In Southern California, the red willow (Sa/ix laevigata Bebb) hosts a variety of gall-inducing parasitic insects. However, little is known about the ecology of these parasites, particularly the characterization of their microclimate preferences. This study explores the relationship between microclimate and gall frequencies in S. laevigata in the Ballona Wetlands and Temescal Canyon, and gall count correlated with biotic and abiotic factors such as soil pH, soil moisture and willow density. Significantly more galls per leaf were found at Temescal Canyon than Ballona Wetlands. Although the number of galls per leaf correlated negatively with soil pH, soil moisture content and canopy openness, only site and gall location were found to significantly predict the number of galls. These results suggest that additional or interacting microclimate factors may influence gall frequencies between Temescal Canyon and the Ballona Wetlands.
Vilgalys, T., R. Sears, E. Hand, S. Morledge-Hampton, and V. Carmona-Galindo (2014).Exploration of climate influences on the abundance of galls on red willow (Salix /aevigata) across two riparian communities in Southern California. Journal of Ecology and the Natural Environment 6(5): 164-169.