Based on what you have shared with us, the Landlord does not need a reason to fail to renew. If the lease is up on 8/1/12 and the Landlord provides the proper written notice to you, then the lease will terminate on 8/1/12. If the Landlord fails to give proper notice then it appears that you will be under a month-to-month lease which means either party can terminate (without reason) on 30 days written notice to the other.
This response does not create an attorney-client relationship and is not intended to provide legal advice for your specific situation.
No, this is not an eviction; and no, the landlord does not need a reason not renew a lease. Based on the facts provided, if you receive a notice from the landlord within 30 days prior to expiration of the lease, you have to move out by the end of the month. If no notice is received, you can remain on the premises on month-to-month basis. Although period tenancy does not have a definite period, one thing to keep in mind is that according to the terms of your lease, either you or the landlord must provide a 30 day notice to the other prior to terminating said tenancy.