Linking hydrological, geomorphological and biological properties in hyper-arid conditions: Distribution processes of a dominant clonal cactus by runoff

ALMIRÓN, M.; MARTINEZ CARRETERO, EDUARDO ENRIQUE; KALUZA NAVAS; ROTHIS LUIS

AUSTRAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018

1442-9985

The objective was to analyze the asexual spread of Tephrocactus aoracanthus (Cactaceae) 17 related to runoff triggered by torrential summer rains in a hyper-arid desert. Through a 18 manipulative essay, 30 joints were placed in the mainstream of an alluvial fan and 30 joints out 19 of the alluvial fan, without runoff influence (control). All joints were labelled, and their weight20 and diameter were measured. After each rain event with runoff, joints were surveyed identifying 21 their spatial coordinates and environmental context. For this, two factors with two levels each 22 one were selected: position respect to both microrelief (channels with concentrated runoff, or 23 inter-channels as flat areas between channels, without runoff) and vegetation (entangled or not24 entangled to shrubs). Through a geographic information system, changes in slope angle and 25 rugosity of terrain were analyzed. Linear regressions were performed between the partial 26 displacement of joints and their weight and diameter, grouped according to environmental 27 context before each rainfall. None of the joints of the control treatment were moved, but all 28 joints located in the mainstream did. Three great events triggered a mean displacement of 480.429 m; 103.0 m and 33.2 respectively (the mean movement of all joints was 577.12 m). As they 30 moved, the joints passed through several different environmental contexts, increasing the 31 proportion of joints entangled in vegetation and in inter-channel position.32 Until not rooted, joints could be displaced by runoff in an anisotropic process, with an evident 33 effect of slope angle and rugosity of terrain. On the other hand, no direct relationship was found 34 between the displacement and the magnitude of the event, or both the size and the weight of 35 joints. This paper offers new information on the dispersal mechanism of clonal plants, related to 36 conditions and enabling its agamic dispersal over long distances.