Research & Conservation Report

Abstract

In the first study of its kind, TD Drezner at the University of Wisconsin has quantified and statistically analyzed the spatial relationships between saguaros and the plants that serve to protect them as they grow, a.k.a. nurse plants. Thirty populations of C. gigantea in the northern Sonoran Desert were examined and catalogued based on their proximity to each other and to nurse plants of three types: leguminous trees; small, densely canopied Ambrosia shrubs; and the larger, less dense L. tridentata. The study found that all young saguaros favor being as close to the base of plants as possible, but they tend to prefer trees and shrubs with denser canopies. The author concludes that “microclimate differences are the most likely factor shaping cacti-nurse association in the harsh desert environment.” Drezner tD. Plant facilitation in extreme environments: the nonrandom distribution of saguaro cacti (Carnegiea gigantea) under their nurse associates and the relationship to nurse architecture. Journal of Arid Environments, in press.