Tillandsia lomas delimitation

Whaley, Oliver Q., Orellana-Garcia, Alfonso & Pecho-Quispe, Juan Octavio, 2019, An Annotated Checklist to Vascular Flora of the Ica Region, Peru-with notes on endemic species, habitat, climate and agrobiodiversity, Phytotaxa 389 (1), pp. 448-450 : 448-450

Tillandsia lomas delimitation

Tillandsia and herbaceous lomas rarely overlap to form significant ecotones between one another; they occupy climatically and edaphically distinct landscape units ( Figs. 3 , 4 ). Elevation and aspect determine the temperature inversion and wind speeds that concentrate fog with resultant vegetation. We observed this limit at ca. 930 m elev. for herbaceous lomas, although it is more variable for Tillandsia lomas according to the species and latitude. Growing at ca. 1150 m elev., Tillandsia latifolia holds the upper altitudinal limit for the genus in the coastal lomas of Ica, thriving in the most xeric environment. In Chile and Peru, Dillon et al. (1991, 2011) and Pinto (2005) found herbaceous lomas vegetation had an elevation threshold around 900–1200 m. It appears that Tillandsia lomas in Chile occurs at higher elevations than in Peru. Oka & Ogawa (1984a) suggest a latitudinal correlation between Tillandsia lomas occurrence and elevation, where altitudinal limits increase southwards. From 8– 19°S, Tillandsia lomas distribution increases with altitude; as such at 9– 13°S (Lima being 12°S), occurring at 80–500 m elev. Southwards, in northern Chile (18– 20°S), Tillandsia lomas occurs at 1000–1300 m elev. More recently, Tillandsia virescens Ruiz & Pav. was recorded growing at 3800 m elev. in Arica (18°S) and Iquique (19°S) ( Pinto 2005). Rutllant et al. (2003) suggest that this may be a response to the marine air layer, diurnal solar heating and circulation affecting the heights of the thermal inversion air base.

Tillandsia lomas species (arenic and lithophytic) have radical adaptations, including roots with a loss of absorbing function. The short finger-like roots are exclusively for anchorage; the micro-morphology (and possibly exudates) contribute to their adhering function ( Brighigna et al. 1990). We observed how ‘arenic’ Tillandsia species retain dead structures (including roots), anchoring themselves in precise localities to occupy sandy and free-draining ‘sweet spots’, where fog moisture can be intercepted but is not retained in the soil. Moisture would rot the anchoring structure, allowing the wind to blow plants out of fog interception. This explains how Tillandsia cannot thrive within herbaceous lomas that is characterised by seasonal soil moisture retention. Aeolian sand is the principle substrate for Tillandsia arenic species in Ica, these are: Tillandsia landbeckii Phil. , T. latifolia , T. marconae W.Till & Vitek. , T. paleacea C.Presl. and T. purpurea . These species are found on dune margins of the pre-cordillera and on dry secondary ridge lomas (see Fig. 3 map). Tillandsia lomas in Ica constitutes the largest area of lowland vegetation, outside cultivated areas (1500 km 2), covering an area (south of the Río Pisco) of ca. 693 km 2.

Figures

FIGURE 3. Vegetation map of Ica. Showing: key vegetation types, national reserve (R.N.) protected areas, lomas, Prosopis forest relicts (low density), ancient Prosopis tree sites, collection localities, major rivers and towns. (illustration: OW with thanks to Justin Moat).

FIGURE 4. Vegetation survey transects of coastal lomas of Ica. Vegetation survey transects (25 km), run perpendicular westwards