Ash tends to raise soil pH when applied (makes soil less acidic). Most pines prefer a slightly acid soil pH, not sure about cedar. Ash is mostly composed of micro nutrients - plants use these in small amounts compared to N, P, and K - too because it's the unburned mineral portions of the wood. There is probably some P2O5 (fertilizer form of P) in there too. Nitrogen is lost during the burning process. I would save the ash for the vegetable garden (or the lawn if gardening isn't your thing), it will do more good there.