Many tropical pioneer species depend on the presence of highseeddensities inthesoil forsuccessful recruitment following canopy disturbance (Cheke et al. 1979, Dalling & Hubbell 2002, Guevara Sada & Gómez Pompa 1972, Whitmore 1983). However determinants of variation in the composition and abundance of soil seed banks remain poorly understood. Seed bank densities can be affected by rates of seed ...

The aim of this paper is to provide a theoretical model that can account for price fluctuations in depletable resource markets. We do so by introducing learning into a Hotelling-style duopoly model of optimal resource depletion. Before the depletable resource becomes scarce, the self-confirming equilibrium of the model mirrors noncooperative rational expectations equilibrium in that supply is h...

Zambian farmers have extensive experience with maize hybrids and input subsidies. Like other countries in Eastern and Southern Africa, the successful development and diffusion of improved maize seed in Zambia during the 1970s and 1980s was supported by strong government commitment to parastatal grain and seed marketing and subsidized provision of services to maize growers. When this system was ...