Do nurse plants enhance cactus survival under global warming? Experimental evidence from Coryphantha maiz-tablasensis, a threatened species

Climate change poses a significant threat to arid and semiarid ecosystems, where drought, high solar radiation, and extreme temperatures limit plant regeneration. This study evaluated whether nurse plants can mitigate the effects of global warming and enhance the survival of Coryphantha maiz-tablasensis, a threatened cactus endemic to the Chihuahuan Desert. The experiment was conducted in San Luis Potosí, Mexico, using open-top chambers to simulate warming in two contrasting habitats: an abandoned agricultural field and beneath the canopy of Neltuma laevigata (mesquite), a common nurse plant. Simulated warming significantly increased air temperature, particularly in open areas. Although rainfall and soil moisture were lower under the mesquite canopy, cactus survival was substantially higher in this habitat—100 % in control plots and 95 % in warming plots—compared to 90 % survival in open control plots and complete mortality in open warming plots. These findings indicate that direct exposure to elevated temperatures and solar radiation is lethal to saplings. The results underscore the critical role of N. laevigata in buffering microclimatic extremes and supporting cactus regeneration. Incorporating nurse plants into conservation and restoration strategies may help reduce population loss under future climate change scenarios and ensure the long-term persistence of threatened cactus species.