Regeneration of California Oak Woodlands 2001 - 20051

The first (1981-1984) and second (1991-1994) statewide inventories of California’s oak woodlands found low levels of regeneration for several common oak species. In 2001, a new statewide inventory of California’s oak woodlands was initiated, with 10 percent of field plots measured each year. The first five years of data (2001-2005) were used to examine regeneration and sapling distributions in common oak woodland types. Blue oak (Quercus douglasii Hook. & Arn.), valley oak (Quercus lobata Nee), and coast live oak (Quercus agrifolia Nee) forest types are characterized by low numbers of saplings, having mean levels of 60.5 (+/10.2), 22.2 (+/-9.8), and 77.8 (+/18.7) trees per acre for all species of trees in the 1 to 5 inches diameter breast height (DBH) class. In this third decade of monitoring, diameter distributions for blue oak and valley oak departed from the expected inverse-J shape. Better information on population-wide growth and mortality of saplings would be useful for understanding whether these observations indicate trouble ahead for the long-term sustainability of these oak species.