Association between nurse plants and saguaros (Carnegiea gigantea) in the western Sonora

The objectives in this work were to determine nurse species associated with the saguaro, as well as the diversity of plant species in the saguaro patch. We also recorded the presence of termites on saguaro green tissues to evaluate their existence and possible causes for their presence. At each site a point-centered quarter transect was used, where the data on the closet saguaros were taken for size and height, percent litter soil coverage, and termite activity, as well as floristic composition, plant species cover, and the dimension of the associated patch of vegetation. Data on 55 saguaros showed the most common nurse species were Larrea tridentata, Olneya tesota, Parkinsonia microphylla, and Ambrosia deltoidea. Twenty-one (21) saguaro individuals were found distributed in different patches where Olneya tesota and Parkinsonia microphylla showed the most species diversity. Termite activity was present in saguaros with little or no litter cover in the soil. This is the first work focusing on the causes for the increase of termite invasion of live saguaro tissues.