Effect of brousse tigrée on the dynamics of nurse–protégé interactions of a cactus in the Chihuahuan Desert

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 permanent plots monitored between 2008 and 2019. The differential association of E. enneacanthus with potential nurse plants was evaluated using an interaction network, under the hypothesis of strict association of the seedlings and juveniles with nurse species. In addition, χ2 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.

Damage in a saguaro (Carnegiea gigantea) population in the El Pinacate and Gran Desierto de Altar Biosphere Reserve, Sonora, Mexico

“…Its distribution is limited to the north by freezing conditions, to the south possibly by competitive relationships with other plants, and to the east by the Sierra Madre Occidental, while to the west (where the studied population is located) the limiting factor could be the scarcity of summer rains, which are of great importance for the recruitment of new individuals (Yetman et al, 2020). Saguaro populations occur in tiger bush ("brousse tigrée") patches because of the facilitative relationships between nurse plants and protected species (Aranda-Pineda et al, 2021;Drezner, 2006).…”

Population dynamics of three cloud forest ferns of different growth form

“…Demographic analyses of plant populations provide synthetic information on the processes that determine population growth and identify important stages in the life cycle (Franco & Silvertown, 2004). Therefore, demography has been a very useful tool in management and conservation programs for populations of angiosperms and gymnosperms (Aranda‐Pineda et al, 2021; Salguero‐Gómez et al, 2015; Salguero‐Gómez & de Kroon, 2010; Vandermeer & Goldberg, 2003). In the demographic models of 102 plant species, survival contributed most to the estimated values of finite rates of population growth (λ), although growth and reproduction were also important in species with short life histories or associated with the first successional phases of the ecosystem (Franco & Silvertown, 2004).…”