Helping western forests heal.
P1 The prognosis is poor for US forest ecosystems. The dry forest ecosystems of the American West, especially those once dominated by open ponderosa pine forests, are in widespread collapse. We are now witnessing sudden leaps in aberrant ecosystem behaviour long predicted by ecologists and conservation professionals (see Nature 407, 5; 2000). Trends over the past half-century show that the frequency, intensity and size of wildfires will increase — by orders of magnitude — the loss of biological diversity, property and human lives for many generations to come.