Jack Dykinga / Road winding through aspen trees (Populus tremuloides) in autumn, Dixie National Forest, Boulder Mountain, Utah. October 2013.

Tim Fitzharris / Mount Rundle, Johnson Lake, Banff National Park, Alberta, Canada

Michael W. Richards / Domesticated Indian elephants (Elephas maximus) being walked to forest at sunset, Pench Tiger Reserve, Madhya Pradesh, India

Mark Hamblin / 2020VISION / Scots pine forest extending up to natural tree line, with bracken (Pteridium aquilinum) in foreground, Rothiemurchus, Cairngorms NP, Scotland, UK, September 2011

Inaki Relanzon / Bujaruelo Valley with stream and waterfall and snow above the tree line; mixed deciduous and coniferous forest, Ordesa and Monte Perdido National Park, Pyrenees, Spain. October 2009

Christian Ziegler / Red-eyed Tree Frog (Agalychnis callidryas) three males sitting on a stem, Soberania National Park, Panama

Pete Oxford / Scaled Dove (Columbina squammata) four huddled together on branch, Brazil

Gerry Ellis / Oil pipeline crossing taiga, Alaska

Mark Moffett / Leafcutter Ant (Atta cephalotes) workers carrying leaves to nest, French Guiana

Tui De Roy / Palm trees and water flowing on beach on Palmyra Atoll, a wet, equatorial atoll with fringing reefs, native forests and abundant seabirds, Palmyra Atoll National Wildlife Refuge, US Line Islands

Andy Rouse / Bengal tiger (Panthera tigris) female walking followed by two cubs. Along lake shore, Ranthambhore National Park, India.

Sven Zacek / Winter sunset over Muddus National Park, Norrbotten County, Sweden. October 2015.