Straddling the border of Poland and Belarus, the Bialowieza Forest is home to 20,000 animal species, including roughly a quarter of the world's bison population. At nearly 600 square miles, it is the largest remaining section of the continent's oldest primeval forest, which once stretched across the entire European plain. Its delicate ecosystem, largely untouched by humans, dates back to the Ice Age, some 10,000 years ago.

(De Agostini / G. Cappelli Universal Images Group/Newscom)

That this ancient forest, a UNESCO World Heritage Site since 1979, and its wildlife are so well preserved is a testament to decades of conservation efforts. But, despite such protection, the Bialowieza Forest remains threatened by a deadly force: An infestation of bark beetles that are consuming spruce trees at an alarming rate.

The situation has splintered environmentalists. Many are adamant the infestation is a natural part of the forest and must be left alone. Others — including the Polish government — are uncompromising in the belief that humans have a duty to actively stop the infestation by chopping down trees where the bark beetles live. For now, the Polish government has won — the logging campaign began in the spring of 2016. But in 2017, a World Heritage Site committee will evaluate the logging's consequences on the otherwise undisturbed ecosystem and determine a new conservation plan. Until then, take a closer look at what's left of Europe's lush primeval forest and its inhabitants.

(REUTERS/Kacper Pempel)

(REUTERS/Kacper Pempel)

A Laetiporus Murrill mushroom called "Chicken of the woods" grows on a tree in a protected area of Bialowieza forest. | (REUTERS/Kacper Pempel)

(REUTERS/Kacper Pempel)

(REUTERS/Kacper Pempel)

(REUTERS/Kacper Pempel)

(REUTERS/Kacper Pempel)

A tree marked for culling. In May, authorities began sanitary logging, chopping down infested trees along routes used by tourists. | (REUTERS/Kacper Pempel)

(REUTERS/Kacper Pempel)