Spatial variation in seed dispersal and recruitment of Stenocereus thurberi, a columnar cactus from northwestern Mexico

Seed dispersal promotes gene flow, reduces intraspecific competition, maintains population dynamics, and enables the colonization of new or disturbed habitats. In the Sonoran Desert—where extreme aridity and high temperatures limit seedling establishment—the fate of a seed largely depends on the dispersal agent, the distance traveled, and the microhabitat in which it is deposited.

This project evaluates spatial variation in the seed dispersal patterns of a long-lived cactus species, Stenocereus thurberi, across three ecologically contrasting sites in the Sonoran Desert: Carbó, Punta Chueca, and El Pitayal (southern region).

The research begins with vegetation cover characterization and the identification of nurse plant species at each site. Reproductive phenology will be assessed through temporal monitoring of flowers and fruits, and fruits will be collected to measure mass, seed number, and sugar content.

To identify the main seed dispersers and predators, the team will use camera traps, mist nets, and feces collection. Digestive dispersal will also be assessed by sampling soil beneath the canopy of trees, shrubs, the mother plant, and open areas.

Finally, laboratory germination experiments will be conducted using three types of seeds: those recovered from soil, obtained from feces, and extracted directly from fruits. This study will provide insight into the seed dispersal and predation processes of a long-lived species, whose recruitment is episodic and depends on key plant-animal interactions for its persistence.