To lease and to lease out are essentially interchangeable in this context, since the sentence specifies both parties to the lease arrangement.
To lease simply means that one is in a leasing contract; it does not indicate whether one is the tenant or the landlord.
To lease out indicates that the speaker is the landlord. So...
We lease the land
...is an incomplete statement. It could be read that 'we' rent the land from someone else - indeed, that would be the plainest reading.
We lease out the land OR We lease the land out
Both of these are complete. They indicate that 'we' are the owner of the land, and we allow someone else to use it according to a contract.
We lease the land to the Forestry Commission
This is complete. It indicates that 'we' own the land, and the Forestry Commission are the tenants.
In your example sentence the "out" is redundant, but not incorrect. Since it also specifies the direction of the lease - from the speaker to the Forestry Commission - it is not strictly necessary to include out. While it's not necessary, it's not incorrect, either. This means that both sentences are effectively identical in meaning.