WASHINGTON (AP) _ The amount of land in North America protected from development tripled over the past three decades, yet pollution, hunting and loss of habitat still threaten at least 235 plants and animals, a new study by the United States, Canada and Mexico says.
Since 1970, the acreage off limits to development rose from 247 million to 741 million acres _ about 15 percent of the continent's land surface.
Creation of new wildnerness areas account for the increase. Those include a doubling in the size of U.S. areas in 1980 with the enactment of the Alaska National Interest Lands Act. Nineteen new ``biosphere reserves'' were created in Mexico in the 1990s, and Canada has tripled the area of protected sites over the past three decades, the study said.
But increased trade across borders raises the need for more collaboration to protect against threats such as the spread of nonnative species, said the study released Monday by the Montreal-based Commission for Environmental Cooperation.
The study was required under the North American Free Trade Agreement's environmental accord and provides the first government-backed snapshot of the overall status of the continent's ecology. It was submitted to the three nations' top environmental officials.
The hope is that the study and future ones like it will help the NAFTA countries better track the impact of trade and other economic activity on shared issues such as migratory species and water resources.
For example, the nations haven't protected species by establishing multinational wildlife corridors to link fragmented habitats, said Janine Ferretti, the commission's executive director.
``By addressing the issues together, the three countries can gain more in terms of economic efficiency,'' she said. ``They can also share information, they can share technology.''
The study said natural disasters such as the Mexico City earthquake of 1985, the Mississippi flood of 1993 and the ice storm in eastern Canada and the northeastern United States in 1998 are becoming more frequent, in part due to El Nino cycles.
Nearly 90 percent of U.S. and Canadian households, and more than 30 percent of Mexican households now own motor vehicles, leading to a decline in public transportation and in the vitality of urban core areas, the study said.
The commission also compiles a separate annual survey of pollution sources. Mexico has yet to start reporting on its pollution. The commission said the United States and Canada also don't have adequate reporting systems for keeping up with motor vehicles, agriculture and some kinds of mining.