Studying the Ecological Relationship Between Elevation and Carnegiea gigantea Branching Patterns in Saguaro National Park West

Okrucky, Caleb

AP student report on saguaro branching research, directly studying the relationship between the number of arms a Saguaro grows and changes in elevation. Saguaro branching is a term used by scientists to refer to the extensions a saguaro grows from the main stem. Branching is a result of reproductive fitness. This is because each arm on the cactus has the same reproductive abilities as the main stem. Branching could be affected by any number of environmental influences such as precipitation, sunshine, height, nurse trees, elevation. Four hundred and twelve Saguaros were studied and data consisting of elevation as well as the number of arms grown was recorded. Data trends showed that overall, Saguaro branching became not only less common in higher elevations but also the number of arms growing on Saguaros became less frequent at higher elevations. There are many reasons for these observations but they are not limited to; Saguaro climate dependency, decreased precipitation and standing water at higher elevations and decreased humidity at higher elevations. The goal of this study was strictly to observe and theorize on the relationship between elevation change and the frequencies of Saguaro branching. There were a greater number of arms observed more frequently at lower elevations and as elevation increases, branching becomes less frequent and the number of arms grown decreases.