The role of biomass in shifting cultivation

Shifting cultivation has traditionally been characterized as a highly productive system in terms of the ratio of energy outputs to inputs. This characterization, however, does not take into account the energy contribution of the natural vegetation cleared in preparing the field for cultivation. As a result, the central feature of shifting cultivation, the exploitation of the natural vegetationsoil complex as a substitute for human labor, has been ignored. The omission of the biomass contribution can be attributed to both a focus on the practices involved rather than the underlying strategy of the shifting cultivator, and an excessive preoccupation with the renewability of the energy sources involved in different agricultural systems. A definition of shifting cultivation is proposed that focuses attention on the relationship between the natural vegetationsoil complex and the shifting cultivator. Two methods of including the energy contribution of forest biomass in calculating the productivity of shifting cultivation systems are compared. When the biomass contribution is included, shifting cultivation appears to be an extremely unproductive system of agriculture.I would like to thank Bill Denevan, Chris Uhl, Christine Padoch, Tom Klak, Bob Buschbacher, and Mimi Kranichfeld for their comments on earlier versions of this paper.     

Community Studies in Latin America

Revolt Against the Dead: The Modernization of a Mayan Community in the High- lands of Guatemala. Douglas E. Brintnall .
Agrarian Reform and Peasant Economy in Southern Peru. David Guillet .
San Rafael: Camba Town. Ally MacLean Stearman .     

拉丁美洲药用植物

本文简介了拉丁美洲药用植物的总体情况,30多种重要种类的产地、药用部位、活性成分、功效,以及常用种类的简要情况。     

Eltor cholera in Latin America

Cholera epidemics in South and Central America in the period 1991-1999 are characterized. The mechanisms of existence of Vibrio eltor in environmental objects have been substantiated. The causes and conditions of endemic foci formation which determine the infection spread not only within the countries of the subcontinent, but also far beyond its borders are shown. The effectiveness of cholera control interventions is evaluated.     

Epidemiology of sporotrichosis in Latin America

Summary Applying the concept of epidemiological chain, it is successively analyzed: the etiologic agent, Sporothrix schenckii and its natural reservoirs (sources of infection); the different ways that infecting particles may reach man (mechanisms of infection); the susceptible population and the population at risk; the incidence and distribution by sex and age in countries of Latin America; the prevalence of the disease according to clinical cases in dermatological clinics and the variation of incidence rates in some countries with time; the influence of the environment mainly climatic conditions on the geographic distribution of the disease.Finally, according to Mackinnon's hypothesis, the climate could have a determining role on the predominance of a certain clinical form on another in different countries.This paper was presented at the X^th ISHAM Congress, Barcelona, Spain, 1988.     

Ethics and genetics in Latin America

Genetic research in human beings poses deep ethical problems, one being the problem of distributive justice. If we suppose that genetic technologies are able to produce visible benefits for the well being of people, and that these benefits are affordable to only a favored portion of society, then the consequence is obvious. We are introducing a new source of inequality. In the first section of this paper, I attempt to justify some concern for the distributive consequences of applying genetics to human beings. This concern transcends a mere preoccupation for material equality. I argue that genetic inequality can undermine the very basis of social cooperation, at least regarding health care. The second section is more practical. My aim is to defend how, at least in some legal and cultural frameworks (such as those clearly apparent in some Latin American countries), the undesired distributive consequences of genetics are more likely to arise and more difficult to avoid.