The treeless ecosystem of mosses, lichens, and berry plants is giving way to shrub land and boreal forest. As scientists study the transformation, they are discovering that major warming-related events, including fires and the collapse of slopes due to melting permafrost, are leading to the loss of tundra in the Arctic.

Since the government's collapse after a coup last March, Madagascar's rainforests have been plundered for their precious wood and unique wildlife. But now there are a few encouraging signs, as officials promise a crackdown on illegal logging and ecotourists begin to return to the island.

A number of biologists are challenging the long-held orthodoxy that alien species are inherently bad. In their contrarian view, many introduced species have proven valuable and useful and have increased the diversity and resiliency of native ecosystems.

Although it is a heavily urbanized nation, fully two-thirds of Japan remains woodlands. Yet many of the forests are timber plantations inhospitable to wildlife, especially black bears, which are struggling to survive in one of the most densely populated countries on Earth.

In the Yaak Valley of Montana, environmentalists have been talking to loggers, snowmobilers and other longtime opponents of wilderness protection about the future of public lands. Their accord is part of a cooperative effort that could lead to the first wilderness-area designation in the state in a quarter century.

Clearing land for cattle is responsible for 80 percent of rainforest loss in the Brazilian Amazon. But with Amazon ranching now a multi-billion dollar business, corporate buyers of beef and leather, including Wal-Mart, are starting to demand that the destruction of the forest be halted.

As Borneo's rain forests are razed for oil palm plantations, wildlife centers are taking in more and more orphaned orangutans and preparing them for reintroduction into the wild. But the endangered primates now face a new threat — there is not enough habitat where they can be returned.

The clearing of Indonesia’s rain forest for palm oil plantations is having profound effects threatening endangered species, upending the lives of indigenous people, and releasing massive amounts of carbon dioxide into the atmosphere.

Despite the creation of protected areas in the Amazon and other tropical regions, rain forests worldwide are still being destroyed for a simple reason: They are worth more cut down than standing. But with deforestation now a leading driver of global warming, a movement is growing to pay nations and local people to keep their rain forests intact.

With soaring prices for agricultural goods and new demand for biofuels, the clearing of the world's largest rain forest has accelerated dramatically. Unless forceful measures are taken, half of the Brazilian Amazon could be cut, burned or dried out within 20 years.