Losses due to clearing for urbanization and agriculture have been compounded by regeneration failure within many existing stands. Sapling populations in many oak woodlands are insufficient to offset mortality of older trees, leading to a gradual conversion of oak woodland to oak savanna and finally to annual grassland. Suppression of regeneration in areas that would otherwise be suitable for oak growth seems to be a recent phenomenon (within the past 60 to 80 years), and is in many cases due to long-term livestock grazing. In many woodlands that have been impacted by long-term grazing, the degradation of the ecosystem is so profound that oak woodland vegetation may not recover for many decades after grazing is eliminated, if it recovers at all.
Oak reproduction problems in woodlands and savannas used as livestock range usually do not extend to horticultural situations. Besides being fairly easy to grow in cultivation, many California oaks volunteer readily in horticultural settings such as flower beds, shrub plantings, and lawns. These horticultural environments are safe sites for oak reproduction: favorable environments that may differ substantially from adjacent oak woodlands located no more than a short distance away. The key to restoring oaks to their former range lies in recreating safe sites for oak reproduction.
In these pages, we have described specific techniques that can be used to help reestablish oaks in areas where they once grew. To establish new oaks, we need to ensure that: