Open lands are falling to urban sprawl. Between 1992 and 1997, almost 160,000 acres per year of farms, forests, and rural lands were lost to urban development. Half of the state's natural areas remain unprotected. Standing against these encroachments are the state's almost two dozen land trusts. Mostly voluntary, these groups provide services and assistance, including conservation easements, strategic estate planning, and land transfers to private landowners who seek to protect open spaces.