Figure 3

Average number of seeds of the three dominant shrub genera (Ceanothus, Arctostaphylos, and Prunus) per 0.01 m³ (1 m × 1 m × 0.01 m depth) in six layers from the top of the forest floor to 10 cm deep in mineral soil at 22 unburned forested sites in northern California. Layer 2+ is the upper duff from the top of the duff to 2 cm above mineral soil, layer 2-0 is the lower duff from 2 cm down to mineral soil, layer 0–2 is the top 2 cm of mineral soil, layer 2–4 is from 2 cm to 4 cm deep, layer 4–6 is from 4 cm to 6 cm deep, layer 6–10 is from 6 cm to 10 cm deep.