Trees have been on the earth for 390 million years, according to woodland biologist Artur Cisar-Erlach. Through photosynthesis, trees produce the air we breathe and form the soil beneath our feet. His obsession with wood started during his early training as a cabinet maker. He describes how Kenyans are using charcoal from trees in yogurt-making, and a Swiss cheesemaker is using the cambium layer of spruce trees to age cheese. His new book is “ The Flavor of Wood. ”