I'm a little unclear on the The Magic the Gathering card Hickory Woodlot
Hickory Woodlot enters the battlefield tapped with two depletion counters on it.
Tap, Remove a depletion counter from Hickory Woodlot: Add {G}{G} to your mana pool. If there are no depletion counters on Hickory Woodlot, sacrifice it.
The card is a land, so can it be tapped without removing a depletion counter to produce mana as normal?
Do you sacrifice it immediately after removing the counter? In other words do you have to have counters on it to use it's ability or can you use it one last time without?