I recently planted a tree in a Keren Kayemet forest in Eretz Israel. I heard from someone that this is a mitzvah, but when I asked a rabbi he wasn't sure although he acknowledged it was a very good thing to do for Eretz Israel. Is planting a tree in Eretz Israel a mitzvah?
R Eliezer Melamed (Rosh Yeshiva in Har Bracha) writes that it is
We have already learned that the mitzvah of settling the Land of Israel does not involve only conquering it, but also requires the settling and developing of every part of it. The Ramban stresses this point that "We should not leave the Land under foreign rule or desolate, as it says: you should inherit the land and settle it."
Planting fruit trees in the Israel fulfills one aspect of this mitzvah, which obligates Am Yisrael to cultivate every part of the Land and not to leave it desolate. [...] Those living in Eretz Yisrael, however, have the mitzvah of planting fruit trees regardless of their profession.
The Chatam Sofer writes (in his commentary on Masechet Sukkah 36) that working the Land of Israel in order to harvest its holy fruit fulfills the mitzvah of settling the Land and the mitzvah commanding Am Yisrael to harvest the grains of the Land.
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