Non-selective Harvesting Research Articles

Bifurcation Analysis of a Discrete Amensalism Model

By using model discretization of the piecewise constant argument method, a discrete amensalism model with nonselective harvesting and Allee effect is formulated. The dynamic analysis of the model is studied and the existence and stability of the equilibrium point are discussed. The fold bifurcation and flip bifurcation at the equilibrium point of the system are proved by using the bifurcation theory and the center manifold theorem. In order to control flip bifurcation and restore the system to a stable state, a hybrid control strategy of parameter perturbation and state feedback is adopted. Finally, the effectiveness of the theoretical results and the control strategy is verified by numerical simulations.

The role of farming systems in the adoption of pest management practices: the case of the oriental fruit fly Bactrocera dorsalis in mango orchards in Senegal

Description of the suject. In Africa, pest pressure has led researchers, policymakers, and international development stakeholders to develop and disseminate innovative pest management strategies. However, farmers reject some pest management strategies due to economic constraints, agronomic problems, or incompatibilities with their strategies, knowledge bases, and visions of desirable change. Objectives. In this paper, we study the pest management practices employed by mango producers from different farming systems against the fruit fly Bactrocera dorsalis, as well as the factors determining the level of engagement of these producers in managing this pest. Method. We surveyed 304 Senegalese mango growers affected by the invasive fruit fly Bactrocera dorsalis to understand which farming systems’ features could explain the adoption level of fruit fly management tools through multivariate data analysis. Results. Three types of farming systems characterized by a coherent set of varietal choices, orchard management, harvest practices, commercial outlets, and fruit fly management practices are identified: (1) Intensive farming systems supplying the export market with the variety Kent and using a large set of orchard management tools and harvest practices to eliminate fruit flies, (2) Extensive farming systems supplying various varieties of mangoes with a dominance of Kent to both export and domestic markets, with access to fruit fly management tools from public services, (3) Gathering farming systems characterized by zero-input, high varietal diversity, difficult market access, non-selective harvest practices, and fruit fly management rarely practiced. Conclusions. The farming systems form a gradient of increasing use of fruit fly management tools and inputs, access to extension services, and export market orientation. Their coexistence in the same territories significantly contributes to the inefficiency of the control measures against Bactrocera dorsalis. Our results support the premise that in Africa, the adoption of pest management tools is more deeply integrated into the practices of certain producers compared to others, due to internal and external factors influencing the operation.

Innovative Selective Harvesting Technology for Cauliflower: A Design Approach using Plant Characteristics

Traditional manual harvesting methods for cauliflower are labor-intensive, time-consuming, and costly, and non-selective harvesting often leads to significant yield losses due to immature curds being harvested. To address these challenges, there is growing interest in developing selective cauliflower harvesters that can accurately identify and harvest mature and healthy cauliflower heads while minimizing damage and waste. This research paper focuses on the determination of design parameters for an efficient and adaptive selective cauliflower harvester based on a comprehensive understanding of the physical and mechanical properties of cauliflower plants. Two cauliflower varieties, Pusa Meghna, and Pusa Sharad, were studied to measure various physical properties such as plant width, height, curd diameter, curd depth, stalk diameter, stalk length, and stalk moisture content. Additionally, cutting force was measured to design the cutting unit of the harvester. The results revealed that design parameters, including frame height, width, length, cutter length, and cutter height, should be tailored to the specific physical properties of cauliflower plants to optimize the selective harvesting process. This research contributes valuable insights to the advancement of agricultural robotics and engineering, laying the groundwork for the development of sophisticated selective cauliflower harvesters.

Dynamic Behaviors of a Commensalism Model Incorporating Nonselective Harvesting in a Partial Closure

A commensalism model incorporating nonselective harvesting in a partial closure is proposed and studied in this paper. Local and global stability properties of the equilibria are investigated, respectively. Our study shows that depending on the fraction of the stock available for harvesting, the system may be extinct, partial survival, or two species coexist in a stable state. Numeric simulations are carried out to show the feasibility of the main results.

The Harvest Effect on Dynamics of Northern Fur Seal Population: Mathematical Modeling and Data Analysis Results

We examine population trends in light of male harvest data considering the long-time series of population data on northern fur seals at Tyuleniy Island. To answer the question has the way males were harvested influenced the population trajectory, we analyzed the visual harem size and birth rate dynamics of the population, as well as the strategy and intensity of the harvest. We analyzed the dynamics of the sex ratio in the early (1958–1988) period to estimate parameters in the late period (1989–2013) based on the observed number of bulls and pups, while utilizing the distribution of reproductive rates obtained from pelagic sealing. Using a matrix population model for the observed part of the population (i.e., the male population), we analyzed the population growth rate associated with changes in both birth and survival rates considering the stochastic effects. Observations allow us to reject the hypothesis of nonselective harvest. Among the variety of natural and anthropogenic factors that could contribute to the decrease in the birth rate in the population, the effect of selective harvesting seems to be the most realistic.

Qualitative analysis and control of predator switching on an eco-epidemiological model with prey refuge and harvesting

In this paper, an eco-epidemiological model has been studied where disease of prey population is modelled by a Susceptible–Infected (SI) scheme. Prey switching strategy is adopted by predator population when they are provided with two types of prey, susceptible and infected prey. However switching may happen due to several reasons such as shortage of preferable prey or risk in hunting the plentiful prey. In this work, we have proposed a prey–predator system with a particular type of switching functional response where a predator feeds on susceptible and infected prey but it switches from one type of prey to another when a particular prey population becomes lower. Both the species are supposed to be commercially viable and undergo constant non-selective harvesting. The stability aspects of the switching models around the infection-free state from a local as well as a global perspective has been investigated. Our aim is to study the role of harvesting and refuge of susceptible population on the dynamics of disease propagation and/or annihilation of an epidemiological model under consideration of switching phenomena. Numerical simulations are done to demonstrate our analytical results.

Population responses to harvest depend on harvest intensity, demographics, and mate replacement in sandhill cranes

Recent examinations of hunting’s impact on populations of long-lived species illustrate the rarity of strong compensatory responses. The extent to which sandhill crane populations exhibit compensatory, partially compensatory, or additive responses to harvest mortality is poorly known. To examine how sandhill crane harvests might impact resident, breeding crane populations, we simulated harvests of a well-studied population of individually marked birds at varying harvest intensities and degrees of selectivity within the social structure of territorial and non-territorial cranes. Simulations occurred in a demographically-explicit stochastic population model developed from a previous long-term (2000–2014) study of a sandhill crane population at carrying capacity in southcentral Wisconsin, USA. Non-selective harvest models that did not account for reproductive lags after territorial birds replaced lost mates produced additive responses and resulted in declining populations when ≥ 7% of the population was harvested annually. When models of non-selective harvest incorporated reproductive lags, this threshold was reduced to ≥ 5%. Harvesting at or above 5% harvest intensities continuously decreased population size over a 100-year period. In all models of selective harvests, when only non-territorial birds were harvested, all populations returned to equilibrium. Population responses to harvest are sensitive to the number of territorial birds harvested, and this sensitivity increases when accounting for lags in reproduction stemming from mortality-induced mate replacement. If possible, limiting harvest of territorial birds from any one specific population would help maintain stability of populations when implementing a hunt. This study provides evidence for harvest impacts at a localized scale, and it represents an important first step toward better understanding the potential impacts of hunting on population responses at a regional scale, especially where resident, territorial birds might be harvested.

Optimal harvesting and stability of a predator-prey model for fish populations with schooling behavior.

In this paper, the schooling behavior of prey fish population in a predator-prey interaction is investigated. By taking an economical interest which can be elaborated by the presence of nonselective harvesting into consideration, we studied the dynamical behavior. The existence, positivity and boundedness of solution have been established. The analysis of the equilibrium states is presented by studying the local and the global stability. The possible types of local bifurcation that the system can undergoes are discussed. The effect of fishing effort on the evolution of the species is examined. Further, by using Pontryagin's maximum principle a proper management strategy has been used for avoiding the extinction of the considered species and maximizing the benefits. For the validation of the theoretical result, several of graphical representations have been used.

Dynamical analysis of an aquatic amensalism model with non-selective harvesting and Allee effect.

In this paper, in order to explore the inhibition mechanism of algicidal bacteria on algae, we constructed an aquatic amensalism model with non-selective harvesting and Allee effect. Mathematical works mainly gave some critical conditions to guarantee the existence and stability of equilibrium points, and derived some threshold conditions for saddle-node bifurcation and transcritical bifurcation. Numerical simulation works mainly revealed that non-selective harvesting played an important role in amensalism dynamic relationship. Meanwhile, we proposed some biological explanations for transcritical bifurcation and saddle-node bifurcation from the aspect of algicidal bacteria controlling algae. Finally, all these results were expected to be useful in studying dynamical behaviors of aquatic amensalism ecosystems and biological algae controlling technology.

THE EXISTENCE AND STABILITY OF ORDER-1 PERIODIC SOLUTIONS FOR AN IMPULSIVE KOLMOGOROV PREDATOR-PREY MODEL WITH NON-SELECTIVE HARVESTING

<abstract> In this paper, we focus on a general state-dependent Kolmogorov predator-prey model subject to non-selective harvesting along with delivery. Certain criteria are established for the existence, non-existence and multiplicity of order-1 impulsive periodic solutions to the system. Based on the geometric phase analysis and the method of Poincaré map or successor function with Bendixson domain theory, three typical types of Bendixson domains (i.e., Parallel Domain, Sub-parallel Domain and Semi-ring Domain) are introduced to deal with the discontinuity of the Poincaré map or successor function. We incorporate two discriminants $ \Delta_1 $ and $ \Delta_2 $ to link with the existence, non-existence and multiplicity as well as the stability of order-1 periodic solutions. At the same time, we locate the order-1 periodic solutions with the help of three characteristic points and the parameters ratio of delivery over harvesting. The results show that there must exist at least one order-1 periodic solution when the trajectory, that is tangent to the mapping line, can hit the impulsive line. While the trajectory tangent to the mapping line cannot hit the impulsive line, there is not necessary the existence of an order-1 periodic solution, which means the impulsive control may be invalid after finite times stimulation or suppression. In conclusion, we reveal that the delivery can prevent the predator from extinction and stabilize the order-1 periodic solution. </abstract>

非选择性半封闭捕获对具有恐惧效应的Lotka-Volterra捕食–食饵模型的动力性行为影响研究

非选择性半封闭捕获对具有恐惧效应的Lotka-Volterra捕食–食饵模型的动力性行为影响研究

On a predator-prey system interaction under fluctuating water level with nonselective harvesting

Abstract A predator-prey model interaction under fluctuating water level with non-selective harvesting is proposed and studied in this paper. Sufficient conditions for the permanence of two populations and the extinction of predator population are provided. The non-negative equilibrium points are given, and their stability is studied by using the Jacobian matrix. By constructing a suitable Lyapunov function, sufficient conditions that ensure the global stability of the positive equilibrium are obtained. The bionomic equilibrium and the optimal harvesting policy are also presented. Numerical simulations are carried out to show the feasibility of the main results.

Exploring Balanced Harvesting by Using an Atlantis Ecosystem Model for the Nordic and Barents Seas

“Balanced Harvesting” (BH) has been suggested as a possible strategy to meet the objectives of the Ecosystem Approach to Fisheries, ensuring a high sustainable yield while maintaining ecosystem structure and function. BH proposes a moderate fishing mortality in proportion to productivity spread across the widest possible range of species, stocks, and sizes in an ecosystem producing a sustainable and overall non-selective harvest. The Norwegian and Barents Seas have been subjected to moderate fishing pressure on commercial species, and elements of an ecosystem-based approach to management for many years, but not the fishing pattern proposed by BH. By using an Atlantis ecosystem model of the Nordic and Barents Seas, we investigated the effects of applying a BH regime to a region with existing successful fisheries management. This was done by running simulations with combinations of historic fishing pressure and fishing mortality rates proportional to 25% of the productivity of most species and sizes. The simulations were then compared to a control run where the historical fisheries were applied. The model results showed that implementing a BH regime in the Norwegian and Barents Seas would only produce marginal increases in total yields of currently commercially exploited stocks, likely because the Norwegian fisheries are already mostly well managed. However, expanding the fishery to include species that are not commercially exploited today did produce higher yields, especially on lower trophic levels. This study represents the first attempted examination of implementing BH based on productivity using an Atlantis ecosystem model, as well as the first investigation of BH in the Norwegian and Barents Seas. We use this model as a case study to identify the gains that species-based BH can be expected to give over well-implemented traditional fisheries management rather than simply comparing to an over-exploited system.

Individual behavior drives ecosystem function and the impacts of harvest.

Current approaches for biodiversity conservation and management focus on sustaining high levels of diversity among species to maintain ecosystem function. We show that the diversity among individuals within a single population drives function at the ecosystem scale. Specifically, nutrient supply from individual fish differs from the population average >80% of the time, and accounting for this individual variation nearly doubles estimates of nutrients supplied to the ecosystem. We test how management (i.e., selective harvest regimes) can alter ecosystem function and find that strategies targeting more active individuals reduce nutrient supply to the ecosystem up to 69%, a greater effect than body size-selective or nonselective harvest. Findings show that movement behavior at the scale of the individual can have crucial repercussions for the functioning of an entire ecosystem, proving an important challenge to the species-centric definition of biodiversity if the conservation and management of ecosystem function is a primary goal.

Gompertzian law of growth for reserved area fishery model with non-selective harvesting in unreserved area

This paper deals with the combined harvesting of two species from a prey-predator fishery model in an unreserved area of a marine aquatic eco-system where in primary phase of life the prey species is in marine protected areas (reserved areas). In a reserved area no harvesting and no predation can occur So prey species can grow smoothly and after that they migrate to unreserved open access areas where harvesting and predation are permitted. These kinds of fisheries are a good process to maintain the prey-predator biomass level up to a good size in the long run. They can also prevent species extinction. Here the prey follows the Gompertz law of growth in both reserved and unreserved areas. Initially the dynamic behaviour of the system was studied under a deterministic case with local stability and bionomic equilibrium. The optimal harvesting policy is studied using Pontryagian’s maximum principle. In second part of the work, we investigated the stability of the model under stochastic arena using Gaussian white noise. Finally, a comparison has been made. Moreover, the model has also been discussed through numerical example.

The influence of partial closure for the populations to a non-selective harvesting Lotka\u2013Volterra discrete amensalism model

In this paper, a non-selective harvesting Lotka–Volterra amensalism discrete model incorporating partial closure for the populations is proposed and studied. By applying the relevant conclusions of difference inequality and some calculation technique, sufficient conditions are obtained to ensure the permanence and extinction of the system. By constructing a suitable Lyapunov function, sufficient conditions that ensure the global attractivity of the system are obtained. Finally, numerical simulations show the feasibility of our results.

Impact of land use on woody aboveground biomass in Miombo woodlands of western Zambia – comparison of three allometric equations

Globally, the intensification of land use for agriculture, timber and fuel is considered the leading threat to the diversity and biomass of forests and woodlands. To suggest management options, it is important to understand the patterns and drivers of diversity, structure, biomass and carbon stock of woodland vegetation. In this study we used data from three sites in the Miombo woodlands of western Zambia, which are subject to low, medium and high land-use intensity. We sampled 20 plots of 1 000 m² at each of these sites. Woody vegetation was sampled for richness and structure to provide an understanding of the impact of land-use intensity. Woody plant species richness was not affected by land-use intensity. However, an ANOVA revealed that stem diameter at breast height (DBH) was higher at the low land-use intensity (national park) than at medium and high land-use intensities (selective timber harvest, and non-selective harvest for crop fields and timber). We tested three different allometric equations (one global and two regionally adapted) to determine woody aboveground biomass (AGB) and carbon stock at the three sites. The estimated AGB using the regionally adapted allometric equation of Ryan et al. and the global tropical equation of Brown et al. revealed that the AGB for low and high land-use intensity sites were significantly different from each other with the medium land-use intensity site being intermediate. We concluded that DBH and AGB estimations were influenced by the land-use intensity in the Miombo woodlands as suggested by other studies in the tropical forest and woodlands.

The Effect of non-Selective Harvesting in Predator-Prey ModelWith Modified Leslie-Gower and Holling Type II Shemes

The Effect of non-Selective Harvesting in Predator-Prey ModelWith Modified Leslie-Gower and Holling Type II Shemes

Mechanisation of white asparagus harvest – overview and perspectives

Harvesting white asparagus spears is exhausting, and labour- and cost-intensive. Since more than 60 years, growers and manufacturers contemplate to facilitate this process. In this article, the history of mechanisation of white asparagus harvest is described. Three processes can be distinguished, hand harvest supported by different harvesting aids, non-selective harvest, i.e. the whole ridge is cut, and selective harvesters, which are still in development. At the moment, hand harvesting with pushed carriages and hand harvest with one row electric harvesting aids are the predominantly used approaches. The performance of single row harvesting aids can be further improved by shift operation. Two workers use one harvester and harvest twice 4 h per day. In this case, one person can harvest up to 0.8 ha d-1.

Bifurcations in a Diffusive Predator–Prey Model with Beddington–DeAngelis Functional Response and Nonselective Harvesting

In this paper, we discuss the dynamics of a predator–prey model with Beddington–DeAngelis functional response and nonselective harvesting. By using the Lyapunov–Schmidt reduction, we obtain the existence of spatially nonhomogeneous steady-state solution. The stability and existence of Hopf bifurcation at the spatially nonhomogeneous steady-state solution with the change of a specific parameter are investigated by analyzing the distribution of the eigenvalues. We also get an algorithm for determining the bifurcation direction of the Hopf bifurcating periodic solutions near the nonhomogeneous steady-state solution. Finally, we show some numerical simulations to verify our analytical results.