Introduction
Introduction
Earth's biodiversity — the profusion of plants and animals that work together to support life — continues to shrink. Species are going extinct at a rate most scientists find alarming — possibly as many as 150 a day — while the populations of many surviving species are declining rapidly. Endangered species range from plants and large animals such as tigers and rhinoceroses to smaller creatures such as insects and honeybees. All play key roles in sustaining healthy ecosystems, which provide a variety of costly environmental services for free, such as filtering water and scrubbing carbon from the air. Some researchers believe the Earth could be approaching a so-called tipping point, in which biodiversity loss causes global ecosystems to change rapidly and dramatically, but other scientists ...