Simon Matthias May

The Atacama Desert hosts a unique ecosystem formed by the sand-dwelling Tillandsia landbeckii, which extends over hundreds of square kilometers. This vegetation relies primarily on fog as its main water source; however, aeolian sand also plays a crucial role in the long-term persistence of both the species and the overall plant community. The terrain is sloped and exposed to the prevailing wind direction. Tillandsia forms regular banding patterns oriented orthogonally to these landscape features. In this study, we aim to elucidate the abiotic–biotic interactions between sand properties and vegetation characteristics through a comparative approach. Three populations – Caldera, Oyarbide and Arica –, each spanning several square kilometers in the southern, central, and northern regions of the Chilean Atacama Desert, were selected to compare wind regimes, terrain structure, sand and substrate properties, and vegetation structure in order to identify common principles that maintain vegetation integrity. Data were collected from six climate stations, 1,246 substrate samples, population genomic data from 718 individuals, as well as satellite imagery and digital terrain models. Our findings demonstrate that regional wind systems transport sand from distant source areas, while near the ground, Tillandsia vegetation reduces wind velocity and traps sand, leading to the formation of moderately sorted sandy substrates that are similar across all three populations. Sites lacking or containing dead Tillandsia individuals often differ significantly in substrate characteristics. Genetic analyses indicate that Tillandsia populations exhibit strong spatial structure albeit recruiting high genetic diversity and an excess of heterozygosity, reflecting adaptation to the dynamic environmental conditions. We conclude that sand represents an essential component of this ecosystem, while Tillandsia, as the dominant biotic factor, actively shapes and maintains this distinctive desert environment.

The Atacama Desert hosts a unique ecosystem formed by the sand-dwelling Tillandsia landbeckii, which extends over hundreds of square kilometers. This vegetation relies primarily on fog as its main water source; however, aeolian sand also plays a crucial role in the long-term persistence of both the species and the overall plant community. The terrain is sloped and exposed to the prevailing wind direction. Tillandsia forms regular banding patterns oriented orthogonally to these landscape features. In this study, we aim to elucidate the abiotic–biotic interactions between sand properties and vegetation characteristics through a comparative approach. Three populations – Caldera, Oyarbide and Arica –, each spanning several square kilometers in the southern, central, and northern regions of the Chilean Atacama Desert, were selected to compare wind regimes, terrain structure, sand and substrate properties, and vegetation structure in order to identify common principles that maintain vegetation integrity. Data were collected from six climate stations, 1,246 substrate samples, population genomic data from 718 individuals, as well as satellite imagery and digital terrain models. Our findings demonstrate that regional wind systems transport sand from distant source areas, while near the ground, Tillandsia vegetation reduces wind velocity and traps sand, leading to the formation of moderately sorted sandy substrates that are similar across all three populations. Sites lacking or containing dead Tillandsia individuals often differ significantly in substrate characteristics. Genetic analyses indicate that Tillandsia populations exhibit strong spatial structure albeit recruiting high genetic diversity and an excess of heterozygosity, reflecting adaptation to the dynamic environmental conditions. We conclude that sand represents an essential component of this ecosystem, while Tillandsia, as the dominant biotic factor, actively shapes and maintains this distinctive desert environment.

The Atacama Desert hosts a unique ecosystem formed by the sand-dwelling Tillandsia landbeckii, which extends over hundreds of square kilometers. This vegetation relies primarily on fog as its main water source; however, aeolian sand also plays a crucial role in the long-term persistence of both the species and the overall plant community. The terrain is sloped and exposed to the prevailing wind direction. Tillandsia forms regular banding patterns oriented orthogonally to these landscape features. In this study, we aim to elucidate the abiotic–biotic interactions between sand properties and vegetation characteristics through a comparative approach. Three populations – Caldera, Oyarbide and Arica –, each spanning several square kilometers in the southern, central, and northern regions of the Chilean Atacama Desert, were selected to compare wind regimes, terrain structure, sand and substrate properties, and vegetation structure in order to identify common principles that maintain vegetation integrity. Data were collected from six climate stations, 1,246 substrate samples, population genomic data from 718 individuals, as well as satellite imagery and digital terrain models. Our findings demonstrate that regional wind systems transport sand from distant source areas, while near the ground, Tillandsia vegetation reduces wind velocity and traps sand, leading to the formation of moderately sorted sandy substrates that are similar across all three populations. Sites lacking or containing dead Tillandsia individuals often differ significantly in substrate characteristics. Genetic analyses indicate that Tillandsia populations exhibit strong spatial structure albeit recruiting high genetic diversity and an excess of heterozygosity, reflecting adaptation to the dynamic environmental conditions. We conclude that sand represents an essential component of this ecosystem, while Tillandsia, as the dominant biotic factor, actively shapes and maintains this distinctive desert environment.

The Atacama Desert hosts a unique ecosystem formed by the sand-dwelling Tillandsia landbeckii, which extends over hundreds of square kilometers. This vegetation relies primarily on fog as its main water source; however, aeolian sand also plays a crucial role in the long-term persistence of both the species and the overall plant community. The terrain is sloped and exposed to the prevailing wind direction. Tillandsia forms regular banding patterns oriented orthogonally to these landscape features. In this study, we aim to elucidate the abiotic–biotic interactions between sand properties and vegetation characteristics through a comparative approach. Three populations – Caldera, Oyarbide and Arica –, each spanning several square kilometers in the southern, central, and northern regions of the Chilean Atacama Desert, were selected to compare wind regimes, terrain structure, sand and substrate properties, and vegetation structure in order to identify common principles that maintain vegetation integrity. Data were collected from six climate stations, 1,246 substrate samples, population genomic data from 718 individuals, as well as satellite imagery and digital terrain models. Our findings demonstrate that regional wind systems transport sand from distant source areas, while near the ground, Tillandsia vegetation reduces wind velocity and traps sand, leading to the formation of moderately sorted sandy substrates that are similar across all three populations. Sites lacking or containing dead Tillandsia individuals often differ significantly in substrate characteristics. Genetic analyses indicate that Tillandsia populations exhibit strong spatial structure albeit recruiting high genetic diversity and an excess of heterozygosity, reflecting adaptation to the dynamic environmental conditions. We conclude that sand represents an essential component of this ecosystem, while Tillandsia, as the dominant biotic factor, actively shapes and maintains this distinctive desert environment.

The Atacama Desert hosts a unique ecosystem formed by the sand-dwelling Tillandsia landbeckii, which extends over hundreds of square kilometers. This vegetation relies primarily on fog as its main water source; however, aeolian sand also plays a crucial role in the long-term persistence of both the species and the overall plant community. The terrain is sloped and exposed to the prevailing wind direction. Tillandsia forms regular banding patterns oriented orthogonally to these landscape features. In this study, we aim to elucidate the abiotic–biotic interactions between sand properties and vegetation characteristics through a comparative approach. Three populations – Caldera, Oyarbide and Arica –, each spanning several square kilometers in the southern, central, and northern regions of the Chilean Atacama Desert, were selected to compare wind regimes, terrain structure, sand and substrate properties, and vegetation structure in order to identify common principles that maintain vegetation integrity. Data were collected from six climate stations, 1,246 substrate samples, population genomic data from 718 individuals, as well as satellite imagery and digital terrain models. Our findings demonstrate that regional wind systems transport sand from distant source areas, while near the ground, Tillandsia vegetation reduces wind velocity and traps sand, leading to the formation of moderately sorted sandy substrates that are similar across all three populations. Sites lacking or containing dead Tillandsia individuals often differ significantly in substrate characteristics. Genetic analyses indicate that Tillandsia populations exhibit strong spatial structure albeit recruiting high genetic diversity and an excess of heterozygosity, reflecting adaptation to the dynamic environmental conditions. We conclude that sand represents an essential component of this ecosystem, while Tillandsia, as the dominant biotic factor, actively shapes and maintains this distinctive desert environment.

Aeolian erosion of the alluvial deposits in the hyper-arid core of the Atacama Desert appears in several sites in the form of deflation hollows. Despite constituting signs of degradation of the unique and ancient landscape, their architecture and formation is as yet poorly understood. Ground-penetrating radar (GPR) is an effective way to image the internal structure of such aeolian landforms, and in this study, eight 200-500 m GPR profiles were acquired across deflation hollows and an eroded alluvial fan. A 400 MHz antenna was used, penetrating more than 3 m deep. Evaporitic crusts and salt-cemented layers were identified and mapped. In the leeward side of hollows, younger aeolian deposits can be differentiated from the older alluvial sediments, and similarities were found in the radar facies of several eroded surfaces. This work reveals the shallow subsurface architecture of the aeolian cover and alluvial deposits and provides new insights into the landscape formation in hyper-arid environments through the use of GPR.

The Atacama Desert hosts a unique ecosystem formed by the sand-dwelling Tillandsia landbeckii , which extends over hundreds of square kilometers. This vegetation relies primarily on fog as its main water source; however, aeolian sand also plays a crucial role in the long-term persistence of both the species and the overall plant community. The terrain is sloped and exposed to the prevailing wind direction. Tillandsia forms regular banding patterns oriented orthogonally to these landscape features. In this study, we aim to elucidate the abiotic–biotic interactions between sand properties and vegetation characteristics through a comparative approach. Three populations - Caldera, Oyarbide and Arica -, each spanning several square kilometers in the southern, central, and northern regions of the Chilean Atacama Desert, were selected to compare wind regimes, terrain structure, sand and substrate properties, and vegetation structure in order to identify common principles that maintain vegetation integrity. Data were collected from six climate stations, 1,246 substrate samples, population genomic data from 718 individuals, as well as satellite imagery and digital terrain models. Our findings demonstrate that regional wind systems transport sand from distant source areas, while near the ground, Tillandsia vegetation reduces wind velocity and traps sand, leading to the formation of moderately sorted sandy substrates that are similar across all three populations. Sites lacking or containing dead Tillandsia individuals often differ significantly in substrate characteristics. Genetic analyses indicate that Tillandsia populations exhibit strong spatial structure albeit recruiting high genetic diversity and an excess of heterozygosity, reflecting adaptation to the dynamic environmental conditions. We conclude that sand represents an essential component of this ecosystem, while Tillandsia , as the dominant biotic factor, actively shapes and maintains this distinctive desert environment. Graphical Generated based on own drawings and iterative improvements using ChatGPT while providing own peer-reviewed research contributions as input and baseline information (MAK). Short summary: We exemplify unimodal regional wind systems facilitating sand transport toward Tillandsiales. Tillandsiales show a low-energy wind system allowing sand accumulation of predominant grain sizes available at each site. Thereby Tillandsia landbeckii modifies and maintains its own microenvironment. Genomic data reveal high clonality and excess of heterozygosity promoting fitness in a hyperarid environment, and abiotic factors drive the selection of diverse and adaptive Tillandsia phenotypes.

The hyperarid conditions of the central Atacama Desert, characterized by extremely low precipitation and high evaporation rates, create a unique environment where geomorphic stability is generally considered to be exceptionally high. Terrestrial cosmogenic nuclide-based surface exposure ages suggest that many surfaces underwent limited to no geomorphic changes since the Neogene or early Pleistocene. However, a number of recent studies reveal more recent landscape-scale geomorphic activity and link this to slightly wetter episodes during the Quaternary. In order to determine drivers of geomorphic activity, we performed a multi-proxy analysis of five profiles situated in alluvial deposits along a climatic transect from the coastal plain to the upper reaches of the Coastal Cordillera (~ 0–2000 m a.s.l.), combining single-grain feldspar luminescence dating with geochemistry, granulometry, and field observations. Alluvial deposits are prone to heterogeneous bleaching; therefore, we tested the bleachability of the feldspars and found a shallow effective bleaching depth (< 2 cm) and high near-surface bleachability. The five profiles studied could be grouped into geomorphological active and stable sites, based on our multi-method approach. Profiles located on geomorphologically active surfaces show evidence of recent sediment deposition and, in one case, vertical grain transport. In contrast, stable surfaces preserve reworking signals relating to bioturbation at the coast and desert pavement formation in the hyperarid Coastal Cordillera. While no clear chronological trend along the west–east climatic gradient could be found, two phases of widespread geomorphic surface activity – ~ 50 ka and during the last ~ 5 ka – coincide with regionally wetter intervals compiled from other studies. Our findings highlight the value of single-grain luminescence data for reconstructing local sediment dynamics and soil reworking in arid environments, and the need to account for both depositional and post-depositional processes in paleoenvironmental interpretations.