# User's Contributions

Displaying 1 - 15 of 26 records found.
Title
Type

### A model of robustness tradeoffs in social-ecological system

Model
Feedback control systems in general exhibit inherent robustness-fragility tradeoffs. That is, by becoming very robust to a given set of disturbances for maintaining stability, feedback systems necessarily introduce hidden fragilities to disturbances outside this set. Even a small unanticipated disturbance can initiate cascading system-wide failures as a result. The model presented here demonstrates this phenomenon. In Anderies et al. (2012), an agricultural production system is illustrated as...
09 Aug 2016

### A Two-Sector Growth Model: Economic Development, Demographics, and Renewable Resources

Model
This is a two-sector growth model that couples the dynamics of human demographics and a renewable resource base. The two sectors are agricultural and manufacturing sectors. To capture both the positive (Malthusian) and negative (modern growth) type relationships between population growth and output, it is important to model the shifting composition of output from agricultural to manufacturing as growth occurs. Thus, the model is a two sector (productions and consumptions in...
09 Aug 2016

### Analyzing the Impact of Agave Cultivation on Famine Risk in Arid Pre-Hispanic Northern Mexico

Model
Here, a simple model of a subsistence economy based solely on the cultivation of maize and agave is presented. While maize is an annual plant that humans can eat and store, agave is a perennial plant that can be used for multiple purposes: as edible materials yielding caloric values and as fiber materials for producing items like clothing, ropes, and baskets.  This model tries to capture the essence of a cultivation strategy of a portfolio of plants that have differing levels of sensitivity...
09 Aug 2016

### Animated demonstration of the Lorenz Model

Model
Animated demonstration of the Lorenz model and its sensitivity to initial conditions.  The simulation starts with twenty points very close to each other, and follows them as they move further away. The starting values differ in the fifth and sixth significant digits of a single coordinate. The Lorenz model was developed by Edward Lorenz in 1963 to study fluid mechanics.The model is a three-dimentional system of differential equations. Specifically, the model describes the convection motion of a...
09 Aug 2016

### Australian Rangelands Model

Model
This model tells a story of resilience of a rangeland system in Australia. Anderies et al. (2002) provides the following overview of the model. "We developed a stylized mathematical model to explore the effects of physical, ecological, and economic factors on the resilience of a managed fire-driven rangeland system. Depending on grazing pressure, the model exhibits one of three distinct configurations: a fire-dominated, grazing-dominated, or shrub-dominated rangeland system. Transaction costs...
09 Aug 2016

### Brander-Taylor Model

Model
This is the original Brander-Taylor Easter Island model. Brander and Taylor (1998) describes the model as the following: "The paper presents a general equilibrium model of renewable resource and population dynamics related to the Lotka-Volterra predator-prey model, with man as the predator and the resource base as the prey. We apply the model to the rise and fall of Easter Island, showing that plausible parameter values generate a 'feast  and famine" pattern of cyclical adjustment in...
09 Aug 2016

### Brander-Taylor model and variations

Case
Brander-Taylor Easter Island Model and its variations. Brander and Taylor (1998) summarizes the background of the model as the following. Easter Island (also called Rapa Nui) is a small Pacific island over 2,000 miles (3,200 km) from the coast of Chile, with a population (as of the early 1990's) of about 2,100. For the past two centuries, Easter Island has been regarded as a major archaeological and anthropological mystery. In particular, the Polynesian civilization in place at the time of...
09 Aug 2016

### Conflict between groups of players in coupled socio-economic and ecological dynamics

Model
This is a model for the coupled dynamics of conflict between two different user groups regarding their socioeconomic choice (between cooperative and non-cooperative collective action) and nutrient loading input level into a lake water system. Suzuki and Iwasa (2009),gives the following overview of the model. "Conflict among multiple groups is a major source of difficulty in environmental conservation. People are often divided into various groups that have different social factors, sometimes  ...
09 Aug 2016

### Culture and Human Agro-ecosystem Dynamics: the Tsembaga of New Guinea

Model
The model of Tsembaga agro-ecology explores the coupled dynamics involving population growth, renewable resource base, resource consumption by humans, and the self-regulating effect of cultural ritual. The model demonstrates that the cultural ritual of Tsembaga (Kaiko) can stabilize the Tsembaga population and its resource level. This is achieved by attenuating wildly fluctuating limit cycles of population and resource levels down to desirable small-amplitude cycles. Anderies (1998) describes...
09 Aug 2016

### Fishery Model

Model
This is a standard Gordon-Schaefer model that simulates a simple open-access fishery in discrete time. A fishery stock grows logistically and is harvested by humans. Fishers always exert too much effort and harvest fish at a level that is socially NOT optimal. This happens because fishers are driven to harvest until their net profit drops down to zero. A socially optimal level of harvesting effort is attained when marginal cost of harvesting effort and marginal revenue from harvesting become...
09 Aug 2016

### Lorenz Model

Model
This simple model was developed by Edward Lorenz in 1963 to study fluid mechanics (based on Navier-Stokes equations). It is the first ever model of a chaotic dynamical system. Chaos arises when a deterministic, nonlinear dynamical system exhibits long-term unpredictability in behavior due to sensitivity to initial conditions.The model is a three-dimentional system of differential equations. Specifically, the model describes the convection motion of a fluid in a small idealized "Rayleigh-...
09 Aug 2016

### Lotka-Volterra Competition

Model
Symmetric competition model
09 Aug 2016

### Non-linear dynamics of population and natural resources: The emergence of different patterns of development

Model
This model explores the long-term dynamic interaction between the exploitation of natural resources and population growth. This is a variant of Brander and Taylor (1998). The reference article, D'Alessandro (2007), gives the following description of the model. "Two new assumptions are introduced: i) the disaggregation of the ecological complex into two different resources; ii) irreversibility —namely, an inexorable tendency to exhaustion when the renewable resource stock is below a certain...
09 Aug 2016

### Paradox of marine protected areas: suppression of fishing may cause species loss

Model
This is a simple model of a prey–predator system in two areas, one of which receives fishing activity (fishing ground) and another that does not (MPA: marine protected area). Takashina et al. 2012 gives the following description of the model. "A number of fish and invertebrate stocks have been depleted by overexploitation in recent years. To address this, marine protected areas (MPAs) are often established to protect biodiversity and recover stocks. We analyzed the potential impact of...
09 Aug 2016

### Pezzey-Anderies Model

Model
This model describes the Pezzey-Anderies extension to the Brander-Taylor Easter Island model. In addition to the parameters in the Brandor-Taylor model, Pezzey and Anderies have introduced $tax$ and $h_m$. Pezzey and Anderies (2003) gives the following overview: "We extend the Brander–Taylor model of population and resource development in an isolated society by adding a resource subsistence requirement to people's preferences. This improves plausibility; amplifies population overshoot and...
09 Aug 2016