 The county's southern portion has some protected serpentine barrens, a rare ecosystem where toxic metals in the soil inhibit plant growth, resulting in the formation of natural grassland and savanna.These barrens include the New Texas Serpentine Barrens, privately owned land managed by The Nature Conservancy, and Rock Springs Nature Preserve, a publicly accessible preserve with hiking trails owned and managed by the Lancaster County Conservancy.Lancaster County leads the nation in farmland preservation.