The phytogeography and ecology of the coastal Atacama and Peruvian Deserts

Abstract

Where coastal topography is low and flat, the clouds dissipate inward over broad areas with little biological impact, but where isolated mountains or steep coastal slopes intercept the clouds, a fog-zone develops. This moisture allows the development of plant communities termed lomas formations. These floristic assemblages function as islands separated by hyperarid habitat devoid of plant life. Since growth is dependent upon available moisture, an understanding of climatic patterns is essential in efforts to interpret present-day plant distributions. Topography and substrate combine to influence patterns of moisture availability. The ecological requirements and tolerances of individual species ultimately determines community composition. Species endemism exceeds 40% and suggests that the lomas formations have evolved in isolation from their nearest geographic neighbors in the Andes. While the arid environment is continuous, there appears to be a significant barrier to dispersal between 18° and 22°S latitude in extreme N Chile, Less than 7% of a total flora, estimated at nearly 1000 species, occur on both side of this region. -from Authors