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Introduction: In sub-Saharan Africa, pre-weaning young stock mortality (YSM) is in the order of 20 to 30% across most livestock species and production systems. High YSM has significant economic implications for livestock keepers, but few studies provide estimates of the “cost of YSM.” This study explores a bio-economic herd modeling approach to estimate the “cost of YSM” at farming/livestock system level. Methods: The static zero-growth version of DYNMOD was used to calculate the annual physical and monetary output of a sheep flock consisting of 100 breeding females at dierent levels of lamb mortality. Production parameter values and prices were taken from recently published research. Calculations were carried out for values of lamb mortality decreasing from 30% to 0% in 5% intervals, with 20% representing the “baseline” YSM. Calculations were repeated for a “high” fertility scenario (100% vs. 59% parturition rate) to gauge the sensitivity of the cost of YSM to another parameter determining flock productivity. Results: The relation of revenue per head and YSM is close to linear over the range of analyzed YSM with 1% decrease in YSM resulting in an increase in revenue per animal of approximately 1%. At the higher fertility rate, the absolute cost of YSM to sheep farmers is higher while the relative increase in revenue per animal resulting from YSM reduction is lower. The estimated dierence in revenue of the 100-ewe flock between the 20% and 0% lamb mortality scenarios (at baseline fertility) amounts to approximately USD 90 per additionally surviving lamb, which is far above its market value. Discussion: Reduced lamb mortality ultimately impacts flock revenue through increased sales of “mature” animals, which embody the value of a lamb plus the revenue/profit from raising it to marketable age/weight. The modeling results suggest that foregone profit is an important component of the systemic “cost of YSM.” Consequently, expected profit per animal, in addition to its current market value, is essential for estimating the absolute cost of YSM at farming system level [ABSTRACT FROM AUTHOR]

Measures to enhance boreal forests’ biodiversity and climate change mitigation potential are high on the policy agenda. Site productivity influences management, ecological attributes, and economic outcomes. However, national-level analyses of management implementation in response to policies considering site productivity are lacking. We analyzed impacts of a carbon policy (Carb), a biodiversity policy (Bio) and a combined biodiversity and carbon policy (BioCarb) in Norway using a simulation-optimization framework, assessing impacts on forest management, timber harvest, ecological attributes, and carbon fluxes until year 2140. Management alternatives were simulated in the single-tree simulator TreeSim before being fed into a market model NorFor to compare policy outcomes to a business-as-usual (BAU) scenario. All policies led to decreased harvests. Old forests expanded from the current 3% to cover 21% or more of the productive forest area in all scenarios. Impacts of policies depended on site productivity. On low-productive land, management under Bio mirrored BAU, while the Carb and BioCarb policies yielded more set-asides. On high-productive land, management intensity under the Carb policy was similar to BAU but the Bio and BioCarb policies resulted in more set-asides and more old forest. Thus, on low-productive land, the carbon policy showed to have the strongest impact on forest management, while on high-productive land, the biodiversity policy had the strongest impact. With geographical site-productivity gradients, the two policies exhibited different regional effects. The study shows that ex-ante analyses with appropriate tools can provide relevant information of multiple consequences beyond the stated aims which should be considered in policy design.

Southern Africa has been experiencing long-term changes in its climate and future projections imply that droughts should last longer and become more intense in southern Africa. Already, the region has been experiencing an increase in consecutive drought years. This study contributes to the literature by using bio-economic modeling to simulate the impact of future droughts on food security in southern Africa and identify plausible pathways for enhancing regional food security under drought. Food production and food security in southern Africa were projected under drought using an adjusted version of a multi-market and multi-commodity global model, the International Model for the Policy Analysis of Agricultural Commodities and Trade (IMPACT), version 3.2. The results suggest that with moderate economic growth and no drought, southern Africa would not become wealthy enough to mitigate food insecurity by 2040. In this context, recurrent droughts would worsen food security by severely affecting the production of maize, the key staple food in the region. With consecutive two-year regional droughts, like what was experienced in 2014/15 and 2015/16, most countries would experience an increase of at least 10% in the number of people at risk of hunger within a single year. Key measures which could help enhance food security under droughts include (1) breeding for stress-resilient maize (resistance to both heat and drought stresses); (2) promote crop and diet diversification, especially in countries highly dependent on maize as a staple food crop; and (3) invest in rainwater harvesting. [ABSTRACT FROM AUTHOR]

IntroductionIn sub-Saharan Africa, pre-weaning young stock mortality (YSM) is in the order of 20 to 30% across most livestock species and production systems. High YSM has significant economic implications for livestock keepers, but few studies provide estimates of the “cost of YSM.” This study explores a bio-economic herd modeling approach to estimate the “cost of YSM” at farming/livestock system level.MethodsThe static zero-growth version of DYNMOD was used to calculate the annual physical and monetary output of a sheep flock consisting of 100 breeding females at different levels of lamb mortality. Production parameter values and prices were taken from recently published research. Calculations were carried out for values of lamb mortality decreasing from 30% to 0% in 5% intervals, with 20% representing the “baseline” YSM. Calculations were repeated for a “high” fertility scenario (100% vs. 59% parturition rate) to gauge the sensitivity of the cost of YSM to another parameter determining flock productivity.ResultsThe relation of revenue per head and YSM is close to linear over the range of analyzed YSM with 1% decrease in YSM resulting in an increase in revenue per animal of approximately 1%. At the higher fertility rate, the absolute cost of YSM to sheep farmers is higher while the relative increase in revenue per animal resulting from YSM reduction is lower. The estimated difference in revenue of the 100-ewe flock between the 20% and 0% lamb mortality scenarios (at baseline fertility) amounts to approximately USD 90 per additionally surviving lamb, which is far above its market value.DiscussionReduced lamb mortality ultimately impacts flock revenue through increased sales of “mature” animals, which embody the value of a lamb plus the revenue/profit from raising it to marketable age/weight. The modeling results suggest that foregone profit is an important component of the systemic “cost of YSM.” Consequently, expected profit per animal, in addition to its current market value, is essential for estimating the absolute cost of YSM at farming system level.

Southern Africa has been experiencing long-term changes in its climate and future projections imply that droughts should last longer and become more intense in southern Africa. Already, the region has been experiencing an increase in consecutive drought years. This study contributes to the literature by using bio-economic modeling to simulate the impact of future droughts on food security in southern Africa and identify plausible pathways for enhancing regional food security under drought. Food production and food security in southern Africa were projected under drought using an adjusted version of a multi-market and multi-commodity global model, the International Model for the Policy Analysis of Agricultural Commodities and Trade (IMPACT), version 3.2. The results suggest that with moderate economic growth and no drought, southern Africa would not become wealthy enough to mitigate food insecurity by 2040. In this context, recurrent droughts would worsen food security by severely affecting the production of maize, the key staple food in the region. With consecutive two-year regional droughts, like what was experienced in 2014/15 and 2015/16, most countries would experience an increase of at least 10% in the number of people at risk of hunger within a single year. Key measures which could help enhance food security under droughts include (1) breeding for stress-resilient maize (resistance to both heat and drought stresses); (2) promote crop and diet diversification, especially in countries highly dependent on maize as a staple food crop; and (3) invest in rainwater harvesting.

The major constraint to beef production in Tanzania is low production of Tanganyika Shorthorn Zebu (TSZ) cattle, the main source of beef in Tanzania. This necessitates the need for a targeted improvement of TSZ cattle to enhance its beef production. However, there is no clear objective on which trait of TSZ should be targeted as a breeding objective and the basis for its selection. This study aimed to develop breeding objective by evaluating different desired traits of Tanganyika Shorthorn Zebu (TSZ) in terms of economic value. A total of 64 commercial TSZ cattle farmers were sampled and interviewed. Bio-economic modeling method was used to derive economic values (EVs) of traits linked to beef production. Among the traits captured in the model, includes body weight at maturity (WM), longevity (L), weaning weight (WW), age at first calving (AFC), and post-weaning daily weight gain (PoDG). WM and L had negative EVs whereas WW, AFC and PoDG had positive EVs. Therefore, WW, PoDG and AFC are recommended for consideration for inclusion as traits of interest when breeding TSZ for beef production. [ABSTRACT FROM AUTHOR]

IntroductionVillage tank cascade systems (VTCSs) were built in ancient Sri Lanka as autonomous and climate-resilient agro-ecological systems. This study examines crop choices, farming profitability, and environmental sustainability under alternative rainfall regimes and market interventions in the Mahakanumulla VTCS of the Anuradhapura district.MethodA bio-economic model was developed to represent farming activities in the VTCS for the 2018-19 Maha and 2019 Yala cultivation seasons with data gathered from secondary sources and a key informant survey. The objective function of the model was the maximization of profits from farming. Resource limits were set for four types of land (highlands and lowlands in the Maha and Yala seasons), two types of labor (hired and family), and twelve-monthly water constraints. Six different models were developed for the six sub-divisions of the VTCS, considering the water-management hierarchy of the system. The models were simulated under alternative rainfall regimes and market interventions. The optimal crop mixes, farm profits, and shadow prices of resources associated with the baseline scenarios were compared with those of the counterfactual scenarios.Results and discussionThis analysis clearly illustrated that water and labor are the key determinants of the system. Also, when 922 ha of lowlands and 205 ha of uplands were allocated per annum for crop cultivation under normal environmental conditions, the annual profitability of the VTCS was LKR 111 million. During drought periods, a sharp reduction in profits was observed in the Maha season. Year-round drought caused a 77% profit reduction compared to the baseline. The Maha drought alone caused a reduction of 47%. The introduction of a buy-back arrangement for chili and maize helped farmers to increase profits by 185 and 28%, respectively, under normal climate scenarios, turning to 954 and 5% during extreme drought scenarios, compared to the baseline. The least nitrate leaching and soil losses occurred in green chili cultivation. The introduction of market-based solutions is recommended to address extreme climate events experienced by the rural communities dependent on the VTCSs in Sri Lanka.

Multiple strategies are available that could reduce nitrogen (N) fertilizer use in agricultural systems, ranging from voluntary adoption of new N management practices by farmers to government regulations. However, these strategies have different economic and political costs, and their relative effectiveness in decreasing N leaching has not been evaluated at scale, particularly concerning potential trade-offs in crop yield and profitability. To inform policy efforts in the US Midwest, we quantified the effects of four policy scenarios designed to reduce fertilizer N inputs without sacrificing maize yields below 95%. A simulated dataset for economically optimum N rates and corresponding leaching losses was developed using a process-based crop model across 4,030 fields over 30 years. Policy scenarios were (1) higher N prices, (2) N leaching fee, (3) N balance fee, and (4) voluntary reduction of N use by farmers, each implemented under a range of sub-levels (low to high severity). Aggregated results show that all policies decreased N rates and N leaching, but this was associated with an exponential increase in economic costs. Achieving an N leaching reduction target of 20% has an estimated pollution control cost of 30–37 US$/ha, representing 147 million US$/year when scaled up to the state level, which is in the range of current government payments for existing conservation programs. Notably, such control of N losses would reduce the environmental impact of agriculture on water quality (externalities) by an estimated 524 million US$/year, representing an increase in society welfare of 377 million US$/year. Among the four policies, directly charging a fee on N leaching helped mitigate economic losses while improving the point source reduction effect (i.e., targeting fields that were leaching hotspots) and better internalization effect (i.e., targeting fields with higher environmental impact costs). This study provides actionable data to inform the development of cost-effective N fertilizer regulations by integrating changes in crop productivity and N losses in economic terms at the field level. [ABSTRACT FROM AUTHOR]

Multiple strategies are available that could reduce nitrogen (N) fertilizer use in agricultural systems, ranging from voluntary adoption of new N management practices by farmers to government regulations. However, these strategies have different economic and political costs, and their relative effectiveness in decreasing N leaching has not been evaluated at scale, particularly concerning potential trade-offs in crop yield and profitability. To inform policy efforts in the US Midwest, we quantified the effects of four policy scenarios designed to reduce fertilizer N inputs without sacrificing maize yields below 95%. A simulated dataset for economically optimum N rates and corresponding leaching losses was developed using a process-based crop model across 4,030 fields over 30 years. Policy scenarios were (1) higher N prices, (2) N leaching fee, (3) N balance fee, and (4) voluntary reduction of N use by farmers, each implemented under a range of sub-levels (low to high severity). Aggregated results show that all policies decreased N rates and N leaching, but this was associated with an exponential increase in economic costs. Achieving an N leaching reduction target of 20% has an estimated pollution control cost of 30–37 US$/ha, representing 147 million US$/year when scaled up to the state level, which is in the range of current government payments for existing conservation programs. Notably, such control of N losses would reduce the environmental impact of agriculture on water quality (externalities) by an estimated 524 million US$/year, representing an increase in society welfare of 377 million US$/year. Among the four policies, directly charging a fee on N leaching helped mitigate economic losses while improving the point source reduction effect (i.e., targeting fields that were leaching hotspots) and better internalization effect (i.e., targeting fields with higher environmental impact costs). This study provides actionable data to inform the development of cost-effective N fertilizer regulations by integrating changes in crop productivity and N losses in economic terms at the field level.

Soil quality is an important determinant of agricultural productivity and environmental quality. Despite its importance, few economic models incorporate sustainable soil management. The objective of this study is to develop and illustrate FARManalytics: a bio-economic model to gain quantitative insight in the economic value of sustainable soil management. First, we defined a comprehensive set of chemical, physical and biological soil quality indicators and quantitative rules on how these indicators respond to farmers' production management over time. Second, we introduce an economic calculation framework that enables accurate calculation of the contribution of different production management decisions towards farm income using Activity-Based-Costing. The set of soil quality indicators and economic calculations serve as the basis for the bio-economic model FARManalytics, which consists of two modules: (1) the PM calculator , a module that calculates the impact of current production management on soil quality and farm economics and (2) the PM optimizer , a module that uses Mixed-Integer-Linear-Programming to maximize farm incomewithin predefined soil quality indicator constraints. The decision variables are the crop rotation, cover crops, manure & fertilizer application and crop residue management. We illustrate the added value of the model by applying it to an extensive and intensive farm type, both on clay and sandy soil. These farm types are derived from the Farm Accountancy Data Network (FADN) in the Netherlands. FARManalytics demonstrates that it is possible to increase farm income with up to €940 ha−1 year−1 on clay soil and up to €683 ha−1 year−1 on sandy soil, while meeting all soil quality targets except subsoil compaction vulnerability. The latter was among the most limiting soil quality indicators for the farm types in this study, together with soil organic matter input, wind erosion vulnerability and plant-parasitic nematodes. FARManalytics integrates the impact of production management decisions on soil quality and economics at farm level. Combined with representative farm types, the bio-economic modeling approach of FARManalytics can provide useful information for policy support. FARManalytics can also be tailored to provide decision support for individual farms, based on data that is commonly available on arable farms at low cost. [Display omitted] • Sustainable soil management is important for agricultural productivity but often lacking in economic models. • The FARManalytics model integrates soil quality, farm economics and farmers' production management. • The objective is to gain insight in the economic value of sustainable soil management via bio-economic modeling. • Farm income can be raised up to €940 ha−1 year−1 while meeting all soil quality target values except subsoil compaction. • FARManalytics can be used to inform policy decisions and can be tailored at individual farm level using existing data. [ABSTRACT FROM AUTHOR]

Multispecies bio-economic models are useful tools to give insights into ecosystem thinking and ecosystem-based management. This paper developed an age-structured multispecies bio-economic model that includes the food web relations of the grey seal, salmon, and herring, along with salmon and herring fisheries in the Baltic Sea. The results show that the increasing seal population influences salmon fisheries and stock, but the impacts on the harvest are stronger than on the stock if the targeted management policies are obeyed. If seal population growth and a low herring stock occur simultaneously, the salmon harvest could face a serious threat. In addition, scenarios of the multispecies management approach in this paper reveal a benefit that our model can evaluate the performance of different fisheries with identical or different management strategies simultaneously. The results show the most profitable scenario is that both fisheries pursuit aggregated profits and reveal a trade-off between herring fisheries and salmon fisheries. Our model indicates that the herring harvest level and the approaches to managing herring fisheries can influence the performance of salmon fisheries. The study also demonstrates a way to develop a multispecies bio-economic model that includes both migratory fish and mammalian predators. [ABSTRACT FROM AUTHOR]

Lake Naivasha fishery has been one of the most known sources of protein for most fringe communities in and around Naivasha. About 4000 livelihoods depend on the lake's fishery resource, both directly and indirectly, thus pose concerns on the future sustainability. The ultimate aim of this study was to explore efforts, costs and optimum levels of fishery exploitation in Lake Naivasha. The study relied on fish landings and fishing effort statistics recorded between 1980 and 2017 by Fisheries Department. Data was analyzed using Gordon Schaefer's model and excel operating software. A regression model was run to develop graphs that explained the relationship between total costs, total revenues, harvests and number of boats. Consequently to the main aim, the study sought to determine the total costs of fishing along with revenues generated. Findings show an increase in number of operational boats from twenty-six (26) in 1980 to fifty boats (50) in 2013. Thereafter, fishing boats increased significantly to one hundred and seventy-six (176) by 2017. Such a significant and unprecedented increase in efforts adversely affected natural fish stock and brooders of the major fish species in the fishery. Information in this paper will inform decisions on resource economics and management of fishing activities in Lake Naivasha, Kenya. [ABSTRACT FROM AUTHOR]

Dairy development provides substantial potential economic opportunities for smallholder farmers in East Africa, but productivity is constrained by the scarcity of quantity and quality feed. Ruminant livestock production is also associated with negative environmental impacts, including greenhouse gas (GHG) emissions, air pollution, high water consumption, land-use change, and loss of biodiversity. Improved livestock feeding and forages have been highlighted as key entry point to sustainable intensification, increasing food security, and decreasing environmental trade-offs including GHG emission intensities. In this perspective article, we argue that farming systems approaches are essential to understand the multiple roles and impacts of forages in smallholder livelihoods. First, we outline the unique position of forages in crop-livestock systems and systemic obstacles to adoption that call for multidisciplinary thinking. Second, we discuss the importance of matching forage technologies with agroecological and socioeconomic contexts and niches, and systems agronomy that is required. Third, we demonstrate the usefulness of farming systems modeling to estimate multidimensional impacts of forages and for reducing agro-environmental trade-offs. We conclude that improved forages in East Africa are at a crossroads: if adopted by farmers at scale, they can be a cornerstone of pathways toward sustainable livestock systems in East Africa. [ABSTRACT FROM AUTHOR]

Globally, agriculture is a significant contributor to greenhouse gas emissions. The environment (e.g., soils and climate) and management influence agricultural greenhouse gas emissions and the potential to reduce emissions. For agriculture to contribute to greenhouse gas abatement in the long term, it is important to identify low-cost mitigation actions that farmers can adopt. It is hypothesized that greenhouse gas abatement potential and the associated costs will differ substantially between environments in Australia. Seven alternative management scenarios were identified as both suitable for adoption across different grain growing environments in Australia and potentially able to provide greenhouse gas abatement. The Agricultural Production Systems Simulator was used to simulate these alternative management scenarios over a 25-year period and analyze the potential for Australian grain farmers, across contrasting environments, to increase soil organic carbon stocks and/or reduce nitrous oxide emissions. This analysis was paired with a whole-farm economic analysis to determine the implications of the different greenhouse gas abatement scenarios on farm profitability. Results from case studies in Australia's three main grain growing regions demonstrate that significant heterogeneity exists in the biophysical potential and costs to reduce greenhouse gas emissions across locations. The maximum predicted abatement potential for the case study sites varied from 0.34 to 2.03 metric tons of carbon dioxide equivalents per hectare per year. In most simulations, greenhouse gas abatement came at a cost to farmers ranging from 0.11 Australian dollars (AUD) to more than 300 AUD per metric ton of abated carbon dioxide equivalent. This is the first study to explore the costs of mitigation including multiple greenhouse gases and grain farming case studies across Australia. These findings can inform the future development of effective climate change mitigation policies, which frequently use national default values in their design. [ABSTRACT FROM AUTHOR]

A prerequisite for an international fisheries agreement (IFA) to be stable is that parties expect the benefits from joining the agreement to exceed the benefits from free riding on the agreement, and parties only comply with the agreement as long as this is true. The agreement, therefore, implicitly builds on an expectation of the ecological condition of the natural resource. Game theoretical models often assume that all parties have the same (often perfect) information about the resource and that the exploitation is an equilibrium use of the stock. As stated by experts in natural science, the fish ecology still has many open questions, for example how to predict population dynamics, migration patterns, food availability, etc. In some cases, parties disagree about the state, abundance, and migration of a stock, which can reduce the possibilities of reaching an agreement for exploitation of the stock. This paper develops a model and applies it to the North-East Atlantic mackerel fishery, in order to analyze an IFA under different ecological scenarios, and also combines the model with the economic theory of entry deterrence. The model is used empirically to determine whether the parties with original access to the resource have an advantage when forming an agreement with a new party in having the ability to fish the stock down to a smaller size and thereby prevent another party from entering into the fishery. With a basis in entry deterrence, combined with lack of information, the paper illustrates the obstacles that have made an agreement for the North-East Atlantic mackerel so difficult to achieve. [ABSTRACT FROM AUTHOR]

This study uses a bio-economic model to assess the capacity of the Columbia River to provide a selection of four ecosystem services and estimates the actual use of those services in terms of net economic welfare. Our findings reinforce the observation that Columbia River habitat supports production of valuable fish species that provide: (i) food production from commercial fishing, (ii) recreational fishing, (iii) tribal subsistence fishing, and (iv) nutrient cycling services. Relative to the status quo, a 10% greater prioritization of salmon conservation via shifts in the flow regime would generate an increase of $4.8 million/yr in the net economic benefit from these services. A return to pristine flow conditions would raise this value to $19.5 million/yr. Re-prioritizing hydropower production to average 1976–1980 flow levels would result in a $3.5 million/yr loss of net economic benefits. Recreational fishing is the most important ecosystem service we assessed. Under some scenarios, this sector generates twice the value of the next largest sector (commercial fishing). Although managers have placed greater emphasis on fish conservation in recent decades, opportunities for gains in economic welfare from fish production in the Columbia River may not be fully exploited, particularly considering that our conservation scenario only minimally alters the flow regime relative to the hydropower priority scenario. [ABSTRACT FROM AUTHOR]

Mastitis is an inflammation of the mammary gland that is considered to be one of the most frequent and costly diseases in the dairy industry. Also in Ethiopia, bovine mastitis is one of the most frequently encountered diseases of dairy cows. However, there was no study, so far, regarding the costs of clinical mastitis and only two studies were reported on costs of subclinical mastitis. Presenting an appropriate and complete study of the costs of mastitis will help farmers in making management decisions for mastitis control. The objective of this study was to estimate the economic effects of mastitis on Ethiopian market-oriented dairy farms. Market-oriented dairy farming is driven by making profits through selling milk in the market on a regular basis. A dynamic stochastic Monte-Carlo simulation model (bio-economic model) was developed taking into account both clinical and subclinical mastitis. Production losses, culling, veterinarian costs, treatment, discarded milk, and labour were the main cost factors which were modeled in this study. The annual incidence of clinical mastitis varied from 0 to 50% with a mean annual incidence of 21.6%, whereas the mean annual incidence of subclinical mastitis was 36.2% which varied between 0 and 75%. The total costs due to mastitis for a default farm size of 8 lactating cows were 6,709 ETB per year (838 ETB per cow per year). The costs varied considerably, with 5th and 95th percentiles of 109 ETB and 22,009 ETB, respectively. The factor most contributing to the total annual cost of mastitis was culling. On average a clinical case costs 3,631 ETB, varying from 0 to 12,401, whereas a sub clinical case costs 147 ETB, varying from 0 to 412. The sensitivity analysis showed that the total costs at the farm level were most sensitive for variation in the probability of occurrence of clinical mastitis and the probability of culling. This study helps farmers to raise awareness about the actual costs of mastitis and motivate them to timely treat and/or take preventive measures. As a results, the dairy industry will improve. [ABSTRACT FROM AUTHOR]

Integrating agronomic information into economic models is required for simulating farming systems so as to better determine how agriculture can adapt to a continuously changing global economic and physical environment. In this respect, farm level mathematical programming bio-economic models can provide valuable insights for examining current and future pressures on resource use. Although a necessary condition for the effective use of such models is their calibration against observed data on input use, this information may not always be available, particularly at higher geographical scales. Imperfect or missing input markets pose an additional challenge to modelers. To overcome these difficulties, we present a theoretical framework for calibrating water-nitrogen yield response functions, which are used to represent the bio-physical aspects of crop production in bio-economic farm models at the European Union level. The method is based on the simulation results of an agronomic model, while the calibration criterion derives from the first-order conditions for farmers' profit maximization and utilizes all available information from the Farm Accountancy Data Network. The method is tested on maize-producing farms in two regions in France. [ABSTRACT FROM AUTHOR]

Fisheries management must address multiple, often conflicting objectives in a highly uncertain context. In particular, while the bio-economic performance of trawl fisheries is subject to high levels of biological and economic uncertainty, the impact of trawling on broader biodiversity is also a major concern for their management. The purpose of this study is to propose an analytical framework to formally assess the trade-offs associated with balancing biological, economic and non-target species conservation objectives. We use the Australian Northern Prawn Fishery (NPF), which is one of the most valuable federally managed commercial fisheries in Australia, as a case study. We develop a stochastic co-viability assessment of the fishery under multiple management objectives. Results show that, due to the variability in the interactions between the fishery and the ecosystem, current management strategies are characterized by biological and economic risks. Results highlight the trade-offs between respecting biological, economic and non-target species conservation constraints at each point in time with a high probability and maximizing the net present value of the fishery. [ABSTRACT FROM AUTHOR]

The purpose of this article is to investigate the link between marine pollution and marine renewable resources. An extended bio-economic model of a fishery is developed to include nutrient enrichment and built into a general model of the polluting and fishery sector with nutrient concentration and fish stock as state variables. The marginal damage function for nutrient enrichment is derived. This function can be compared with the marginal abatement cost and hence it provides a basis for policies that balance the use of nutrients in land-based industries (for example agriculture) with the external cost to the marine environment. The model is empirically applied to the case of the Baltic Sea, where Eastern Baltic cod fisheries are affected by nutrient enrichment. The results indicate that nitrogen loading needs to be reduced slightly (around 1 %) to reach optimal levels. The results also show that the optimal fishery policy plays a more important role in producing the net benefits than nitrogen reduction policies do. Further, the impact on the productivity of the fish stock from pollution reduction is higher when an optimal policy is followed. [ABSTRACT FROM AUTHOR]

This study presents economically optimal management of uneven-aged mixed mountain forests that takes into account tree growth variability. We divided 9846 silver fir ( Abies alba), beech ( Fagus sylvatica), and spruce ( Picea abies) trees measured on 898 forest inventory plots in the Snežnik and Leskova dolina management units (4905 ha, Dinaric mountains, Slovenia) into three growth classes (slow-, medium-, and fast-growing trees) to simulate optimal forest management over a period of 100 years with respect to changing tree growth, stand density, diameter distribution, and tree species composition. We developed a density-dependent and stage and growth-structured matrix transition model which-simultaneous to the long-term stand dynamics projection-scheduled optimal harvesting to maximize the net present value using a nonlinear approach. The ecology of tree species was considered by using tree species-specific and stand-density and diameter-dependent logistic functions for ingrowth, transition, and mortality. The model projected a shift in tree species composition from fir-dominated to beech-dominated forests within 100 years. A change from harvesting slow- and fast-growing trees as if they all had medium growth to growth-sensitive harvesting increased the net revenue and maintained the uneven-aged stand structure. Optimal harvest diameters varied among growth classes, time periods, and tree species according to the economic maturity of individual trees and ranged from 12 (pre-commercial thinning) to 72 cm (target diameter). The simulation highlights the potential of improved bio-economic models for increasing yield from uneven-aged forests and scheduling optimal management regimes with multiple objectives. [ABSTRACT FROM AUTHOR]

This study extended a bio-economic fishery model to establish an explicit link between coastal and estuarine ecosystems ecological composition (biodiversity) and functional (nutrient supply) attributes and the dynamics and productivity of KZN coastal fisheries. Results confirmed the importance and strong contribution of the tested ecological attributes. In-sample simulation indicates that current fishing efforts and harvest rates are sustainable, but are sensitive to changes in nutrient influx and rainfall. This confirms the need to modify conventional fisheries models to include environmental variables as additional predictors of fish stocks in addition to historical catch records and catch effort for management and control of fishing efforts and permits. This study provided confirmation of the strong linkage between nutrient levels and productivity of coastal fisheries thus enabling investigation of runoff and rainfall related climate change effects on the KZN fisheries. [ABSTRACT FROM AUTHOR]

Two key challenges in conservation management are: (1) how to quantify and manage the risk that natural populations will fall below critical thresholds and (2) how to fund recovery plans should a population do so. Statistically estimated, process-based simulation models of two distinct fish populations are used to forecast the species population levels, and capture the risk of crossing a management defined trigger point. We show how to calculate the environmental derivative price, which is the amount a risk-neutral investor would require for promising a pay-out should the species abundance fall below the trigger level. The approach provides the potential for environmental derivatives to support species recovery, and a method for measuring the underlying 'health' of a managed population and calculating risk-cost tradeoffs among alternative management strategies. [ABSTRACT FROM AUTHOR]

We develop a programming model of crop production to predict the effects of environmental policies on agriculture and the environment. The model is calibrated against acreages, yields, and exogenous supply elasticities following positive mathematical programming. In addition, crop production functions are calibrated to yield elasticities with respect to nitrogen and irrigation obtained from a biogeochemical model. We study the effects of a nitrogen tax in Yolo County, California, intended to mitigate nitrogen pollution from field crops. The behavioral and environmental responses to the tax are largely due to intensive margin adjustments. Sizable reductions in nitrate leaching are achieved at a low social cost. [ABSTRACT FROM AUTHOR]

This paper uses the World Trade Model with Climate Sensitive Land (WTMCL) to evaluate possible future land-use changes associated with adaptations to climate change in a globalized world. In this approach, changes in regional agricultural production, which are based on comparative advantage, define patterns of land use change in agriculture in all regions of the world. We evaluate four scenarios that combine assumptions about future increases in food demand and future changes in land endowments of different productivities associated with climatic conditions: each scenario generates distinct patterns of regional specialization in the production of agricultural commodities and associated land-use change. The analysis also projects future food availability under the simulated conditions and the direction of likely changes in prices of the major agricultural commodity groups. [ABSTRACT FROM AUTHOR]

Abstract: Provisioning of ecosystem services (ES) in mountainous regions is predicted to be influenced by i) the direct biophysical impacts of climate change, ii) climate mediated land use change, and iii) socioeconomic driven changes in land use. The relative importance and the spatial distribution of these factors on forest and agricultural derived ES, however, is unclear, making the implementation of ES management schemes difficult. Using an integrated economic–ecological modeling framework, we evaluated the impact of these driving forces on the provision of forest and agricultural ES in a mountain region of southern Switzerland. Results imply that forest ES will be strongly influenced by the direct impact of climate change, but that changes in land use will have a comparatively small impact. The simulation of direct impacts of climate change affects forest ES at all elevations, while land use changes can only be found at high elevations. In contrast, changes to agricultural ES were found to be primarily due to shifts in economic conditions that alter land use and land management. The direct influence of climate change on agriculture is only predicted to be substantial at high elevations, while socioeconomic driven shifts in land use are projected to affect agricultural ES at all elevations. Our simulation results suggest that policy schemes designed to mitigate the negative impact of climate change on forests should focus on suitable adaptive management plans, accelerating adaptation processes for currently forested areas. To maintain provision of agricultural ES policy needs to focus on economic conditions rather than on supporting adaptation to new climate. [Copyright &y& Elsevier]

Highlights: [•] Livestock in dry Mediterranean climates depend on dry plant residues over summer. [•] Sporadic summer rainfall causes degradation of these feed sources. [•] Two novel ephemeral legumes produced high quality feed in response to summer rain. [•] Bio-economic modeling showed ephemerals increased profit and feed stability. [Copyright &y& Elsevier]

Abstract: This study develops a bio-economic model framework to optimize the management of aquatic invasive species. Stochastic dynamic programming is applied to investigate when and to what extent a society should engage in efforts to reduce the likelihood of an invasion, to control and eradicate a newly established population, and to adapt to damages. The framework is parameterized for a potential Asian clam (Corbicula fluminea) invasion in the warm water discharge area of a nuclear power plant planned on the northern shores of the Baltic Sea. The sensitivity analysis reveals three distinct strategies: an adaptive strategy, which reduces the damage that an existing invasive species population causes to the private sector; a preventive strategy, which delays the invasion and the resulting damage; and a mitigative strategy, which puts effort into timely detection, control and eradication of the newly established population. Choice of the optimal strategy is sensitive to the unit costs and effectiveness of the measures required, to the level of externalities and to the size of the clam population after the invasion has been detected. The results emphasize the need for the energy sector to identify and internalize the external costs of potential invasions when making any large-scale investment plans. [Copyright &y& Elsevier]

Abstract: A new modeling approach which combined survival probabilities for spruce with financial optimization showed a considerably reduction in financial risk in spruce (Picea abies [L.] Karst.) stands with an admixture of a 20% proportion of beech (Fagus sylvatica L.). The admixture enhanced the stability of the spruce component against natural hazards, such as storm or insect damage. Here, these new survival investigations were integrated into a bio-economic modeling approach called silvicultural economics. A new failure model which includes the benefits of ecological interactions for decreasing hazard risk for spruce was developed. The modeling technique is based on Monte-Carlo-Simulation and on simultaneous portfolio optimization of management strategies under risk. Area proportions were allocated as decision variables to each tree species and to regeneration harvests at various points in time in order to achieve the maximum financial return given a predefined, acceptable risk. The simultaneous optimization led to a mixed – and, through long regeneration periods – to an uneven-aged forest stand, for almost all predefined risk-levels. In addition, for a selection of possible even-aged tree species compositions, a stand-level mixture (including the species interactions of the new model) was compared with the same species proportion at the stand level, but consisting of two separated parts of spruce and beech (thus excluding species interactions). For all even-aged and interacting mixtures that were investigated, a higher expected return and a lower financial risk were achieved when compared to the identical even-aged mixture proportions without interactions. When the timing and distribution of regeneration harvests was also optimized (as opposed to using a clear-cut strategy) there was a slight loss in financial return, but the reduction in risk was even greater, given the same tree species proportion – especially in cases with a low beech admixture. Compared to the simulation which excluded the stabilizing effect of beech on spruce, the variant with interacting tree species allowed for higher spruce proportions and shorter regeneration cycles for the same acceptable risk. [Copyright &y& Elsevier]

As a result of anthropogenic activities, ozone is produced in the surface atmosphere, causing direct damage to plants and reducing crop yields. By combining a biophysical crop model with an economic supply model we were able to predict and quantify this effect at a fine spatial resolution. We applied our approach to the very varied French case and showed that ozone has significant productivity and land-use effects. A comparison of moderate and high ozone scenarios for 2030 shows that wheat production may decrease by more than 30% and barley production may increase by more than 14% as surface ozone concentration increases. These variations are due to the direct effect of ozone on yields as well as to modifications in land use caused by a shift toward more ozone-resistant crops: our study predicts a 16% increase in the barley-growing area and an equal decrease in the wheat-growing area. Moreover, mean agricultural gross margin losses can go as high as 2.5% depending on the ozone scenario, and can reach 7% in some particularly affected regions. A rise in ozone concentration was also associated with a reduction of agricultural greenhouse gas emissions of about 2%, as a result of decreased use of nitrogen fertilizers. One noteworthy result was that major impacts, including changes in land use, do not necessarily occur in ozone high concentration zones, and may strongly depend on farm systems and their adaptation capability. Our study suggests that policy makers should view ozone pollution as a major potential threat to agricultural yields. [Copyright &y& Elsevier]

Significant decline of biodiversity in farmlands has been reported for several decades. To limit the negative impact of agriculture, many agro‐environmental schemes have been implemented, but their effectiveness remains controversial. In this context, the study of economic drivers is helpful to understand the role played by farming on biodiversity. The present paper analyzes the impact of risk aversion on farmland biodiversity. Here “risk aversion” means a cautious behavior of farmers facing uncertainty. We develop a bio‐economic model that articulates bird community dynamics and representative farmers selecting land uses within an uncertain macro‐economic context. It is specialized and calibrated at a regional scale for France through national databases. The influence of risk aversion is assessed on ecological, agricultural, and economic outputs through projections at the 2050 horizon. A high enough risk aversion appears sufficient to both manage economic risk and promote ecological performance. This occurs through a diversification mechanism on regional land uses. However, economic calibration leads to a weak risk‐aversion parameter, which is consistent with the current decline of farmland birds. Spatial disparities however suggest that public incentives could be necessary to reinforce the diversification and bio‐economic effectiveness. [ABSTRACT FROM AUTHOR]

High dissolved CO2 levels in tank water are potentially detrimental to the production and welfare of Atlantic salmon smolts in Norwegian hatcheries. A potential welfare action for reducing CO2 levels is to deploy CO2 stripping technology. The economic consequences of using this approach were modelled using a bio-economic decision analysis tool. Results from the model showed that farmers can improve fish welfare and their profits by utilizing CO2 stripping technology, as costs of implementing the welfare action were less than the potential bio-economic benefits that can be achieved through improved productivity and any potential added value for improving the welfare of smolts. [ABSTRACT FROM AUTHOR]

Fin damage can be common in farmed juvenile Atlantic salmon and is both directly harmful to the welfare of the fish and a potential sign of poor rearing conditions. Fin damage can be reduced during freshwater production by the use of feeding systems that deliver food in accordance with the fish's current appetite, rather than at fixed times. The bio-economic implications of feeding fish to appetite using demand feeding technology were modelled with the BENEFISH decision analysis tool. Using figures for Scottish smolt production, results from the model show that implementing demand feeders generates welfare benefits, but at a clear economic cost. [ABSTRACT FROM AUTHOR]

This article summarizes the framework that translated data from multiple disciplines into a bio-economic decision tool for modeling the costs and benefits of improving fish welfare in commercial aquaculture. This decision tool formed the basis of a recent EU research project, BENEFISH which was funded via the European Commission's Sixth Framework (FP6) initiative. The bio-economic decision model can incorporate biological data, productivity data, micro (farm) and macro (industry) level economic data, and consumer marketing and business to business data. It can identify areas for potential added value that might be achieved by improving fish welfare across a range of species and husbandry systems within European aquaculture. This article provides a brief overview of the minimum data requirements for successfully modeling the bio-economic impacts of improvements in farmed fish welfare using the model developed during the BENEFISH project. It also highlights potential bottlenecks and the minimum prerequisites for each potential data set to be used for successful modeling. [ABSTRACT FROM AUTHOR]

Abstract: The 2003 CAP reform considerably affects cropping patterns in European agriculture. At the same time the imperatives of the Water Framework Directive (WFD) are expected to modify irrigation decisions especially in Southern Europe where irrigated agriculture utilizes about 70–80% of total water. The paper uses a nonlinear optimization model that incorporates rain-fed, irrigated and fodder crops to examine the impacts of water pricing and CAP reform on cropping patterns, water use, irrigation technology use and farm returns in the region of Thessaly, Greece. The results indicate that, although there are important trade-offs between water pricing (WFD) and decoupling (CAP reform), water use is more sensitive to water pricing in the post-reform CAP. [Copyright &y& Elsevier]

Abstract: Tedera (Bituminaria bituminosa C.H. Stirt var. albomarginata) is a drought tolerant perennial legume originating in the Canary Islands. This study evaluates the potential role and value of tedera in dryland mixed crop and sheep production systems in southern Australia. Regional variants of the bio-economic model MIDAS are used to assess tedera in farming systems at two locations. The analysis considers the quantity and quality of feed produced by tedera, the ability of other forages to complement or substitute for tedera and its impact on meat versus wool-producing sheep flocks. The results indicate that tedera offers the potential to increase farm profits by up to 26% and be grown on ∼28% of a low rainfall mixed enterprise farm. On a high rainfall mixed enterprise farm tedera may boost profit by up to 58% and be grown on ∼75% of the farm. The modelled increases in farm profit were large and relate to savings in supplementary feed and higher stocking rates. The results of our analysis suggest additional experimental and breeding work is required but the current state of knowledge is consistent with tedera becoming an important forage in southern Australian farming systems. [Copyright &y& Elsevier]

We investigate the interactions between natural resource-based poverty traps and food security for smallholder farms in highland Kenya using a recently developed system dynamics bio-economic model. This approach permits examination of the complex interactions and feedback between farm household economic decision-making and long-term soil fertility dynamics that characterize persistent poverty and food insecurity among smallholders in rural highland Kenya. We examine the effects of changing initial endowments of land and stocks of soil organic matter on smallholders' well being, as reflected in several different indicators. We show that larger and higher quality land endowments permit accumulation of cash and livestock resources and conservation of soil organic matter relative to smaller or more degraded farms. This suggests the existence of asset thresholds that divide food secure households from food insecure ones. [ABSTRACT FROM AUTHOR]

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Abstract: In order to analyze impacts of climate change on managed grassland systems and to project potential changes in farmers’ management practices in response to altered climatic conditions, we develop a modeling approach that integrates a process-based grassland model into an economic model. This economic model describes farmers’ decision making with respect to input use and accounts for production levels, production risks, fodder quality as determined by the grassland composition, and environmental protection. We apply the bio-economic model to an intensively managed grassland system with a geographic focus on the Swiss Plateau. Our results show an increase of future production risks in grassland production due to climate change. Projected changes in yield levels, grassland composition and optimal responses of risk-averse farmers are dependent on the assumptions concerning cross-compliance obligations, forage quality and particularly on the assumed effect of elevated CO2 concentrations: Grasslands yields will increase under future climatic conditions only if the benefits of rising atmospheric CO2 concentrations are taken into account. Without this potential benefit, climate change will lead to less intensive input use and lower grassland yields. [ABSTRACT FROM AUTHOR]