban Eutrophic Wetland

Time-varying nonlinear modeling and analysis of algal bloom dynamics

The ecological dynamic models of algal bloom in existence are of poor environmental adaptability and hard to reflect nonlinear dynamic change of algal bloom formation mechanism. To solve this problem, time variable is applied to mechanism-based model according to algal bloom nonlinear dynamic in this paper, and mechanism feature of algal bloom is represented by time function model and effecting function model. Data-driven modeling approaches including tabu search and genetic algorithm are also adopted to optimize structure and parameter for the time-varying nonlinear modeling to improve environmental adaptability and accuracy of the model. High-precision numerical solutions of the optimized time-varying nonlinear model is obtained by fourth-order Adams predictor–corrector method. This method finally realizes effective prediction of algal bloom.

Stochastic Sensitivity Analysis and Control for Ecological Model with the Allee Effect

In this paper, we discuss a problem of the analysis and prevention of catastrophic shifts in ecosystems with stochastic environment. For the solution of this problem in models of ecological dynamics, a new approach based on the stochastic sensitivity functions technique is suggested and applied to a stochastically forced predator-prey model with the Allee effect. For this population model, we analyze a phenomenon of noise-induced extinction using the method of confidence domains. By controlling those domains we provide a stable coexistence of both species and prevent the noise-induced extinction.

Modeling discrete-variable stochastic dynamics: Ecological populations, gene networks, and a nanotube ion channel

Many complex systems in both the physical and life sciences can be modeled as interacting elements with discrete-value variables. In most of these systems, stochasticity plays an important role. This paper examines an ecological population dynamics model, a simple model of a gene regulatory network, and a model for the conductance of a nanotube ion channel. The interplay of discrete-value variables, stochasticity, and nonlinear dynamics produces fascinating phenomena that are important in many areas of physics and biology.

Dual invasion analysis: a general model of novel ecological dynamics due to Bt product and resistant pests in wild settings

Transgenic Bt crops have been integrated as a central component of the agricultural policies of many nations across the globe due to their insecticidal properties. While focus on increased yield resulting from the use of Bt crops has overshadowed the concerns of pest populations developing resistance, resistance has been recently discovered in even highly managed fields. One issue that has received less attention is the resulting set of ecological dynamics from escaped Bt products into wild settings. I present a differential equation model of the ecological interaction between a wild plant–pest community and an invading Bt toxin-producing plant and the ensuing evolution of pest resistance. Key to this model investigation is the assumption of energy costs with both the production of Bt toxin by Bt plants and the resistance to Bt toxin exhibited by resistant pest individuals. Results show that persistence of the initial invading Bt plant population is possible through an intransitive loop dynamic. Furthermore, coexistence of wild-type plants and pests as well as Bt-producing plants and resistant pests is possible through the dynamics resultant from energy trade-offs.

Changes in phytoplankton biomass due to diversion of an inflow into the Urayama Reservoir

The three-dimensional hydrodynamic Estuary, Lake and Coastal Ocean Model (ELCOM) coupled with the ecological Computational Aquatic Ecosystem DYnamics Model (CAEDYM) was applied to Urayama Reservoir in order to examine the effect of an inflow bypass on the water quality in the reservoir. The bypass system functions by intaking water from upstream of the reservoir and transferring it to the reservoir selective withdrawal tower in order to avoid turbid-water withdrawal. The model was calibrated using data measured in 2009. Simulated results of water temperature, dissolved oxygen, turbidity, nutrients and four groups of phytoplankton (cyanobacteria, diatoms, chlorophytes and cryptophytes) were in good agreement with field measurements. Some bypass operational scenarios and model parameter test scenarios were performed. The results showed that the bypass operation altered the nutrient load and in-reservoir concentrations as well as the heat budget, which changed the water temperature, dissolved oxygen and other water quality parameters, including chlorophyll a (Chla) concentration in the reservoir. Detailed examination of the growth of phytoplankton revealed that cyanobacteria were most affected by the bypass operation because of the interaction between the change of hydrological conditions and the buoyancy control of cells. The results suggested that the operation of the bypass system was useful in decreasing inflow nutrient loads as well as decreasing the transport of the algal biomass from upstream to the dam wall, which generally helped to decrease the magnitude of algal biomass near the offtake region of the reservoir.