The number of land trusts in California increased by 50% in the last five years, reflecting dramatic growth in private conservation efforts across the country.

In a report released Thursday, the Land Trust Alliance found that nationally, land protected by private, nonprofit trusts and conservation groups grew by 54%, or 13 million acres, between 2000 and 2005.

"We think the amount of acreage will continue to increase every year," said James Wyerman, the alliance's communications director. "Every year we've done this, we see not just some growth, but exponential growth."