This photo was taken in 2004. The balls of green on the hillside are Coast Live Oak (Quercus agrifolia) planted from acorn in 1989. They received two years of summer irrigation on this north-facing slope, where Coast Live Oak outcompetes the deciduous Blue Oak and Valley Oak due to greater shade tolerance. In the midground, you see more robust young Coast Live Oak planted from #1 containers in 1988 - these were irrigated for nearly 5 years during the summer, and are growing essentially on the banks of a creek, in alluvial soil. In the foreground are small Coast Live Oaks - the soils in the foreground are heavy black clay and the trees have grown very poorly. Soils can change fast, as shown here, so knowing soils when planting is critical.