Three-dimensional vegetation structure of Tillandsia latifolia on a coppice dune

• A structure-from-motion approach is used to record 3D vegetation structure of sparse plant cover.
• Sand ripples document the influence of dune topography and Tillandsia plants on near-surface air flow.
• A plant height map is used to analyse the alignment of Tillandsia plants with respect to wind direction.
• Alignment of plants in rows allows long-term upright growth due to reduced aeolian erosion at the plant base.

Coppice dunes covered by epiarenic Tillandsia fog vegetation occur in the Peruvian coastal desert. To analyse the three-dimensional vegetation structure on such a coppice dune, a photogrammetric structure-from-motion approach is applied. A photogrammetric plant height map was derived from a digital surface model and a digital terrain model created by this approach. This plant height map is analysed in conjunction with stand-scale vegetation patterns, regional wind direction derived from migrating dunes, near-surface wind direction derived from the orientation of sand ripples and ground observations. Tillandsia vegetation patterns are non-random. Banded and reticulate patterns occur at stand scale. At metre to sub-metre scale, groups of tall plants occur in clusters as well as in rows aligned with air movement. While self-organisation processes related to maximising fog moisture capture by the plants and to coppice dune growth appear to control the development of the banded to reticulate pattern, retaining an upright growing position (and hence continued exposure to fog moisture on decadal time scales) by minimising aeolian erosion at the base of these rootless plants appears to control the development of rows and clusters at metre to sub-metre scale.