Abstract
In the coastal Atacama Desert in Northern Chile plant growth is constrained to so-called ‘fog oases’ dominated by monospecific stands of the genus Tillandsia. Adapted to the hyperarid environmental conditions, these plants specialize on the foliar uptake of fog as main water and nutrient source. It is this characteristic that leads to distinctive macro- and micro-scale distribution patterns, reflecting complex geo-ecological gradients, mainly affected by the spatiotemporal occurrence of coastal fog respectively the South Pacific Stratocumulus clouds reaching inlands. The current work employs remote sensing, machine learning and spatial pattern/GIS analysis techniques to acquire detailed information on the presence and state of <i>Tillandsia spp.</i> in the Tarapacá region as a base to better understand the bioclimatic and topographic constraints determining the distribution patterns of <i>Tillandsia spp.</i> Spatial and spectral predictors extracted from WorldView-3 satellite data are used to map present Tillandsia vegetation in the Tarapaca region. Regression models on Vegetation Cover Fraction (VCF) are generated combining satellite-based as well as topographic variables and using aggregated high spatial resolution information on vegetation cover derived from UAV flight campaigns as a reference. The results are a first step towards mapping and modelling the topographic as well as bioclimatic factors explaining the spatial distribution patterns of Tillandsia fog oases in the Atacama, Chile.
Highlights
The hyperarid coastal zone of northern Chile is home to unique ecosystems which depend on coastal fog as main source of water
As Tillandsia spp. depend on fog as primary water and nutrient source, their spatial distribution is constrained to areas covered by coastal fog of sufficient frequency, duration and intensity (Hesse 2012)
This contribution has demonstrated the application of remote sensing, machine learning and spatial pattern/GIS analysis techniques to acquire detailed information on the spatial distribution of Tillandsia spp. in the Tarapacá region as a base to better understand its bioclimatic and topographic envelope
Summary
The hyperarid coastal zone of northern Chile is home to unique ecosystems which depend on coastal fog as main source of water. Being the remnants of a continuous vegetation belt during the Pliocene, they nowadays occur in disjoint patches, so-called fog oases. The plant organisms existing under these environmental conditions have developed highly specialized adaptation strategies concerning the availability of water. One of the most characteristic vegetation units from Arica (18°20’ S) to the Loa river (21°25’ S) are Tillandsia spp. Tillandsia spp. grow without functional roots and are the ecological dominants over extensive areas of specialized communities called “Tillandsiales” or “Tillandsia lomas” (Westbeld et al, 2009). As Tillandsia spp. depend on fog as primary water and nutrient source, their spatial distribution is constrained to areas covered by coastal fog of sufficient frequency, duration and intensity (Hesse 2012)
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