Tim Fitzharris / Conifers and Lower Yellowstone Falls, Yellowstone River, Grand Canyon of Yellowstone, Yellowstone National Park, Wyoming

Jeff Foott / Desert, Lake Mead, Gold Butte National Monument, Nevada

Jeff Foott / Waterfall, Grand Staircase-Escalante National Monument, Utah

Tim Fitzharris / Rising Wolf Mountain, Glacier National Park, Montana

Tim Fitzharris / Coniferous forest, Jemez Mountains, Santa Fe National Forest, New Mexico

Matthias Breiter / Creek flowing into lake in temperate rainforest, Lake Crescent, Olympic National Park, Washington

Matthias Breiter / Waterfall and creek in temperate rainforest, Merriman Falls, Olympic National Park, Washington

Matthias Breiter / Kestner Creek, Quinault Rainforest, Olympic National Forest, Washington

Matthias Breiter / Kestner Creek, Quinault Rainforest, Olympic National Forest, Washington

Matthias Breiter / Kestner Creek, Quinault Rainforest, Olympic National Forest, Washington

Ingo Arndt / Dwarf Cypress (Taxodium sp) trees in grassland, Everglades National Park, Florida

Scott Leslie / Longleaf Pine (Pinus palustris) forest, Okefenokee National Wildlife Refuge, Georgia