Brazilian paramos. II. Macro- and mesoclimate of the campos de altitude and affinities with high mountain climates of the tropical Andes and Costa Rica

摘要

A basic analysis of the macro- and mesoclimate of the Brazilian campos de altitude, a series of cool-humid mountain grasslands in southeastern Brazil, is presented. Beginning at altitudes of 1800-2000 m, the campos de altitude are found atop the highest summits of the main ranges of the southeastern Brazilian Highlands, between the states of Santa Catarina and Minas Gerais/Espirito Santo. Macro- and mesoclimatic parameters for the campos de altitude are derived from both original data and previously reported results. Parameters include approximate radiation budgets, temperature lapse rates, seasonal and diurnal patterns in temperature, occurrence of frost, elevational gradients in precipitation, and interannual and seasonal patterns in precipitation. Using multivariate techniques and simple numerical contrasts, the climate of the campos de altitude is compared to climates of other tropical and temperate alpine sites. With respect to patterns of seasonality and the marked influence of polar frontal activity, the macroclimate of the campos de altitude is typically tropical-marginal. However, in reference to actual temperature and precipitation values, the length and profundity of the dry season, average humidities and cloudiness, the climate of the campos de altitude more closely corresponds to that of more inner-tropical systems. These commonalities are best developed with respect to paramo climates of the northern Andes and, especially, Costa Rica. Their very different latitudinal and geographic positions notwithstanding, the campos de altitude and high mountain formations of the N. Andean and Central American Cordillera show clear macroclimatic congruities. In these congruities reside both the environmental basis for strong Andean-southeast Brazilian biogeographic connections, and the context within which evolutionary and ecological parallelisms have developed in the biota of these two widely separate neotropical mountain systems.