Browsing by Author "Boehm, Christoph"

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    Evaluating the isotopic composition of leaf organic compounds in fog-dependent Tillandsia landbeckii across the coastal Atacama Desert: Implications for hydroclimate reconstructions at the dry limit
    (2024) Jaeschke, Andrea; Boehm, Christoph; Schween, Jan H.; Schefuss, Enno; Koch, Marcus A.; Latorre, Claudio; Contreras, Sergio; Rethemeyer, Janet; Wissel, Holger; Luecke, Andreas
    Fog is an important component of the coastal climate of northern Chile and southern Peru. Moisture and nutrients from fog maintain highly endemic vegetation (lomas) as well as unique Tillandsia landbeckii ecosystems that thrive at elevations of ca. 900-1200 m asl. Although this epiphytic CAM bromeliad is well adapted to the extreme climate, declining Tillandsia stocks observed over the past decades question the long-term survival with ongoing climate change. Here, we aim at better understanding the hydroclimatic signal encoded in the leaf organic compounds of Tillandsia landbeckii across the Atacama Desert's coastal mountain range (ca. 18-21 degrees S). First, we investigate spatiotemporal patterns of fog occurrence and related moisture sources available for the plants applying a new satellite -based fog -detection approach. We then use stable carbon, oxygen and hydrogen ( delta 13 C, delta 18 O, delta D) isotope analysis of leaf wax n -alkanes and cellulose to identify photosynthetic pathway as well as environmental and physiological processes that shape the isotopic composition in Tillandsia landbeckii . We find that leaf wax n -alkanes and cellulose reflect the balance of climatic and physiological drivers differently. While n - alkane delta D values more closely follow changes in precipitation delta D, evaporative enrichment seems to have a dominant influence on cellulose delta 18 O values. Cellulose delta D values are highly enriched compared to n -alkane delta D values, likely reflecting a predominant metabolic imprint on delta D. delta 13 C signatures in the organic compounds are valid proxies for CAM activity. Our results prove the general applicability of the isotopic biomarkers for reconstructing environmental change in the coastal Atacama Desert. This approach can be extended globally to west -coast deserts that share fog as a major source of moisture.