The needles are long. Around here, people put down redwood bark to keep the weeds out of their garden. These pine needles are acting as the same type of benefit.

When I expand the house (I'm in permit approval at the moment) my plan is to rototill the ground and rototill the needles and the gravel into the soil. The needles will add nutrients to the soil, and the rocks will disperse underground and allow air pockets and water to form around the rocks for aeration.

Contrarian, extraordinaire