A 10-year decrease in plant species richness on a neotropical inselberg: detrimental effects of global warming?

19 20 The census of vascular plants across a ten-year interval (1995-2005) at the fringe of a 21 neotropical rainforest (Nouragues inselberg, French Guiana, South America) revealed that 22 species richness decreased, both at quadrat scale (2 m 2 ) and at the scale of the inselberg (three 23 transects, embracing the whole variation in community composition). Juvenile stages of all 24 tree and shrub species were most severely affected, without any discrimination between life 25 and growth forms, fruit and dispersion types, or seed sizes. Species turnover in time resulted 26 in a net loss of biodiversity, which was inversely related to species occurrence. The most 27 probable cause of the observed species disappearance is global warming, which severely 28 affected northern South America during the last 50 years (+2°C), with a concomitant increase 29 in the occurrence of aridity. 30 3