Question: Why is it nevertheless not Patur from Ma'aser because he declared it Hefker (seeing as Hefker is Patur from Ma'aser)?

Answer #1: Like Beis Hillel, who holds in Maseches Pe'ah (Perek 6, Mishnah 1) that it is not Hefker unless one declares it Hefker for poor and rich alike, like Sh'mitah.

Source: And the Yerushalmi learns from Sh'mitah, from the Pasuk "Tishmetenah u'Netashtah". 'Why does the Torah write "u'Netashtah"? To teach us that there is another 'Netishah' which is comparable to it (to the Sh'mitah). And what is that? That is what one renders Hefker for the poor and to the rich'.

Answer #2: Alternatively, it goes even according to Beis Shamai, who holds that 'Hefker for the poor is considered Hefker'. And the reason is as it explains there - because the Torah writes "for the poor and the rich ... ". Why does the Pasuk add "Ta'azov osam"?

Answer #2 (cont.): To teach us that there is another 'Azivah' which is similar to this one (Pe'ah). And what is that? "Hefker for the poor and not the rich.

Answer #2 (concl.): Nevertheless, here he is Chayav, because it is 'Hefker be'Ta'us'.

Conclusion: By Pe'ah itself however, everyone agrees that one is Patur from Ma'aser, as the Sifri Darshens "And the Levi shall come since he does not have a portion and an inheritance together with you"- 'to preclude this (Pe'ah) where the Levi does have an inheritance, because if he is poor, he takes Pe'ah'.

Clarification: Rashi explains that 'Chatzitzah invalidates by Kodshim, because the Torah writes "And the Kohen shall take" - The Kohen needs to take it with his body'.

Question: But by Lulav we don't say that - when, in Perek Lulav ha'Gazul (Succah 37.) in connection with the Din that forbids someone to take a Lulav with a cloth, Rava says that 'Lekichah via something else is called Lekichah'?

Answer: The Ri answers that there it is speaking about somebody who is holding the Lulav using a cloth like a pair of tweezers, where he wound the cloth around the Lulav, and held the cloth, so that the cloth actually helps him to hold the Lulav. Under such circumstances it is not considered a Chatzitzah.

Proof: Indeed, it is implied in that Sugya, that this is how the Gemara is speaking, since the Gemara says there that 'One should not squeeze the Lulav together with the Hadasim and the Aravos, in case the leaves fall off, and it will be a Chatzitzah.

Proof (cont.): Rava says that Miyn be'Miyno (the same species) is not considered a Chatzitzah.

Proof (concl.): Thei implies that a different species would be a Chatzitzah. That is because the case there is similar to the case in our Sugya, where he wrapped his hand in the cloths, and in such a case it is considered a Chatzitzah.