Using the trees that figure so prominently in his tremendous novel as models for its structure, Richard Powers follows nine characters in rotation, building a strong, complex narrative from their stories the way a tree grows from one growth ring to the next. Focusing on the many kinds of relationships people can have with trees, The Overstory (W.W. Norton, $27.95) dramatizes our casual appreciation of nature and our ignorance of it, our increasing exploitation of it, and our shock and regret at what we’ve done to it. But while some characters want the clearcutting to stop, and break human laws in favor of higher ones, others see only the economic reasons why logging should continue. Force doesn’t work for either side, Powers shows, so what is the answer? Meanwhile, another character builds video worlds of stunning verisimilitude. Yet another character collects seeds for a world seed bank, acutely aware of her inability to preserve the ecosystems that nurture these seeds. She’s also done pioneering research, discovering that trees communicate with each other, warn each other, heal each other; this is perhaps the true “understory” we’ve lost, so absorbed by the deafening “overstory” of our own kind that we can’t recognize anything else.