can dryad arbor tap for land the turn its played

[flien2]

can dryad arbor tap for forest the turn it is played

[Kenji]

Dryad Arbor has summoning sickness the turn it is played, so it cannot be tapped for mana.

Please remember -- lands are not mana, and mana is not land. I'm sure you realize this, but the terminology is important. Lands are the cards themselves, such as Forest or Dryad Arbor -- mana is what they produce. Lands are tapped for mana, and said mana can be used to cast spells or activate abilities.

When a card wants you to put a land onto the battlefield, then that's what the card will say -- see Evolving Wilds, Cultivate and countless other cards that illustrate this point.