Orsolya Haarberg / Snow covered Norway spruce (Picea abies) trees at the treeline, Stubba Nature Reserve, Laponia, Sweden, February 2013.

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

Gerrit Vyn / Kangaroo Ridge in the North Cascades, in winter, Okanogan National Forest, Washington, USA, November 2010

Wild Wonders of Europe / Schandy / Young Caucasian brown bear (Ursus arctos meridionalis) maybe 2 years, grazing on slopes above the treeline, Alibek valley near Dombay, Caucasus, Russia, Teberdinsky biosphere reserve, July 2008

Heather Angel / Alpine rose (Rhododendron ferrugineum) in montane grassland above treeline. Giau Pass / Passo di giau, Dolomites, Italy. July 2011.

Heather Angel / Alpine rose (Rhododendron ferrugineum) in montane grassland above treeline. Giau Pass / Passo di giau, Dolomites, Italy. July 2011.

Peter Mather / Kathleen Lake beneath Kings Throne mountain, Kluane National Park, Yukon, Canada

Sumio Harada / Mount Wilbur, Glacier National Park, Montana

Matthias Breiter / Coastal flats in front of taiga treeline, Hudson Bay, Manitoba, Canada

Matthias Breiter / Coastal flats in front of taiga treeline, Hudson Bay, Manitoba, Canada

Jussi Murtosaari / Treeline emerald dragonfly (Somatochlora sahlbergi), newly emerged female, Lapland, Finland, July.

Jussi Murtosaari / Treeline emerald dragonfly (Somatochlora sahlbergi), newly emerged male, Lapland, Finland, July.