if on the surface they will probably be ok. but if you dig them in then as they decompose they will upset the balance of your soil. do you have an area where you can store them for about 6 months.

Seaburn's suggestion is a good one - best left to decompose a bit before using them as a mulch. if you try to use them now as a mulch, you will need to apply lots of nitrogen rich feed during this year for your plants, preferably under the mulch at first, and then watered on every six weeks.