Not sure what you mean by respawn? Being able to cause the trees to spawn once again after the initial blow up and respawn?
I know theres rumors of this occurring, but yet to see anyone confirm this... I was at the initial blow up of the Yucca tree in both Fel and Tram and seen 3 respawn in Fel and 11 respawn in Tram. This made for a total of 16 on the shard..