Abstract

Studying biodiversity in extreme environments allow us to understand how individuals and whole ecological communities are able survive at the limits for life. We characterized plant biodiversity in the hyperarid core of Atacama Desert as a first step to understand the unique features of Atacama plant communities that allowed them to survive under harsh abiotic conditions. In Atacama, plants must overcome aridity, high radiation and nutritional shortage among other extreme abiotic conditions. Plant biodiversity in the hyperarid Atacama varies over time in response to fluctuating environmental conditions from interannual to decadal timescales. Multiple life habit strategies are utilized in this environment. However, one common life form are annual plants, which can avoid drought years by forming soil seed banks that germinate when conditions are more suitable. In order to determine the composition of plant communities in the western slope of the Andes in the Atacama Desert, we performed plant diversity surveys over seven consecutive years in an altitudinal transect. We observed a total of 71 different plant species with significant inter annual variation (31 to 63 species) and species persistence (years of appearance, from one to seven years). Environmental DNA in surface soil samples complemented the surveys and revealed hidden plant diversity. DNA barcode analysis revealed 7 new taxa in the area, and a wide distribution of plant DNA. To complement field and molecular surveys, we performed an analysis of soil seed banks using the seedling emergence method. The soil seed bank proxy shows that viable seeds have wider ranges than observed plants. Our results show an increasing plant richness and composition in the study area, and an adaptive flexibility of the communities to the changes in the climate gradient of the Andes in Atacama Desert.