Martorell C., Patiño P., Globose cacti (Mammillaria) living on cliffs avoid high temperatures in a hot dryland of Southern Mexico, Journal of Arid Environments, 2006, 67(4):541-552, doi: 10.1016/j.jaridenv.2006.03.021
An experiment with six Mammillaria crucigera plants compares stem, substrate and air temperatures on a gypsum cliff and the flat ground above it during the dry season in Oaxaca. A radiation model presents annual and seasonal light input for different rock aspects. The second section analyses slope inclination and site elevation for ten species and tests the relationship between their mean values while accounting for phylogeny.