Trees have made an alliance with another amazing microscopic symbiont, mycorrhiza fungi. Beneath the typical tree, roots generally reach half as deep and twice as wide as the tree we see above ground. When the roots of two trees touch, a battle for dominance usually ensuesunless the mycorrhiza fungi are on the scene. Forest scientist David Perry of Oregon State University has found that these fungi not only reduce competition between the trees but also link together roots from trees of the same or even different species. In one experiment, Perry grew seedlings and watched their roots join through the mycorrhiza. Then the scientist cast shade over one of the seedlings. The shaded tree began to draw nutrients from the sunlit tree through the fungal linkage between them.
“Thanks to these fungi,” says Perry, “It could be that a whole forest is linked together like a community. If one tree has access to water, another to nutrients, a third to sunlight, the trees apparently can share with one another.”