This paper provides a numerical general equilibrium assessment of policies to reduce tropical deforestation in Cameroon. Market failure mainly in the form of national and international externalities and policy failures such as highly distorted product markets are identified as major sources of overexploitation. The ecological effects of deforestation control are shown to depend crucially upon i...

Global bifurcation analysis of a class of general predator–prey models with a strong Allee effect in prey population is given in details. We show the existence of a point-to-point heteroclinic orbit loop, consider the Hopf bifurcation, and prove the existence/uniqueness and the nonexistence of limit cycle for appropriate range of parameters. For a unique parameter value, a threshold curve separ...

At the time of European settlement, the relative importance of insects in the diets of Australian Aborigines varied across the continent, reflecting both the availability of edible insects and of other plants and animals as food. The hunter-gatherer lifestyle adopted by the Australian Aborigines, as well as their understanding of the dangers of overexploitation, meant that entomophagy was a sus...

This article investigates the design of incentives in a dynamic adverse selection framework where agents' production technologies display learning effects and agents' learning rates are private knowledge. In a simple two-period model with full commitment available to the principal, we show that whether learning effects are overor underexploited crucially depends on whether more efficient agents...

Following the overexploitation of sea turtle populations, conservation measures are now in place in many areas. However, the overall impact of these measures is often unknown because there are few long time-series showing trends in population sizes. In a recent paper, George Balazs and Milani Chaloupka chart the number of green turtles Chelonia mydas nesting in Hawaii over the past 30 years and...

Discrete and commercially important patches of weathervane scallops ( Patinopecten caurinus ) are found in the northeastern Pacific Ocean. Little is known about weathervane scallop life history and population structure, but the species is vulnerable to overexploitation because of their large size and long lifespan. Here we describe 16 polymorphic microsatellite loci developed to study the relat...

D espite the grim view of resource overexploitation and the collapse famously described in Hardin’s (1) much-cited ‘‘Tragedy of the Commons,’’ we now know that local governance institutions have the potential to overcome common pool resource dilemmas. A growing literature (2, 3), including Chhatre and Agrawal’s analysis of forest commons (4) in this issue of PNAS, demonstrates the conditions of...

Global bifurcation analysis of a class of general predator-prey models with a strong Allee effect in prey population is given in details. We show the existence of a point-to-point heteroclinic orbit loop, consider the Hopf bifurcation, and prove the existence/uniqueness and the nonexistence of limit cycle for appropriate range of parameters. For a unique parameter value, a threshold curve separ...

After volcanic explosions or tidal waves had defaunated several islands near New Guinea, bird species number rapidly returned to equilibrium on coral islets and rapidly returned to quasi-steady-state values limited by regrowth of vegetation in lowland forest of larger islands. However, reequilibration in montane forest has been limited by slow dispersal of the birds. Colonists have been drawn d...