Clonality and Dynamics of Leaf Abscission of Gambel Oaks at Small Spatial Scales in Utah

The Intermountain West of the United States supports a mosaic of Gambel oak (Quercus gambelii Nutt.) clumps interspersed with grassland. Both the tree and shrub forms of Gambel oak are typically found in distinct clumps that have often been presumed to be single clones, although quantitative evidence to support this is minimal. We examined the patterns of clonality within and between oak clumps and explored the variance in phenology of leaf abscission within and among clones and clumps in a study site in the Wasatch Mountains, Utah, USA. Using amplified fragment length polymorphism analysis, we genotyped multiple stems within 10 clumps of Gambel oaks in Red Butte Canyon. Nine of the 10 clumps were monoclonal (each a single distinct genet). The 10th clump was composed of 2 genets. To characterize the genetic influence on leaf abscission phenology, we compared the timing of abscission of individually marked leaves among genets, ramets, and branches. Of these three levels of organization, genet membership had the greatest influence on timing of leaf abscission, and branch membership had the smallest influence. Our results suggest that clonal diversity may be an important metric of phenotypic and ecological diversity in Gambel oak landscapes.