XVI International Botanical Congess

Phenology data of flowering and fruiting from the pioneer species Salix hindsiana, S. laevigata, Populus fremontii, and the climax Acer negundo ssp. californicum and Juglans hindsii were weekly monitored to compare to climatic and favorable germination sites occurrence on the Putah creek riparian ecosystem. The pioneers showed a short reproductive period, 110 days from flowering to seed dispersal, while the climax showed a 2 to 3 times longer period, to mach specific and appropriated germination and establishment conditions. Pioneers dispersal period occur early April during the summer and soil moisture is only available close to the creek. On the other hand, climax species dispersal period is late fall/early winter where temperature is lower during the rain season. Therefore, dispersal period and seasonal events seems to be related to species spatial distribution (zonation) on the edge of the creek.