Mountain gradients are ideal laboratories for studying species range changes. In this study of 363 plant species in bloom collected in five segments across the 1,200 m (4158’) Finger Rock elevation gradient in the Santa Catalina Mountains north of Tucson, AZ, we looked for changes in species flowering ranges over a 20-year period.

Results/Conclusions

Ninety-three species (25.6%) exhibited a significant change in the elevation at which they flowered from the first half to the second half of the record, with the majority of these changes occurring at higher elevations. Most of the species exhibiting the changes were perennial plants. Interestingly, changes in flowering range were not specific to certain elevations or biomes; rather, range changes occurred all across the gradient. The changes reported in this study are concurrent with significant increases in summer temperatures across the region and are consistent with observed changes around the globe.