ORIGINAL ARTICLE Effect of brousse tigrée on the dynamics of nurse–protégé interactions of a cactus in the Chihuahuan Desert José A. Aranda-Pineda 1 | Pedro L. Valverde 2 | Alberto Búrquez 3 | Jordan Golubov 4 | María C. Mandujano 1 1 Laboratorio de Genética y Ecología, Departamento de Ecología de la Biodiversidad, Instituto de Ecología, Universidad Nacional Autónoma de México, UNAM. Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico 2 Departamento de Biología, Universidad Autónoma Metropolitana-Iztapalapa, Ciudad de México, Mexico 3 Departamento de Ecología de la Biodiversidad, Instituto de Ecología, Universidad Nacional Autónoma de México, Hermosillo, Mexico 4 Departamento El Hombre y su Ambiente, Universidad Autónoma Metropolitana- Xochimilco, Ciudad de México, Mexico Correspondence María C. Mandujano, Laboratorio de Genética y Ecología, Departamento de Ecología de la Biodiversidad, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510. México. Email: mcmandujano@iecologia.unam. mx; mcmandujano@gmail.com Funding information Consejo Nacional de Ciencia y Tecnología, Grant/Award Number: 221362; Global Environment Facility, Grant/Award Number: GEF 00089333 Abstract A nurse–protégé relationship is a frequent facilitation interaction in deserts that allows the recruitment of new individuals of many species. Our aim was to evaluate the relationship of Echinocereus enneacanthus during its life cycle and its nurse plants in the brousse tigrée (tiger bush) vegetation of the Chihuahuan Desert. The population structure of the cactus is skewed toward adult stages, which are commonly found in the bare areas of the brousse tigrée, whereas juveniles are located in the vegetated bands. The vegetation structure and the nurse–protégé relationship were determined using censuses of 19 per- manent plots monitored between 2008 and 2019. The differential association of E. enneacanthus with potential nurse plants was evaluated using an interac- tion network, under the hypothesis of strict association of the seedlings and juveniles with nurse species. In addition, χ 2 tests and standardized residuals were fitted among likely nurse species, weighted by the cover of the nurse and of the areas without vegetation. The study species, as well as the nurse plants, had an aggregated distribution pattern. The interaction network showed that the frequency of the association with nurse plants decreased as the size of the protégé individuals increased. At the same time, there were differences in the establishment of E. enneacanthus under particular nurse plants; Prosopis glandulosa and Hilaria mutica were the most important. The nurse–protégé relationship for seeds and seedlings is integral to the vegetation bands of the brousse tigrée. KEYWORDS Cactaceae, ecological networks, establishment, facilitation, nurse plants 1 | INTRODUCTION Facilitation occurs when one of the parties modifies the environment in ways that permit the survival, growth or reproduction of the other species (Callaway, 1995; Callaway, 2007; Holmgren, Scheffer, & Hustos, 1997; Stachowicz, 2001). A nurse–protégé interaction (biotic: plant–plant; abiotic: rock/crack-plant) is a notable facili- tation interaction in which one species of a plant or abi- otic structure acts as a nurse for another plant by generating suitable conditions under its canopy that allow the establishment of new individuals of a different species (Callaway, 1995; Cody, 1993; Munguía-Rosas & Sosa, 2008; Peters, Martorell, & Ezcurra, 2008; Received: 2 September 2020 Revised: 19 February 2021 Accepted: 1 March 2021 DOI: 10.1111/1442-1984.12329 Plant Species Biol. 2021;1–13. wileyonlinelibrary.com/journal/psbi © 2021 The Society for the Study of Species Biology 1