Abstract

ZENTENO RUIZ, Freddy S.; LOPEZ, Ramiro Pablo  and  LARREA ALCAZAR, Daniel M.. Patterns of spatial distribution of Parodia maassii (Heese) A. Berger (Cactaceae) in a semi-desert of the subtropical Andes, the prepuna. Ecología en Bolivia [online]. 2009, vol.44, n.2, pp.99-108. ISSN 1605-2528.

In this study, we analyzed the spatial pattern of Parodia maassii, a globose cactus of the subtropical Andes. Specifically, we evaluated the relation between the spatial pattern of this cactus species and dominant woody strata of the locality where the study took place. Our data showed a marked clustered pattern of P. maassii in 1-10 m patches, suggesting that facilitation (nurse plant syndrome) could be functioning in this Andean drought-stressful habitat, affecting the early stages of the establishment of the species. We recorded, however, a positive attraction of their individuals with perennial bushes at small scales (<2 m) and repulsion at intermediate scales (9-13 m). A possible explanation indicates that the cactus species needs the shade of the shrubs in order to get established, but that later it prefers open areas where it grows better. Field tests in which seedlings are placed below shrubs and open areas are required to support this possibility.

Keywords : Globose cacti; Facilitation; K function of Ripley; O function of Wiegand-Moloney; Arid zones.

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