Thinking Like a Tree (and Other Forms of Ecological Thinking)

In the rain forests of Costa Rica, there is an unusual type of tree known as a “walking tree.” It is a strange looking tree. At the base of the tree is a tangle of roots, rising about a meter above the ground. It looks as if someone yanked the tree straight up out of the ground, leaving about a meter of its roots exposed above ground level. According to rain-forest guides, the walking tree actually changes its location over time (although very slowly). How does the tree move? The roots act as a type of evaluation system, searching for good soil for the tree. If there is good soil on the north side of the tree, the roots on that side dig in deeply and hold firmly. If the soil on the south side isn’t as good, the roots on that side remain shallow and weak. As the roots on the north side become stronger and deeper, the whole tree gradually shifts toward the north, pulled by the strong roots in that direction. As the tree moves, new roots grow around the new location, some of them extending even further to the north. If the roots find even better soil there, the whole tree will, over time, shift even more to the north. Or, if there is better soil to the east, the tree will slowly shift to the east. We might say that the walking tree follows a TREE strategy: • Test Randomly (send out roots in all directions) • Evaluate (determine which roots find the best soil) • Elect (choose which direction to move, based on the information from the roots)