local ecology and local ecologist are participants in Blog Action Day. This photograph was taken on Friday, October 12, the first full day of rain this season. I was struck by two things: (1) the volume of runoff along the sidewalk and street and (2) the inability of the soil in the tree well to absorb throughfall and stem flow water. In the Bay Area, the fall is the best time to plant trees and other vegetation. Our neighborhoods and cities need more trees, but we should also maintain our existing trees. One type of maintenance is improving soil permeability so that less of our rainfall becomes runoff. The decomposition of mulch helps to aerate the soil; lower layers of vegetation - planted simultaneously with a new tree to prevent root damage - also helps to maintain soil permeability. For established trees, the soil can be aerated by carefully creating two-inch wide, twelve-inch deep, (avoid cutting the large, woody roots) and filling the holes with pea gravel, sand, or a mix of compost and one of the former materials. Plant and maintain our public shade trees and urban forest!