Effects of Aridity on Plant Diversity in the Northern Chilean Andes: Results of a Natural Experiment

Hyperarid climates in western South America from 15°S to 29°S, extending up to 3,000 m in the northern Chilean Andes, result primarily from the Andes intercepting precipitation from the Intertropical Convergence during which i cie is thought to have increased from east to west, as opposed to west to east, as occurs north of 25% today.For t les remaining intact vegetation belts (desert scrub, Andean, and high Andean) by hriday on à d scale.Although diversity (measured as a synthetic characteristic e areas of highest rainfall, annual herbs gain greatest prominence in areas d intermediate aridity, while woody species were propottionately a "d strongly represented under extreme dry The wo ood y habit is generally more common in the northern Andes eee in some eh North.pete plant also seen in many species-rich, climatically benign tropical plant communities.The hypo othesis is developed that harsh arid environments of the northern Chilean Andes and in species-rich tropical communities, respectively.We predict that additional life-history trait similarities (e.g., in reeding systems) will emerge for the plant species of abiotically and biotically "harsh" environments, respectively.