This paper is part of an interdisciplinary and interinstitutional study1 involving biology,biotechnology and humanities researchers with the aim of examining the gaps as well as the opportunities that bioeconomics mac...This paper is part of an interdisciplinary and interinstitutional study1 involving biology,biotechnology and humanities researchers with the aim of examining the gaps as well as the opportunities that bioeconomics macrosegment offers to Brazil.For this,it adopted an action-research methodology based on interviews with stakeholders that work directly in the sector.Eighteen actors were contacted among researchers,experts and entrepreneurs,of which ten gave face-to-face interviews,with open questionnaires,semi-structured.From the analysis of these data,and from a vast theoretical framework,the article delimits biomass as a pillar of bioeconomics and points out the emerging trends of this science such as“green chemistry”and biotechnology.This is a field that condenses an important economic potential and a great capacity to develop mechanisms for the environment’s preservation.By analyzing the production chain and its interfaces,the article reveals that Brazil,although it has an undeniable capacity to emerge as a world protagonist in sustainable production,still lacks well-defined public policies that invest in innovation,in addition to the consumer culture’s transformation,production and economic development focused on non-renewable products.展开更多
Public authorities frequently mandate public or private agencies to manage their renewable natural resources.Contrary to the agency,which is an expert in renewable natural resource management,public authorities usuall...Public authorities frequently mandate public or private agencies to manage their renewable natural resources.Contrary to the agency,which is an expert in renewable natural resource management,public authorities usually ignore the sustainable level of harvest.In this note,we first model the contractual relationship between a principal,who owns the renewable natural resource,and an agent,who holds private information on its sustainable level of harvest.We then look for the Pareto-optimal allocations.In the situation of an imperfect information setting,we find that the Pareto-optimal contracting depends on the probability that the harvesting level stands outside the sustainability interval.The information rent held by the agent turns out to be unavoidable,such that stepping outside the sustainability interval implies the possibility of depletion of the renewable natural resource.This,in turn,compromises the maintenance of the ecological balance in natural ecosystems.展开更多
In this article,we investigate a fractional-order singular Leslie-Gower prey-predator bioeconomic model,which describes the interaction bet ween populations of prey and predator,and takes into account the economic int...In this article,we investigate a fractional-order singular Leslie-Gower prey-predator bioeconomic model,which describes the interaction bet ween populations of prey and predator,and takes into account the economic interest.We firstly obtain the solvability condition and the st ability of the model sys tem,and discuss the singularity induced bifurcation phenomenon.Next,we introduce a st ate feedback controller to elimina te the singularity induced bifurcation phenomenon,and discuss the optimal control problems.Finally,numerical solutions and their simulations are considered in order to illustrate the theoretical results and reveal the more complex dynamical behavior.展开更多
Land degradation is one of the severe environmental problems in China. In order to combat land degradation, a soil conservation program was introduced since 2000 to reduce soil erosion by converting slope-cultivated l...Land degradation is one of the severe environmental problems in China. In order to combat land degradation, a soil conservation program was introduced since 2000 to reduce soil erosion by converting slope-cultivated land into forestry and pasture. This paper represents the first systematic attempt to investigate the impact of the soil conservation program on land degradation in the loess plateau. The results indicate that the soil conservation program to convert slope fields into forest or pasture is an effective way to combat soil erosion. However, a subsidy that is higher than profit of land use activity of slope fields before their conversion into forest and pasture is needed to encourage farmers to join the conservation program. A policy measure to encourage and assist farmers to develop sedentary livestock by using crops produced from fields as well as fodder and forage grass from the converted slope fields might contribute to combat soil erosion. Increase in off-farm job opportunities may encourage households to reduce cultivation in slope fields. That implies a policy measure to encourage rural urbanization might contribute to combat soil erosion.展开更多
The present research developed a bioeconomic model for control of Californian thistle （Cirsium arvense L. Scop.） in intensive, lowland sheep pastures in New Zealand. Production costs included two control methods： h...The present research developed a bioeconomic model for control of Californian thistle （Cirsium arvense L. Scop.） in intensive, lowland sheep pastures in New Zealand. Production costs included two control methods： herbicides and defoliation, with defoliation encompassing both physical means and biocontrol measures. The model was used to examine the economic value of a research programme into biological control of the weed, given several different future scenarios. These scenarios were high herbicide prices, a price premium for lamb raised without chemical herbicides, and development of herbicide resistance. The model results were used to estimate national impacts. If the only change in the agricultural sector was the cost of the biocontrol to the nation＇s farmers, the research programme to find an effective biocontrol agent had little economic impact. If other factors changed, such as the price of petroleum or levels of herbicide resistance in the weed. the model＇s results suggested that intensive sheep farming could grow or shrink by as much as NZ$219 million dollars over five years. In the latter case, having an alternative control method reduced potential losses and increased potential gains, resulting in a net benefit of between NZ$81 million and NZ$153 million. This work extended prior research in several ways. First. Californian thistle reproduces via root buds, which affected the modelling of weed behaviour. Secondly, the model allowed optimistation over continuous levels of weed control for two different methods. Thirdly, the model accounted for both weed control and damage to nitrogen-fixing clover from herbicide use. Finally, the research investigated optimal weed control in several different alternative future states.展开更多
Artisanal fisheries are characterized by using a vast array of different fishing gears and target species. Such heterogeneity has traditionally complicated their management and the availability of accurate data on fis...Artisanal fisheries are characterized by using a vast array of different fishing gears and target species. Such heterogeneity has traditionally complicated their management and the availability of accurate data on fishing effort and incomes. This study identifies and characterizes the métiers currently used by an artisanal fishing fleet based in a coastal Atlantic region in South-Europe (Asturias, Northwest Spain), by applying an integrated method of analysis which combines administrative data on fishing licenses, daily sales statistics and information from surveys. As a result, 21 artisanal fishing métiers have been identified, with special relevance of the trammel net (targeting Lophius spp.), the Merluccius longline and the Merluccius gillnet métiers. Spatio-temporal patterns of fishing effort have been also described, and outputs and inputs demands per métier have been quantified. It has been also found a high degree of alternation between different métiers during the fishing season and significant differences in terms of technical aspects and workforce. Finally, fishermen’s short- and long-term strategies (métier choice) are discussed, different comparisons are made on the basis of other South-European studies and main findings are linked to artisanal fisheries management.展开更多
This study presents a bioeconomic model after analyzing the commercial profitability of Nile tilapia under biofloc(BFT)and green water(GWT)technologies.Environmental stochasticity was evaluated using the parameters ob...This study presents a bioeconomic model after analyzing the commercial profitability of Nile tilapia under biofloc(BFT)and green water(GWT)technologies.Environmental stochasticity was evaluated using the parameters obtained in Yucatan’s rainy(RN)and dry(DR)seasons.The productive impact was measured by analyzing the 10-year cash flow.Both systems demonstrated profitability with a positive NPV and 450 g harvest weight in the short term.The unit cost of production results for the GWT was lower than for the BFT.The long-term simulation involved an investment of $410,279 USD for 30 tanks,resulting in a positive return for GWT.BFT showed negative long-term profitability at the current selling price($2.36 USD/kg).Profitability improved as the sales price increased by 11% and 22% for RN-BFT and DR-BFT,respectively.This bioeconomic model is pioneering in tilapia production in BFT and GWT and provides valuable data to achieve better yield and profitability.展开更多
The paper analyzes the influence of a susceptible-infectious-susceptible （SIS） infectious disease affecting both fish and broiler species. The paper also considers a joint SIS project of fish and broiler in which th...The paper analyzes the influence of a susceptible-infectious-susceptible （SIS） infectious disease affecting both fish and broiler species. The paper also considers a joint SIS project of fish and broiler in which the growth rates of both species vary with available nutrients and environmental carrying capacities of biomasses. The nutrients for both species are functions of the biomasses of the two species. The harvesting rates of fish and broiler depend linearly on common effort function. It is assumed that the diseases are trans- mitted to the susceptible populations by direct contact with the infected populations. Using the medicine, some portion of the infected populations are transmitted to the sus- ceptible populations. The existence of steady states and their stability are investigated analytically. The joint profit of the SIS model is maximized using Pontryagin＇s max- imum principle and corresponding optimum harvesting rates are also obtained. Using Mathematica software~ the models are illustrated and the optimum results are obtained and presented in tabular and graphical forms.展开更多
This paper studies a prey-predator singular bioeconomic system with time delay and diffusion, which is described by differential-algebraic equations. For this system without diffusion, there exist three bifurcation ph...This paper studies a prey-predator singular bioeconomic system with time delay and diffusion, which is described by differential-algebraic equations. For this system without diffusion, there exist three bifurcation phenomena： Transcritical bifurcation, singularity induced bifurcation, and Hopf bifurcation. Compared with other biological systems described by differential equations, singularity induced bifurcation only occurs in singular system and usually links with the expansion of population. When the diffusion is present, it is shown that the positive equilibrium point loses its stability at some critical values of diffusion rate and periodic oscillations occur due to the increase of time delay. Furthermore, numerical simulations illustrate the effectiveness of results and the related biological implications are discussed.展开更多
In this paper, a three-species system consisting of two predators which are in mutual- ism with each other and preying on the same single prey is considered. Also, the prey and first predator are harvested under optim...In this paper, a three-species system consisting of two predators which are in mutual- ism with each other and preying on the same single prey is considered. Also, the prey and first predator are harvested under optimal conditions. The values of the biological parameters depend on the collection of data from the experts as well as on the nature of the environment in which prey predator system are considered. So the biological para- meters are not precise in reality. This paper presents a different approach to study the prey-predator model with imprecise biological parameters. All the possible equilibrium points are identified and the local as well as global stability criteria under imprecise- ness are discussed. The possibility of existence of bionomic equilibrium is discussed. The optimal harvesting policy is studied using Pontryagin＇s maximum principle. Numerical examples are provided to support the proposed approach.展开更多
文摘This paper is part of an interdisciplinary and interinstitutional study1 involving biology,biotechnology and humanities researchers with the aim of examining the gaps as well as the opportunities that bioeconomics macrosegment offers to Brazil.For this,it adopted an action-research methodology based on interviews with stakeholders that work directly in the sector.Eighteen actors were contacted among researchers,experts and entrepreneurs,of which ten gave face-to-face interviews,with open questionnaires,semi-structured.From the analysis of these data,and from a vast theoretical framework,the article delimits biomass as a pillar of bioeconomics and points out the emerging trends of this science such as“green chemistry”and biotechnology.This is a field that condenses an important economic potential and a great capacity to develop mechanisms for the environment’s preservation.By analyzing the production chain and its interfaces,the article reveals that Brazil,although it has an undeniable capacity to emerge as a world protagonist in sustainable production,still lacks well-defined public policies that invest in innovation,in addition to the consumer culture’s transformation,production and economic development focused on non-renewable products.
基金financially supported by a grant overseen by the French National Forestry Office through the Forests for Tomorrow International Teaching and Research Chair(Convention particulière n°1/2013)supported by the French National Research Agency through the Laboratory of Excellence ARBRE,a part of the Investments for the Future Program(ANR 11--LABX-0002-01).
文摘Public authorities frequently mandate public or private agencies to manage their renewable natural resources.Contrary to the agency,which is an expert in renewable natural resource management,public authorities usually ignore the sustainable level of harvest.In this note,we first model the contractual relationship between a principal,who owns the renewable natural resource,and an agent,who holds private information on its sustainable level of harvest.We then look for the Pareto-optimal allocations.In the situation of an imperfect information setting,we find that the Pareto-optimal contracting depends on the probability that the harvesting level stands outside the sustainability interval.The information rent held by the agent turns out to be unavoidable,such that stepping outside the sustainability interval implies the possibility of depletion of the renewable natural resource.This,in turn,compromises the maintenance of the ecological balance in natural ecosystems.
文摘In this article,we investigate a fractional-order singular Leslie-Gower prey-predator bioeconomic model,which describes the interaction bet ween populations of prey and predator,and takes into account the economic interest.We firstly obtain the solvability condition and the st ability of the model sys tem,and discuss the singularity induced bifurcation phenomenon.Next,we introduce a st ate feedback controller to elimina te the singularity induced bifurcation phenomenon,and discuss the optimal control problems.Finally,numerical solutions and their simulations are considered in order to illustrate the theoretical results and reveal the more complex dynamical behavior.
文摘Land degradation is one of the severe environmental problems in China. In order to combat land degradation, a soil conservation program was introduced since 2000 to reduce soil erosion by converting slope-cultivated land into forestry and pasture. This paper represents the first systematic attempt to investigate the impact of the soil conservation program on land degradation in the loess plateau. The results indicate that the soil conservation program to convert slope fields into forest or pasture is an effective way to combat soil erosion. However, a subsidy that is higher than profit of land use activity of slope fields before their conversion into forest and pasture is needed to encourage farmers to join the conservation program. A policy measure to encourage and assist farmers to develop sedentary livestock by using crops produced from fields as well as fodder and forage grass from the converted slope fields might contribute to combat soil erosion. Increase in off-farm job opportunities may encourage households to reduce cultivation in slope fields. That implies a policy measure to encourage rural urbanization might contribute to combat soil erosion.
文摘The present research developed a bioeconomic model for control of Californian thistle （Cirsium arvense L. Scop.） in intensive, lowland sheep pastures in New Zealand. Production costs included two control methods： herbicides and defoliation, with defoliation encompassing both physical means and biocontrol measures. The model was used to examine the economic value of a research programme into biological control of the weed, given several different future scenarios. These scenarios were high herbicide prices, a price premium for lamb raised without chemical herbicides, and development of herbicide resistance. The model results were used to estimate national impacts. If the only change in the agricultural sector was the cost of the biocontrol to the nation＇s farmers, the research programme to find an effective biocontrol agent had little economic impact. If other factors changed, such as the price of petroleum or levels of herbicide resistance in the weed. the model＇s results suggested that intensive sheep farming could grow or shrink by as much as NZ$219 million dollars over five years. In the latter case, having an alternative control method reduced potential losses and increased potential gains, resulting in a net benefit of between NZ$81 million and NZ$153 million. This work extended prior research in several ways. First. Californian thistle reproduces via root buds, which affected the modelling of weed behaviour. Secondly, the model allowed optimistation over continuous levels of weed control for two different methods. Thirdly, the model accounted for both weed control and damage to nitrogen-fixing clover from herbicide use. Finally, the research investigated optimal weed control in several different alternative future states.
文摘Artisanal fisheries are characterized by using a vast array of different fishing gears and target species. Such heterogeneity has traditionally complicated their management and the availability of accurate data on fishing effort and incomes. This study identifies and characterizes the métiers currently used by an artisanal fishing fleet based in a coastal Atlantic region in South-Europe (Asturias, Northwest Spain), by applying an integrated method of analysis which combines administrative data on fishing licenses, daily sales statistics and information from surveys. As a result, 21 artisanal fishing métiers have been identified, with special relevance of the trammel net (targeting Lophius spp.), the Merluccius longline and the Merluccius gillnet métiers. Spatio-temporal patterns of fishing effort have been also described, and outputs and inputs demands per métier have been quantified. It has been also found a high degree of alternation between different métiers during the fishing season and significant differences in terms of technical aspects and workforce. Finally, fishermen’s short- and long-term strategies (métier choice) are discussed, different comparisons are made on the basis of other South-European studies and main findings are linked to artisanal fisheries management.
基金the National Council of Science and Technology(CONACYT)for the Ph.D.scholarship granted to BSP(grant number 297693/633432).
文摘This study presents a bioeconomic model after analyzing the commercial profitability of Nile tilapia under biofloc(BFT)and green water(GWT)technologies.Environmental stochasticity was evaluated using the parameters obtained in Yucatan’s rainy(RN)and dry(DR)seasons.The productive impact was measured by analyzing the 10-year cash flow.Both systems demonstrated profitability with a positive NPV and 450 g harvest weight in the short term.The unit cost of production results for the GWT was lower than for the BFT.The long-term simulation involved an investment of $410,279 USD for 30 tanks,resulting in a positive return for GWT.BFT showed negative long-term profitability at the current selling price($2.36 USD/kg).Profitability improved as the sales price increased by 11% and 22% for RN-BFT and DR-BFT,respectively.This bioeconomic model is pioneering in tilapia production in BFT and GWT and provides valuable data to achieve better yield and profitability.
文摘The paper analyzes the influence of a susceptible-infectious-susceptible （SIS） infectious disease affecting both fish and broiler species. The paper also considers a joint SIS project of fish and broiler in which the growth rates of both species vary with available nutrients and environmental carrying capacities of biomasses. The nutrients for both species are functions of the biomasses of the two species. The harvesting rates of fish and broiler depend linearly on common effort function. It is assumed that the diseases are trans- mitted to the susceptible populations by direct contact with the infected populations. Using the medicine, some portion of the infected populations are transmitted to the sus- ceptible populations. The existence of steady states and their stability are investigated analytically. The joint profit of the SIS model is maximized using Pontryagin＇s max- imum principle and corresponding optimum harvesting rates are also obtained. Using Mathematica software~ the models are illustrated and the optimum results are obtained and presented in tabular and graphical forms.
基金This work was supported by the National Science Foundation of China under Grant No. 60974004 and Natural Science Foundation of China under Grant No. 60904009.
文摘This paper studies a prey-predator singular bioeconomic system with time delay and diffusion, which is described by differential-algebraic equations. For this system without diffusion, there exist three bifurcation phenomena： Transcritical bifurcation, singularity induced bifurcation, and Hopf bifurcation. Compared with other biological systems described by differential equations, singularity induced bifurcation only occurs in singular system and usually links with the expansion of population. When the diffusion is present, it is shown that the positive equilibrium point loses its stability at some critical values of diffusion rate and periodic oscillations occur due to the increase of time delay. Furthermore, numerical simulations illustrate the effectiveness of results and the related biological implications are discussed.
文摘In this paper, a three-species system consisting of two predators which are in mutual- ism with each other and preying on the same single prey is considered. Also, the prey and first predator are harvested under optimal conditions. The values of the biological parameters depend on the collection of data from the experts as well as on the nature of the environment in which prey predator system are considered. So the biological para- meters are not precise in reality. This paper presents a different approach to study the prey-predator model with imprecise biological parameters. All the possible equilibrium points are identified and the local as well as global stability criteria under imprecise- ness are discussed. The possibility of existence of bionomic equilibrium is discussed. The optimal harvesting policy is studied using Pontryagin＇s maximum principle. Numerical examples are provided to support the proposed approach.
