Tree Blog

Quercus agrifolia vs. Quercus lobata | Planted Same Day Stanford

This photo shows a set of Coast Live Oaks (Quercus agrifolia) growing next to a set of Valley Oak (Quercus lobata) at the Dish above Stanford. All trees were planted the same day back in 1992. Throughout the Dish, from thin hilltop soils lacking access to groundwater, all the way to deep alluvial soils with moderate groundwater access, Coast Live Oak notably outperforms Valley Oak. For many years, it was standard practice to plant multiple species at each planting site, Coast Live Oak, Valley Oak, and even Blue Oak (Quercus douglasii). Coast Live Oak dominates these multi-species sites. In places, the Coast Live Oaks have been pruned back to allow the slower Valley Oak to gain a foothold. 15 years after the first of this pruning was done, the Coast Live Oaks had thoroughly reasserted themselves, suggesting futility to the efforts. Blue Oak growth has been so slow and inconsistent as to barely warrant mention, with many dead. Blue Oak is one of many canaries worldwide, warning of profound shifts already occurring in the biosphere, with other shifts very likely on the way.

Dave Muffly