Vegetation growth and landscape genetics of Tillandsia lomas at its dry limits in the Atacama Desert shows fine-scale response to environmental parameters

<p>1. Ecosystems at its dry limits have been studied while focusing on species biology, fitness and interactions of biotic and abiotic parameters; however, the interactive effects of these parameters remain under-explored and, therefore, information is often lacking about the putative effect of global climate change on these ecosystems.</p> <p>2. Here, we conducted an analysis of the interplay of fine-scale landscape genetics and biotic and abiotic factors of terrestrial <i>Tillandsia</i> lomas in the hyperarid Atacama Desert, characterized by a fog-dependent vegetation type consisting of almost one single vascular plant species only.</p> <p>3. We showed that metapopulations of <i>Tillandsia landbeckii</i> are genetically connected over many hundreds of squarekilometres, and despite a large potential to propagate clonally genetic diversity is structured, regionally and locally. On landscape-level genetic diversity correlates well with fitness parameters such as growth, flowering and vegetation density, and we observed also fine-scaled correlation with a 3-D landscape model indicating a positive feedback with saisonal fog occurrence and availability. The various interdependies of biotic and abiotic factors also result in regular linear banding patterns of vegetation arranged orthogonally towards landscape slope. <i>Ex-situ</i> growth experiments indicate that <i>T. landbeckii</i> growths at optimal rates within this extreme, hyperarid environment, and we can extrapolate mean biomass production for this particular ecosystem.</p> <p>4. <i>Synthesis.</i> Our results suggest that the unique ecosystem of terrestrial <i>Tillandsia</i> lomas in the hyperarid Atacama Desert is an evolutionary balanced and fine-scaled system. Vegetation itself is built up by long-lived and persistent modules. We developed a descriptive model of the various interacting factors, thereby highlighting also a severe threat caused by global climate change.</p>