Agricultural Settlement and Ecological Crisis in the Ecuadorian Amazon Frontier

This article discusses several structural factors in the policy environment of Ecuador thought to determine the process of occupation by agricultural colonists of the country's segment of Amazonia and the emerging land settlement patterns in the region. These factors are fundamentally concerned with (a) national sovereignty interests over remote, peripheral territories characterized by low population density and ill-defined land ownership, (b) the reduction of demographic and social pressures in other regions of the country, and (c) the extension of the agricultural frontier. For economic and geopolitical reasons, the Ecuadorian state is likely to maintain a moderate and rather ineffectual set of incentives supporfted by the current legislation to allow the occupation of the Amazon region. Consequently, as migrants continue to flow into the easily degradable areas of the Amazon, and without increased population carrying capacity outrside the Amazon, some conversion of the rainforest environment of eastern Ecuador to other uses is certain to continue. A more detailed microlevel understanding of the interrelationship among factors influencing land-use decisions by settler farmers is needed to find policy-entry points.     

INTERREGIONAL FEEDBACKS IN INPUT-OUTPUT MODELS: THE LEAST UPPER BOUND*

ABSTRACT. The least upper bound to the overall percentage error resulting from the omission of interregional feedbacks in input-output analysis is defined. This limiting value is the most informative of all upper bounds. A procedure for its computation is outlined and a number of experiments, using U.S. data, are discussed.     

Symbionts in a stromatoporoid-chaetetid association from the Middle Devonian Burdekin Basin,north Queensland

A spectacular association between a chaetetid, a stromatoporoid (Salairella sp.), and straight, vertical tubes interpreted to have housed symbiotic worms is reported from the Givetian Burdekin Formation, Burdekin Basin, north Queensland. The final growth surface of Salairella sp. shows skeletal distortion characterised by long, rather continuous coenosteles and coenostroms with upturned edges. This distorted interface was probably the result of spatial competitive interaction between the encrusting chaetetid and the underlying stromatoporoid. Neither sediment infilling, erosion or surface breakage occurs on the final growth surface of the stromatoporoid skeleton. As such, the growth of the Salairella sp. specimen appears to have been supressed by the encrusting chaetetid. Worm tubes are continuous through the distorted interface without interruption. The skeletal association also suggests that the round, straight, vertical tubes had a symbiotic intergrowth relationship initially with the stromatoporoid and, subsequently, the chaetetid.