Economic models of shifting cultivation: a review

This chapter reviews farm-level economic models of shifting cultivation and those of deforestation and soil conservation related to shifting cultivation. Although economists have made significant progress in modeling shifting cultivation over the last two decades, extant economic models neither clearly distinguish between primary and secondary forests nor address potential roles of on-farm soil conservation in shifting cultivation. Developing a unified farm model of primary forest clearing, forest fallowing, and on-farm soil conservation is needed to examine effective policies for protecting primary forest and maintaining sustainable secondary fallow forest. The chapter points to promising avenues for future modeling.

Constraints or Cooperation? Determinants of Secondary Forest Cover Under Shifting Cultivation

This study examines the drivers of land use in a shifting cultivation system with forest fallow. Forest fallow provides on-farm soil quality benefits, local hydrological regulation, and global public goods. An optimal control model demonstrates that farmers have an incentive to fallow less than is socially optimal, though market failures limiting crop production can have a countervailing effect by encouraging fallow. An econometric model estimated using data from the Brazilian Amazon suggests that fallowing does not result from internalization of local fallow services but instead is associated with poor market access and labor and liquidity constraints.forest, farms, fallow, ecosystem services, land use, spatial econometrics, Brazil, credit, International Development, Land Economics/Use,

Payments and Mechanism Design

We use mechanism design to study efficient intertemporal payment arrangements when the ability of agents to perform certain welfare-improving transactions is subject to random and unobservable shocks. Efficiency is achieved via a payment system that assigns balances to participants, adjusts them based on the histories of transactions, and periodically resets them through settlement. Our analysis has several implications for the design of actual payment systems. Efficiency requires that, in order to overcome informational frictions, agents participating in transactions that do not involve monitoring frictions subsidize those that are subject to such frictions. Optimal settlement frequency should balance liquidity costs from settlement against the need to provide intertemporal incentives. Settlement costs must be borne by agents for whom the incentives to participate in the system are highest. Finally, an increase in settlement costs implies that, in order to counter a higher exposure to default, the frequency of settlement must increase and, at the same time, the volume of transactions must decrease.Payment Systems, Frequency of Settlement, Liquidity Costs, Subsidization across Transactions

A dynamic model of the payment system

The authors study the design of efficient intertemporal payment arrangements when the ability of agents to perform certain welfare-improving transactions is subject to random and unobservable shocks. Efficiency is achieved via a payment system that assigns balances to participants, adjusts them based on the histories of transactions, and periodically resets them through settlement. Their analysis addresses two key issues in the design of actual payment systems. First, efficient use of information requires that agents participating in transactions that do not involve monitoring frictions subsidize those that are subject to such frictions. Second, the payment system should explore the trade-off between higher liquidity costs from settlement and the need to provide intertemporal incentives. In order to counter a higher exposure to default, an increase in settlement costs implies that the volume of transactions must decrease, but also that the frequency of settlement must increase. ; Also issued as Payment Cards Center Discussion Paper No. 07-14Payment systems

TRANSFORMATION OF FALLOW SYSTEMS UNDER POPULATION PRESSURE

In a fallow-cultivation model with biomass regeneration, we find the population-poverty-degradation linkage via the discount rate: slight increases in the discount rate result in increased cropping frequency and much lower soil fertility. Aggregating gives transitions equation declining in fertility and increasing in the fallow:cultivation ratio.Land Economics/Use,

Nonlinearity and chaos in economic models: implications for policy decisions

This survey paper discusses the policy implications that can be expected from the recent research on nonlinearity and chaos in economic models. Expected policy implications are interpreted as a driving force behind the recent proliferation of research in this area. In general, it appears that no new justification for policy intervention is developed in models of endogenous fluctuations, although this conclusion depends in part on the definition of equilibrium. When justified, however, policy tends to be very effective in these models.Macroeconomics ; Economic stabilization

"Hysteresis in Dynamic General Equilibrium Models with Cash-in-Advance Constraints"

In this paper, we investigate equilibrium cycles in dynamic general equilibrium models with cash-in-advance constraints. Our findings are two-fold. First, in such models, if an equilibrium cycle exists, then there also exists a continuum of equilibrium cycles in its neighborhood. Second, the limit cycle, to which a dynamic path converges, varies continuously according to the initial distribution of the money holdings. Thus, temporary shocks that affect the initial distribution have permanent effects in such models; that is, such models exhibit hysteresis. Furthermore, we also explore the logic behind the results.

Network-constrained models of liberalized electricity markets: the devil is in the details

Numerical models for electricity markets are frequently used to inform and support decisions. How robust are the results? Three research groups used the same, realistic data set for generators, demand and transmission network as input for their numerical models. The results coincide when predicting competitive market results. In the strategic case in which large generators can exercise market power, the predicted prices differed significantly. The results are highly sensitive to assumptions about market design, timing of the market and assumptions about constraints on the rationality of generators. Given the same assumptions the results coincide. We provide a checklist for users to understand the implications of different modelling assumptions