Members of the 2008 Siberian Forest Expedition (Ross Nelson, Guoqing Sun, and Paul Montesano) pose with reindeer antleers discovered along the Kotuykan River.

The view to the east as Paul Montesano, Jon, Ranson, and Guoqing Sun take a knee on the cliffs overlooking the confluence of the Kotuykan and Kotuy Rivers

Jon Ranson working on an expedition blog post along the Kotuykan River in northern Siberia, July 2008.

The cliffs above the confluence of the Kotuykan and Kotuy Rivers in northern Siberia.

A solitary Larix gmellini stands beside relic wood and sun-bleached reindeers antlers on a plateau above the Kotuykan River.

Members of the 2012 Siberian Forest Expedition to the Embenchime River in central Siberia.

Day 1 alongside the Mi-8 helicopter at the landing site along the Embenchime River in summer 2012.

Guoqing Sun measures the diameter of an enormous specimen in Corcovado National Park on Costa Rica's wild Osa Peninsula in March 2014.

Siberia's Damschen landscape as seen from the air.

Diseased forests.