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Evolutionary Agroecology theory predicts that the relationship between population yield and individual fitness among genotypes of a crop species is unimodal, and experimental evidence supports this. We test the theory further by investigating the role of resource availability on this relationship by comparing growth and reproductive output of three old and three modern cultivars of wheat (Triticum aestivum) in mixture and monocultures grown at three resource levels. The relationship between population grain yield and individual fitness (mean individual grain yield in mixture) of genotypes was resource dependent in a way that is consistent with the theory: when resource levels are low and limit individual growth directly, individual and population yield are positively correlated. When resource levels are high and the growth of individual plants is limited by competition for these resources, the relationship between individual fitness and population yield becomes negative. There was evidence for the unimodal relationship at the intermediate resource level. Old cultivars had higher fitness than newer cultivars at all three resource levels. Old cultivars had higher yields at low resource levels, but the newer cultivars yielded more when resource levels were high. Evaluating individual fitness and population yield in different environments may help wheat breeders to develop locally adapted, cooperative cultivars to increase production across large wheat-producing areas. [ABSTRACT FROM AUTHOR]

Shrubs are usually adapted to stressful environments in which soil resources are limited, and thus, roots are fundamental for their biological success. However, root measures are challenging to collect, especially in field conditions and at the individual level. For this study, we collected data on the three‐dimensional distribution of fine root biomass of twenty‐three individuals belonging to three shrub species in a mediterranean shrubland in central Spain: gum rockrose Cistus ladanifer, rosemary Salvia rosmarinus, and hairy‐fruited broom Cytisus striatus. Our goal was to determine the soil‐foraging strategies adopted by the plants. We hypothesized that plants would show stabilizing niche differences explaining the high plant biodiversity characteristic of mediterranean shrublands and that they would follow the game theory model's prediction of exploitative segregation of roots behaving territorially but also over‐proliferating roots close to their stem and engaging in a root tragedy of the commons. We found that two‐thirds to three‐fourths of the biomass was belowground, and the system's productivity was roughly 500–600 g C m−2 year−1. Only rosemary plants competed with neighbors following the exploitative segregation predictions. Broom plants had the shallowest and most widespread root systems but significantly reduced their root range toward competing neighbors. Gum rockrose presented deep, narrow root systems avoiding extensive overlap with neighbors but did not appear to respond to competitive pressure levels. Shrubs appeared to stratify their roots at different soil depths, supporting the niche segregation hypothesis. [ABSTRACT FROM AUTHOR]

Our research question is whether it is possible and how to counteract "the tragedy of the commons" if facing various limitations of real‐world economies. To answer it, we derive regulatory tax–subsidy systems and self‐enforcing environmental agreements in a problem of extraction of common renewable resources. The first considered limitation is that the feasible class of tax–subsidy systems may have a compl icated form, for example, there are transition periods for smooth reduction of fishing. The alternative limitation is that there is no institution that can impose taxes or subsidize, so sustainability can be achieved only by self‐enforcing international agreements. The next limitation is in those agreements: we assume that it takes time to detect a defection. We study these enforcement tools in a continuous‐time version of a Fish War type game with n $n$ countries, with fish indispensable for their economies. We calculate the social optimum, a Nash equilibrium, and partial cooperation equilibria. The Nash equilibrium leads to the depletion of fish, while the social optimum typically results in sustainability. For partial cooperation, only two‐country coalitions are stable. We calculate tax–subsidy systems that enforce maximization of joint payoff, also if there are additional constraints, and we propose an algorithm that looks for such a system in an arbitrary class of regulatory tax–subsidy systems. For the international agreement with imperfect monitoring, we are interested in the maximal detection delay for which the agreement remains self‐enforcing. Counterintuitively, the more the players, the more stable the agreement. [ABSTRACT FROM AUTHOR]

Evolutionary Agroecology theory predicts that the relationship between population yield and individual fitness among genotypes of a crop species is unimodal, and experimental evidence supports this. We test the theory further by investigating the role of resource availability on this relationship by comparing growth and reproductive output of three old and three modern cultivars of wheat (Triticum aestivum) in mixture and monocultures grown at three resource levels. The relationship between population grain yield and individual fitness (mean individual grain yield in mixture) of genotypes was resource dependent in a way that is consistent with the theory: when resource levels are low and limit individual growth directly, individual and population yield are positively correlated. When resource levels are high and the growth of individual plants is limited by competition for these resources, the relationship between individual fitness and population yield becomes negative. There was evidence for the unimodal relationship at the intermediate resource level. Old cultivars had higher fitness than newer cultivars at all three resource levels. Old cultivars had higher yields at low resource levels, but the newer cultivars yielded more when resource levels were high. Evaluating individual fitness and population yield in different environments may help wheat breeders to develop locally adapted, cooperative cultivars to increase production across large wheat-producing areas.

Scholars tend to study international organisations as selective clubs. Theorising organisations as clubs, however, obscures an important aspect of their evolution that is connected to the goods they produce. Some organisations produce goods that are increasingly attractive and accessible to non-members. Those organisations face pressures to enlarge beyond the optimal size suggested by club theory, changing the experience of membership fundamentally. Over time, lower exclusivity, increased rivalry, and tighter governance structures shift the organisation from producing club-goods to managing common resource pools. The case of the European Union illustrates this transformation. By theorising the EU as a collection of common resources pools rather than a club, this study underscores how the EU accompanied the pressure for greater inclusiveness and competition for resources with reforms to strengthen member states' self-discipline and multilateral surveillance. Such institutional reforms were and remain necessary for any international organisation to avoid the tragedy of the commons. [ABSTRACT FROM AUTHOR]

• Deviation from Nash behavior manifests as behavioral responses to property rights regimes. • A non-parametric test can detect and quantify behavioral responses. • An individual fishing vessel quota policy shifts behavior away from the tragedy of the commons. Commons problems present behavioral dilemmas, with tensions between individual and collective rationality. When users of a common-pool resource are not effectively excluded, the collective behavior of individuals pursuing their self-interests dissipates economic surplus. We derive a non-parametric test of whether individuals' collective behavior in resource extraction is consistent with the canonical commons model, namely Nash tragedy-of-the-commons behavior. Our approach allows for an arbitrarily concave, differentiable production function of total inputs and for heterogeneous agents with arbitrarily convex, differentiable costs of supplying inputs. We extend the test to allow for unobserved total output. We also define distance from the data to the model and develop statistical tests using the distance metric. Applying our approach to panel data of Norwegian commercial fishing vessels, we find the results of our test are consistent with the economic intuition that, in the absence of property rights, tragedy-of-the-commons behavior dissipates surplus. Significantly, we find property rights reforms move firms away from Nash tragedy-of-the-commons behavior. [ABSTRACT FROM AUTHOR]

Public right of access, everyman's or everyone's right, freedom to roam, right of public access to the wilderness and the right to roam are terms used for concepts that give people an independent right of access to forest land and rural areas for recreational or passage purposes. Access is not a self-evident right nor are the practices in different countries resolved alike. In this paper, we review how the public right of access is resolved in different countries, with a focus on cases in Sweden and Finland. We highlight problems that arise when the right of access enables extensive use of the land by the public and may make everyone's right prone to features related to the tragedy of the commons. We find that the code regarding public access depends largely on cultural, historical, and political differences and thus has no international or unambiguous definition as to what it includes or should include. The concept has worked considerably well throughout time but, as the original reasons for the right have waned and recreational use and demand have increased, the question has been raised whether everyone's right should be redefined to prevent complications between users and landowners. [ABSTRACT FROM AUTHOR]

Fish stocks are declining in marine capture coastal fisheries in West Africa. Many observers have blamed climate change and the system of open access for the decline. Open-access fishing encourages too many people to take up fishing, and the result is overfishing of the stocks. According to such critics, this is a classic example of Hardin's tragedy of the commons, whereby a continuous increase in the number of users of a natural resource eventually leads to the collapse of the resource. The present study, which analysed stakeholders' perceptions about their open-access fishing in Siera Leone's marine fisheries, conducted 32 key informant interviews. Our research found that while they perceived that open-access fishing impacted fish stocks, most Sierra Leone's marine capture fishers did not see open access as a cause of fish decline; instead, they blamed the lack of enforced regulations on the methods and extent of fishing. Accordingly, these fishers favoured the continuation of open access—not least because it helps to alleviate hunger and is a readily available source of protein in Sierra Leone's coastal communities—but accompanied by strict regulations on both the type of fishing gear used and the quantity, size, and species of fish caught. In other words, they preferred regulated open access to unregulated open access. The central government's resolve to regulate its fishery will determine whether it will transition from unregulated open access to regulated open access or other forms of OA. This study recommends detailed research into how to influence political will to enforce regulations. [ABSTRACT FROM AUTHOR]

The study focused on utilizing the four-step model to understand the achieved capabilities and functionings of residents of Ginatilan through the municipality's environmental poverty alleviation programs. Specifically, it examined the sustainability of Ginatilan's usage of natural resources and also utilized the views on the tragedy of the commons, as well as environmental and relational peace as frameworks. This article provided strategic recommendations for managing rural communities in the future. A case study was conducted in Barangay Anao and Mangaco, where household surveys, interviews, and document analyses were done through qualitative content analysis (QCA). Results show that the Municipality of Ginatilan's utilization of its natural resources through its environmental poverty alleviation programs is economically, environmentally, and socially sustainable. This research also has seen a positive relationship between sustainability and peace, and both domains require consideration of social, environmental, economic, and political dimensions to attain overall sustainability of natural resources. [ABSTRACT FROM AUTHOR]

The functioning of groups and societies requires that individuals cooperate on public goods such as healthcare and state defense. More often than not, individuals face multiple public goods and must choose on which to cooperate, if at all. Such decisions can be difficult when public goods are attractive on one dimension (e.g., being "efficient" in providing comparatively high returns) and unattractive on another (e.g., creating inequality by providing some group members greater returns than others). We examined how people manage such decision conflicts in five preregistered experiments (N =900) that confronted participants with two public goods that varied in efficiency and (in)equality of returns. People cooperated more on the comparatively efficient public good and on the equal-return (vs. unequal-return) public good (Experiment 1), yet when the unequal-returns public good was also the most efficient, individuals cooperated comparatively more on this unequal-but-efficient public good when they themselves benefitted the most from inequality (Experiments 2-4). Low beneficiaries largely ignored public goods efficiency and preferentially cooperated on the equal-rather than unequal-returns public good. Expectations (Experiments 2-4), preferences for revising the multiple-public-goods provision problems' choice architecture (Experiments 3-4), and descriptive norms held by uninvolved arbitrators (Experiment 5) echoed these cooperation patterns, but uninvolved arbitrators deemed it socially appropriate to cooperate more on the equal than the unequal public good regardless of beneficiary position. We discuss implications for theory and policy on cooperation. [ABSTRACT FROM AUTHOR]

Through 2019, the Caspian Sea excluded, the majority (54–60%) of Earth's irrigation-impacted endorheic lake and sea (ELS) areal extent has been lost in basins that contain as much as 20% of global irrigated agricultural land. Estimates of irrigated agriculture contribution to ELS desiccation based on a steady-state water balance equation for endorheic basins generally agree that this contribution is on the order of 70–90% at the global scale. However, large uncertainties or errors in attribution – as large as 100% – are observed with respect to particular ELS, suggesting that attributions based on a single irrigated agriculture dataset, should be treated cautiously. The observed areal contraction in ELS attributed to irrigated agriculture corresponds to an estimated one-third decrease in ELS volume, excluding the Caspian Sea. Such volumetric decrease is expected to at least double solute concentration in 40–47% of Earth's ELS. [ABSTRACT FROM AUTHOR]

This study examines War's Inefficiency Puzzle in a resource bargaining model, where the nature of the resource (e.g., water or land) can influence resource division valuation. In the model, an embedded resource conflict or contest model equilibrium constitutes the disagreement point. We first show that the Puzzle holds across all winner-take-all conflict forms in a generalized family given a standard bargaining (in the shadow of conflict) framework. When introducing resource division discounts, we find conditions in which a bargaining solution does not exist such that conflict is chosen over settlement. Resource division discounts can cause conflict to be chosen over any settlement point in the feasible set, thus providing a solution to War's Inefficiency Puzzle. This solution does not assume that a resource cannot be divided. It only assumes that division may lead to division discounts. We then consider a generalization of a classic tragedy of the commons model and find that division of an innate commons leads to division discounts as an equilibrium outcome. [ABSTRACT FROM AUTHOR]

In recent years, widespread peatland degradation has occurred in Indonesia as a result of both natural events and human activities. Although there is a strong push for restoration from national and international stakeholders, at the local level, farmers and communities are still widely managing peatlands with unsustainable practices including their conversion into agricultural land. To understand the causes of such a challenging situation, we carried out a survey to investigate the drivers of local livelihoods in the typical peatland village community of Kayu Labu in South Sumatra Province. Our findings showed that while the unsustainable practices adopted do not align with either the long-term interests of this community or the wider public interest, they do align with the best socioeconomic interests of the farmers. A preliminary examination of the livelihood options chosen illustrates the strong contrast between public and private interests. In particular, in local communities like Kayu Labu, the profit margins for oil palm and rubber are higher than those for sustainable alternatives. We conclude that, to address the problem of peatland degradation and to design successful and sustainable peatland restoration initiatives, decision-makers need to understand the local socioeconomic situation, people’s livelihoods, and their expectations. A key option is to increase the roles and responsibilities of local communities in determining the rules that relate to land management. Only then are regulatory and policy interventions likely to improve peatland conservation and restoration outcomes.

Ecological instability caused by pollution, climate change, or by exogenous distortions in the food chain of biological organisms may increase the average natural death rate of certain species, or it may increase the variance of their natural death rate, or both. Here, rational noncooperative strategic harvesting in a predator–prey ecosystem that is subject to exogenous environmental disturbances is studied through an example that delivers analytical solutions. When players exploit only one of two interacting species, then in symmetric Markovian–Nash equilibrium: (i) the 'tragedy of the commons' holds and (ii) when exogenous factors increase and/or make more volatile the natural geometric death rate of the species under exploitation (of the non-harvested species) each player's harvesting rate increases (decreases) and the commons problem is intensified (mitigated). [ABSTRACT FROM AUTHOR]

Should you reduce your energy consumption? Tragically enough, it may be better for you, and for everyone involved, to refrain from doing so even if you care about the climate. Given this tragedy, why cooperate? This paper defends the view that not cooperating is morally problematic because it is not universalizable (in a Kantian sense). That is, I will argue that we have universalizability-based reasons to cooperate as long as we have a preference for ‘collective success’ (e.g. a sustainable planet). The problem is that defectors let others fix the problem for them, and in this way make an unfair exception of themselves. Moreover, even when selected agents might not share this preference, they still have to cooperate for the sake of others. [ABSTRACT FROM AUTHOR]

In recent years, widespread peatland degradation has occurred in Indonesia as a result of both natural events and human activities. Although there is a strong push for restoration from national and international stakeholders, at the local level, farmers and communities are still widely managing peatlands with unsustainable practices including their conversion into agricultural land. To understand the causes of such a challenging situation, we carried out a survey to investigate the drivers of local livelihoods in the typical peatland village community of Kayu Labu in South Sumatra Province. Our findings showed that while the unsustainable practices adopted do not align with either the long-term interests of this community or the wider public interest, they do align with the best socioeconomic interests of the farmers. A preliminary examination of the livelihood options chosen illustrates the strong contrast between public and private interests. In particular, in local communities like Kayu Labu, the profit margins for oil palm and rubber are higher than those for sustainable alternatives. We conclude that, to address the problem of peatland degradation and to design successful and sustainable peatland restoration initiatives, decision-makers need to understand the local socioeconomic situation, people's livelihoods, and their expectations. A key option is to increase the roles and responsibilities of local communities in determining the rules that relate to land management. Only then are regulatory and policy interventions likely to improve peatland conservation and restoration outcomes. [ABSTRACT FROM AUTHOR]

Fish stocks are declining in marine capture coastal fisheries in West Africa. Many observers have blamed climate change and the system of open access for the decline. Open-access fishing encourages too many people to take up fishing, and the result is overfishing of the stocks. According to such critics, this is a classic example of Hardin’s tragedy of the commons, whereby a continuous increase in the number of users of a natural resource eventually leads to the collapse of the resource. The present study, which analysed stakeholders’ perceptions about their open-access fishing in Siera Leone’s marine fisheries, conducted 32 key informant interviews. Our research found that while they perceived that open-access fishing impacted fish stocks, most Sierra Leone’s marine capture fishers did not see open access as a cause of fish decline; instead, they blamed the lack of enforced regulations on the methods and extent of fishing. Accordingly, these fishers favoured the continuation of open access—not least because it helps to alleviate hunger and is a readily available source of protein in Sierra Leone’s coastal communities—but accompanied by strict regulations on both the type of fishing gear used and the quantity, size, and species of fish caught. In other words, they preferred regulated open access to unregulated open access. The central government’s resolve to regulate its fishery will determine whether it will transition from unregulated open access to regulated open access or other forms of OA. This study recommends detailed research into how to influence political will to enforce regulations.

The lack of pasture space in the Ferlo is nowadays the major concern of herders and various development actors in the sylvopastoral zone. It appears to be the main (re)known symptom, almost habitual, of the cyclical crises affecting pastoralism in Senegal. On the face of it, this situation can be interpreted as a banal ‘tragedy of the commons’, characterised by a significant increase in pressure on the resource, which is itself poorly managed since it belongs to everyone, and whose regeneration is furthermore hampered by both natural (climatic disruption) and anthropogenic (overgrazing, progression of the agricultural front) factors. However, in this situation as in others, the tragedy of the commons is a flawed, even simplistic, interpretative scheme, focusing mainly on the effects of animal demography and community management of grazing land, which are considered to be deleterious. A more detailed analysis of the various factors involved in this "grazing crisis" and the observation of the adaptive strategies of the farmers and the responses proposed by the differents organisations (ngos etc.) supporting the sector (fodder crops, food supplements in particular) lead to the formulation of other hypotheses: the fodder shortage might be the inevitable but underestimated consequence of a long series of interventions in the field of pastoral water supply. Also this crisis might reflect the exhaustion of the entire pastoral breeding model and the beginnings of a profound (and perhaps radical) transformation whose prospects remain uncertain. Rather than a tragedy with an inescapable end, should it not be seen as a turning point for the Ferlo and for pastoralist farming as it exists in the present conditions?

This exposition introduces a groundbreaking model that elucidates the role of societal norms and the preconscious in shaping cooperative behaviour, particularly with an eye towards averting the tragedy of the commons as conceptualised by the Prisoner’s Dilemma. Moving beyond the confines of rational-choice paradigms, this study harmonises Weber’s sociological theories with Freudian psychological insights, unveiling the nuanced interplay between conscious decision-making and deeper, preconscious motivations towards cooperation. It argues that an intricate understanding of both societal norms and the preconscious is crucial for crafting effective strategies to tackle the challenges of collective resource management.

What factors have driven the dramatic depletion of fishery resources in the South China Sea, and how have states responded? This article demonstrates that a complex mix of political, economic, and security drivers has led to the fishing crisis in the South China Sea in the fashion of a classic "tragedy of the commons." Although states have attempted to solve this problem by cooperating through bilateral, regional, and international arrangements, the article argues that states have also sought to exploit the situation as part of "hybrid" or "gray zone" strategies that blur the lines between private and public actors and between law enforcement and military activities. It identifies four mechanisms through which the conditions associated with the tragedy of the commons enable states to put fishers and fishing regulation on the frontlines of defending their territorial claims in the South China Sea. [ABSTRACT FROM AUTHOR]

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This study investigates the roles of informal gatekeepers in the context of First Nations health care in Canada. While existing literature focuses on gatekeeping by professionals, such as corporate board members, auditors, general practitioners, and specialists, we present empirical evidence on the role of informal First Nations' gatekeepers in a health care system. Gatekeepers engage with government and First Nations along a continuum of gatekeeping functions. Drawing on common pool theory, we use a case study to understand the gatekeepers' roles. We identify First Nations gatekeepers' roles to include health care program control, resource control, and ecosystem control. We also find that these gatekeepers constitute a viable long‐enduring common pool resource institution that can be useful for the federal government's phased approach in transitioning health care governance to the First Nations. [ABSTRACT FROM AUTHOR]

How can consumers be encouraged to take better care of public goods? Across four studies, including two experiments in the field and three documenting actual behaviors, the authors demonstrate that increasing consumers' individual psychological ownership facilitates stewardship of public goods. This effect occurs because feelings of ownership increase consumers' perceived responsibility, which then leads to active behavior to care for the good. Evidence from a variety of contexts, including a public lake with kayakers, a state park with skiers, and a public walking path, suggests that increasing psychological ownership enhances both effortful stewardship, such as picking up trash from a lake, and financial stewardship, such as donating money. This work further demonstrates that the relationship between psychological ownership and resulting stewardship behavior is attenuated when there are cues, such as an attendance sign, which diffuse responsibility among many people. This work offers implications for consumers, practitioners, and policy makers with simple interventions that can encourage consumers to be better stewards of public goods. [ABSTRACT FROM AUTHOR]

Common-pool resources (CPR) are shared by multiple individuals. Many natural or manmade CPRs are limited: maximization of their use for individual gain may bring negative consequences for all users. The current study simulated CPR management by children, with a digital game. The player extracted fish (CPR) using three types of cards varying in extraction power. Fishing returned points needed to remain "alive" in the game. In a baseline with unlimited and unshared resources, children used predominantly the most powerful card, with shorter interresponse time between successive fishing responses. An intervention phase followed, when resources were limited and shared with virtual players. A vertical bar signaled the number of fish, which decreased with extraction and increased periodically to simulate fish reproduction. With continued experience in the game, five of six children succeeded in moderating the extraction rhythm, earning enough points to stay "alive" in the game and avoiding CPR exhaustion. Their strategies combined decreasing the use of the most powerful card and increasing the frequency of longer IRTs, which allowed for regeneration of resources. Continued exposure to the contingencies shaped a more sustainable behavior. For most natural resources, however, it is not possible to shape sustainable extraction by repeated exposure to negative consequences, because resources may be permanently exhausted. The simulation of CPR management by children may, however, reveal variables and processes involved in sustainable behavior and may also be a valuable educational tool to teach sustainable behavior and the dangers of irresponsible use of CPR. [ABSTRACT FROM AUTHOR]

This essay begins with a trialogue on the definitions of "common property" and introduces two "traditions" of interpreting property rights. The older, traced to Gordon (1954) and propagated by Cheung (1970), distinguishes common from communal property; the younger, to Ciriacy-Wantrup & Bishop (1975) and made popular by Ostrom (2000), calls "commons" (communal in the sense of the older tradition) "common property. With the help of three matrices, the essay summarises the two traditions and explains that property rights and access are two distinct dimensions, respectively de jure and de facto, of resource enjoyment. [ABSTRACT FROM AUTHOR]

Growth redundancy, the overgrowth of resource-foraging organs in crop stands, is often detrimental to yield and is thus called a 'tragedy of the commons'. A tragedy can also arise owing to the plastic overproduction of competitive structures when intra-variety individuals forage in close proximity to each other. However, little is known about the sensitivity of crop varieties and resource availability to this 'plastic' tragedy. Pot experiments were designed to investigate this issue. The root competition environment was imposed by growing two plants of the same variety in mesh and plastic partitions. Two wheat varieties (old Monkhead and modern 92-46) were used, and two resource levels were established. Compared with 92-46, Monkhead allocated more biomass to stems and leaves and concurrently less to seeds. We identified intra-variety neighbour effects only in 4 out of 24 allometric comparisons with a small magnitude. Allometric data also revealed a lowered response to fertilizer addition in 92-46 than in Monkhead. Based on a limited sample size, our results revealed a trade-off between above-ground vegetative growth and crop yield. This trade-off resulted in a tragedy of the commons in old Monkhead and enhanced yields in modern 92-46. The tragedy of the commons in wheat may generally arise from genetically fixed traits in terms of growth redundancy in old varieties, rather than from the plastic behaviour of individuals. Modern 92-46 may adopt a conservative strategy of resource use, whereas old Monkhead employs an exploitative strategy. Our findings highlight breeders should select genotypes with low individual competitiveness. [ABSTRACT FROM AUTHOR]

Garrett Hardin's The Tragedy of the Commons is a classic piece of academic literature in geography and cognate fields. Applying theories of embodied cognition and performance pedagogies, this paper presents a classroom-based activity that can be used to teach the concepts of The Tragedy of the Commons in a way that will likely intersect with students' own lived experiences more meaningfully than Hardin's central example of a group of livestock owners making use of a shared field for grazing. The activity involves a dialogue among five student volunteer actors that iteratively portrays a group of friends trying to negotiate their own advantages alongside a sense of equity in the context of dividing the cost of a shared meal. During and after the performance, key opportunities are presented for the instructor to lead a discussion about Hardin's "tragedy" as well as the solutions he proposes by which it might be overcome. The model of scripted performance plus impromptu discussion used here can be applied to the teaching of other complex topics in the geography classroom. [ABSTRACT FROM AUTHOR]

【Objective】 Promote the rational use of groundwater resources and solve the problem of groundwater overexploitation. 【Method】 This paper conducts an economic analysis on the property of the "tragedy of the commons" over-exploitation of groundwater in the well-irrigated area, proposes a solution to the "tragedy of the commons" in the over-exploitation of groundwater in the well-irrigated area, and studies the initial distribution model of agricultural water rights in the well-irrigated area. It also analyzes the benefits and costs of household-based agricultural water rights in well-irrigated areas, and puts forward improvement suggestions for household-based agricultural water rights in well-irrigated areas. 【Result】 The overexploitation of groundwater is related to the "unrestricted" water intake of farmers in well irrigation areas. The existing agricultural water rights in well irrigation areas belong to the "village group" water rights system, and the definition of water rights is vague. Farmers use excessive groundwater for farmland irrigation, leading to the "tragedy of the commons" of groundwater overexploitation in well irrigation areas. The high cost of defining agricultural water rights in well-irrigated areas is the root cause of the unclear definition of agricultural water rights in well-irrigated areas. 【Conclusion】 The clear definition of agricultural water rights to households is helpful to solve the problem of groundwater overexploitation "the tragedy of the commons". In the process of defining water rights, measures should be taken to improve the construction of modern metering facilities, establish farmers' water use associations, introduce contractual water-saving management models and Measures such as establishing a transfer mechanism for surplus water rights in well-irrigated areas can reduce the cost of defining agricultural water rights, thereby promoting the definition of agricultural water rights in well-irrigated areas to households, improving the efficiency of agricultural water rights in well-irrigated areas, and optimizing the allocation of groundwater resources in well-irrigated areas.

Abstract In agriculture and plant breeding, plant traits may be favoured because they benefit neighbouring plants and ultimately increase total crop yield. This idea of promoting cooperation among crop plants has existed almost as long as W.D. Hamilton's inclusive fitness (kin selection) theory, the leading framework for explaining cooperation in biology. However, kin selection thinking has not been adequately applied to the idea of cooperative crops. Here, I give an overview of modern kin selection theory and consider how it explains three key strategies for designing cooperative crops: (1) selection for a less‐competitive plant type (a ‘communal ideotype’); (2) group‐level selection for yield; and (3) exploiting naturally selected cooperation. The first two strategies, using artificial selection, have been successful in the past but suffer from limitations that could hinder future progress. Instead, I propose an alternative strategy and a new ‘colonial ideotype’ that exploits past natural selection for cooperation among the modules (e.g., branches or stems) of individual plants. More generally, I suggest that Hamiltonian agriculture—a kin selection view of agriculture and plant breeding—transforms our understanding of how to improve crops of the future.

Plastic waste is one of the most notorious of all environmental issues – and also a hard problem to solve. From marine conservationists to engineers, many people have addressed the problem by tapping into technological solutions or attempting to raise public awareness, yet there are only limited examples of behavioural explanations for why people continue to litter in public places such as waterways. In this research, we examine the impact of settlement location (source, transition and floodplain zone) and perceived difficulties in getting the necessary resources. Focusing on river basins in Bali and East Java, we will also assess people's willingness to contribute resources in a Public Good Game, as a hypothetical reflection of their shares in community's greater good. We found that people living upstream contributed more to public good, but failed to correlate the effect of perceived difficulties in gaining resources to their contribution. [ABSTRACT FROM AUTHOR]

We study a class of non-cooperative aggregative games—referred to as social purpose games—in which the payoffs depend separately on a player's own strategy (individual benefits) and on a function of the strategy profile which is common to all players (social benefits) weighted by an individual benefit parameter. This structure allows for an asymmetric assessment of a common social benefit across players. We show that these games have a weighted potential, and we investigate its properties. We investigate the payoff structure and the uniqueness of Nash equilibria and social optima. Furthermore, following the literature on partial cooperation, we investigate the leadership of a single coalition of cooperators, while the rest of players act as non-cooperative followers. In particular, we show that social purpose games admit the emergence of a stable coalition of cooperators for the subclass of strict social purpose games. As a particular application, we study a standard formulation of the tragedy of the commons. We show that there emerges a single stable coalition of cooperators that curbs the over-exploitation of the common resource. [ABSTRACT FROM AUTHOR]

Nurdles have been referred to by some as a global environmental disaster. However, relative to the controversies surrounding industrial fracking practices, such as public health and safety associated with extraction of shale gas (as well as shale oil), the problems with nurdles are not as widely known. In this article, we highlight that fracking and nurdles are interrelated: fracking processes are a major source of the raw materials used to produce nurdles, which are tiny plastic pellets polluting our waters. Our contention is that a key question for analysis of fracking is how to regulate the externalities associated with downstream products produced in the fracking process. This article takes insights from Elinor Ostrom and scholars of the Bloomington School of Political Economy—such as polycentricity, diversity of collective action problems (CAPs), coproduction, and institutional diversity—to analyze nurdles pollution as a global commons problem. Nurdles generate widespread, large-scale negative externalities that are difficult to contain and address within a fixed geographical boundary governed by a static jurisdictional authority. Using the case of the Royal Dutch Shell cracker plant in Beaver County, Pennsylvania, we show that nurdles present complex and nested challenges that require coproduction, with citizen monitoring playing an essential role in mitigating negative externalities. We demonstrate the efficacy of applying polycentric approaches toward addressing CAPs associated with nurdles. [ABSTRACT FROM AUTHOR]