Are nurse plants always necessary for succulent plants? Observations in northeastern Mexico, including endangered and threatened species

Abstract

In harsh environments some plant species grow under the shelter of other plants. This spatial association known as nurse-protégé interaction is common in arid and semiarid environments. In here we studied the spatial association of six cacti (Ariocarpus retusus, Astrophytum asterias, Echinocactus texensis, Cylindropuntia leptocaulis, Sclerocactus scheeri and Mammillaria heyderi) and one Asparagaceae (Manfreda longiflora) to other plant species. We determined whether they occurred more often under other plants, if they grew very near them or at an angle that provided shade. Manfreda longiflora always grew under the canopy of other plants. Ariocarpus retusus, Astrophytum asterias, Cylindropuntia leptocaulis, and Mammillaria heyderi occurred equally under nurse plants and in open spaces. Echinocactus texensis and Sclerocactus scheeri occurred more often than expected in open areas, but Sclerocactus scheeri occurred shaded from the afternoon sun. We argue that nurse-protégé interactions are less common in our study site due to higher rainfall than that in other studied environments.