Dav4

The mulch, being in contact with the ground, would essentially maintain the same temperature as the ground. In other words, it wouldn't heat up much. As far as air circulation, I would think mulch has much more air in it, due to its large chunky nature, then say regular garden soil, which still has plenty enough oxygen for trees growing in your yard. Again, no worries. I've heard some folks will use old white t- shirts or sheets to wrap their pots with during the heat of the summer- white reflects heat. Others, particularly in the south or west, use shade cloth tents to protect the trees from intense summer sun.

Dave