At Yahoo news, an article had the headline "You Should Never Pile Mulch
Around A Tree In Your Yard". The article links to another one at
Women's Health, but that one does not have the same headline

The Yahoo headline is an alarmist generalization. If followed, it might
mean the loss of some trees. Western oaks -- especially the valley
white oak (Quercus lobata) and the coast live oak (Quercus agrifolia) --
need a thick mulch of leaves across their entire root zone. These trees
are adapted to a climate where significant rain falls only for a few
months in the winter. Without a thick mulch, the soil in which they
grow will get too hot and dry in the summer.

Of course, Yahoo's Web site provides NO method for reporting problems
with its news articles.

--
David E. Ross
Climate: California Mediterranean, see
http://www.rossde.com/garden/climate.html
Gardening diary at http://www.rossde.com/garden/diary